Slashdot Mirror

The Los Alamos National Lab wrote in 2012 that "For over 20 years the military, the commercial aerospace industry, and the computer industry have known that high-energy neutrons streaming through our atmosphere can cause computer errors." Now an anonymous reader quotes Computerworld: When your computer crashes or phone freezes, don't be so quick to blame the manufacturer. Cosmic rays -- or rather the electrically charged particles they generate -- may be your real foe. While harmless to living organisms, a small number of these particles have enough energy to interfere with the operation of the microelectronic circuitry in our personal devices... particles alter an individual bit of data stored in a chip's memory. Consequences can be as trivial as altering a single pixel in a photograph or as serious as bringing down a passenger jet.

A "single-event upset" was also blamed for an electronic voting error in Schaerbeekm, Belgium, back in 2003. A bit flip in the electronic voting machine added 4,096 extra votes to one candidate. The issue was noticed only because the machine gave the candidate more votes than were possible. "This is a really big problem, but it is mostly invisible to the public," said Bharat Bhuva. Bhuva is a member of Vanderbilt University's Radiation Effects Research Group, established in 1987 to study the effects of radiation on electronic systems.
Cisco has been researching cosmic radiation since 2001, and in September briefly cited cosmic rays as a possible explanation for partial data losses that customer's were experiencing with their ASR 9000 routers.

An anonymous reader writes: Scientists from Los Alamos National Laboratory have successfully uploaded and applied a software patch to NASA's Curiosity Rover on Mars. The patch fixes a focusing problem that cropped up in November when the laser that helps to focus one of its cameras failed. "Without this laser rangefinder, the ChemCam instrument was somewhat blind," said Roger Wiens, ChemCam principal investigator at Los Alamos. "The main laser that creates flashes of plasma when it analyzes rocks and soils up to 25 feet [7.6 meters] from the rover was not affected, but the laser analyses only work when the telescope projecting the laser light to the target is in focus." Before the fix, scientists had to shoot images at nine different focus settings to distill a decent set of data. Now, they say the new software results in better images in a single shot than even before the laser broke down. The program that runs the instrument is only 40 kilobytes in size.

Science_afficionado (932920) writes "Vanderbilt University scientists reported significant progress toward creating 'homo minutus' — a benchtop human — at the Society of Toxicology meeting on Mar. 26 in Phoenix. The advance is the successful development and analysis of a human liver construct//organ-on-a-chip that responds to exposure to a toxic chemical much like a real liver. The achievement is the first result from a five-year, $19 million multi-institutional effort led by Los Alamos National Laboratory (LANL), to develop four interconnected human organ constructs — liver, heart, lung and kidney — that are based on a highly miniaturized platform nicknamed ATHENA (Advanced Tissue-engineered Human Ectypal Network Analyzer). The project is supported by the Defense Threat Reduction Agency. Similar programs to create smaller-scale organs-on-chips are underway at the Defense Advanced Research Projects Agency and the National Institutes of Health."

Daniel_Stuckey writes "No man is an island, but evolutionarily, each person functions like one for the HIV virus. That's according to Thomas Leitner, a researcher working on a project aimed at creating technology for tracking HIV through a population. The technology, which is being studied at the Los Alamos National Laboratory, may allow people to identify who infected them with the virus, a development that could have major implications in criminal proceedings. "If you're familiar with Darwin's finches, you have a population of birds on one island and they keep moving and evolving as they spread to other islands so that each population is a little different," Leitner said. "With HIV, it's the same. Every person infected with HIV has a slightly different form of the virus. It's the ultimate chameleon because it evolves this way.""

schwit1 writes "In a paper published today on the Los Alamos astro-ph preprint service, astronomers propose that as many as eleven past extinction events can be linked to the Sun's passage through the spiral arms of the Milky Way. (You can download the paper here [pdf].) From the paper: 'A correlation was found between the times at which the Sun crosses the spiral arms and six known mass extinction events. Furthermore, we identify five additional historical mass extinction events that might be explained by the motion of the Sun around our Galaxy. These five additional significant drops in marine genera that we find include significant reductions in diversity at 415, 322, 300, 145 and 33 Myr ago. Our simulations indicate that the Sun has spent ~60% of its time passing through our Galaxy's various spiral arms.'"

schwit1 writes "In a paper published today on the Los Alamos astro-ph preprint service, astronomers propose that as many as eleven past extinction events can be linked to the Sun's passage through the spiral arms of the Milky Way. (You can download the paper here [pdf].) From the paper: 'A correlation was found between the times at which the Sun crosses the spiral arms and six known mass extinction events. Furthermore, we identify five additional historical mass extinction events that might be explained by the motion of the Sun around our Galaxy. These five additional significant drops in marine genera that we find include significant reductions in diversity at 415, 322, 300, 145 and 33 Myr ago. Our simulations indicate that the Sun has spent ~60% of its time passing through our Galaxy's various spiral arms.'"

schwit1 writes "In a paper published today on the Los Alamos astro-ph preprint service, astronomers propose that as many as eleven past extinction events can be linked to the Sun's passage through the spiral arms of the Milky Way. (You can download the paper here [pdf].) From the paper: 'A correlation was found between the times at which the Sun crosses the spiral arms and six known mass extinction events. Furthermore, we identify five additional historical mass extinction events that might be explained by the motion of the Sun around our Galaxy. These five additional significant drops in marine genera that we find include significant reductions in diversity at 415, 322, 300, 145 and 33 Myr ago. Our simulations indicate that the Sun has spent ~60% of its time passing through our Galaxy's various spiral arms.'"

The Bad Astronomer writes "A experiment called IceCube — consisting of sensitive light detectors buried deep in the Antarctic ice — has detected two ultra-high-energy neutrinos, each with over a peta-electronVolt of energy (a quadrillion times the energy of a visible light photon), the highest energy neutrinos ever seen. The two events, nicknamed Bert and Ernie, have a 99% chance of originating outside our galaxy, likely created either by a supermassive black hole or an exploding gamma-ray burst."

Covalent writes "The Large Hadron Collider, the world's largest and most powerful particle accelerator and the 'Big Bang machine' that was used to discover what appears to be the long-sought Higgs boson particle (as announced July 4), may have another surprise up its sleeve this year: The LHC looks to have produced a new type of matter, according to a new analysis of particle collision data by scientists at MIT and Rice University. The new type of matter, which has yet to be verified, is theorized to be one of two possible forms: Either 'color-glass condensate' — a flattened nucleus transformed into a 'wall' of gluons, which are smaller binding subatomic particles, or it could be 'quark-gluon plasma,' a dense, soup or liquid-like collection of individual particles."

New submitter schrodingersGato writes "Researchers at the Los Alamos campus of the National High Magnetic Field Laboratory achieved a record-setting 100.75 Tesla magnetic field. To do this, scientists placed a resistive magnet (a sophisticated electromagnet) coupled to massive bank of capacitors within another magnet fixed at a 'lower' magnetic field. A short-lived pulse two million times stronger than the Earth's magnetic field was generated. The magnet itself made an eerie sound as it was energized (video). Prepare for the birth of Magneto!"

cekerr writes with this excerpt from an article in Nature "The wavefunction is a real physical object after all, say researchers. ... the new paper, by a trio of physicists led by Matthew Pusey at Imperial College London, presents a theorem showing that if a quantum wavefunction were purely a statistical tool, then even quantum states that are unconnected across space and time would be able to communicate with each other. As that seems very unlikely to be true, the researchers conclude that the wavefunction must be physically real after all. David Wallace, a philosopher of physics at the University of Oxford, UK, says that the theorem is the most important result in the foundations of quantum mechanics that he has seen in his 15-year professional career. 'This strips away obscurity and shows you can't have an interpretation of a quantum state as probabilistic,' he says."

gbrumfiel writes "Two weeks ago, researchers claimed particles called neutrinos were travelling faster-than-light and violating the laws of special relativity. But now it looks as though general relativity might be behind the experiment's unusual result. An independent analysis claims that the original experiment, known as OPERA, failed to take into account differences in earth's gravitational field between the neutrino source and the OPERA detector. As Nature News reports, gravity can distort time according to Einstein's theory, and the effect could explain why neutrinos appear to arrive 60 nanoseconds ahead of schedule. The OPERA team is now reviewing the new analysis."

Lord Northern writes "According to several news sources, NASA's Kepler mission is said to be able to detect habitable moons orbiting planets in other star systems. Kepler is a space telescope designed to detect exoplanets. Its mission will have it orbiting the Sun for 3.5 years, after which we'll be able to tell if any of our neighboring stars actually have planetary systems around them. However, apparently we will be able to detect not only exoplanets, but also exomoons orbiting those exoplanets. The Kepler team came to that conclusion after running a computer simulation which found that the telescope was sensitive enough to detect the gravitational pull of an orbiting moon (PDF). This means that the data expected by the end of the mission is going to be very rich, and it is said that moons as small as 0.2 times the mass of earth could be detected. Further details about the Kepler mission are available from NASA."

katarn writes "General Fusion is a startup proposing they can create commercially viable fusion using acoustic shock waves, triggered by 220 precisely controlled pneumatic pistons. Their approach is based on a US Naval research concept called 'Linus' and old research done by General Atomics. They feel we now have the high-speed, digital processing capable of pulling off this feat, where decades ago the technology was not available. I think we can hold off on the 'vaporware' claims for a bit; everyone is aware of the horrible track record for turning fusion concepts into reality, but they don't claim to be the first with the idea or that there are not substantial challenges in the way. If nothing else, it is a fascinating concept." Los Alamos National Laboratory has further details on this type of fusion, and longtime LANL researcher Ronald Kirkpatrick did an external assessment (PDF) of General Fusion's plans. Popular Science had a lengthy story about the company a while back. The reason they're back in the headlines now is that they've secured enough funding to begin work on a prototype reactor.

Several readers including houbou and DigitumDei sent links to what may be the first-ever image of a planet orbiting a sun-like star (research paper). The giant planet, the mass of 8 Jupiters, orbits its star at 330 AU, or 11 times the distance to Neptune's orbit. If the imaged object does turn out to be a planet — and it's not certain it is — then theories of planet formation may have to be adjusted. "The bulk of the material from which planets might form is significantly closer to the parent star... The outermost parts of such disks wouldn't contain enough material to assemble a Jupiter-mass planet at the distance from the star... at which the Toronto team found the faint object."

lindik writes "As part of their research efforts aimed at building real-time human-level artificial vision systems inspired by the brain, MIT graduate student Nicolas Pinto and principal investigators David Cox (Rowland Institute at Harvard) and James DiCarlo (McGovern Institute for Brain Research at MIT) recently assembled an impressive 16-GPU 'monster' composed of 8x9800gx2s donated by NVIDIA. The high-throughput method they promote can also use other ubiquitous technologies like IBM's Cell Broadband Engine processor (included in Sony's Playstation 3) or Amazon's Elastic Cloud Computing services. Interestingly, the team is also involved in the PetaVision project on the Roadrunner, the world's fastest supercomputer."

An anonymous reader writes "What cool things can be done with the 100,000+ cores of the first petaflop supercomputer, the Roadrunner, that were impossible to do before? Because our brain is massively parallel, with a relatively small amount of communication over long distances, and is made of unreliable, imprecise components, it's quite easy to simulate large chunks of it on supercomputers. The Roadrunner has been up only for about a week, and researchers from Los Alamos National Lab are already reporting inaugural simulations of the human visual system, aiming to produce a machine that can see and interpret as well as a human. After examining the results, the researchers 'believe they can study in real time the entire human visual cortex.' How long until we can simulate the entire brain?"

crlove writes "LA Times reports, 'The University of California today won its hard-fought bid to continue operating the Los Alamos National Laboratory in New Mexico, beating back a challenge from a Lockheed Corp.-University of Texas team to run the nuclear weapons research facility... For months, the New Mexico laboratory had been shaken by allegations and revelations of theft, fraud, security lapses and lax oversight.'"

dr. loser writes "The CERN newsletter reports that a new paper by scientists at the University of Victoria has demonstrated that one of the prime observational justifications for the existence of dark matter can be explained without any dark matter at all, by a proper use of general relativity! What does this imply for cosmology and particle physics, both of which have been worrying about other aspects of dark matter?"

Oscar Boykin writes "New Scientist is running a story on using the social network in email as a P2P network. The idea is that email networks have structure that is conducive to a type of search called percolation search . This means email clients could query the social network of email users to filter spam. This story is based on a preprint available."

Oscar Boykin writes "New Scientist is running a story on using the social network in email as a P2P network. The idea is that email networks have structure that is conducive to a type of search called percolation search . This means email clients could query the social network of email users to filter spam. This story is based on a preprint available."

wjwlsn writes "Back in the day (2 billion years ago), even before the time of iron men and wooden reactors, Mother Nature had mastered nuclear power. She built a passively safe system at Oklo that had fully automatic control and built-in waste containment, and operated it safely for about 150 million years. Now researchers at Washington University in St. Louis have deduced the operational characteristics by examining the isotopic composition of xenon contained in rock samples taken from the reactor site. More details at Eurekalert."

An anonymous reader writes "The old adage that 'no one can hear you scream in space' seems to have its own variant when Los Alamos scientists announced today their latest designs for the 'traveling wave engine', a derivative of the classic, pistonless Stirling device. Because it uses helium as an oscillating gas in a long tube, the design works kind of like a high-pitched loudspeaker at maximum efficiency. Another description combines a refrigerator and whistle to make an engine."

colonist writes "University of California scientists at Los Alamos National Laboratory and chemists from Duke University have recently grown a four-centimeter-long, single-wall carbon nanotube (SWNT): a new world record. Previous SWNTs were a few millimeters long. Yuntian Zhu and his colleagues used a process called 'catalytic chemical vapor deposition' from ethanol (alcohol) vapor. From their abstract: 'Our results suggest the possibility of growing SWNTs continuously without any apparent length limitation.' Zhu: 'although this discovery is really only a beginning, the continued development of longer length carbon nanotubes could result in nearly endless applications. Actually, the potential uses for long carbon nanotubes are probably limited only by our imagination.'"

dread minerva writes "This week, Los Alamos and Sandia National Laboratories publicly reported that sensitive material stored on removable data storage devices was missing." In Sandia's case, "According to the Las Vegas Sun, this 'prompted the lab to halt all classified work Thursday while officials conduct a wall-to-wall inventory of sensitive data.' Sandia also reported that a 'computer floppy disk was missing.' However, according to the Albuquerque Journal, 'lab officials said they don't believe it contains any weapons information or any other information that could harm national security,' only admitting that the material on the disk was classified. Due to these latest events, LANL has shut down all work on classified projects as of Friday." (Read more below.) Update: 07/17 21:21 GMT by T : A correction -- research was shut down only at LANL (not, as I mistakenly claimed, at Sandia) -- and an update: Sandia's missing disk was recovered.

"These snafus have led the government to open up the labs to defense-contracting bids for the first time in their 60+ year history (until now the labs have been run by UC-Berkeley). As NPR reported on Friday, the researchers at the labs were upset by this move, as they are afraid of the labs losing their academic nature. Perhaps the best question to ask in this situation is why these labs are still using removable data storage devices to store sensitive information."

(Other institutions, including The University of Texas system, are also angling for a share of the lab's management.)

Joanne Pransky's tongue is firmly in her cheek a fair amount of the time as she answers your questions, but much of what she says is thought-provoking, especially in light of speculations like Marshall Brain's Robotic Nation essays about the inevitable spread of robotic devices in our society.

Human Nature - by skywalker107

Do you think we will ever be able to program robots to understand and possibly copy human nature?

Joanne:

Assuming that you mean human nature as a human conditioning (personality) that has been experienced in human existence, I believe that robots will be comprised of both software and hardware and that the combination of their programs and various sensors will help them to learn, understand, and communicate with humans in a human's environment. In my eyes, it won't be as simple as just downloading a particular 'understanding' program - it will be unique to the combination of the overall structure and systems each robot will have combined with its perceptions and interactions with its surroundings (e.g., a domestic robot will understand humans more than a mining robot will, and a domestic robot in a home with many people of different ages, genders, etc., will understand humans more than a robot who lives with a sole individual). I think robots will be able to communicate with us verbally and to understand what we are saying, but not understand in terms of empathy, sympathy, or in a visceral way. In terms of copying human nature, I foresee an emulation of human nature in order to respond, interact, and work with other humans, and though some humans may perceive a future robo-personality as a 'copy', to me it will always be a robotic nature, though possibly housed in a very human-like shell.

Re: Human Nature - by jbrader

To which I would like to add: do you think there is any reason to try to copy human nature? I can see the point in having machines understand humans as it could make communicating with robots and computers easier. But why try to make an artificial human? It seems as though we have more than enough of the real thing already.

Joanne:

Depending upon how you define artificial, most of us humans are already physically 'artificial' in that we have in some way technologically augmented our organic selves - lasik, pacemakers, structural implants, cochlea implants, neural prostheses, electroactive polymer actuators, and in the next few months, for a few paralyzed individuals, a neural interface implant as part of a U.S. clinical study which will provide them with a permanent interface to a computer.

It is this ongoing quest for humans bettering themselves and wanting to live longer and more qualitatively, that an artificial human will at some point result, whether 'artificial' will be defined as more than 50% of a human's biological body parts merging with technology or whether 'artificial' is an automonous robotic being that looks like a human in order to best serve and work with humans in an environment that is set up for humans. In the latter case, I believe 'copying human nature' will be more of an indirect consequence (a result of an effective response system in sophisticated, higher performing, higher communications robots), rather than as a direct attempt.

Aren't you just another shameless tech self-publicizing... - by Sanity

I spent a while looking through the "publications" section of your website to seek out the "hard academic underpinnings" that Roblimo mentioned, but all I could find there were a selection of puff-piece articles, vaguely gushing about a brave new robotic future (without actually saying anything that Asmov didn't cover years ago, but he did it with infinitely more elegance and forsight). Which brings me to my question: Do you do any scientifically valuable research? I ask because you seem like just another shamelessly self-publicising cyber-pundit, much like the UK's Kevin Warwick [kevinwarwick.org.uk] (who, famously claimed to be the world's first cyborg after implanting a dog-tracking chip in his arm).

Joanne:

I am not a scientist nor an engineer, and therefore my goal has never been to do scientific research. My goal, by humorously proclaiming myself as the World's First Robotic Psychiatrist (and the real Susan Calvin) 18 years ago, was and still is, to educate the public, that group of people that buy the National Enquirer, watch American Idol, and read puff-piece articles. My objective is to make them aware of robotics, a technology that will have more of an impact on their lives than the automobile, PC, and the internet, by 'translating' the technology developed by roboticists so that the public can understand its benefits as opposed to fearing them, something that I think is more common in the U.S. due to how robots have been perceived over the years via the media and Hollywood. Thus, I was immediately interested in the practical, not theoretical applications of robotics, and informing the masses about them.

Here's more detail:

In the 80s, (after graduating from Tufts University in child development - mostly cognitive development, which by the way, Marvin Minsky's book, Society of Mind is based on), I sold computers to small businesses - doctors, lawyers, accountants, etc. At the time, this was not an easy task as business operations were manual and few were readily willing to automate them. For those that did, however, the burden usually fell on the secretary, who was typically female, whether she liked it or not. Expectations were way off - the business owners thought the computer and all the information would be up and running in no time, and the secretaries feared they'd lose their jobs to their computers. When personal computers became a commodity in the late 80s, executives bought them - and often they just sat on their desks, never used.

If people can't program their VCRs, nevermind use their PCs, I thought, how will we as a society be ready for a robot in our home to do our dishes? It was then, in 1986, that I proclaimed myself as the World's First Robotic Psychiatrist, and brought Susan Calvin to life. There was no formal course of study for robopsychology. Therefore, I became the first in my field and gave myself credentials (and actually received an official U.S. Trademark later on). I was pioneering unchartered territory.

Being the World's First Robotic Psychiatrist was a tongue-in-cheek way of saying that one day, like pets, when robots co-existed with humans, they may actually develop problems similar to humans. It was a way for me to get the public to think about the future of technology while increasing their current awareness. If a non-engineering 5 ft. tall woman understands the technology, subliminally, so will the rest of the public. (And this is another topic altogether, but I believe females will be the primary purchasers of domestic and household robots, yes, for all types of purposes). Robotic Psychiatry during my lifetime, I believed, would not be to program robots, but to ready the humans (though I always hoped that there would be patients that, like Susan Calvin, I could communicate verbally with and observe their behaviors within their environments). The best way to make the U.S. masses aware is through the medium of television. For years, various people - Joan Embery, Jack Hanna, et al - have been bringing rare animals onto The Tonight Show and the Letterman Show. Millions of people got to see rare monkeys peeing and koalas clinging. It was funny, entertaining yet educational. That's exactly what I wanted to do with robots, especially considering most people had never seen one.

While researching robotic developments that might be of interest to the general public, I decided to engross myself completely in the robotics industry while at the same time learn about robots in science fiction. I met Asimov in 1989 at a World Science Fiction Convention and continued correspondence until he was too sick to do so any longer. He dubbed me the 'Real Susan Calvin' (in writing).

In 1991, I began working for an industrial robot manufacturer. I attended the company's programming and maintenance classes and wrote technical manuals and eventually ended up where I wanted to, in sales and marketing. During the ten years I worked for Sankyo Robotics, I must have visited hundreds of manufacturing plants. You name it and I saw it made: cars, golf balls, jelly beans, eyeglasses, IUDs, robots (in Japan), french fries, and the list goes on. However, in each case, I was there to sell SCARA robots - SCARA, the acronym for a type of robot arm developed in Japan in the 70s that stood for selective compliance assembly robot arm.

Yup, my job was to go into factories and try to justify why they should invest in SCARAs (being from the northeast, it sounded more like Scare Har to me. How did we allow this acronym to become nomenclature in the U.S.??). Regardless if the manufacturing engineering manager was knowledgeable on robotics and could easily justify automating his process, if the executive(s) in charge of the money were not accepting of robotics, even if it saved them $, there was often great resistance at the corporate level. No amount of scientific evidence would change their mind to their opposition to technology. (Though it was fun to get them to try, and one year I succeeded in breaking company sales records.)

Also while at Sankyo in the early 90s, I ran a RoboCamp for kids in the summer in which kids not only built robot kits, but learned about industrial robots. Ten years later, I developed a curriculum for elementary school children called "Robots and Me", a program that fosters the robot/child interaction.

In 1996, I was asked by MCB University Press out of England, to be the U.S. Associate Editor for their journals, Service Robot, Industrial Robot (IR), Sensor Review, and Assembly Automation. My main role was (and still is with Industrial Robot Journal ) to research innovative robotic technologies here in the States, and work with the developers of the technology to get them to contribute a technical article on their findings. Industrial Robot Journal is in its 31st year, is an internationally respected journal, listed in all the important citation indexes and regularly used as the publisher of choice by the world's leading practicing industrial, service and healthcare roboticists. I've published many articles for Service Robot Journal and Industrial Robot Journal and one of them, an article on surgeons' view of RoboDoc, the first surgical robot in the world (which was manufactured by Sankyo Robotics, the robot company I worked for) won a literary award and was referenced by the International Federation of Robotics in their annual World Robotics publication two years in a row. I am now the U.S. Associate Editor for the world's first International Journal of Medical Robotics and Computer Assisted Surgery, being launched as you read this. Do I do the scientific research for the medical robotic companies? No, but I help them educate clinicians and surgeons worldwide by getting them published and reporting their innovative applications.

The above represent some of my efforts over the years.

Ongoing research and scientific developments in robotics are a necessity, but without real world exposure and acceptance, the inventions may not survive. Robotics cannot go forward without the simbionic relationship of all those things occurring. I hope, therefore, that you will see that I am not a scientist, but someone helping to bring others' robotic developments to the forefront.

About Human-Robot Relationships... - by MagiGraphX

I've watched too much Chobits perhaps, but is it right for a human to fall in love with an artificially intelligent (and emotional) robot? Just a thought of what could happen...

Joanne:

Is it wrong for a human to fall in love with a sentient robot? Humans have loved all sorts of machines for years - their cars, boats, computers, their Aibos....imagine how we'll feel when the computer-face of our dreams with its robotic body lives with us (I know, this is sounding like the movie Cherry 2000). Robots will offer companionship to those who are lonely, to those who feel more comfortable with a robot than with a human, and falling in love will be a natural phenomenon out of coexisting with them. But will they love us back in the same way? They may love us in terms of being loyal, subservient, trustworthy, etc., but I don't think they'll ever experience how we as humans define "falling in love". And how will this make us feel if a robot does not feel the same way as we do for it?

Falling in love is just part of the issue - will sexual relations between a human and a robot be right? To me, it's more right than those immoral relations that occur between a teacher and student, a parent and child, a priest and altar boy, and the list goes on. Sex with a robot could decrease the rampant spreading of Aids and other diseases and possibly even help to decrease violence.

A whole host of other issues may arise: Will it be legal to love a robot? Will a robot love us back out of being subservient while really loving another robot? Will humans who love other humans feel rejected when their partner falls in love with a robot? I think any of these situations may be feasible, though not in the near future.

Future of robots? - by Merkuri22

We've all seen the movies and read the books about machines in the future, and frankly most of these stories portray robots and AI as terrifying things that humanity will end up battling with for supremicy of the planet. Do you think there are any truths to these stories? Will robots compete with us in the future for jobs and/or living space? Do you ever see robots and humans living side by side as equals, or do you think they will always be subservient machines? Or, even, do you think robots will surpass us one day as the dominant force on the planet?

Joanne:

My view of robots is that they are tools used to assist humans to do the mundane, the dangerous, the difficult, etc. Put more simply, I also see a computer as a tool - attach mobility, manipulators, and sensors to my computer and you've got a robot that can do a lot more for me.

I don't see humans competing with robots for jobs - I see them doing the jobs we don't want or shouldn't be doing, and creating more jobs for humans. This is perhaps one of the biggest misconceptions - that "Robots take jobs away". Robots help companies stay competitive (by helping produce better quality products at a lower cost, and allowing companies to meet the changing demands of customers); thus, robots help save jobs that otherwise may have been lost, and help create new jobs (although not always the same type of job). Perhaps if there were more robotic automation in place, there would have been less jobs going offshore...

As a side note: The Wall Street Journal recently (Friday, April 2) cited some Bureau of Labor Statistics (BLS) predictions back in 1988 and looked at the results through 2000...."Of 20 occupations that the BLS predicted in 1988 would suffer the greatest losses between 1988 and 2000, half actually grew. The agency predicted that the number of assemblers in electrical and electronic factories would drop 173,000, a 44% decrease. Twelve years later, there were 45,000 more, an 11% increase. Neither outsourcing nor robots made as much of a dent as the BLS expected."

Source: Robotic Industries Association

Living space - I don't see us competing there, either. In some of Asimov's stories, robots were actually banned from earth. They didn't need what we humans need to survive and they did their work on other planets.

Robots will be in different sizes and shapes for a multitude of tasks and we've certainly found space for all our appliances, computers and TVs, and thus we will welcome our robotic assistants. Having more robotic assistants that can allow us to stay in the convenience of our home longer may decrease the need for as many buildings such as day care facilities, nursing homes, assisted living care facilities and hospitals, particularly as the worldwide aging population continues to rapidly increase.

I see robots living and working with us side by side, but not necessarily as 'equals'. They are designed to be better than humans at some things (much like computers), but I don't see them as 'equals' either, i.e., having the same needs as humans do. Robots may surpass our own abilities, but having a robot uprise where robots want to dominate the planet, I don't buy it.

Interesting books on the subject by Dr. Hans Moravec, "Mind Children" and "Robot: Mere Machine to Transcedent Mind."

What form will A.I. take? - by mykepredko

A bit of a navel gazing question for you; what form do you think A.I. will take when somebody finally comes up with a program that is accepted as intelligent?

My own feeling is that the first A.I. program will simulate a simple life form (like a worm) instead of a highly complex and communicative form like humans. This goes against what Dr. Minsky believes A.I. should be, but I can't honestly believe that our first interaction with an intelligent mechanism would with something with similar capabilities to ourselves, but with something with the same mental capabilities and capacities as a bug. The important aspects of Aritficial Intelligence will be making sense of its environments and learning from experience. To demonstrate that the Intelligence is learning is observing and testing the Intelligence's application of this knowledge. What are your thoughts?

Joanne:

The definition of artificial intelligence is still an age old debate (right up there with what is a robot), and there are plenty of artificially intelligent forms today (that are accepted as intelligent) being used in both software (AI agents, computer games, etc.) and in robotics. ASCI Purple, built by IBM, is supposedly the world's most powerful supercomputer, capable of carrying out 100 trillion operations per second, which some believe could be approaching the processing power of the human brain. Two famous roboticists share your view of a simple life form (bugs/insects) with their behavior based robotics: Dr. Rodney Brooks who pioneered Subsumption Architecture, which provides an incremental method for building robot control systems linking perception to action; and Dr. Mark Tilden with his processorless, autonomous, intelligent BEAM (Biology, Electronics, Aesthetics, Mechanics) Robotics which uses simple analog circuits. (Also, check out his latest humanoid, RoboSapien. It will be a HUGE success.) I agree that the important aspects of artificial intelligence are making sense of its environment and able to learn from its experiences.

My question... - by hookedup

Dr. Joanne Pransky, do you see Asimov's 3 laws of robotics playing a role in our relationship with robots in the future? Since most of our technological advances seem to come from developing warfare systems, will the 3 laws be left by the wayside, or will it become an integral part of robotics in the years to come.

Joanne:

I think safety for humans has and will continue to be a critical part of robotics, but I don't think Asimov's three laws, though brilliant as they are (here goes my entire career as Susan Calvin), will suffice exactly as is as a postulate for all robots.

You brought up a good point - that of warfare systems, something robots are well suited for. As a matter of fact, just last week CNN reported what a great moment for it was for iRobot Corporation when they were told by the Pentagon that one of its PackBots was destroyed in action for the first time, meaning the life of a human may have been saved.

Though Packbots are used for battlefield reconnaisance, in the future, other robots may certainly be utilized in the front line of fire for destroying enemies (not that I'm a proponent of war nor killing humans (nor destroying robots for that matter), but certainly I'd rather see a robot hurt than any human). There are many situations in which we can envision security robots having to injure some humans to protect others and in each situation, a robot would have to make the best decision it can, as we humans must do at times, with its understanding of the information at hand.

For intelligent robots in the real world, the Three Laws as they stand now, will not work effectively, although I believe there will be some other similar safeguards that they will need to adhere to.

Human Features of Robots / Bonding with robots - by jhouserizer

Over the years, there has been a fair amount of debate about whether robots should take on human forms, especially with regards to having detailed life-like faces. Some robot designers, wary of this debate, have settled on giving their creations near human-like faces [theconnection.org].

My question is in relation to this topic. Do you think that people (and "sentient robots" that may exist some day) will be be overall better served if robots are readily distinguishable from humans? How strongly will this affect our "bonding" with robots and their bonding with us? Dogs for instance look quite different from humans, but many a family-pet seems to believe itself to be a real part of the family, and sometimes even seem to think themselves to be human. How will this affect the way we deal with "death" of a robot?

Joanne:

I think it depends on both the task at hand, and who the user is, that will determine if humans will be better served by robots that are readily distinguishable from humans. My Roomba is a robot that is perfectly well-designed for vacuuming so in this case the answer is yes, I am glad that it is distinguishable. Personally, I am more concerned that a robot do its job well and less concerned about what it looks like.

However, I still think that humans in general will relate and bond more easily to anthropomorphic robotic companions. I think it will be easier for most to accept and communicate with robots that look like themselves. Even when we communicate with other humans, we are conditioned to look into someones eyes to gauge how we're doing in the conversation. When someone's wearing sunglasses, it's harder to determine how they're responding to us. I think we're going to want to look into the eyes of a robot to know it's listening to us and we may want it to smile, frown, etc., much like a human face.

But exactly like a human, as you say indistinguishable, is an excellent question. The Uncanny Valley theory, described by Japanese roboticist Masahiro Mori, addresses just this issue. Mori found that people tend to empathize more with robots that are more humanlike, but if the robot becomes too human at a certain point, the robot becomes repulsive to the human. So what's the answer - a robot that is slightly, but not too indistinguishable?

People will bond with their robots regardless of how distinguishable or indistinguishable they physically are, and yes, I do believe that like our pets, we will mourn their "death." I've always believed that our initial relationships with them will be similar to our relationships with pets. That means that some humans will: buy them matching clothes and jewelry; take pictures of them on Santa's lap; pay for an extra seat on the airplane to have them fly with them; make sure that their wills provide for their maintenance contracts and all the latest upgrades when they outlive them; fight over who gets to keep them in a divorce suit; and if owners feel a robot is depressed, they will even take them to a robotic psychiatrist for a weekly family encounter session. Humorous or not, it will no doubt be interesting

Artificial intelligence without embodiment? - by macshune

As an undergraduate philosophy student interested in the theoretical implications of A.I., could you tell me what your thoughts are on the validity of the assumption that artificial intelligence is possible separate from the notion of embodiment? I think the lack of consideration given embodiment is one reason why artificial intelligence researchers have come up empty-handed so far in their quest to synthesize a conscious, self-reflective entity. To ask the question more succinctly, do you think a mind needs a body and possibly and environment to interact with in order to be conscious, or can a mind exist and know itself independent of an external context?

Joanne:

I don't think that the quest of AI researchers has been to synthesize a conscious, self-reflective entity as it has been to emulate the human thought and reasoning process. As part of this, many researchers believe that for an entity to have artificial intelligence, it must have an understanding of and be able to interact with its environment. Some believe it is the form of an embodied robot, but not necessarily - as long as the machine that simulates human intelligence is receiving information from and responding to its surroundings (e.g., an intelligent computer).

I personally believe that nothing artificial will be able to be truly conscious in the same way a human is; however, there could be some kind of machine consciousness that has similarities to human consciousness, and it could be difficult to dilineate the difference. What if, however, we are able to download a human's brain into a machine that had no embodiment. Ten years later, after continuing to receive stimulus from its surrounding and responding to it, would this machine be considered conscious?

Roborights? - by jrpascucci

Do you believe there will come a time that we will have a 'robot rights' movement? Will it be more credible than most of the 'animal rights' movement, or just a good-hearted (but weak-minded) anthropomorphization of our silicon companion machines?

Someone (Dennis Miller?) once said, animals can have rights as soon as they accept responsibilities. Robots obviously can be given responsibilities (your job is to fit tab A into slot B), but ethically, should they get rights? As soon as someone programs a robot to pass the turing test, and then immediately ask for his rights? Or is it something deeper?

Beyond some kind of second-class entity status, will robots become citizens? Do robots have a god-given right (recall, our rights are considered by the Declaration of Independence to be given us either by 'Nature's God' or by their 'Creator') to freedom of expression, association, religion? The right to bear arms? Do robots have a 'right to work'? "One Robot, One Vote"? Will Robots have to file tax returns? Will there be Robot Courts? Robot Lawyers? Robot Jail? Robot Schools? Robotic Members elected to the Legislature? Some day, will we have a Robot President? Is a Robot built in Japan eligible to be president? What if the robot was shipped from Japan as parts with software, and put together here, does that count?

If you start building a robot, and decide to stop, will that be considered to be a robaboration? Or the work of their 'creator'? And if, after building, you switch it on and then decide you don't like it that much, and power it off again and harvest the parts, is that robomurder and disrobomemberment?

Joanne:

I suppose anything is possible, and perhaps I am blinded by the hopes of an optimistic future long after I am dead, but I just can't see the motivation for robots to do a lot of the things you're describing. I see them as extraordinary mechanisms able to physically and mentally perform many tasks/jobs,and though I see them having behaviors and challenges similar to humans from dealing with humans in a human world, I just don't see them with the innate human emotions that drive a lot of the above `rights' such as the desire for greed, power, freedom, control, etc. I see robots as almost the future perfect child - we help to create them, they're like us and we're responsible for them, but yet they remain quite content serving us humans and implementing their tasks.

That's not to say that I don't think a robot would make a better politician (certainly can't be much worse than some of the human ones we have now) nor that certain robots wouldn't get certain responsibilities (police bots that carry guns), but a desire to vote? For what, so that they can vote against humans allowing robots to get destroyed in a robotic sporting event, against the very reason they were designed in the first place?

However, I do see robotic law as possibly the largest field of law (i.e., humans practicing robotic law). Whose responsible for a robot who 'breaks the law'? Is it the company who manufactured the domestic robot or the hacker who purchased it and had it harm someone in his family?

Regarding a robot rights movement - hopefully we will protect the integrity of our robots. Don't we as humans have a responsibility to use our robots properly and not to misuse or abuse them and shouldn't there be laws in place for those who don't? I suppose if we aren't responsible with our robots, then there could be the need for robots to protect their own interests.

where's the positronic brain? - by futuretaikonaut

In Asimov's robot novels, the assumption was that modern science had invented the positronic brain, which was thought to be capable of actual sentient thought, though most of the robots in the books did so on a very basic and childlike level. It was this that actually gave Dr. Calvin a job... seeing as how the brains had the capacity for original thought, even though it was mostly predictable. As it stands today, and into the foreseeable future, we have invented no such thing capable of acting with original thought. Our hardware has, instead, given the appearance of thought, as it is capacble of so many calculations per second that it appears to come up with things on its own. So, my question is, what use is a robot psychologist if every action that a robot can take is already predetermined by its programming? What new field is there to be discovered that is not already known? In the human mind, we are constantly learning new things about the brain, a mechanism we only barely understand, but what is there to derive from a machine we ourselves create?

Joanne:

I don't agree that every action that a robot can take is already predetermined by its programming - there are some highly sophisticated robots out there that are provided with a set of tools for navigating in their environment and the combinations of these systems are often unpredictable. (The autonomous robotic vehicles at the Darpa Grand Challenge are an example. Communicating real-time data between various systems such as correctional decision-making systems, perception sensor systems, navigational systems, and terrain modeling systems, and translating the results into the movement of a military vehicle or HMMWV is not predetermined.)

Yes, we are constantly learning new things about the brain and as humans and machines merge, who knows what fields it will bring? Could anyone have predicted the types of new fields, say in 1970, the computer industry would bring?

Asimov himself, a few years before his death and nearly 50 years after first writing about robopsychology (and after seeing the burgeoning field of robotics take reality) wrote at the end of the 80s, "Robotic intelligence may be so different from human intelligence that it will take a new discipline - "robopsychology" to deal with it. That is where Susan Calvin will come in. It is she and others like her who will deal with robots, where ordinary psychologists could not begin to do so. And this might turn out to be the most important aspect of robotics, for if we study in detail two entirely different kinds of intelligence, we may learn to understand intelligence in a much more general and fundamental way that is now possible. Specifically, we will learn more about human intelligence than may be possible to learn from human intelligence alone."

Interesting Read: The Age of Spiritual Machines by Ray Kurzweil

Your favorite fictional robotic character - by Strange Ranger

What is your favorite robot/cyborg character in written or film fiction?

Why?

For instance, I'm happy to admit mine is Data from Star Trek: Next Generation. Most especially the earlier seasons. Reason: I'm not much of a "trekkie" but that character made me consider so many different possible aspects of AI and of being not-human. From trying to understand other humans' emotions to his contrast with 'The Borg' down to what it might be like to have an "internal chronometer". For totally different reasons I loved Douglas Adams 'Marvin the Depressed Robot' in HHGTTG.

Joanne:

I have a lot of favorite robot characters - RoboCop, Bicentennial Man, Johnny Number 5 in Short Circuit, and I'm not sure if it's my favorite or that for the past couple of years he's the one I've been thinking about most, but I'd have to say David Swinton in the movie AI. Perhaps it's my maternal, female side coming out, but my reaction to David was very strong. David 'imprinted' his love solely to his mother - unconditionally and forever, yet there were no requirements for her to do the same for her robot child when she decided to activate his code. Usually this is the opposite - we love our children unconditionally although it's not always the reverse. To have this unilateral condition of a one-way commitment on the part of a robot, I found especially disturbing.

gManZboy writes: "Is it an oxymoron to have an efficient supercomputer? Wu-Chun Feng (Los Alamos National Laboratory) doesn't believe so - Green Destiny and its children are Transmeta-based supercomputers that Wu thinks are fast enough, at a fraction of the heat/energy/cost, according to ACM Queue." 240 processors running under 5.2kW (or less!) is nothing to sneeze at. The article offers up this question: might there be other metrics that might be important to supercomputing, rather than relying solely on processing speed?

Roland Piquepaille writes "Bill Camp & Jim Tomkins, from Sandia National Laboratories, have published a 77-page document about the architecture of the Red Storm supercluster being built by Cray Inc. The new nickname for the 40 teraflops system is "Thor's Hammer." Please read the full presentation if you have the time (PDF format, 3.54 MB). This technical analysis gives you the major characteristics of the system which will be operational by August 2004. With its 108 compute cabinets and its 10,368 compute node processors (AMD Opteron running at 2.0 GHz), it is expected to reach 20 teraflops on MP-Linpack. The report also looks at scalability and reliability, which are essential for a sytem which will be expanded to 30,000 processors in the future."

Shipud writes "200 years ago today (Oct. 21) John Dalton revolutionized chemistry by starting the process of turning it into an exact science. He presented the Table of Atomic Weights, at the Manchester literary and Philosophical Society. Dalton's work proposed atoms exist: and not just as an explanatory or philosophical tool. His theory laid the foundations for the periodic table of the elements (1869, Mendeleev), and indeed to all modern chemistry. The molecular weight of compounds is today measured in Daltons, the weight of a hydrogen atom. Read more about Mr. Dalton in today's Nature: a man of many interests, whose atomic theory preceded experimental evidence by a century. Read also about Daltonism -- and why it is named after him."

slavitos writes "The Space Elevator: 2nd International Conference, organized by the Los Alamos National Lab and the Institute for Scientific Research has just finished its work in New Mexico. To be sure, most people still think it's absolutely ridiculous to even consider building such a thing. However, that's exactly what organizers wanted - an open discussion on the issue, plus some free PR."

Well, one science journalist's opinion, anyway. Charles Seife writes for Science magazine and is the author of Alpha and Omega: The Search for the Beginning and End of the Universe. These are his answers to your questions, and they're very detailed, to the point where you may want to set aside more than a few minutes of quiet time to read and digest them. Q1) "Publishing hype" by BobTheLawyer (#6606631)

A1)I'm not embarrassed at all because it's not hype. Scientists now know how the universe will end. Of course, as with all things scientific, there's a big honking asterisk on the word "know," but before I get to that, let me explain why I feel justified in making such an arrogant statement.

We're in the middle of a scientific revolution, in the honest-to-god paradigm-shift sense. This revolution started in 1997 when two groups of astronomers, the High-Z Supernova Search Team and the Supernova Cosmology Project used the bright flashes of a particular type of dying star (a type-Ia supernova) to measure the expansion of the universe at different times in the past. Since then, a whole raft of astronomical observations -- of faint patterns in the afterglow of the big bang, of distributions of galaxies, of the composition of intergalactic clouds of gas, of distortions of light going around massive bodies -- have all forced cosmologists into a remarkable consensus about the composition of the universe and, yes, its fate.

Just to give you a little taste of what the difference in the state of knowledge was like: in 1997, if you asked an astronomer how old the universe is, you'd get an answer somewhere between 12 and 15 billion years. Now, you'll get an answer of 13.7 billion years, plus or minus about 100 million. That's a big jump in precision. Similarly, before 1997, nobody had a clue how the universe would end; now, cosmologists agree on its fate. Some of the details haven't been worked out (what an understatement!), but the gross picture of the ultimate fate of the cosmos seems to be pretty well established for the first time in history. And by the end of the decade, a lot of the details will be fleshed out.

The ongoing revolution isn't just astronomical; it's physical. A decade ago, nobody knew whether neutrinos have mass. (For those who aren't particle physicists, neutrinos are particles that so rarely interact with matter that they can easily pass through the Earth without noticing the big chunk of mass they've passed through. This property makes them exceedingly hard to study.) Now, neutrino physicists are in accord -- and they've concluded that neutrinos, collectively, weigh about as much as all the visible stars and galaxies in the universe combined. High-energy physicists are using an accelerator in Long Island to recreate the condition of the universe a few microseconds after the big bang. By next year, they will formally announce the creation of a new state of matter that existed only in the very, very early universe. (There are alreadystrong hints that they've succeeded.) And another particle accelerator under construction in Geneva is very likely going to discover the particle responsible for exotic dark matter. (More on this shortly.)

All these experiments, all these observations, are pointing in exactly the same direction; they reveal the composition of the universe and its fate. But as with any good scientific revolution, such as relativity or quantum mechanics, it generates more questions than it answers. Scientists now know how the universe will end, but that understanding comes at the cost of a new mystery in physics.

As to the asterisk on the word "know," scientists are acutely aware that their theories are subject to revision. But at the same time, they have good reasons for being confident about their theories -- and they are more confident about some theories than about others. The new cosmological picture that's emerged has a darn high confidence rating; extraordinary claims require extraordinary proof, and the scientific world wouldn't accept the ideas of dark matter, much less dark energy, if there weren't a number of independent lines of evidence that forced scientists to make that conclusion. And while they're not confident about many of the details of the cosmos and the mechanisms that shape it, they are pretty sure that the overall picture is correct. (More on this coming, too.)

Q2) [Almost] Serious question! by Noryungi (#6606694)

and

Q3) Why does the rate of expansion change? by Anonymous Coward (#6606745)

A2,3) The universe will end in... umm... you really want me to give away the ending to my book?

Actually, I reveal the answer in chapter four, because the understanding of the fate of the universe is just the beginning of the current cosmological revolution. So it's not a spoiler to say...

-- drum roll -- the universe will die a heat death, or "Dark & Cold" by your terminology.

In a big bang universe governed by the laws of general relativity, there are two possibilities. (Actually, there are more than two, but all the cases boil down to two real outcomes.) Big crunch or heat death, fire or ice.

The fate of the universe depends on how the universe expands. In general, things that expand cool down and things that are compressed heat up. (This is what causes a propane container to feel so cold after a barbecue -- all the gas that expanded.) After the big bang the universe was extremely hot and was seething with energy. As it expanded, it cooled; free-roaming quarks condensed into protons and neutrons, and wound up as hydrogen, helium, and a handful of other light elements and isotopes. About 400,000 years after the big bang, the universe cooled enough so that the electrons could combine with the nuclei and form neutral atoms. Now, about 14 billion years later, the universe is a pretty cool place.

The expansion of the universe is like a cannonball shot into the air. As the cannonball flies ever higher, the force of gravity tries to drag it back to earth, reducing its upward velocity and slowing it down as it zooms upward. If gravity is very strong, then the cannonball rapidly loses its speed and quickly comes crashing back to the ground. On the other hand, if gravity is very weak, then the cannonball might escape the pull of the earth entirely and zoom away into outer space.

Similarly, the big bang gave the universe an initial cannonshot of expansion. If the mutual gravitational attraction of the objects in the universe is very strong (if there's a lot of matter in the universe) the expansion will slow down, halt, and eventually reverse itself. After the cooling phase of expansion, the universe will begin to swallow itself, getting smaller and smaller each day. This will make it heat up. The skies will get brighter and brighter as galaxies and stars get closer and closer together, and eventually, the universe will become a bath of radiation once more. Electrons will separate from atoms, atoms and then protons and neutrons will shiver into their components, and the universe will collapse in a "big crunch," a reverse big bang. The cosmos will die a death by fire.

On the other hand, if there's not much matter in the universe, then the expansion of the universe will continue forever. The expansion will slow down, but it will never halt and never reverse itself. The universe continues to cool down, and for a long time, space will look pretty much as it does now. Stars will be born and die, and galaxies will age. The night sky would get darker and darker as distant objects get too dim to view, and eventually, as the hydrogen in the universe is consumed, stars and galaxies will begin to wink out. Many billions of years hence, the universe will be a lifeless soup of dim light and dead matter. It will be a death by ice.

In 1997 and 1998, the two supernova teams used the brightness of distant supernovae to measure the rate of expansion at different times in the past. (Because the speed of light is finite, looking into the distance is the same as looking into the past. This causes no end of tense problems when writing a book about cosmology.) What they found was absolutely gobsmacking. Not only was the universe's expansion not slowing down very much -- it was speeding up! The cannonball was zooming into the air faster and faster as if it were propelled by some sort of weird antigravity force. Not only was the cannonball going to escape, it is so OUTTA HERE! This means a death by ice.

Yegads -- an antigravity force. This was a really hard thing for scientists (and probably you) to accept. But there's a number of different lines of evidence that support the idea, and in the book I go through those lines of evidence in great detail. I'll have to settle for a brief summary here. In 2000, a balloon experiment known as Boomerang took very detailed pictures of the ubiquitous afterglow of the big bang, the cosmic microwave background (CMB). This afterglow has hot and cold spots in it, and for years, scientists have been making very, very detailed predictions about the size and distribution of those spots. The results of the Boomerang experiment and the DASI and WMAP experiments matched those predictions incredibly well, giving scientists great confidence in the underlying theory. It also allowed them to figure out the amount of matter and energy in the universe, and 73% of the "stuff" in the cosmos was dark energy, this antigravity force.

There are a number of other lines of evidence, too; the current distribution of galaxies, for example, implies the presence of an antigravity force, and just last month, scientists made a very nice measurement of something known as the late integrated Sachs-Wolfe effect. This effect can't occur unless you have something like dark energy counteracting gravity's pull.

Unfortunately, a fuller exposition requires a lot more writing -- it takes up several chapters in my book. (Shameless plug). But in summary, there's a number of independent observations that all point to the existence of a dark energy. Furthermore, the theories underlying the idea have made very specific predictions that have been verified with incredible precision. It's extraordinary stuff, but no matter how scientists look at it, they're forced by extraordinary evidence to make the same conclusion.

Yes, it's true that scientists don't know the mechanism of dark energy (though they're not entirely at sea) but there's little doubt that the cannonball is zooming into space faster and faster. They don't know precisely why, but the universe is being pushed toward its icy death by an antigravity force. Scientists are watching it happen.

And you don't need to wait billions of years to know the outcome -- you don't need to observe something directly to conclude that it's going to happen. The planet Pluto was discovered in 1930. So why don't people object to the statement that it takes about 250 years to complete an orbit? Just as you don't have to wait until 2180 to confirm the conclusions of Newtonian dynamics, you don't need to witness the end of the universe to be able to figure out its fate or validate the theory that leads you to that prediction.

Q4) Dark Matter by notcreative (#6606772)

A4) You are correct; the nature and location of dark matter are crucial puzzles in modern cosmology, but I think that the answers will be pretty much in hand by the end of the decade.

I've already mentioned results (most notably WMAP) that reveal the amount of "stuff" in the universe, and 73% of it is dark energy. The rest is matter. But the grand total of the matter locked up in visible stars is a mere 0.5% of the stuff in the universe. What is the other 26.5%? That's dark matter, and, in fact, there are two different types.

Scientists have known for decades that most of the matter in the universe is invisible to telescopes. In the 1960s, Vera Rubin measured the motion of stars wheeling around the center of the Andromeda galaxy and concluded that there had to be a lot more matter pulling on those stars than could be seen.

Despite what some contrarians say, dark matter isn't dogma; viable alternatives, like Moti Milgrom's MOND are taken seriously, if not accepted. Unfortunately, all of the alternatives, including MOND, fail in crucial ways. Besides, you can see dark matter, both directly and indirectly. The MACHO and OGLE projects see the twinkle of stars caused by a passing chunk of dark matter, and they can see the distortion of light caused by a huge amount of unseen mass sitting on the fabric of spacetime. (Distant galaxies are stretched into arcs around this gravitational lens.) This is allowing scientists to figure out just where dark matter resides. But at the same time, a number of observations lead scientists to conclude that the minority of the matter (dark or light) in the universe is ordinary, atomic matter -- the stuff of stars, planets, and people. Again, it will take too long to describe all the lines of evidence, but one powerful way of measuring the number of atoms in the universe is to look at the proportion of hydrogen to deuterium, helium, and lithium in primordial gas clouds. In the first three minutes of the universe, atoms were fusing, just as they do in a hydrogen bomb. The universe was a giant pressure cooker, turning protons and neutrons into heavier elements. If there are a lot of atoms, then there is a lot of fusion and a lot of heavy elements made; if there are not very many atoms, then the universe winds up being almost entirely hydrogen. By looking at the ratios of heavy elements to light elements, scientists concluded that atomic matter makes up about 4% of the "stuff" in the universe -- which is precisely what other measurements, like the CMB ones -- imply, too.

So, 27% of the stuff in the universe is matter: 4% "atomic" matter, leaving 23% to be made of "exotic" matter, stuff that's not made of atoms. I've already described some of that exotic matter; neutrinos make up about 0.5% of the stuff in the universe, about the same as the visible matter in the universe. What's the remainder?

That's the big open question, but one that I'd wager will be solved by the end of the decade. There are very good reasons -- particle physics ones, rather than cosmological ones -- for believing that the main constituent of dark matter is a proposed particle known as the LSP. If it is, then the LHC accelerator in Geneva will find it. If not, then the LSP almost certainly doesn't exist and the puzzle will be compounded -- but I think that scientists are extremely optimistic. Again, there's lots more detail in the book about the justification for this.

Q5) variable constants by Cally (#6607000)

A5) The point's well taken, and I'll get to it after a few remarks.

First, you're right in that the supernovae serve much the same purpose as Cepheid variable stars do -- they're both objects of known brightness, or "standard candles," that allow astronomers to make a precise measurement of the distance to a faraway galaxy. However, they are not the same thing. Cepheids are stars that pulsate and the rate of that pulsation reveals its intrinsic brightness. They're what Hubble used to spot the expansion of the universe in the 1920s, but they're relatively dim and impossible to find in very distant galaxies. Type-Ia supernovae are standard candles that are much, much brighter than Cepheids, and so can be seen halfway across the universe. (And as you note, since distant supernovae mean ancient supernovae, they reveal the expansion rate of the universe billions of years ago.)

Second, the time-varying speed of light (or more precisely, the time-varying fine structure constant) is a controversial idea. The scientists that made the observation in question are pretty solid and they're taken seriously. However, my impression is that mainstream thinking is that the results are due to a systematic error. That aside, the effect, even if real, is very small, and it has nothing to do with interpreting the data from standard candles. The interpretation there is quite well established; there's little question that scientists are seeing an expansion of the universe;. Alternative theories, like tired light, fail in countless ways and scientists have even seen the relativistic time dilation caused by the motion of the distant object.

But, yes, it's natural for a layperson to conclude that the concordance cosmological model is looking increasingly kludge-y, and you're naturally led to wonder whether scientists are trying to prop up a failing model with the equivalent of epicycles or aether. I don't think this is the case for a few reasons.

For one thing, the theory isn't really getting added to and made more complex; it's getting subtracted from and being made more simple. This seems counterintuitive, but it comes from the fact that modern big bang theory is really a class of theories, rather than one set-in-stone dictum about the way the universe is. All these theories agree on the basic physics about the manner of the universe's birth, the forces that drive the universe, and the physics behind them; the difference between the theories are the values of a handful of parameters that are not predicted by the theory. These parameters are inputs rather than outputs, and by pinning down the values of these inputs, the acceptable class of theories gets narrower and narrower.

Dark energy is one of these inputs. Although nobody took it seriously before 1998 -- everyone thought that the value of the parameter in question was zero -- it was lurking there nonetheless. It turns out that this parameter is not only non-zero, it's really big, much to everyone's surprise. But this doesn't add complexity to the model, especially since other parameters, such as the "curvature" of the universe as a whole, which many physicists thought would be non-trivial, turn out not to be important after all. (In other words, the universe seems to be slate flat, rather than saddle-shaped or sphere-like.)

So, from a mathematical viewpoint, the model is no more complex than it was in 1997, and is, in fact, significantly leaner. But what about from a physical viewpoint? Dark matter and dark energy seem to fly in the face of Occam. But here, too, the increase in complexity is much less than it appears. Long before this cosmological revolution, astronomers knew that dark matter had to exist; more recently, they've begun to see it. Even without worrying about cosmological questions, astrophysicists had accepted the existence of dark matter. Cosmological measurements like WMAP showed that these astrophysicists were right -- it was an independent confirmation that dark energy exists and that it comes in two forms, something that other astronomers had concluded a while ago.

Dark energy, on the other hand, has more claim to being a "hack" to the theory. It really is something new and unexpected (even though it was always a mathematical possibility, nobody in the physics world suspected it actually existed.) Nevertheless, the groundwork was already there, and modern big bang theory implicitly requires the existence of a form of dark energy in the very early universe. And since the 1930s, scientists knew that even the deepest vacuum is full of energy and can exert pressure (something known as the Casimir effect, which I describe in this book and in my previous book, Zero: The Biography of a Dangerous Idea). Thus, the idea of dark energy wasn't completely alien to physics before 1997, and in some sense, it was a necessary component.

Yes, it's possible that scientists are looking at the cosmos in the wrong way, and somebody will establish a simpler, more elegant theory that takes all these threads and weaves them together. (More on this shortly.) But at the moment, far from having a kludged-up theory, cosmologists have a leaner (if weirder) theory than ever before -- one that makes very precise predictions that are getting verified with stunning accuracy. I think this argues for increased confidence in the theory rather than for increased fear that it's falling apart.

Q6) Universe's container by bios10h (#6606748)

A6) It freaks a lot of people out. There's a lot of philosophical problems with having an infinite universe -- for example, if the universe is truly infinite, and if, as scientists believe, the number of quantum states of a finite volume is finite, then it's hard to escape the conclusion that, some great distance away, there's a bizarro-you on bizarro-earth reading bizarro-Slashdot. On the other hand, there's no positive evidence that I can think of that the universe is truly infinite; it's just the sparest conclusion in a mathematical sense, if not a philosophical sense.

But an infinite universe is not a foregone conclusion. Earlier this year, Max Tegmark at the University of Pennsylvania published an intriguing paper that looked at slight anomalies in the WMAP data that seem to imply that the universe is not only finite, but shaped like a donut. Nobody takes the idea terribly seriously, not even the author, because there are other statistical tests that seem to rule the donut-shaped universe out. But it's the sort of thing that people are looking at very closely.

Whether it's finite or infinite, in a mathematical sense, there's really no need for the universe to be "in" anything -- there are models where our universe is embedded in a higher-dimensional space, but there are models where it isn't. Philosophically, though, I don't see any advantage to embedding the universe in something bigger -- as you say, it just punts the problem forward. (Who, then, will contain the containers?)

It's one of those things that is hard to get comfortable with -- and even when you accept it, it sometimes can cause pangs of uncertainty. Quantum mechanics does this, too... it's just something that's hard to wrap your head around. Take solace in the fact that it's hard for everyone else, too.

Q7) How ultimate is the end of the universe? by Lane.exe (#6606766)

A7) If there were a collapse-type universe, yes, there could be a reboot and a new big bang. (And if Microsoft built the universe, a reboot would be coming sooner rather than later. *duck*)

In fact, the theory behind the cosmic microwave background stemmed from calculations to see whether this was possible. Remember the expansion-cooling/contraction-heating bit I mentioned a while ago? A physicist at Princeton was trying to figure out whether matter would break apart into its constituents in a collapsing universe, so he looked at how the universe heated up as it compressed. He then realized that his calculations worked equally well in reverse -- the young expanding universe was very hot but cooling -- and it had to have an afterglow: the CMB.

There are restrictions on this rebirth argument, though. For one thing, the fact that the universe will expand forever prevents a big crunch in our future, so we're at the end of the line if such a line existed. And in 2001, Alan Guth proved a mathematical theorem that shows that bang/crunch/bang universes can't have an infinite history; they must have started some finite time in the past. (Though there are a few ways around the theorem if you reject a few assumptions.) So yes, it's possible, but there is no reason to believe it actually happened, and there are very good reasons for thinking it won't happen in the future.

Q8) comparable ramifications? by sstory (#6606658)

A8) I'm not going to give the usual B.S. answers about spinoffs (though there are some). And I'm not going to evade the question by saying that genomics hasn't yielded any transformation, because the potential is certainly there. But I will answer this question obliquely.

If I asked you, "Quick! What's the most important scientific achievement of the 20th century?" how would you respond?

You would probably answer relativity or quantum mechanics, or perhaps the Apollo landings. Probably some would say the atom bomb. I suspect that only a handful of people would mention the computer, and even fewer people would say penicillin. (Am I right?)

Science has two faces -- it can transform society (for better or worse), and it can advance human knowledge. The two are not inextricably bound, though they often come together.

Relativity was a profound shift in our understanding of the way the universe works, but you have to look pretty hard to see a direct effect on our lives. Conversely, penicillin wasn't a central advance in understanding biological systems, but it affected all of us -- I suspect many people here on Slashdot wouldn't be alive today without penicillin and its descendants.

For me, though, relativity is a greater scientific triumph than penicillin -- even though penicillin is probably much more important to us. It altered our view of the universe and gave us a greater understanding of the fundamental laws of the universe -- it was a philosophical advance as much as it was a technical one. That's why we seem to admire Einstein more than Fleming and Newton more than Jenner.

The present cosmological revolution won't change our lives dramatically; heck, a good spam filter would probably have more direct effect on our quality of life. But at the same time, it will finally answer some of the most ancient questions of humanity -- where did the universe come from and how will it end -- and when it ends, we will have a firm grasp of the answer of the latter if not the former. It will be a towering intellectual achievement, and I think that is what will set it apart from even the human genome project.

Q9) What is the next paradigm shift? by geeber (#6606890)

A9) I disagree with the idea that there's no paradigm shifts left -- indeed, I think we're in the middle of one now. I think that it will be associated with one in the Standard Model of particle physics that will begin before the end of the decade.

It's hard to say where future paradigm shifts lie, but there are lots and lots of outstanding questions in science, some of which are incredibly basic, yet totally out of scientists' reach. For example, neurologists have a very good idea about how individual neurons work -- how they connect and communicate. But when it comes to explaining how a large sloppy hunk of neurons becomes a conscious entity, they're completely at sea. I don't think there's even a good definition of consciousness, which is crucial if you're going to study it seriously. Even more basic -- scientists are struggling to define what life is. There's a heck of a lot more work to do, and plenty of room for paradigm shifts.

Speaking of paradigm shifts, I'd like to take a bit of issue with the term (which I've used myself a number of times in the responses to these questions.)

For those who don't know, the idea of a "paradigm shift" comes from Thomas Kuhn's Structure of Scientific Revolutions, a seminal work in history of science. While I think that Kuhn's idea of a paradigm shift has a lot of merit -- models and philosophies do change suddenly and dramatically in the face of mounting conflicting evidence and despite resistance -- I think the term itself is misleading. It implies the complete abandonment of one idea and acceptance of a replacement.

In my view, this is not the way modern science works -- I think that science is cumulative. Each model extends and corrects the previous one, and while there might be a dramatic shift philosophically, there is almost never a dramatic shift physically. Relativity, for example, made a profound change in the way we think about time and space and gravity, yet the functional difference between Newton and Einstein is pretty small. All these complicated tensor equations are approximately equal to Newton's laws in the vast, vast majority of cases -- it's only under conditions of extreme gravity, extreme speed, extreme energy, or extreme time that relativistic predictions diverge from Newton's. Similarly with quantum mechanics.

While I think that relativity and quantum mechanics are paradigm shifts, they're not rejections of the Newtonian picture as much as they are extensions. The paradigm shift can be huge philosophically, but its effects tend to be small in magnitude. And with these small corrections, scientists extend the applicability of their model of the universe -- they can explain the orbit of Mercury or the photoelectric effect -- and in the cases where Newton's laws were strong, these models boil down to Newton's laws.

If I remember my Kuhn correctly, he explicitly rejected the idea of cumulative science; he really saw each model getting completely replaced by its successor, rather than as an extension -- and this leads, at least in my view, to the excesses of postmodernism.

I think that this issue goes to the heart of the questions about how scientists can be sure about the end of the universe if their models can be replaced at any time. To that I'd argue that, yes, all models are provisional, but even with "paradigm shifts" models are usually extended rather than replaced. The central findings of the previous model still hold with good accuracy in most cases, even if the philosophical underpinnings are badly shaken. Maybe scientists are missing some crucial understanding that will simplify the way we look at the universe -- and scientists are seriously pondering alternate models to things as widely accepted as the inflationary big bang -- but even if such a shift occurs, it probably won't invalidate today's discoveries.

Q10) What will it mean? by boatboy (#6607285)

A10) One thing's certain. If I knew the answers, I'd be even more insufferable than I am now.

Seriously, I'm not sure that knowing the answers would have a profound moral and sociological effect. While I think that asking and answering big questions is a hallmark of a prospering society, a society doesn't necessarily draw strength or stability from its intellectual curiosity. (For example, Athenian democracy lasted only about 80 years if I remember right.) Even the most profound philosophical ideas can wind up having little real effect on the everyday functioning of a civilization -- for example, I think that Godel's incompleteness theorem hasn't changed society in the slightest.

As for the next big question, I think there are some in biology: what is life? What is consciousness? How did life arise? Are we alone in the universe? In physics, I think there are profound questions yet to be answered in a realm that I'd describe as "information theory" in the broadest sense -- what's really going on in a black hole? What makes quantum mechanics so weird? And I think that answering the question about the true nature of dark energy will probably have to await a future cosmological revolution. But one of the wonderful things about science is that you don't really know what big questions are within your grasp until you begin to grasp them. We'll know the next revolution when it appears.

Editor's note: Due to long answer lengths, we linked to the questions instead of running them directly here in order to keep this page from getting too large. This was an experiment. If you have comments or questions about Slashdot interview formatting, please email Roblimo.

Well, one science journalist's opinion, anyway. Charles Seife writes for Science magazine and is the author of Alpha and Omega: The Search for the Beginning and End of the Universe. These are his answers to your questions, and they're very detailed, to the point where you may want to set aside more than a few minutes of quiet time to read and digest them. Q1) "Publishing hype" by BobTheLawyer (#6606631)

A1)I'm not embarrassed at all because it's not hype. Scientists now know how the universe will end. Of course, as with all things scientific, there's a big honking asterisk on the word "know," but before I get to that, let me explain why I feel justified in making such an arrogant statement.

We're in the middle of a scientific revolution, in the honest-to-god paradigm-shift sense. This revolution started in 1997 when two groups of astronomers, the High-Z Supernova Search Team and the Supernova Cosmology Project used the bright flashes of a particular type of dying star (a type-Ia supernova) to measure the expansion of the universe at different times in the past. Since then, a whole raft of astronomical observations -- of faint patterns in the afterglow of the big bang, of distributions of galaxies, of the composition of intergalactic clouds of gas, of distortions of light going around massive bodies -- have all forced cosmologists into a remarkable consensus about the composition of the universe and, yes, its fate.

Just to give you a little taste of what the difference in the state of knowledge was like: in 1997, if you asked an astronomer how old the universe is, you'd get an answer somewhere between 12 and 15 billion years. Now, you'll get an answer of 13.7 billion years, plus or minus about 100 million. That's a big jump in precision. Similarly, before 1997, nobody had a clue how the universe would end; now, cosmologists agree on its fate. Some of the details haven't been worked out (what an understatement!), but the gross picture of the ultimate fate of the cosmos seems to be pretty well established for the first time in history. And by the end of the decade, a lot of the details will be fleshed out.

The ongoing revolution isn't just astronomical; it's physical. A decade ago, nobody knew whether neutrinos have mass. (For those who aren't particle physicists, neutrinos are particles that so rarely interact with matter that they can easily pass through the Earth without noticing the big chunk of mass they've passed through. This property makes them exceedingly hard to study.) Now, neutrino physicists are in accord -- and they've concluded that neutrinos, collectively, weigh about as much as all the visible stars and galaxies in the universe combined. High-energy physicists are using an accelerator in Long Island to recreate the condition of the universe a few microseconds after the big bang. By next year, they will formally announce the creation of a new state of matter that existed only in the very, very early universe. (There are alreadystrong hints that they've succeeded.) And another particle accelerator under construction in Geneva is very likely going to discover the particle responsible for exotic dark matter. (More on this shortly.)

All these experiments, all these observations, are pointing in exactly the same direction; they reveal the composition of the universe and its fate. But as with any good scientific revolution, such as relativity or quantum mechanics, it generates more questions than it answers. Scientists now know how the universe will end, but that understanding comes at the cost of a new mystery in physics.

As to the asterisk on the word "know," scientists are acutely aware that their theories are subject to revision. But at the same time, they have good reasons for being confident about their theories -- and they are more confident about some theories than about others. The new cosmological picture that's emerged has a darn high confidence rating; extraordinary claims require extraordinary proof, and the scientific world wouldn't accept the ideas of dark matter, much less dark energy, if there weren't a number of independent lines of evidence that forced scientists to make that conclusion. And while they're not confident about many of the details of the cosmos and the mechanisms that shape it, they are pretty sure that the overall picture is correct. (More on this coming, too.)

Q2) [Almost] Serious question! by Noryungi (#6606694)

and

Q3) Why does the rate of expansion change? by Anonymous Coward (#6606745)

A2,3) The universe will end in... umm... you really want me to give away the ending to my book?

Actually, I reveal the answer in chapter four, because the understanding of the fate of the universe is just the beginning of the current cosmological revolution. So it's not a spoiler to say...

-- drum roll -- the universe will die a heat death, or "Dark & Cold" by your terminology.

In a big bang universe governed by the laws of general relativity, there are two possibilities. (Actually, there are more than two, but all the cases boil down to two real outcomes.) Big crunch or heat death, fire or ice.

The fate of the universe depends on how the universe expands. In general, things that expand cool down and things that are compressed heat up. (This is what causes a propane container to feel so cold after a barbecue -- all the gas that expanded.) After the big bang the universe was extremely hot and was seething with energy. As it expanded, it cooled; free-roaming quarks condensed into protons and neutrons, and wound up as hydrogen, helium, and a handful of other light elements and isotopes. About 400,000 years after the big bang, the universe cooled enough so that the electrons could combine with the nuclei and form neutral atoms. Now, about 14 billion years later, the universe is a pretty cool place.

The expansion of the universe is like a cannonball shot into the air. As the cannonball flies ever higher, the force of gravity tries to drag it back to earth, reducing its upward velocity and slowing it down as it zooms upward. If gravity is very strong, then the cannonball rapidly loses its speed and quickly comes crashing back to the ground. On the other hand, if gravity is very weak, then the cannonball might escape the pull of the earth entirely and zoom away into outer space.

Similarly, the big bang gave the universe an initial cannonshot of expansion. If the mutual gravitational attraction of the objects in the universe is very strong (if there's a lot of matter in the universe) the expansion will slow down, halt, and eventually reverse itself. After the cooling phase of expansion, the universe will begin to swallow itself, getting smaller and smaller each day. This will make it heat up. The skies will get brighter and brighter as galaxies and stars get closer and closer together, and eventually, the universe will become a bath of radiation once more. Electrons will separate from atoms, atoms and then protons and neutrons will shiver into their components, and the universe will collapse in a "big crunch," a reverse big bang. The cosmos will die a death by fire.

On the other hand, if there's not much matter in the universe, then the expansion of the universe will continue forever. The expansion will slow down, but it will never halt and never reverse itself. The universe continues to cool down, and for a long time, space will look pretty much as it does now. Stars will be born and die, and galaxies will age. The night sky would get darker and darker as distant objects get too dim to view, and eventually, as the hydrogen in the universe is consumed, stars and galaxies will begin to wink out. Many billions of years hence, the universe will be a lifeless soup of dim light and dead matter. It will be a death by ice.

In 1997 and 1998, the two supernova teams used the brightness of distant supernovae to measure the rate of expansion at different times in the past. (Because the speed of light is finite, looking into the distance is the same as looking into the past. This causes no end of tense problems when writing a book about cosmology.) What they found was absolutely gobsmacking. Not only was the universe's expansion not slowing down very much -- it was speeding up! The cannonball was zooming into the air faster and faster as if it were propelled by some sort of weird antigravity force. Not only was the cannonball going to escape, it is so OUTTA HERE! This means a death by ice.

Yegads -- an antigravity force. This was a really hard thing for scientists (and probably you) to accept. But there's a number of different lines of evidence that support the idea, and in the book I go through those lines of evidence in great detail. I'll have to settle for a brief summary here. In 2000, a balloon experiment known as Boomerang took very detailed pictures of the ubiquitous afterglow of the big bang, the cosmic microwave background (CMB). This afterglow has hot and cold spots in it, and for years, scientists have been making very, very detailed predictions about the size and distribution of those spots. The results of the Boomerang experiment and the DASI and WMAP experiments matched those predictions incredibly well, giving scientists great confidence in the underlying theory. It also allowed them to figure out the amount of matter and energy in the universe, and 73% of the "stuff" in the cosmos was dark energy, this antigravity force.

There are a number of other lines of evidence, too; the current distribution of galaxies, for example, implies the presence of an antigravity force, and just last month, scientists made a very nice measurement of something known as the late integrated Sachs-Wolfe effect. This effect can't occur unless you have something like dark energy counteracting gravity's pull.

Unfortunately, a fuller exposition requires a lot more writing -- it takes up several chapters in my book. (Shameless plug). But in summary, there's a number of independent observations that all point to the existence of a dark energy. Furthermore, the theories underlying the idea have made very specific predictions that have been verified with incredible precision. It's extraordinary stuff, but no matter how scientists look at it, they're forced by extraordinary evidence to make the same conclusion.

Yes, it's true that scientists don't know the mechanism of dark energy (though they're not entirely at sea) but there's little doubt that the cannonball is zooming into space faster and faster. They don't know precisely why, but the universe is being pushed toward its icy death by an antigravity force. Scientists are watching it happen.

And you don't need to wait billions of years to know the outcome -- you don't need to observe something directly to conclude that it's going to happen. The planet Pluto was discovered in 1930. So why don't people object to the statement that it takes about 250 years to complete an orbit? Just as you don't have to wait until 2180 to confirm the conclusions of Newtonian dynamics, you don't need to witness the end of the universe to be able to figure out its fate or validate the theory that leads you to that prediction.

Q4) Dark Matter by notcreative (#6606772)

A4) You are correct; the nature and location of dark matter are crucial puzzles in modern cosmology, but I think that the answers will be pretty much in hand by the end of the decade.

I've already mentioned results (most notably WMAP) that reveal the amount of "stuff" in the universe, and 73% of it is dark energy. The rest is matter. But the grand total of the matter locked up in visible stars is a mere 0.5% of the stuff in the universe. What is the other 26.5%? That's dark matter, and, in fact, there are two different types.

Scientists have known for decades that most of the matter in the universe is invisible to telescopes. In the 1960s, Vera Rubin measured the motion of stars wheeling around the center of the Andromeda galaxy and concluded that there had to be a lot more matter pulling on those stars than could be seen.

Despite what some contrarians say, dark matter isn't dogma; viable alternatives, like Moti Milgrom's MOND are taken seriously, if not accepted. Unfortunately, all of the alternatives, including MOND, fail in crucial ways. Besides, you can see dark matter, both directly and indirectly. The MACHO and OGLE projects see the twinkle of stars caused by a passing chunk of dark matter, and they can see the distortion of light caused by a huge amount of unseen mass sitting on the fabric of spacetime. (Distant galaxies are stretched into arcs around this gravitational lens.) This is allowing scientists to figure out just where dark matter resides. But at the same time, a number of observations lead scientists to conclude that the minority of the matter (dark or light) in the universe is ordinary, atomic matter -- the stuff of stars, planets, and people. Again, it will take too long to describe all the lines of evidence, but one powerful way of measuring the number of atoms in the universe is to look at the proportion of hydrogen to deuterium, helium, and lithium in primordial gas clouds. In the first three minutes of the universe, atoms were fusing, just as they do in a hydrogen bomb. The universe was a giant pressure cooker, turning protons and neutrons into heavier elements. If there are a lot of atoms, then there is a lot of fusion and a lot of heavy elements made; if there are not very many atoms, then the universe winds up being almost entirely hydrogen. By looking at the ratios of heavy elements to light elements, scientists concluded that atomic matter makes up about 4% of the "stuff" in the universe -- which is precisely what other measurements, like the CMB ones -- imply, too.

So, 27% of the stuff in the universe is matter: 4% "atomic" matter, leaving 23% to be made of "exotic" matter, stuff that's not made of atoms. I've already described some of that exotic matter; neutrinos make up about 0.5% of the stuff in the universe, about the same as the visible matter in the universe. What's the remainder?

That's the big open question, but one that I'd wager will be solved by the end of the decade. There are very good reasons -- particle physics ones, rather than cosmological ones -- for believing that the main constituent of dark matter is a proposed particle known as the LSP. If it is, then the LHC accelerator in Geneva will find it. If not, then the LSP almost certainly doesn't exist and the puzzle will be compounded -- but I think that scientists are extremely optimistic. Again, there's lots more detail in the book about the justification for this.

Q5) variable constants by Cally (#6607000)

A5) The point's well taken, and I'll get to it after a few remarks.

First, you're right in that the supernovae serve much the same purpose as Cepheid variable stars do -- they're both objects of known brightness, or "standard candles," that allow astronomers to make a precise measurement of the distance to a faraway galaxy. However, they are not the same thing. Cepheids are stars that pulsate and the rate of that pulsation reveals its intrinsic brightness. They're what Hubble used to spot the expansion of the universe in the 1920s, but they're relatively dim and impossible to find in very distant galaxies. Type-Ia supernovae are standard candles that are much, much brighter than Cepheids, and so can be seen halfway across the universe. (And as you note, since distant supernovae mean ancient supernovae, they reveal the expansion rate of the universe billions of years ago.)

Second, the time-varying speed of light (or more precisely, the time-varying fine structure constant) is a controversial idea. The scientists that made the observation in question are pretty solid and they're taken seriously. However, my impression is that mainstream thinking is that the results are due to a systematic error. That aside, the effect, even if real, is very small, and it has nothing to do with interpreting the data from standard candles. The interpretation there is quite well established; there's little question that scientists are seeing an expansion of the universe;. Alternative theories, like tired light, fail in countless ways and scientists have even seen the relativistic time dilation caused by the motion of the distant object.

But, yes, it's natural for a layperson to conclude that the concordance cosmological model is looking increasingly kludge-y, and you're naturally led to wonder whether scientists are trying to prop up a failing model with the equivalent of epicycles or aether. I don't think this is the case for a few reasons.

For one thing, the theory isn't really getting added to and made more complex; it's getting subtracted from and being made more simple. This seems counterintuitive, but it comes from the fact that modern big bang theory is really a class of theories, rather than one set-in-stone dictum about the way the universe is. All these theories agree on the basic physics about the manner of the universe's birth, the forces that drive the universe, and the physics behind them; the difference between the theories are the values of a handful of parameters that are not predicted by the theory. These parameters are inputs rather than outputs, and by pinning down the values of these inputs, the acceptable class of theories gets narrower and narrower.

Dark energy is one of these inputs. Although nobody took it seriously before 1998 -- everyone thought that the value of the parameter in question was zero -- it was lurking there nonetheless. It turns out that this parameter is not only non-zero, it's really big, much to everyone's surprise. But this doesn't add complexity to the model, especially since other parameters, such as the "curvature" of the universe as a whole, which many physicists thought would be non-trivial, turn out not to be important after all. (In other words, the universe seems to be slate flat, rather than saddle-shaped or sphere-like.)

So, from a mathematical viewpoint, the model is no more complex than it was in 1997, and is, in fact, significantly leaner. But what about from a physical viewpoint? Dark matter and dark energy seem to fly in the face of Occam. But here, too, the increase in complexity is much less than it appears. Long before this cosmological revolution, astronomers knew that dark matter had to exist; more recently, they've begun to see it. Even without worrying about cosmological questions, astrophysicists had accepted the existence of dark matter. Cosmological measurements like WMAP showed that these astrophysicists were right -- it was an independent confirmation that dark energy exists and that it comes in two forms, something that other astronomers had concluded a while ago.

Dark energy, on the other hand, has more claim to being a "hack" to the theory. It really is something new and unexpected (even though it was always a mathematical possibility, nobody in the physics world suspected it actually existed.) Nevertheless, the groundwork was already there, and modern big bang theory implicitly requires the existence of a form of dark energy in the very early universe. And since the 1930s, scientists knew that even the deepest vacuum is full of energy and can exert pressure (something known as the Casimir effect, which I describe in this book and in my previous book, Zero: The Biography of a Dangerous Idea). Thus, the idea of dark energy wasn't completely alien to physics before 1997, and in some sense, it was a necessary component.

Yes, it's possible that scientists are looking at the cosmos in the wrong way, and somebody will establish a simpler, more elegant theory that takes all these threads and weaves them together. (More on this shortly.) But at the moment, far from having a kludged-up theory, cosmologists have a leaner (if weirder) theory than ever before -- one that makes very precise predictions that are getting verified with stunning accuracy. I think this argues for increased confidence in the theory rather than for increased fear that it's falling apart.

Q6) Universe's container by bios10h (#6606748)

A6) It freaks a lot of people out. There's a lot of philosophical problems with having an infinite universe -- for example, if the universe is truly infinite, and if, as scientists believe, the number of quantum states of a finite volume is finite, then it's hard to escape the conclusion that, some great distance away, there's a bizarro-you on bizarro-earth reading bizarro-Slashdot. On the other hand, there's no positive evidence that I can think of that the universe is truly infinite; it's just the sparest conclusion in a mathematical sense, if not a philosophical sense.

But an infinite universe is not a foregone conclusion. Earlier this year, Max Tegmark at the University of Pennsylvania published an intriguing paper that looked at slight anomalies in the WMAP data that seem to imply that the universe is not only finite, but shaped like a donut. Nobody takes the idea terribly seriously, not even the author, because there are other statistical tests that seem to rule the donut-shaped universe out. But it's the sort of thing that people are looking at very closely.

Whether it's finite or infinite, in a mathematical sense, there's really no need for the universe to be "in" anything -- there are models where our universe is embedded in a higher-dimensional space, but there are models where it isn't. Philosophically, though, I don't see any advantage to embedding the universe in something bigger -- as you say, it just punts the problem forward. (Who, then, will contain the containers?)

It's one of those things that is hard to get comfortable with -- and even when you accept it, it sometimes can cause pangs of uncertainty. Quantum mechanics does this, too... it's just something that's hard to wrap your head around. Take solace in the fact that it's hard for everyone else, too.

Q7) How ultimate is the end of the universe? by Lane.exe (#6606766)

A7) If there were a collapse-type universe, yes, there could be a reboot and a new big bang. (And if Microsoft built the universe, a reboot would be coming sooner rather than later. *duck*)

In fact, the theory behind the cosmic microwave background stemmed from calculations to see whether this was possible. Remember the expansion-cooling/contraction-heating bit I mentioned a while ago? A physicist at Princeton was trying to figure out whether matter would break apart into its constituents in a collapsing universe, so he looked at how the universe heated up as it compressed. He then realized that his calculations worked equally well in reverse -- the young expanding universe was very hot but cooling -- and it had to have an afterglow: the CMB.

There are restrictions on this rebirth argument, though. For one thing, the fact that the universe will expand forever prevents a big crunch in our future, so we're at the end of the line if such a line existed. And in 2001, Alan Guth proved a mathematical theorem that shows that bang/crunch/bang universes can't have an infinite history; they must have started some finite time in the past. (Though there are a few ways around the theorem if you reject a few assumptions.) So yes, it's possible, but there is no reason to believe it actually happened, and there are very good reasons for thinking it won't happen in the future.

Q8) comparable ramifications? by sstory (#6606658)

A8) I'm not going to give the usual B.S. answers about spinoffs (though there are some). And I'm not going to evade the question by saying that genomics hasn't yielded any transformation, because the potential is certainly there. But I will answer this question obliquely.

If I asked you, "Quick! What's the most important scientific achievement of the 20th century?" how would you respond?

You would probably answer relativity or quantum mechanics, or perhaps the Apollo landings. Probably some would say the atom bomb. I suspect that only a handful of people would mention the computer, and even fewer people would say penicillin. (Am I right?)

Science has two faces -- it can transform society (for better or worse), and it can advance human knowledge. The two are not inextricably bound, though they often come together.

Relativity was a profound shift in our understanding of the way the universe works, but you have to look pretty hard to see a direct effect on our lives. Conversely, penicillin wasn't a central advance in understanding biological systems, but it affected all of us -- I suspect many people here on Slashdot wouldn't be alive today without penicillin and its descendants.

For me, though, relativity is a greater scientific triumph than penicillin -- even though penicillin is probably much more important to us. It altered our view of the universe and gave us a greater understanding of the fundamental laws of the universe -- it was a philosophical advance as much as it was a technical one. That's why we seem to admire Einstein more than Fleming and Newton more than Jenner.

The present cosmological revolution won't change our lives dramatically; heck, a good spam filter would probably have more direct effect on our quality of life. But at the same time, it will finally answer some of the most ancient questions of humanity -- where did the universe come from and how will it end -- and when it ends, we will have a firm grasp of the answer of the latter if not the former. It will be a towering intellectual achievement, and I think that is what will set it apart from even the human genome project.

Q9) What is the next paradigm shift? by geeber (#6606890)

A9) I disagree with the idea that there's no paradigm shifts left -- indeed, I think we're in the middle of one now. I think that it will be associated with one in the Standard Model of particle physics that will begin before the end of the decade.

It's hard to say where future paradigm shifts lie, but there are lots and lots of outstanding questions in science, some of which are incredibly basic, yet totally out of scientists' reach. For example, neurologists have a very good idea about how individual neurons work -- how they connect and communicate. But when it comes to explaining how a large sloppy hunk of neurons becomes a conscious entity, they're completely at sea. I don't think there's even a good definition of consciousness, which is crucial if you're going to study it seriously. Even more basic -- scientists are struggling to define what life is. There's a heck of a lot more work to do, and plenty of room for paradigm shifts.

Speaking of paradigm shifts, I'd like to take a bit of issue with the term (which I've used myself a number of times in the responses to these questions.)

For those who don't know, the idea of a "paradigm shift" comes from Thomas Kuhn's Structure of Scientific Revolutions, a seminal work in history of science. While I think that Kuhn's idea of a paradigm shift has a lot of merit -- models and philosophies do change suddenly and dramatically in the face of mounting conflicting evidence and despite resistance -- I think the term itself is misleading. It implies the complete abandonment of one idea and acceptance of a replacement.

In my view, this is not the way modern science works -- I think that science is cumulative. Each model extends and corrects the previous one, and while there might be a dramatic shift philosophically, there is almost never a dramatic shift physically. Relativity, for example, made a profound change in the way we think about time and space and gravity, yet the functional difference between Newton and Einstein is pretty small. All these complicated tensor equations are approximately equal to Newton's laws in the vast, vast majority of cases -- it's only under conditions of extreme gravity, extreme speed, extreme energy, or extreme time that relativistic predictions diverge from Newton's. Similarly with quantum mechanics.

While I think that relativity and quantum mechanics are paradigm shifts, they're not rejections of the Newtonian picture as much as they are extensions. The paradigm shift can be huge philosophically, but its effects tend to be small in magnitude. And with these small corrections, scientists extend the applicability of their model of the universe -- they can explain the orbit of Mercury or the photoelectric effect -- and in the cases where Newton's laws were strong, these models boil down to Newton's laws.

If I remember my Kuhn correctly, he explicitly rejected the idea of cumulative science; he really saw each model getting completely replaced by its successor, rather than as an extension -- and this leads, at least in my view, to the excesses of postmodernism.

I think that this issue goes to the heart of the questions about how scientists can be sure about the end of the universe if their models can be replaced at any time. To that I'd argue that, yes, all models are provisional, but even with "paradigm shifts" models are usually extended rather than replaced. The central findings of the previous model still hold with good accuracy in most cases, even if the philosophical underpinnings are badly shaken. Maybe scientists are missing some crucial understanding that will simplify the way we look at the universe -- and scientists are seriously pondering alternate models to things as widely accepted as the inflationary big bang -- but even if such a shift occurs, it probably won't invalidate today's discoveries.

Q10) What will it mean? by boatboy (#6607285)

A10) One thing's certain. If I knew the answers, I'd be even more insufferable than I am now.

Seriously, I'm not sure that knowing the answers would have a profound moral and sociological effect. While I think that asking and answering big questions is a hallmark of a prospering society, a society doesn't necessarily draw strength or stability from its intellectual curiosity. (For example, Athenian democracy lasted only about 80 years if I remember right.) Even the most profound philosophical ideas can wind up having little real effect on the everyday functioning of a civilization -- for example, I think that Godel's incompleteness theorem hasn't changed society in the slightest.

As for the next big question, I think there are some in biology: what is life? What is consciousness? How did life arise? Are we alone in the universe? In physics, I think there are profound questions yet to be answered in a realm that I'd describe as "information theory" in the broadest sense -- what's really going on in a black hole? What makes quantum mechanics so weird? And I think that answering the question about the true nature of dark energy will probably have to await a future cosmological revolution. But one of the wonderful things about science is that you don't really know what big questions are within your grasp until you begin to grasp them. We'll know the next revolution when it appears.

Editor's note: Due to long answer lengths, we linked to the questions instead of running them directly here in order to keep this page from getting too large. This was an experiment. If you have comments or questions about Slashdot interview formatting, please email Roblimo.

Well, one science journalist's opinion, anyway. Charles Seife writes for Science magazine and is the author of Alpha and Omega: The Search for the Beginning and End of the Universe. These are his answers to your questions, and they're very detailed, to the point where you may want to set aside more than a few minutes of quiet time to read and digest them. Q1) "Publishing hype" by BobTheLawyer (#6606631)

A1)I'm not embarrassed at all because it's not hype. Scientists now know how the universe will end. Of course, as with all things scientific, there's a big honking asterisk on the word "know," but before I get to that, let me explain why I feel justified in making such an arrogant statement.

We're in the middle of a scientific revolution, in the honest-to-god paradigm-shift sense. This revolution started in 1997 when two groups of astronomers, the High-Z Supernova Search Team and the Supernova Cosmology Project used the bright flashes of a particular type of dying star (a type-Ia supernova) to measure the expansion of the universe at different times in the past. Since then, a whole raft of astronomical observations -- of faint patterns in the afterglow of the big bang, of distributions of galaxies, of the composition of intergalactic clouds of gas, of distortions of light going around massive bodies -- have all forced cosmologists into a remarkable consensus about the composition of the universe and, yes, its fate.

Just to give you a little taste of what the difference in the state of knowledge was like: in 1997, if you asked an astronomer how old the universe is, you'd get an answer somewhere between 12 and 15 billion years. Now, you'll get an answer of 13.7 billion years, plus or minus about 100 million. That's a big jump in precision. Similarly, before 1997, nobody had a clue how the universe would end; now, cosmologists agree on its fate. Some of the details haven't been worked out (what an understatement!), but the gross picture of the ultimate fate of the cosmos seems to be pretty well established for the first time in history. And by the end of the decade, a lot of the details will be fleshed out.

The ongoing revolution isn't just astronomical; it's physical. A decade ago, nobody knew whether neutrinos have mass. (For those who aren't particle physicists, neutrinos are particles that so rarely interact with matter that they can easily pass through the Earth without noticing the big chunk of mass they've passed through. This property makes them exceedingly hard to study.) Now, neutrino physicists are in accord -- and they've concluded that neutrinos, collectively, weigh about as much as all the visible stars and galaxies in the universe combined. High-energy physicists are using an accelerator in Long Island to recreate the condition of the universe a few microseconds after the big bang. By next year, they will formally announce the creation of a new state of matter that existed only in the very, very early universe. (There are alreadystrong hints that they've succeeded.) And another particle accelerator under construction in Geneva is very likely going to discover the particle responsible for exotic dark matter. (More on this shortly.)

All these experiments, all these observations, are pointing in exactly the same direction; they reveal the composition of the universe and its fate. But as with any good scientific revolution, such as relativity or quantum mechanics, it generates more questions than it answers. Scientists now know how the universe will end, but that understanding comes at the cost of a new mystery in physics.

As to the asterisk on the word "know," scientists are acutely aware that their theories are subject to revision. But at the same time, they have good reasons for being confident about their theories -- and they are more confident about some theories than about others. The new cosmological picture that's emerged has a darn high confidence rating; extraordinary claims require extraordinary proof, and the scientific world wouldn't accept the ideas of dark matter, much less dark energy, if there weren't a number of independent lines of evidence that forced scientists to make that conclusion. And while they're not confident about many of the details of the cosmos and the mechanisms that shape it, they are pretty sure that the overall picture is correct. (More on this coming, too.)

Q2) [Almost] Serious question! by Noryungi (#6606694)

and

Q3) Why does the rate of expansion change? by Anonymous Coward (#6606745)

A2,3) The universe will end in... umm... you really want me to give away the ending to my book?

Actually, I reveal the answer in chapter four, because the understanding of the fate of the universe is just the beginning of the current cosmological revolution. So it's not a spoiler to say...

-- drum roll -- the universe will die a heat death, or "Dark & Cold" by your terminology.

In a big bang universe governed by the laws of general relativity, there are two possibilities. (Actually, there are more than two, but all the cases boil down to two real outcomes.) Big crunch or heat death, fire or ice.

The fate of the universe depends on how the universe expands. In general, things that expand cool down and things that are compressed heat up. (This is what causes a propane container to feel so cold after a barbecue -- all the gas that expanded.) After the big bang the universe was extremely hot and was seething with energy. As it expanded, it cooled; free-roaming quarks condensed into protons and neutrons, and wound up as hydrogen, helium, and a handful of other light elements and isotopes. About 400,000 years after the big bang, the universe cooled enough so that the electrons could combine with the nuclei and form neutral atoms. Now, about 14 billion years later, the universe is a pretty cool place.

The expansion of the universe is like a cannonball shot into the air. As the cannonball flies ever higher, the force of gravity tries to drag it back to earth, reducing its upward velocity and slowing it down as it zooms upward. If gravity is very strong, then the cannonball rapidly loses its speed and quickly comes crashing back to the ground. On the other hand, if gravity is very weak, then the cannonball might escape the pull of the earth entirely and zoom away into outer space.

Similarly, the big bang gave the universe an initial cannonshot of expansion. If the mutual gravitational attraction of the objects in the universe is very strong (if there's a lot of matter in the universe) the expansion will slow down, halt, and eventually reverse itself. After the cooling phase of expansion, the universe will begin to swallow itself, getting smaller and smaller each day. This will make it heat up. The skies will get brighter and brighter as galaxies and stars get closer and closer together, and eventually, the universe will become a bath of radiation once more. Electrons will separate from atoms, atoms and then protons and neutrons will shiver into their components, and the universe will collapse in a "big crunch," a reverse big bang. The cosmos will die a death by fire.

On the other hand, if there's not much matter in the universe, then the expansion of the universe will continue forever. The expansion will slow down, but it will never halt and never reverse itself. The universe continues to cool down, and for a long time, space will look pretty much as it does now. Stars will be born and die, and galaxies will age. The night sky would get darker and darker as distant objects get too dim to view, and eventually, as the hydrogen in the universe is consumed, stars and galaxies will begin to wink out. Many billions of years hence, the universe will be a lifeless soup of dim light and dead matter. It will be a death by ice.

In 1997 and 1998, the two supernova teams used the brightness of distant supernovae to measure the rate of expansion at different times in the past. (Because the speed of light is finite, looking into the distance is the same as looking into the past. This causes no end of tense problems when writing a book about cosmology.) What they found was absolutely gobsmacking. Not only was the universe's expansion not slowing down very much -- it was speeding up! The cannonball was zooming into the air faster and faster as if it were propelled by some sort of weird antigravity force. Not only was the cannonball going to escape, it is so OUTTA HERE! This means a death by ice.

Yegads -- an antigravity force. This was a really hard thing for scientists (and probably you) to accept. But there's a number of different lines of evidence that support the idea, and in the book I go through those lines of evidence in great detail. I'll have to settle for a brief summary here. In 2000, a balloon experiment known as Boomerang took very detailed pictures of the ubiquitous afterglow of the big bang, the cosmic microwave background (CMB). This afterglow has hot and cold spots in it, and for years, scientists have been making very, very detailed predictions about the size and distribution of those spots. The results of the Boomerang experiment and the DASI and WMAP experiments matched those predictions incredibly well, giving scientists great confidence in the underlying theory. It also allowed them to figure out the amount of matter and energy in the universe, and 73% of the "stuff" in the cosmos was dark energy, this antigravity force.

There are a number of other lines of evidence, too; the current distribution of galaxies, for example, implies the presence of an antigravity force, and just last month, scientists made a very nice measurement of something known as the late integrated Sachs-Wolfe effect. This effect can't occur unless you have something like dark energy counteracting gravity's pull.

Unfortunately, a fuller exposition requires a lot more writing -- it takes up several chapters in my book. (Shameless plug). But in summary, there's a number of independent observations that all point to the existence of a dark energy. Furthermore, the theories underlying the idea have made very specific predictions that have been verified with incredible precision. It's extraordinary stuff, but no matter how scientists look at it, they're forced by extraordinary evidence to make the same conclusion.

Yes, it's true that scientists don't know the mechanism of dark energy (though they're not entirely at sea) but there's little doubt that the cannonball is zooming into space faster and faster. They don't know precisely why, but the universe is being pushed toward its icy death by an antigravity force. Scientists are watching it happen.

And you don't need to wait billions of years to know the outcome -- you don't need to observe something directly to conclude that it's going to happen. The planet Pluto was discovered in 1930. So why don't people object to the statement that it takes about 250 years to complete an orbit? Just as you don't have to wait until 2180 to confirm the conclusions of Newtonian dynamics, you don't need to witness the end of the universe to be able to figure out its fate or validate the theory that leads you to that prediction.

Q4) Dark Matter by notcreative (#6606772)

A4) You are correct; the nature and location of dark matter are crucial puzzles in modern cosmology, but I think that the answers will be pretty much in hand by the end of the decade.

I've already mentioned results (most notably WMAP) that reveal the amount of "stuff" in the universe, and 73% of it is dark energy. The rest is matter. But the grand total of the matter locked up in visible stars is a mere 0.5% of the stuff in the universe. What is the other 26.5%? That's dark matter, and, in fact, there are two different types.

Scientists have known for decades that most of the matter in the universe is invisible to telescopes. In the 1960s, Vera Rubin measured the motion of stars wheeling around the center of the Andromeda galaxy and concluded that there had to be a lot more matter pulling on those stars than could be seen.

Despite what some contrarians say, dark matter isn't dogma; viable alternatives, like Moti Milgrom's MOND are taken seriously, if not accepted. Unfortunately, all of the alternatives, including MOND, fail in crucial ways. Besides, you can see dark matter, both directly and indirectly. The MACHO and OGLE projects see the twinkle of stars caused by a passing chunk of dark matter, and they can see the distortion of light caused by a huge amount of unseen mass sitting on the fabric of spacetime. (Distant galaxies are stretched into arcs around this gravitational lens.) This is allowing scientists to figure out just where dark matter resides. But at the same time, a number of observations lead scientists to conclude that the minority of the matter (dark or light) in the universe is ordinary, atomic matter -- the stuff of stars, planets, and people. Again, it will take too long to describe all the lines of evidence, but one powerful way of measuring the number of atoms in the universe is to look at the proportion of hydrogen to deuterium, helium, and lithium in primordial gas clouds. In the first three minutes of the universe, atoms were fusing, just as they do in a hydrogen bomb. The universe was a giant pressure cooker, turning protons and neutrons into heavier elements. If there are a lot of atoms, then there is a lot of fusion and a lot of heavy elements made; if there are not very many atoms, then the universe winds up being almost entirely hydrogen. By looking at the ratios of heavy elements to light elements, scientists concluded that atomic matter makes up about 4% of the "stuff" in the universe -- which is precisely what other measurements, like the CMB ones -- imply, too.

So, 27% of the stuff in the universe is matter: 4% "atomic" matter, leaving 23% to be made of "exotic" matter, stuff that's not made of atoms. I've already described some of that exotic matter; neutrinos make up about 0.5% of the stuff in the universe, about the same as the visible matter in the universe. What's the remainder?

That's the big open question, but one that I'd wager will be solved by the end of the decade. There are very good reasons -- particle physics ones, rather than cosmological ones -- for believing that the main constituent of dark matter is a proposed particle known as the LSP. If it is, then the LHC accelerator in Geneva will find it. If not, then the LSP almost certainly doesn't exist and the puzzle will be compounded -- but I think that scientists are extremely optimistic. Again, there's lots more detail in the book about the justification for this.

Q5) variable constants by Cally (#6607000)

A5) The point's well taken, and I'll get to it after a few remarks.

First, you're right in that the supernovae serve much the same purpose as Cepheid variable stars do -- they're both objects of known brightness, or "standard candles," that allow astronomers to make a precise measurement of the distance to a faraway galaxy. However, they are not the same thing. Cepheids are stars that pulsate and the rate of that pulsation reveals its intrinsic brightness. They're what Hubble used to spot the expansion of the universe in the 1920s, but they're relatively dim and impossible to find in very distant galaxies. Type-Ia supernovae are standard candles that are much, much brighter than Cepheids, and so can be seen halfway across the universe. (And as you note, since distant supernovae mean ancient supernovae, they reveal the expansion rate of the universe billions of years ago.)

Second, the time-varying speed of light (or more precisely, the time-varying fine structure constant) is a controversial idea. The scientists that made the observation in question are pretty solid and they're taken seriously. However, my impression is that mainstream thinking is that the results are due to a systematic error. That aside, the effect, even if real, is very small, and it has nothing to do with interpreting the data from standard candles. The interpretation there is quite well established; there's little question that scientists are seeing an expansion of the universe;. Alternative theories, like tired light, fail in countless ways and scientists have even seen the relativistic time dilation caused by the motion of the distant object.

But, yes, it's natural for a layperson to conclude that the concordance cosmological model is looking increasingly kludge-y, and you're naturally led to wonder whether scientists are trying to prop up a failing model with the equivalent of epicycles or aether. I don't think this is the case for a few reasons.

For one thing, the theory isn't really getting added to and made more complex; it's getting subtracted from and being made more simple. This seems counterintuitive, but it comes from the fact that modern big bang theory is really a class of theories, rather than one set-in-stone dictum about the way the universe is. All these theories agree on the basic physics about the manner of the universe's birth, the forces that drive the universe, and the physics behind them; the difference between the theories are the values of a handful of parameters that are not predicted by the theory. These parameters are inputs rather than outputs, and by pinning down the values of these inputs, the acceptable class of theories gets narrower and narrower.

Dark energy is one of these inputs. Although nobody took it seriously before 1998 -- everyone thought that the value of the parameter in question was zero -- it was lurking there nonetheless. It turns out that this parameter is not only non-zero, it's really big, much to everyone's surprise. But this doesn't add complexity to the model, especially since other parameters, such as the "curvature" of the universe as a whole, which many physicists thought would be non-trivial, turn out not to be important after all. (In other words, the universe seems to be slate flat, rather than saddle-shaped or sphere-like.)

So, from a mathematical viewpoint, the model is no more complex than it was in 1997, and is, in fact, significantly leaner. But what about from a physical viewpoint? Dark matter and dark energy seem to fly in the face of Occam. But here, too, the increase in complexity is much less than it appears. Long before this cosmological revolution, astronomers knew that dark matter had to exist; more recently, they've begun to see it. Even without worrying about cosmological questions, astrophysicists had accepted the existence of dark matter. Cosmological measurements like WMAP showed that these astrophysicists were right -- it was an independent confirmation that dark energy exists and that it comes in two forms, something that other astronomers had concluded a while ago.

Dark energy, on the other hand, has more claim to being a "hack" to the theory. It really is something new and unexpected (even though it was always a mathematical possibility, nobody in the physics world suspected it actually existed.) Nevertheless, the groundwork was already there, and modern big bang theory implicitly requires the existence of a form of dark energy in the very early universe. And since the 1930s, scientists knew that even the deepest vacuum is full of energy and can exert pressure (something known as the Casimir effect, which I describe in this book and in my previous book, Zero: The Biography of a Dangerous Idea). Thus, the idea of dark energy wasn't completely alien to physics before 1997, and in some sense, it was a necessary component.

Yes, it's possible that scientists are looking at the cosmos in the wrong way, and somebody will establish a simpler, more elegant theory that takes all these threads and weaves them together. (More on this shortly.) But at the moment, far from having a kludged-up theory, cosmologists have a leaner (if weirder) theory than ever before -- one that makes very precise predictions that are getting verified with stunning accuracy. I think this argues for increased confidence in the theory rather than for increased fear that it's falling apart.

Q6) Universe's container by bios10h (#6606748)

A6) It freaks a lot of people out. There's a lot of philosophical problems with having an infinite universe -- for example, if the universe is truly infinite, and if, as scientists believe, the number of quantum states of a finite volume is finite, then it's hard to escape the conclusion that, some great distance away, there's a bizarro-you on bizarro-earth reading bizarro-Slashdot. On the other hand, there's no positive evidence that I can think of that the universe is truly infinite; it's just the sparest conclusion in a mathematical sense, if not a philosophical sense.

But an infinite universe is not a foregone conclusion. Earlier this year, Max Tegmark at the University of Pennsylvania published an intriguing paper that looked at slight anomalies in the WMAP data that seem to imply that the universe is not only finite, but shaped like a donut. Nobody takes the idea terribly seriously, not even the author, because there are other statistical tests that seem to rule the donut-shaped universe out. But it's the sort of thing that people are looking at very closely.

Whether it's finite or infinite, in a mathematical sense, there's really no need for the universe to be "in" anything -- there are models where our universe is embedded in a higher-dimensional space, but there are models where it isn't. Philosophically, though, I don't see any advantage to embedding the universe in something bigger -- as you say, it just punts the problem forward. (Who, then, will contain the containers?)

It's one of those things that is hard to get comfortable with -- and even when you accept it, it sometimes can cause pangs of uncertainty. Quantum mechanics does this, too... it's just something that's hard to wrap your head around. Take solace in the fact that it's hard for everyone else, too.

Q7) How ultimate is the end of the universe? by Lane.exe (#6606766)

A7) If there were a collapse-type universe, yes, there could be a reboot and a new big bang. (And if Microsoft built the universe, a reboot would be coming sooner rather than later. *duck*)

In fact, the theory behind the cosmic microwave background stemmed from calculations to see whether this was possible. Remember the expansion-cooling/contraction-heating bit I mentioned a while ago? A physicist at Princeton was trying to figure out whether matter would break apart into its constituents in a collapsing universe, so he looked at how the universe heated up as it compressed. He then realized that his calculations worked equally well in reverse -- the young expanding universe was very hot but cooling -- and it had to have an afterglow: the CMB.

There are restrictions on this rebirth argument, though. For one thing, the fact that the universe will expand forever prevents a big crunch in our future, so we're at the end of the line if such a line existed. And in 2001, Alan Guth proved a mathematical theorem that shows that bang/crunch/bang universes can't have an infinite history; they must have started some finite time in the past. (Though there are a few ways around the theorem if you reject a few assumptions.) So yes, it's possible, but there is no reason to believe it actually happened, and there are very good reasons for thinking it won't happen in the future.

Q8) comparable ramifications? by sstory (#6606658)

A8) I'm not going to give the usual B.S. answers about spinoffs (though there are some). And I'm not going to evade the question by saying that genomics hasn't yielded any transformation, because the potential is certainly there. But I will answer this question obliquely.

If I asked you, "Quick! What's the most important scientific achievement of the 20th century?" how would you respond?

You would probably answer relativity or quantum mechanics, or perhaps the Apollo landings. Probably some would say the atom bomb. I suspect that only a handful of people would mention the computer, and even fewer people would say penicillin. (Am I right?)

Science has two faces -- it can transform society (for better or worse), and it can advance human knowledge. The two are not inextricably bound, though they often come together.

Relativity was a profound shift in our understanding of the way the universe works, but you have to look pretty hard to see a direct effect on our lives. Conversely, penicillin wasn't a central advance in understanding biological systems, but it affected all of us -- I suspect many people here on Slashdot wouldn't be alive today without penicillin and its descendants.

For me, though, relativity is a greater scientific triumph than penicillin -- even though penicillin is probably much more important to us. It altered our view of the universe and gave us a greater understanding of the fundamental laws of the universe -- it was a philosophical advance as much as it was a technical one. That's why we seem to admire Einstein more than Fleming and Newton more than Jenner.

The present cosmological revolution won't change our lives dramatically; heck, a good spam filter would probably have more direct effect on our quality of life. But at the same time, it will finally answer some of the most ancient questions of humanity -- where did the universe come from and how will it end -- and when it ends, we will have a firm grasp of the answer of the latter if not the former. It will be a towering intellectual achievement, and I think that is what will set it apart from even the human genome project.

Q9) What is the next paradigm shift? by geeber (#6606890)

A9) I disagree with the idea that there's no paradigm shifts left -- indeed, I think we're in the middle of one now. I think that it will be associated with one in the Standard Model of particle physics that will begin before the end of the decade.

It's hard to say where future paradigm shifts lie, but there are lots and lots of outstanding questions in science, some of which are incredibly basic, yet totally out of scientists' reach. For example, neurologists have a very good idea about how individual neurons work -- how they connect and communicate. But when it comes to explaining how a large sloppy hunk of neurons becomes a conscious entity, they're completely at sea. I don't think there's even a good definition of consciousness, which is crucial if you're going to study it seriously. Even more basic -- scientists are struggling to define what life is. There's a heck of a lot more work to do, and plenty of room for paradigm shifts.

Speaking of paradigm shifts, I'd like to take a bit of issue with the term (which I've used myself a number of times in the responses to these questions.)

For those who don't know, the idea of a "paradigm shift" comes from Thomas Kuhn's Structure of Scientific Revolutions, a seminal work in history of science. While I think that Kuhn's idea of a paradigm shift has a lot of merit -- models and philosophies do change suddenly and dramatically in the face of mounting conflicting evidence and despite resistance -- I think the term itself is misleading. It implies the complete abandonment of one idea and acceptance of a replacement.

In my view, this is not the way modern science works -- I think that science is cumulative. Each model extends and corrects the previous one, and while there might be a dramatic shift philosophically, there is almost never a dramatic shift physically. Relativity, for example, made a profound change in the way we think about time and space and gravity, yet the functional difference between Newton and Einstein is pretty small. All these complicated tensor equations are approximately equal to Newton's laws in the vast, vast majority of cases -- it's only under conditions of extreme gravity, extreme speed, extreme energy, or extreme time that relativistic predictions diverge from Newton's. Similarly with quantum mechanics.

While I think that relativity and quantum mechanics are paradigm shifts, they're not rejections of the Newtonian picture as much as they are extensions. The paradigm shift can be huge philosophically, but its effects tend to be small in magnitude. And with these small corrections, scientists extend the applicability of their model of the universe -- they can explain the orbit of Mercury or the photoelectric effect -- and in the cases where Newton's laws were strong, these models boil down to Newton's laws.

If I remember my Kuhn correctly, he explicitly rejected the idea of cumulative science; he really saw each model getting completely replaced by its successor, rather than as an extension -- and this leads, at least in my view, to the excesses of postmodernism.

I think that this issue goes to the heart of the questions about how scientists can be sure about the end of the universe if their models can be replaced at any time. To that I'd argue that, yes, all models are provisional, but even with "paradigm shifts" models are usually extended rather than replaced. The central findings of the previous model still hold with good accuracy in most cases, even if the philosophical underpinnings are badly shaken. Maybe scientists are missing some crucial understanding that will simplify the way we look at the universe -- and scientists are seriously pondering alternate models to things as widely accepted as the inflationary big bang -- but even if such a shift occurs, it probably won't invalidate today's discoveries.

Q10) What will it mean? by boatboy (#6607285)

A10) One thing's certain. If I knew the answers, I'd be even more insufferable than I am now.

Seriously, I'm not sure that knowing the answers would have a profound moral and sociological effect. While I think that asking and answering big questions is a hallmark of a prospering society, a society doesn't necessarily draw strength or stability from its intellectual curiosity. (For example, Athenian democracy lasted only about 80 years if I remember right.) Even the most profound philosophical ideas can wind up having little real effect on the everyday functioning of a civilization -- for example, I think that Godel's incompleteness theorem hasn't changed society in the slightest.

As for the next big question, I think there are some in biology: what is life? What is consciousness? How did life arise? Are we alone in the universe? In physics, I think there are profound questions yet to be answered in a realm that I'd describe as "information theory" in the broadest sense -- what's really going on in a black hole? What makes quantum mechanics so weird? And I think that answering the question about the true nature of dark energy will probably have to await a future cosmological revolution. But one of the wonderful things about science is that you don't really know what big questions are within your grasp until you begin to grasp them. We'll know the next revolution when it appears.

Editor's note: Due to long answer lengths, we linked to the questions instead of running them directly here in order to keep this page from getting too large. This was an experiment. If you have comments or questions about Slashdot interview formatting, please email Roblimo.

Well, one science journalist's opinion, anyway. Charles Seife writes for Science magazine and is the author of Alpha and Omega: The Search for the Beginning and End of the Universe. These are his answers to your questions, and they're very detailed, to the point where you may want to set aside more than a few minutes of quiet time to read and digest them. Q1) "Publishing hype" by BobTheLawyer (#6606631)

A1)I'm not embarrassed at all because it's not hype. Scientists now know how the universe will end. Of course, as with all things scientific, there's a big honking asterisk on the word "know," but before I get to that, let me explain why I feel justified in making such an arrogant statement.

We're in the middle of a scientific revolution, in the honest-to-god paradigm-shift sense. This revolution started in 1997 when two groups of astronomers, the High-Z Supernova Search Team and the Supernova Cosmology Project used the bright flashes of a particular type of dying star (a type-Ia supernova) to measure the expansion of the universe at different times in the past. Since then, a whole raft of astronomical observations -- of faint patterns in the afterglow of the big bang, of distributions of galaxies, of the composition of intergalactic clouds of gas, of distortions of light going around massive bodies -- have all forced cosmologists into a remarkable consensus about the composition of the universe and, yes, its fate.

Just to give you a little taste of what the difference in the state of knowledge was like: in 1997, if you asked an astronomer how old the universe is, you'd get an answer somewhere between 12 and 15 billion years. Now, you'll get an answer of 13.7 billion years, plus or minus about 100 million. That's a big jump in precision. Similarly, before 1997, nobody had a clue how the universe would end; now, cosmologists agree on its fate. Some of the details haven't been worked out (what an understatement!), but the gross picture of the ultimate fate of the cosmos seems to be pretty well established for the first time in history. And by the end of the decade, a lot of the details will be fleshed out.

The ongoing revolution isn't just astronomical; it's physical. A decade ago, nobody knew whether neutrinos have mass. (For those who aren't particle physicists, neutrinos are particles that so rarely interact with matter that they can easily pass through the Earth without noticing the big chunk of mass they've passed through. This property makes them exceedingly hard to study.) Now, neutrino physicists are in accord -- and they've concluded that neutrinos, collectively, weigh about as much as all the visible stars and galaxies in the universe combined. High-energy physicists are using an accelerator in Long Island to recreate the condition of the universe a few microseconds after the big bang. By next year, they will formally announce the creation of a new state of matter that existed only in the very, very early universe. (There are alreadystrong hints that they've succeeded.) And another particle accelerator under construction in Geneva is very likely going to discover the particle responsible for exotic dark matter. (More on this shortly.)

All these experiments, all these observations, are pointing in exactly the same direction; they reveal the composition of the universe and its fate. But as with any good scientific revolution, such as relativity or quantum mechanics, it generates more questions than it answers. Scientists now know how the universe will end, but that understanding comes at the cost of a new mystery in physics.

As to the asterisk on the word "know," scientists are acutely aware that their theories are subject to revision. But at the same time, they have good reasons for being confident about their theories -- and they are more confident about some theories than about others. The new cosmological picture that's emerged has a darn high confidence rating; extraordinary claims require extraordinary proof, and the scientific world wouldn't accept the ideas of dark matter, much less dark energy, if there weren't a number of independent lines of evidence that forced scientists to make that conclusion. And while they're not confident about many of the details of the cosmos and the mechanisms that shape it, they are pretty sure that the overall picture is correct. (More on this coming, too.)

Q2) [Almost] Serious question! by Noryungi (#6606694)

and

Q3) Why does the rate of expansion change? by Anonymous Coward (#6606745)

A2,3) The universe will end in... umm... you really want me to give away the ending to my book?

Actually, I reveal the answer in chapter four, because the understanding of the fate of the universe is just the beginning of the current cosmological revolution. So it's not a spoiler to say...

-- drum roll -- the universe will die a heat death, or "Dark & Cold" by your terminology.

In a big bang universe governed by the laws of general relativity, there are two possibilities. (Actually, there are more than two, but all the cases boil down to two real outcomes.) Big crunch or heat death, fire or ice.

The fate of the universe depends on how the universe expands. In general, things that expand cool down and things that are compressed heat up. (This is what causes a propane container to feel so cold after a barbecue -- all the gas that expanded.) After the big bang the universe was extremely hot and was seething with energy. As it expanded, it cooled; free-roaming quarks condensed into protons and neutrons, and wound up as hydrogen, helium, and a handful of other light elements and isotopes. About 400,000 years after the big bang, the universe cooled enough so that the electrons could combine with the nuclei and form neutral atoms. Now, about 14 billion years later, the universe is a pretty cool place.

The expansion of the universe is like a cannonball shot into the air. As the cannonball flies ever higher, the force of gravity tries to drag it back to earth, reducing its upward velocity and slowing it down as it zooms upward. If gravity is very strong, then the cannonball rapidly loses its speed and quickly comes crashing back to the ground. On the other hand, if gravity is very weak, then the cannonball might escape the pull of the earth entirely and zoom away into outer space.

Similarly, the big bang gave the universe an initial cannonshot of expansion. If the mutual gravitational attraction of the objects in the universe is very strong (if there's a lot of matter in the universe) the expansion will slow down, halt, and eventually reverse itself. After the cooling phase of expansion, the universe will begin to swallow itself, getting smaller and smaller each day. This will make it heat up. The skies will get brighter and brighter as galaxies and stars get closer and closer together, and eventually, the universe will become a bath of radiation once more. Electrons will separate from atoms, atoms and then protons and neutrons will shiver into their components, and the universe will collapse in a "big crunch," a reverse big bang. The cosmos will die a death by fire.

On the other hand, if there's not much matter in the universe, then the expansion of the universe will continue forever. The expansion will slow down, but it will never halt and never reverse itself. The universe continues to cool down, and for a long time, space will look pretty much as it does now. Stars will be born and die, and galaxies will age. The night sky would get darker and darker as distant objects get too dim to view, and eventually, as the hydrogen in the universe is consumed, stars and galaxies will begin to wink out. Many billions of years hence, the universe will be a lifeless soup of dim light and dead matter. It will be a death by ice.

In 1997 and 1998, the two supernova teams used the brightness of distant supernovae to measure the rate of expansion at different times in the past. (Because the speed of light is finite, looking into the distance is the same as looking into the past. This causes no end of tense problems when writing a book about cosmology.) What they found was absolutely gobsmacking. Not only was the universe's expansion not slowing down very much -- it was speeding up! The cannonball was zooming into the air faster and faster as if it were propelled by some sort of weird antigravity force. Not only was the cannonball going to escape, it is so OUTTA HERE! This means a death by ice.

Yegads -- an antigravity force. This was a really hard thing for scientists (and probably you) to accept. But there's a number of different lines of evidence that support the idea, and in the book I go through those lines of evidence in great detail. I'll have to settle for a brief summary here. In 2000, a balloon experiment known as Boomerang took very detailed pictures of the ubiquitous afterglow of the big bang, the cosmic microwave background (CMB). This afterglow has hot and cold spots in it, and for years, scientists have been making very, very detailed predictions about the size and distribution of those spots. The results of the Boomerang experiment and the DASI and WMAP experiments matched those predictions incredibly well, giving scientists great confidence in the underlying theory. It also allowed them to figure out the amount of matter and energy in the universe, and 73% of the "stuff" in the cosmos was dark energy, this antigravity force.

There are a number of other lines of evidence, too; the current distribution of galaxies, for example, implies the presence of an antigravity force, and just last month, scientists made a very nice measurement of something known as the late integrated Sachs-Wolfe effect. This effect can't occur unless you have something like dark energy counteracting gravity's pull.

Unfortunately, a fuller exposition requires a lot more writing -- it takes up several chapters in my book. (Shameless plug). But in summary, there's a number of independent observations that all point to the existence of a dark energy. Furthermore, the theories underlying the idea have made very specific predictions that have been verified with incredible precision. It's extraordinary stuff, but no matter how scientists look at it, they're forced by extraordinary evidence to make the same conclusion.

Yes, it's true that scientists don't know the mechanism of dark energy (though they're not entirely at sea) but there's little doubt that the cannonball is zooming into space faster and faster. They don't know precisely why, but the universe is being pushed toward its icy death by an antigravity force. Scientists are watching it happen.

And you don't need to wait billions of years to know the outcome -- you don't need to observe something directly to conclude that it's going to happen. The planet Pluto was discovered in 1930. So why don't people object to the statement that it takes about 250 years to complete an orbit? Just as you don't have to wait until 2180 to confirm the conclusions of Newtonian dynamics, you don't need to witness the end of the universe to be able to figure out its fate or validate the theory that leads you to that prediction.

Q4) Dark Matter by notcreative (#6606772)

A4) You are correct; the nature and location of dark matter are crucial puzzles in modern cosmology, but I think that the answers will be pretty much in hand by the end of the decade.

I've already mentioned results (most notably WMAP) that reveal the amount of "stuff" in the universe, and 73% of it is dark energy. The rest is matter. But the grand total of the matter locked up in visible stars is a mere 0.5% of the stuff in the universe. What is the other 26.5%? That's dark matter, and, in fact, there are two different types.

Scientists have known for decades that most of the matter in the universe is invisible to telescopes. In the 1960s, Vera Rubin measured the motion of stars wheeling around the center of the Andromeda galaxy and concluded that there had to be a lot more matter pulling on those stars than could be seen.

Despite what some contrarians say, dark matter isn't dogma; viable alternatives, like Moti Milgrom's MOND are taken seriously, if not accepted. Unfortunately, all of the alternatives, including MOND, fail in crucial ways. Besides, you can see dark matter, both directly and indirectly. The MACHO and OGLE projects see the twinkle of stars caused by a passing chunk of dark matter, and they can see the distortion of light caused by a huge amount of unseen mass sitting on the fabric of spacetime. (Distant galaxies are stretched into arcs around this gravitational lens.) This is allowing scientists to figure out just where dark matter resides. But at the same time, a number of observations lead scientists to conclude that the minority of the matter (dark or light) in the universe is ordinary, atomic matter -- the stuff of stars, planets, and people. Again, it will take too long to describe all the lines of evidence, but one powerful way of measuring the number of atoms in the universe is to look at the proportion of hydrogen to deuterium, helium, and lithium in primordial gas clouds. In the first three minutes of the universe, atoms were fusing, just as they do in a hydrogen bomb. The universe was a giant pressure cooker, turning protons and neutrons into heavier elements. If there are a lot of atoms, then there is a lot of fusion and a lot of heavy elements made; if there are not very many atoms, then the universe winds up being almost entirely hydrogen. By looking at the ratios of heavy elements to light elements, scientists concluded that atomic matter makes up about 4% of the "stuff" in the universe -- which is precisely what other measurements, like the CMB ones -- imply, too.

So, 27% of the stuff in the universe is matter: 4% "atomic" matter, leaving 23% to be made of "exotic" matter, stuff that's not made of atoms. I've already described some of that exotic matter; neutrinos make up about 0.5% of the stuff in the universe, about the same as the visible matter in the universe. What's the remainder?

That's the big open question, but one that I'd wager will be solved by the end of the decade. There are very good reasons -- particle physics ones, rather than cosmological ones -- for believing that the main constituent of dark matter is a proposed particle known as the LSP. If it is, then the LHC accelerator in Geneva will find it. If not, then the LSP almost certainly doesn't exist and the puzzle will be compounded -- but I think that scientists are extremely optimistic. Again, there's lots more detail in the book about the justification for this.

Q5) variable constants by Cally (#6607000)

A5) The point's well taken, and I'll get to it after a few remarks.

First, you're right in that the supernovae serve much the same purpose as Cepheid variable stars do -- they're both objects of known brightness, or "standard candles," that allow astronomers to make a precise measurement of the distance to a faraway galaxy. However, they are not the same thing. Cepheids are stars that pulsate and the rate of that pulsation reveals its intrinsic brightness. They're what Hubble used to spot the expansion of the universe in the 1920s, but they're relatively dim and impossible to find in very distant galaxies. Type-Ia supernovae are standard candles that are much, much brighter than Cepheids, and so can be seen halfway across the universe. (And as you note, since distant supernovae mean ancient supernovae, they reveal the expansion rate of the universe billions of years ago.)

Second, the time-varying speed of light (or more precisely, the time-varying fine structure constant) is a controversial idea. The scientists that made the observation in question are pretty solid and they're taken seriously. However, my impression is that mainstream thinking is that the results are due to a systematic error. That aside, the effect, even if real, is very small, and it has nothing to do with interpreting the data from standard candles. The interpretation there is quite well established; there's little question that scientists are seeing an expansion of the universe;. Alternative theories, like tired light, fail in countless ways and scientists have even seen the relativistic time dilation caused by the motion of the distant object.

But, yes, it's natural for a layperson to conclude that the concordance cosmological model is looking increasingly kludge-y, and you're naturally led to wonder whether scientists are trying to prop up a failing model with the equivalent of epicycles or aether. I don't think this is the case for a few reasons.

For one thing, the theory isn't really getting added to and made more complex; it's getting subtracted from and being made more simple. This seems counterintuitive, but it comes from the fact that modern big bang theory is really a class of theories, rather than one set-in-stone dictum about the way the universe is. All these theories agree on the basic physics about the manner of the universe's birth, the forces that drive the universe, and the physics behind them; the difference between the theories are the values of a handful of parameters that are not predicted by the theory. These parameters are inputs rather than outputs, and by pinning down the values of these inputs, the acceptable class of theories gets narrower and narrower.

Dark energy is one of these inputs. Although nobody took it seriously before 1998 -- everyone thought that the value of the parameter in question was zero -- it was lurking there nonetheless. It turns out that this parameter is not only non-zero, it's really big, much to everyone's surprise. But this doesn't add complexity to the model, especially since other parameters, such as the "curvature" of the universe as a whole, which many physicists thought would be non-trivial, turn out not to be important after all. (In other words, the universe seems to be slate flat, rather than saddle-shaped or sphere-like.)

So, from a mathematical viewpoint, the model is no more complex than it was in 1997, and is, in fact, significantly leaner. But what about from a physical viewpoint? Dark matter and dark energy seem to fly in the face of Occam. But here, too, the increase in complexity is much less than it appears. Long before this cosmological revolution, astronomers knew that dark matter had to exist; more recently, they've begun to see it. Even without worrying about cosmological questions, astrophysicists had accepted the existence of dark matter. Cosmological measurements like WMAP showed that these astrophysicists were right -- it was an independent confirmation that dark energy exists and that it comes in two forms, something that other astronomers had concluded a while ago.

Dark energy, on the other hand, has more claim to being a "hack" to the theory. It really is something new and unexpected (even though it was always a mathematical possibility, nobody in the physics world suspected it actually existed.) Nevertheless, the groundwork was already there, and modern big bang theory implicitly requires the existence of a form of dark energy in the very early universe. And since the 1930s, scientists knew that even the deepest vacuum is full of energy and can exert pressure (something known as the Casimir effect, which I describe in this book and in my previous book, Zero: The Biography of a Dangerous Idea). Thus, the idea of dark energy wasn't completely alien to physics before 1997, and in some sense, it was a necessary component.

Yes, it's possible that scientists are looking at the cosmos in the wrong way, and somebody will establish a simpler, more elegant theory that takes all these threads and weaves them together. (More on this shortly.) But at the moment, far from having a kludged-up theory, cosmologists have a leaner (if weirder) theory than ever before -- one that makes very precise predictions that are getting verified with stunning accuracy. I think this argues for increased confidence in the theory rather than for increased fear that it's falling apart.

Q6) Universe's container by bios10h (#6606748)

A6) It freaks a lot of people out. There's a lot of philosophical problems with having an infinite universe -- for example, if the universe is truly infinite, and if, as scientists believe, the number of quantum states of a finite volume is finite, then it's hard to escape the conclusion that, some great distance away, there's a bizarro-you on bizarro-earth reading bizarro-Slashdot. On the other hand, there's no positive evidence that I can think of that the universe is truly infinite; it's just the sparest conclusion in a mathematical sense, if not a philosophical sense.

But an infinite universe is not a foregone conclusion. Earlier this year, Max Tegmark at the University of Pennsylvania published an intriguing paper that looked at slight anomalies in the WMAP data that seem to imply that the universe is not only finite, but shaped like a donut. Nobody takes the idea terribly seriously, not even the author, because there are other statistical tests that seem to rule the donut-shaped universe out. But it's the sort of thing that people are looking at very closely.

Whether it's finite or infinite, in a mathematical sense, there's really no need for the universe to be "in" anything -- there are models where our universe is embedded in a higher-dimensional space, but there are models where it isn't. Philosophically, though, I don't see any advantage to embedding the universe in something bigger -- as you say, it just punts the problem forward. (Who, then, will contain the containers?)

It's one of those things that is hard to get comfortable with -- and even when you accept it, it sometimes can cause pangs of uncertainty. Quantum mechanics does this, too... it's just something that's hard to wrap your head around. Take solace in the fact that it's hard for everyone else, too.

Q7) How ultimate is the end of the universe? by Lane.exe (#6606766)

A7) If there were a collapse-type universe, yes, there could be a reboot and a new big bang. (And if Microsoft built the universe, a reboot would be coming sooner rather than later. *duck*)

In fact, the theory behind the cosmic microwave background stemmed from calculations to see whether this was possible. Remember the expansion-cooling/contraction-heating bit I mentioned a while ago? A physicist at Princeton was trying to figure out whether matter would break apart into its constituents in a collapsing universe, so he looked at how the universe heated up as it compressed. He then realized that his calculations worked equally well in reverse -- the young expanding universe was very hot but cooling -- and it had to have an afterglow: the CMB.

There are restrictions on this rebirth argument, though. For one thing, the fact that the universe will expand forever prevents a big crunch in our future, so we're at the end of the line if such a line existed. And in 2001, Alan Guth proved a mathematical theorem that shows that bang/crunch/bang universes can't have an infinite history; they must have started some finite time in the past. (Though there are a few ways around the theorem if you reject a few assumptions.) So yes, it's possible, but there is no reason to believe it actually happened, and there are very good reasons for thinking it won't happen in the future.

Q8) comparable ramifications? by sstory (#6606658)

A8) I'm not going to give the usual B.S. answers about spinoffs (though there are some). And I'm not going to evade the question by saying that genomics hasn't yielded any transformation, because the potential is certainly there. But I will answer this question obliquely.

If I asked you, "Quick! What's the most important scientific achievement of the 20th century?" how would you respond?

You would probably answer relativity or quantum mechanics, or perhaps the Apollo landings. Probably some would say the atom bomb. I suspect that only a handful of people would mention the computer, and even fewer people would say penicillin. (Am I right?)

Science has two faces -- it can transform society (for better or worse), and it can advance human knowledge. The two are not inextricably bound, though they often come together.

Relativity was a profound shift in our understanding of the way the universe works, but you have to look pretty hard to see a direct effect on our lives. Conversely, penicillin wasn't a central advance in understanding biological systems, but it affected all of us -- I suspect many people here on Slashdot wouldn't be alive today without penicillin and its descendants.

For me, though, relativity is a greater scientific triumph than penicillin -- even though penicillin is probably much more important to us. It altered our view of the universe and gave us a greater understanding of the fundamental laws of the universe -- it was a philosophical advance as much as it was a technical one. That's why we seem to admire Einstein more than Fleming and Newton more than Jenner.

The present cosmological revolution won't change our lives dramatically; heck, a good spam filter would probably have more direct effect on our quality of life. But at the same time, it will finally answer some of the most ancient questions of humanity -- where did the universe come from and how will it end -- and when it ends, we will have a firm grasp of the answer of the latter if not the former. It will be a towering intellectual achievement, and I think that is what will set it apart from even the human genome project.

Q9) What is the next paradigm shift? by geeber (#6606890)

A9) I disagree with the idea that there's no paradigm shifts left -- indeed, I think we're in the middle of one now. I think that it will be associated with one in the Standard Model of particle physics that will begin before the end of the decade.

It's hard to say where future paradigm shifts lie, but there are lots and lots of outstanding questions in science, some of which are incredibly basic, yet totally out of scientists' reach. For example, neurologists have a very good idea about how individual neurons work -- how they connect and communicate. But when it comes to explaining how a large sloppy hunk of neurons becomes a conscious entity, they're completely at sea. I don't think there's even a good definition of consciousness, which is crucial if you're going to study it seriously. Even more basic -- scientists are struggling to define what life is. There's a heck of a lot more work to do, and plenty of room for paradigm shifts.

Speaking of paradigm shifts, I'd like to take a bit of issue with the term (which I've used myself a number of times in the responses to these questions.)

For those who don't know, the idea of a "paradigm shift" comes from Thomas Kuhn's Structure of Scientific Revolutions, a seminal work in history of science. While I think that Kuhn's idea of a paradigm shift has a lot of merit -- models and philosophies do change suddenly and dramatically in the face of mounting conflicting evidence and despite resistance -- I think the term itself is misleading. It implies the complete abandonment of one idea and acceptance of a replacement.

In my view, this is not the way modern science works -- I think that science is cumulative. Each model extends and corrects the previous one, and while there might be a dramatic shift philosophically, there is almost never a dramatic shift physically. Relativity, for example, made a profound change in the way we think about time and space and gravity, yet the functional difference between Newton and Einstein is pretty small. All these complicated tensor equations are approximately equal to Newton's laws in the vast, vast majority of cases -- it's only under conditions of extreme gravity, extreme speed, extreme energy, or extreme time that relativistic predictions diverge from Newton's. Similarly with quantum mechanics.

While I think that relativity and quantum mechanics are paradigm shifts, they're not rejections of the Newtonian picture as much as they are extensions. The paradigm shift can be huge philosophically, but its effects tend to be small in magnitude. And with these small corrections, scientists extend the applicability of their model of the universe -- they can explain the orbit of Mercury or the photoelectric effect -- and in the cases where Newton's laws were strong, these models boil down to Newton's laws.

If I remember my Kuhn correctly, he explicitly rejected the idea of cumulative science; he really saw each model getting completely replaced by its successor, rather than as an extension -- and this leads, at least in my view, to the excesses of postmodernism.

I think that this issue goes to the heart of the questions about how scientists can be sure about the end of the universe if their models can be replaced at any time. To that I'd argue that, yes, all models are provisional, but even with "paradigm shifts" models are usually extended rather than replaced. The central findings of the previous model still hold with good accuracy in most cases, even if the philosophical underpinnings are badly shaken. Maybe scientists are missing some crucial understanding that will simplify the way we look at the universe -- and scientists are seriously pondering alternate models to things as widely accepted as the inflationary big bang -- but even if such a shift occurs, it probably won't invalidate today's discoveries.

Q10) What will it mean? by boatboy (#6607285)

A10) One thing's certain. If I knew the answers, I'd be even more insufferable than I am now.

Seriously, I'm not sure that knowing the answers would have a profound moral and sociological effect. While I think that asking and answering big questions is a hallmark of a prospering society, a society doesn't necessarily draw strength or stability from its intellectual curiosity. (For example, Athenian democracy lasted only about 80 years if I remember right.) Even the most profound philosophical ideas can wind up having little real effect on the everyday functioning of a civilization -- for example, I think that Godel's incompleteness theorem hasn't changed society in the slightest.

As for the next big question, I think there are some in biology: what is life? What is consciousness? How did life arise? Are we alone in the universe? In physics, I think there are profound questions yet to be answered in a realm that I'd describe as "information theory" in the broadest sense -- what's really going on in a black hole? What makes quantum mechanics so weird? And I think that answering the question about the true nature of dark energy will probably have to await a future cosmological revolution. But one of the wonderful things about science is that you don't really know what big questions are within your grasp until you begin to grasp them. We'll know the next revolution when it appears.

Editor's note: Due to long answer lengths, we linked to the questions instead of running them directly here in order to keep this page from getting too large. This was an experiment. If you have comments or questions about Slashdot interview formatting, please email Roblimo.

Slashback tonight brings a few followups to recent Slashdot postings on the fate of model rocketry in the new, hypercautious America; a few Python gatherings for those who prefer that language to Perl; and a response from Los Alamos to recent claims of lax security. Enjoy!

Besides which, it's the hidden cameras that matter. An anonymous reader adds this followup to the story posted last month about Wired reporter Noah Shachtman's account of sneaking into classified areas at Los Alamos national Laboratory.

"In an email message to all Los Alamos National Laboratory employees, Pete Nanos, the current Director of LANL, responded with information suggesting that the Wired reporter who thought he had broken in to a 'top secret area' had in fact just crossed a cattle fence:

'The Wired reporter clearly did not enter a Laboratory security area. The Laboratory encompasses more than 40 square miles. The security force protects important assets within those boundaries but cannot -- and does not -- protect every square foot of property. Based on the article, it appears the reporter crossed a barbed-wire cattle fence, not a fence that protects a Los Alamos security area.
There is a small security area with several buildings (roughly 400 feet by 400 feet) near the driveway entrance to TA-33. That area is surrounded by a seven-foot-high chain-link fence topped with three strands of barbed wire. A security guard is stationed inside that area seven days a week and 24 hours a day. Clearly, the reporter did not climb that fence.
There are several other buildings outside the security area that are locked for property protection interests. They have no security interests. There are several gates and fenced areas on the TA-33 site, which are there for safety access control, not security.
It's unlikely the reporter would be prosecuted for trespassing; the Laboratory does not have law enforcement authority to prosecute, and none of the proper authorities witnessed the trespass.'"

Perhaps we can have a celebrity deathmatch. hfastedge writes "Ok, now that 2 perl conferences have been mentioned, I've been brought over the edge. Python is a language that is just as old, and arguably better from: most importantly a uniform standard of readability (enforced by using whitespace to delimit blocks (instead of {}), by avoiding overuse of cryptic symbols, and by a culture that strives to keep innovations as "pythonic"), and a rich development community. Anyway, normally, there are Python events in Europe, and a trail at O'Reilly's OSCON. But now, there is a far cheaper event taking place on March 24-28 in Washington DC: http://python.org/pycon/.

Examples of Python in action: 0, 1, 2, 3, 4, 5, 6, 7"

Fly up go phhhhhwwwtttpffffff .... MyNameIsFred writes "Slashdot recently discussed whether anti-terrorism laws would destroy model rocketry. The government has ruled, and the message is clear, "When it comes to the hobby of model rocketry, size does matter. And in this case, the magic number is 62.5 grams. That's the largest amount of propellant a single model rocket engine can have in it and still be exempt from a new set of federal rules that will go into effect May 24." What does this mean for the the big guys in model rocketry, who use engines larger than this?"

Theodore Logan writes "Has the Riemann Hypothesis finally been proved? The proof is a couple of months old, and to the best of my knowledge a Swedish newspaper is the only one to take up the story yet, so there is certainly a possibility that this is a hoax, or a less than watertight proof. But if it turns out to be the real thing, it will, apart from winning the authors eternal fame and glory for finding the holy Grail of modern math, provide them with a cool $1 million as they claim the first Millennium Prize." We had a story a while back about this as well.

morcheeba writes "Wired reported Noah Shachtman gives a first-hand account of his entry into a high-security area at Los Alamos National Laboratory. Yes, there are pictures. It seems that the birthplace of the atom bomb is being guarded by string, backed up by guards with empty holsters. There's a little more info on Noah's Defense Tech website."

sw155kn1f3 writes "Scientists at Los Alamos National Laboratory built a cheap (less than $1k per unit) 294-unit Beowulf claster dedicated to run astrophysics calculations. According to their website it's 85th fastest computer in the world. Seems cool and promising as it made with cheap components and off the shelf hardware."

coryboehne writes "KOB-TV in Albuquerque is reporting that Los Alamos National Labs is warning personnel who are cutting trees in a canyon east of Los Alamos that some trees in the area might be radioactive. The canyon, known as Bayo Canyon, was formerly known as Technical Area 10, and was used for weapons testing from the 1940s until 1961. A full summary of Environmental Direct Penetrating Radation in the Los Alamos area is available from the LANL Meteorology & Air Quality Group"

coryboehne writes "KOB-TV in Albuquerque is reporting that Los Alamos National Labs is warning personnel who are cutting trees in a canyon east of Los Alamos that some trees in the area might be radioactive. The canyon, known as Bayo Canyon, was formerly known as Technical Area 10, and was used for weapons testing from the 1940s until 1961. A full summary of Environmental Direct Penetrating Radation in the Los Alamos area is available from the LANL Meteorology & Air Quality Group"

coryboehne writes "KOB-TV in Albuquerque is reporting that Los Alamos National Labs is warning personnel who are cutting trees in a canyon east of Los Alamos that some trees in the area might be radioactive. The canyon, known as Bayo Canyon, was formerly known as Technical Area 10, and was used for weapons testing from the 1940s until 1961. A full summary of Environmental Direct Penetrating Radation in the Los Alamos area is available from the LANL Meteorology & Air Quality Group"

An anonymous reader writes "LANL will be receiving a 1024 node (2048 processor) LinuxBIOS/BProc based supercomputer late this year. The story is at this location. This system is unique in Linux cluster terms due to no disks on compute nodes, using LinuxBIOS and Beoboot to accomplish booting, and BProc for job startup and management. It is officially known as the Science Appliance, but is affectionately known as Pink to the team that is building much of it."

An anonymous reader writes "LANL will be receiving a 1024 node (2048 processor) LinuxBIOS/BProc based supercomputer late this year. The story is at this location. This system is unique in Linux cluster terms due to no disks on compute nodes, using LinuxBIOS and Beoboot to accomplish booting, and BProc for job startup and management. It is officially known as the Science Appliance, but is affectionately known as Pink to the team that is building much of it."

Paul E writes: " An atlanta company seems to have developed (modified?) a linux clustering platform that is very conducive to FPS games. These guys apparently have built a cluster that will be pushing 2 TerraFlops, which would easily put it between Blue Pacific and Blue Mountain . Interesting that the same time the .mil starts making FPS's, FPS platforms are outperforming some of the top defense labs."

jhiv writes: "The National Nuclear Security Administration (NNSA) reports that 'Los Alamos and Lawrence Livermore national laboratories have completed the first full-system three-dimensional simulations of a nuclear weapon's explosion'. The simulations are two of the largest computer simulations ever attempted, each taking weeks to complete on the ASCI White supercomputer. The Los Alamos team used the ASCI Blue Mountain supercomputer to visualize the results. Additional coverage can be found in this story in the Albuquerque Journal."

jhiv writes: "The National Nuclear Security Administration (NNSA) reports that 'Los Alamos and Lawrence Livermore national laboratories have completed the first full-system three-dimensional simulations of a nuclear weapon's explosion'. The simulations are two of the largest computer simulations ever attempted, each taking weeks to complete on the ASCI White supercomputer. The Los Alamos team used the ASCI Blue Mountain supercomputer to visualize the results. Additional coverage can be found in this story in the Albuquerque Journal."

jhiv writes: "The National Nuclear Security Administration (NNSA) reports that 'Los Alamos and Lawrence Livermore national laboratories have completed the first full-system three-dimensional simulations of a nuclear weapon's explosion'. The simulations are two of the largest computer simulations ever attempted, each taking weeks to complete on the ASCI White supercomputer. The Los Alamos team used the ASCI Blue Mountain supercomputer to visualize the results. Additional coverage can be found in this story in the Albuquerque Journal."

Alien54 writes: "As seen in this UPI Report, Lab-created "dumb holes" - the acoustic, or sound wave analogs of black holes - may provide important experimental evidence for quantum gravity, a theory that unifies atomic and gravitational forces. Dumb holes arise when fluids flowing faster than the speed of sound form regions that trap sound waves. They too have a surface of no return -- the "acoustic horizon". While black holes remain interstellar objects, researchers can create dumb holes (Sonic Black Holes) in a laboratory. Dumb holes that trap sound waves may yield experimental evidence used to understand quantum gravity because these acoustic black holes exhibit all the characteristics - paradoxes included - of their light-wave brethren. well not quite all. For one thing, sonic black holes do not involve gravity and distortions of space and time."

Thomas Colthurst writes "You've no doubt already read the story of ping, but have you ever used it to measure the speed of light?" Here's a case where all that cat5 on college campuses can actually be used for education ;)

webword writes: "Dr. Dobbs is running a story by Ron Minnich on implementing private namespaces for Linux to solve problems in both distributed and cluster computing. This topic hasn't received as much attention as it should. I'm glad that someone published something intelligent and worth reading."