Slashdot Mirror

Science data nerds writes "The White House is consistently and persistently claiming that the US is doing better than Europe in reducing greenhouse gas emissions. This is false — their claim is purely based on carefully selecting the only subset of the data that supports this conclusion. When all the data are used, it is plain that European emissions have declined substantially and US emissions have grown substantially. The article, and this linked analysis, debunk the White House claims."

slashthedot writes "While it is well known that boys have longer ring fingers as compared to index fingers, now some researchers say that the longer the ring finger ratio to index finger, the better boys are at math. In girls, the shorter the ring finger to index finger ratio, the better is their verbal skills. 'The link, according to the researchers, is that testosterone levels in the womb influence both finger length and brain development.'"

sterlingda writes "Physicists at the University of Pittsburgh have demonstrated a new form of matter that melds the characteristics of lasers and superconductors. The work introduces a new method of moving energy from one point to another as well as a low-energy means of producing a light beam like that from a laser. The new state is a solid filled with a collection of energy particles known as 'polaritons' that have been trapped and slowed using a technique similar to that used to produce a Bose-Einstein condensate. The work is published in the May 18 issue of Science (subscription required to read beyond the abstract)."

An anonymous reader writes "Physicists have managed to cool a dime-sized mirror to within one degree of absolute zero. This is the lowest laser-induced freeze yet achieved with a visible object. Laser cooling involves firing pulses of light at a specific frequency that exactly matches an atom's motions."

johkir writes "Last year, evolution was the breakthrough of the year; We found it full of new developments in understanding how new species originate. But we did get a complaint or two that perhaps we were just paying extra attention to the lively political/religious debate that was taking place over the issue, particularly in the United States. Perish the thought! Our readers can relax this year: Religion and politics are off the table, and n-dimensional geometry is on instead. This year's Breakthrough salutes the work of a lone, publicity-shy Russian mathematician named Grigori Perelman, who was at the Steklov Institute of Mathematics of the Russian Academy of Sciences until 2005. The work is very technical but has received unusual public attention because Perelman appears to have proven the Poincaré Conjecture (Our coverage from earlier this year), a problem in topology whose solution will earn a $1 million prize from the Clay Mathematics Institute. That's only if Perelman survives what's left of a 2-year gauntlet of critical attack required by the Clay rules, but most mathematicians think he will. There is also a page of runner-ups. Many of which have been covered here on Slashdot."

johkir writes "Last year, evolution was the breakthrough of the year; We found it full of new developments in understanding how new species originate. But we did get a complaint or two that perhaps we were just paying extra attention to the lively political/religious debate that was taking place over the issue, particularly in the United States. Perish the thought! Our readers can relax this year: Religion and politics are off the table, and n-dimensional geometry is on instead. This year's Breakthrough salutes the work of a lone, publicity-shy Russian mathematician named Grigori Perelman, who was at the Steklov Institute of Mathematics of the Russian Academy of Sciences until 2005. The work is very technical but has received unusual public attention because Perelman appears to have proven the Poincaré Conjecture (Our coverage from earlier this year), a problem in topology whose solution will earn a $1 million prize from the Clay Mathematics Institute. That's only if Perelman survives what's left of a 2-year gauntlet of critical attack required by the Clay rules, but most mathematicians think he will. There is also a page of runner-ups. Many of which have been covered here on Slashdot."

AVIDJockey writes "Researchers at Cornell University in Ithaca, N.Y., built a four-legged robot that can sense damage to its body and figure out how to adjust and keep going. They report the development in Friday's issue of the journal Science. The article states that the robot can, 'generate a conception of itself and then adapt to damage.' This reaffirms advice that states that when the robot uprising finally comes, you should always aim your rocket launcher at the head (or brain nexus)."

hey hey hey writes "In a controversial study, researchers have resurrected a retrovirus that infected our ancestors millions of years ago and now sits frozen in the human genome. Published online by Genome Research this week, the study may shed new light on the history of these genomic intruders, as well as their role in tumors. Although this particular virus, dubbed Phoenix, is a wimpy one, some argue that resuscitating any ancient virus is inherently risky and that the study should have undergone stricter reviews."

eldavojohn writes "Scientists have been busy in Ottawa using lasers to manipulate chemical reactions. While this may not seem like an impressive feat, the implications this has for quantum mechanics is quite large. From the article, "According to Albert Stolow, the NRC team leader, the tool used to alter molecular landscapes has implications beyond the control of chemical reactions. One example already mentioned is in the area of quantum information either to directly encode molecular scale information or to control molecular scale switches. Another application is in developing novel forms of optical microscopy of live cells, where quantum control methods can be used to sharpen images, enhance sensitivity and perhaps even perform molecular scale surgery on individual cells. The electric interaction underlying the NRC technique is an essential tool on the quantum mechanic's workbench. Its application to science and technology could reach deep into the quantum world of the ultrasmall." The article in science was where I caught this initially though it doesn't seem to be free anywhere online. The final words of the summary are "suggesting broad applicability" but only time will tell how far our imaginations will use this research."

Roland Piquepaille writes "Researchers have discovered that ordinary cellulose is a piezoelectric and smart material that can flap when exposed to an electric field. ScienceNOW reports that electricity can give life to cellophane. When you put a very thin layer of gold on each side of cellophane, and that you apply electric current to the gold layers, one positive, one negative, the cellophane curved toward the positive side. If you switch the voltage fast enough, the cellophane starts to act as a wing. So it should be possible to use it to build lightweight flying robots carrying cameras, microphones or sensors for surveillance missions. Read more for additional references and pictures about this electroactive paper (EAPap)."

KingAdrock writes to tell us Sciencemag is reporting that the US Patent and Trademark office (PTO) is floating the idea of an online pilot program to gather public input on patent applications. From the article: "Speaking last week at an open forum, officials said that tapping into the expertise of outside scientists, lawyers, and laypeople would improve the quality of patents -- and might also reduce a backlog that this month topped 1 million applications. "Instead of one examiner, what if you have thousands of examiners reading an application?" says Beth Simone Noveck of New York University Law School, who is an independent advocate of the idea."

An anonymous reader writes "ScienceNOW is reporting that a team of scientists led by Geneticist Jaume Bertranpetit has called into question findings from an earlier study of human prion diseases. The first study, led by John Collinge of University College London, stated that the existence of a gene that codes for prions was a result of a "balancing act" that had kept it in the gene pool for so long. The balancing act was supposedly due to widespread cannibalistic practices in human history. The new report suggests that their results were skewed because of low frequency variations known as 'ascertainment bias.'"

FleaPlus writes "Physicists in England and the Netherlands have unveiled a technique for constructing rigid DNA pyramids. With the technique, trillions of d4's can rapidly self-assemble from a solution of single-stranded DNA. The scientists also showed that single DNA strands called linkers could be used to attach the tetrahedra to each other, acting as a possible building block for 3D nanofabrication."

leonbrooks writes "First a Stanford Medicine Magazine article speaks about RNA 'produced by plants that turn genes on and off', and now a Science Magazine issue says 'For a long time, RNA has lived in the shadow of its more famous chemical cousin DNA and of the proteins that supposedly took over RNA's functions in the transition from the 'RNA world' to the modern one. The shadow cast has been so deep that a whole universe [of RNA] has remained hidden from view, until recently' and speaks of 'an order of magnitude more transcripts than genes', suggesting that more actual coding is done through RNA than DNA. Is everything we know about genetics off-base? (no pun intended)"

Shadow Wrought writes "To celebrate their 125th anniversary Science is running a series of articles on the 125 Questions of Science. The top 25 each link to an article exploring the subject of the question in depth. Included are such questions as: Are we alone in the Universe? What are the limits of conventional computing? How did cooperative behavior evolve?"

Iphtashu Fitz writes "The earthquake that triggered last years tsunami was the largest one recorded in 40 years and kept the planet shaking for weeks according to new reports that are due to be released on Friday. This was the largest earthquake measured so far by a new worldwide array of digital seismic instruments, whose results will appear in six different reports being published in the journal Science tomorrow. The quake broke several records, including the longest fault line (720 to 780 miles) and longest duration (10 minutes). The water displaced by the rise of the sea floor in the quake zone also resulted in a rise of worldwide sea levels of 0.004 inch. In Sri Lanka, more than 1,000 miles from the epicenter, the ground moved nearly 4 inches. As many as 14 smaller quakes were triggered in Alaska when the tremors from this quake reached the northernmost U.S. state."

BishopBerkeley writes "When a drop of ethanol is dropped on a surface at low pressures (1/5 atmosphere or less), it makes no splash. Science offers a brief synopsis and fascinating pictures of the phenomenon. The results seem to confirm the (perhaps counterintuitive) prediction that more viscous liquids are more likely to splash, not less likely . Links to the researchers' home page at U of Chicago (as of now, the site is timing out) and pdf version of the article on arxiv can be found on the Science page also."

Migraineman writes "Over the last year or so, archaeologists in Indonesia unearthed skulls and bones from eight proto-humanoids. Critics have claimed the meter-tall specimens were either pygmies or "aberrant individuals with a pathological condition" like microcephaly. A recent article in Science[subscription] rebuffs the critics, and claims that the specimens are actually a new species - Homo floresiensis. There's a summary article over at Nature."

TarrVetus writes "Science Magazine's The Top Ten Science Breakthroughs of 2004 have been announced. The winner: The NASA Rovers and their evidence of water on Mars. The runner up was the Hobbit species found in Indonesia. Other breakthroughs include cloned human embryos and the first discovered pulsar pair."

johkir writes "A seismologist at the University of California Berkeley Seismological Laboratory has discovered mysterious tremors deep under the San Andreas Fault that may help predict future earthquakes. The episodes of tremors, which he calls chatter, last from four to twenty minutes and are being recorded from as deep as 40 kilometers beneath the surface -- up to four times the depth of normal earthquakes! These tremors also seem to occur a few weeks prior to detectable surface tremors. Article is published in Science Magazine, but you'll need a subscription, and it is covered in the San Francisco Chronicle and a UC Berkeley press release."

FredFnord writes "Well, here's an interesting one: the fine folks at Science Magazine have done an analysis of the last ten years' published scientific articles (articles from crank or non-peer-reviewed publications were not counted) on the subject of global climate change. The results themselves are interesting, but the most remarkable part was that, of the 928 papers they found, 75% accepted that global warming was caused by human activities, either explicitly or implicitly. 25% made no mention either way. And not a single paper asserted otherwise." JamesBell submits this article by a geologist which suggests that the Earth is in serious, imminent, unavoidable danger.

FredFnord writes "Well, here's an interesting one: the fine folks at Science Magazine have done an analysis of the last ten years' published scientific articles (articles from crank or non-peer-reviewed publications were not counted) on the subject of global climate change. The results themselves are interesting, but the most remarkable part was that, of the 928 papers they found, 75% accepted that global warming was caused by human activities, either explicitly or implicitly. 25% made no mention either way. And not a single paper asserted otherwise." JamesBell submits this article by a geologist which suggests that the Earth is in serious, imminent, unavoidable danger.

Sox2 writes "SciScoop is running a story about researchers in Germany who claim to have solved the "mystery" surrounding the evolution of the mamalian eye. The work, published in Science, goes some way to answering the issues raised in the "intelligent design" debate that has become the mainstay of creationist thinking."

ahab_2001 writes "Science Magazine and the National Science Foundation have announced the winners of their second annual Science and Engineering Visualization Challenge. The winners and runner-ups -- in categories including photography, illustration, instructional graphics, and interactive and noninteractive multimedia -- are written up in a collection of articles (accompanied by a slide show) on the Science Web site. There's also information about the competition posted at NSF."

ahab_2001 writes "Science Magazine and the National Science Foundation have announced the winners of their second annual Science and Engineering Visualization Challenge. The winners and runner-ups -- in categories including photography, illustration, instructional graphics, and interactive and noninteractive multimedia -- are written up in a collection of articles (accompanied by a slide show) on the Science Web site. There's also information about the competition posted at NSF."

museumpeace writes "David Appell, one of Techonology Review's bloggers, has posted a quick review of Nature Publishing Group's comparison of candidate positions on Science faulting both for various lame answers. That might save you the trouble of reading all the other coverage at NPG, and the more informative articles published by Science. But if you want a heads-up about which kinds of research will thrive or get the ax in the next four years, you might want to slog through "Kerry and Bush offer their views" . Both publications require registration or payment to access most of their content but the science policy debate is being aired out for free."

An anonymous reader writes "The Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany is reporting in Science Magazine today on an example of successful human to non-human communication: Rico, a collie trained on a vocabulary of 200 words. Their conclusion is that 'brain structures that support this kind of learning are not unique to humans...[Rico has a] retrieval rate comparable to the performance of three-year-old toddlers'. In case you ever wondered if your dog understands what you are saying, Rico 'can learn the names of unfamiliar toys after just one exposure to the new word-toy combination.'"

gdyas writes "This week's Science details the discovery and characterization of a new class of proteins found only in squids called reflectins that create a soft, mirror-like surface by forming silvery reflective plates. The squid combines the use of these mirror-proteins with a lens and musculature that allow it to focus the light produced by symbiotic bacteria in its eyes in order to search for food. The possibilities for these proteins in nanotechnology and optics are very intriguing."

quogmire writes "Australia's ABC reports that biologists from the Universities of Finland and Freiburg (Germany) have finally solved the question of lemming population fluctuations once thought to be caused by lemmings mass-suiciding by plunging off cliffs. 'Lemming populations, they say, surge spectacularly and fall just as quickly, thanks to the combined feasting of four predators: the stoat, arctic fox, snowy owl and a seabird called the long-tailed skua.' The original article (Login required) is published in Science."

quogmire writes "Australia's ABC reports that biologists from the Universities of Finland and Freiburg (Germany) have finally solved the question of lemming population fluctuations once thought to be caused by lemmings mass-suiciding by plunging off cliffs. 'Lemming populations, they say, surge spectacularly and fall just as quickly, thanks to the combined feasting of four predators: the stoat, arctic fox, snowy owl and a seabird called the long-tailed skua.' The original article (Login required) is published in Science."

AstroAce writes "I saw this article about the Yucca Mountain Nuclear waste dump, and was doubly intrigued. Not only did I do lab tech work on a YM grant as an undergrad, but my science advisor said the best thing I could do for science would be to become a Congressman, and get hold of the purse strings (remember SSC, the Super-conducting Super Collider?) I think geeks would be the best representatives of other citizens, making detailed, objective analysis of the issues, arriving at rational conclusions and actions. However, they don't seem to be gregarious enough to be politicians. Are there examples of both?"

TheMatt writes "As reported on PhysicsWeb and published in Science (subscription required), researchers at AIST and co-workers believe they have found evidence of magnetic monopoles. They observed an anomalous Hall effect in a ferromagnetic crystal that they say can only be explained via magnetic monopoles. To refresh your memory, magnetic monopoles are the magnetic analogue of electrons and other charged particles--a "north" or "south" pole only. Dirac in 1931 showed that the existence of a magnetic monopole naturally leads to the quantization of electric and magnetic charge. Thus, showing the existence of just one magnetic monopole would be quite profound for physics, but their mass (> 10^16 GeV) has made searches for them difficult."

MadFarmAnimalz writes "Science Magazine's reporting on the results of the NSF's Science and Engineering Visualisation Challenge and the first prize in the Illustrations category has been claimed by the Innolab 3D File Manager, which was developed on linux. Apparently this involves arranging data in a ferris wheel type structure." The data is arranged by its relationship with its content, rather than by its physical position on a hard drive or its file system.

MadFarmAnimalz writes "Science Magazine's reporting on the results of the NSF's Science and Engineering Visualisation Challenge and the first prize in the Illustrations category has been claimed by the Innolab 3D File Manager, which was developed on linux. Apparently this involves arranging data in a ferris wheel type structure." The data is arranged by its relationship with its content, rather than by its physical position on a hard drive or its file system.

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.

Science magazine writer Charles Seife has written a new book, Alpha and Omega: The Search for the Beginning and End of the Universe. According to Publishers Weekly, Charles claims, "Scientists...now know how the universe will end and are on the brink of understanding its beginning. Their findings will be among the greatest triumphs of science, even towering above the deciphering of the human genome." A brave statement! Charles is happy to answer your questions about ongoing research that is busily revealing the basic nature of life, the universe, and everything in a serious (as opposed to humorous) sense, so ask away. One question per post, please. We'll post the answers as soon as we get them beck.

An anonymous reader writes "The world's toughest organism, able to withstand thousands of time more radiation than a human, is reported by the Weizmann Institute to have its secret to survival as a tightly packed DNA ring. Their Science article indicates that radiation-induced breakages are held tightly packed rather than floating off into the intracellular fluid. The bacteria,Deinococcus radiodurans, was discovered decades ago in canned food that was sterilized using radiation. Red patches appeared in the cans - colonies of the bacterium - setting off questions as to how it could have survived."

McLuhanesque writes "The Globe and Mail is reporting the findings of two researchers that "Mating triggers the development of new neurons in the smell centre of the brain, a finding researchers hope will provide clues on how to trick other parts of the vital organ to repair themselves after injuries caused by strokes or head traumas. ... Dr. Weiss and his colleagues discovered that prolactin levels -- and consequently new neuron production -- surge after mating ... And they found that if prolactin was introduced to the blood system by injection, it also stimulated production of new neurons for the olfactory bulb." For those with a subscription to Science, the abstract of the full article is here ."

McLuhanesque writes "The Globe and Mail is reporting the findings of two researchers that "Mating triggers the development of new neurons in the smell centre of the brain, a finding researchers hope will provide clues on how to trick other parts of the vital organ to repair themselves after injuries caused by strokes or head traumas. ... Dr. Weiss and his colleagues discovered that prolactin levels -- and consequently new neuron production -- surge after mating ... And they found that if prolactin was introduced to the blood system by injection, it also stimulated production of new neurons for the olfactory bulb." For those with a subscription to Science, the abstract of the full article is here ."

immerrath writes "The New York Times has an article [Sorry, tomorrow's article, no Google link yet] on a movement that is rapidly gaining support in the scientific community: the Public Library of Science(PLoS). The founders, Nobel Laureate Harold Varmus, Stanford biologist Pat Brown and Berkeley Lab scientist Michael Eisen, argue that scientific literature cannot be privately controlled or owned by the publishers of scientific journals, and must instead be available in public archives freely accessible by anyone and everyone. This has very important implications for the fundamental principle that Science must transcend all economic, national and other barriers. For a while now, PLoS has been trying to get scientific journals to release the rights to scientific papers; many major journals have not complied -- in response, PLoS is starting PLoS-standard-compliant journals (for which they received a $9 million grant from the Gordon and Betty Moore Foundation), to demonstrate the validity of the idea and persuade academic publishers to adopt the free access model. They even have a GPL-like open access Licence, and their journals have some very prominent scientists on the editorial board. Here is the text of an earlier Newsweek article about PLoS, and here is a Nature Public Debate explaining the issues. Michael Eisen received the 2002 Benjamin Franklin award for his work on PLoS. Don't forget to sign the PLoS open letter!"

Seanasy writes "Recent simulations on the Pittsburgh Supercomputing Center's Terascale Computing System suggest that planet formation may take a lot less time than previously thought. The results were published in SCIENCE."

Slashback with a reader review of the IMAX version of Star Wars Episode Two,the continuing courtship of AIM and ICQ, episode 408 of Futurama, and more, including How to go around the world without going anywhere at all. Read on below!

Give me IV any old day. Rupert writes with a review of the newly IMAX-ified Episode II of the Star Wars saga:

"Since it was my wife's birthday today, last night I took her to see Star Wars: Episode II: Attack of the Clones: IMAX edition. Notwithstanding the overuse of colons, this is a movie worth seeing, even if you think you already saw the movie.

If you haven't already seen AotC, you no doubt have your reasons, and there isn't anything in this edition to make you change your mind. Likewise, the plot still has gaping holes and Anakin is still moody, so if those were enough to make you hate this movie, you won't want to see it again. The action sequences gain little from the new presentation, as objects move too fast across the large screen to follow.

On the other hand, if you want to see the pores in Natalie Portman's skin, or the individual hairs in Christopher Lee's beard, this is the movie you've been waiting for. I suspect that some time was spent re-rendering the digital characters. Yoda, Wattoo and Jex Dexter stood out in close up, looking more real than the human actors.

Some scenes were cut from this edition. Some I didn't miss, such as Ani and Amidala frolicking in the meadow with the giant bed bugs. Others, such as almost all the scenes in Palpatine's office, and many of the Jedi Council made it even harder to follow what was going on.

You might be wondering where you can see the movie."

Always cut with the Groenig. ari_j writes "It looks like Fox is giving us a new season of Futurama. From the page, "Season Premiere Sunday, Nov. 10th at 7PM/6C". Sure enough, my local Fox affiliate is carrying it as stated. From tv.yahoo.com: '"Crimes of the Hot", Episode #408.
Al Gore's head holds an emergency summit in Kyoto, Japan, to deal with global warming caused by robot emissions.'"

This does not look good on a resume. nautical9 writes "As a follow up to Henrick Schon's dismissal from Bell Labs last month for falsifying data, many of his former co-authors are retracting their articles from the AAAS's prestigious Science magazine. It's apparently the largest retraction for the journal ever. Bell labs is also pulling six different patent applications of his. Here's the Wired article."

Is this the basket you ordered for all your eggs? With regard to the AOL / ICQ integration CowboyNeal mentioned the other day, nxtw writes "At this moment, ICQ users can send messages to AIM users, but AIM users cannot send messages to ICQ users or be seen on your buddy list. However, AIM automatically postpends any screenname or group consisting of all numbers with -ICQ when added to your buddy list. (This applies to the beta AIM 5.1.3009 client.)"

They're in Australia, of course they have flying dreams. VileScum writes "Back in May a reader posted this story of an Australian Guy who built a 747 Sim in his garage. As reported in the Sydney Morning Hearld The builder and a group of his friends are now doing a round the world sim flight for charity. The full story can be found here. The details of the actual flight can be found here."

sydlexius writes "A press release from Sandia tells of the discovery of niobium HPA, a chemical that bonds to viruses. Many scientists have been interested in the properties of various HPAs (heteropolyanions), however this is the first such case that is stable in basic and neutral solutions. The Albuquerque Tribune covers the story here. For subscribers of Science Magazine, you can find an article in this month's issue (Abstract)."

EReidJ writes "Washingtonpost.com has a story about what biotechnology means to being post-human. While the article gets a little dorky at times, and the comic-book references somewhat over-the-top, it manages to penetrate well past the surface of what most articles would do. (And come on, admit it, how many of us have daydreamed well into our twenties about doing the kinds of things they only comic book heros can do?) They reference a lot of good material, talk to Kurzweil and Max Moore, and use the excellent Science Magazine issue on this subject for a lot of their material."

AtomicBomb writes "First, it was human; now, it is rice. The gene code for the first important crop will soon be (sort of) available. BBC provides us a few more articles. Hopefully, the genetic informatuion can speed up the breeding of tougher and higher-yielding varieties that will benefit the world's burgeoning population..."

nut writes: "The BBC are carrying this story of new type of LED so precise that it can emit just one photon of light each time it is switched on. It has been developed by scientists from Toshiba Research Limited and the University of Cambridge. It is described in the journal Science, although I can find no mention of it on their website. One of the applications of this is supposedly uncrackable encryption, due to the law of indeterminacy. This application is described fully in 'The Code Book', by Simon Singh, although the method was only theoretical at the time the book was first published."

slugfro writes: "Do faster boot times and RAM that maintains memory after shutdown sound interesting? This article by a Science Magazine author details the study of utilizing the spin of electrons rather than just the charge in electronic devices (hence the name 'Spintronics'). Anyone out there researching this or have more info?" We do a story about MRAM every four months or so, and each time commercial development is a few years in the future. :)

Scott_Marks writes: "Science magazine has a review by Pamela Samuelson on the effect of anticircumvention rules on the pursuit of scientific knowledge. The abstract: 'Scientists who study encryption or computer security or otherwise reverse engineer technical measures, who make tools enabling them to do this work, and who report the results of their research face new risks of legal liability because of recently adopted rules prohibiting the circumvention of technical measures and manufacture or distribution of circumvention tools. Because all data in digital form can be technically protected, the impact of these rules goes far beyond encryption and computer security research. The scientific community must recognize the harms these rules pose and provide guidance about how to improve the anticircumvention rules.'"