Slashdot Mirror
Domain: medium.com
Stories and comments across the archive that link to medium.com.
Stories · 570
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How Earth's Biosignature Will Change As the Planet Dies
KentuckyFC writes "As the Sun expands into a red giant, life on Earth will die away. Now astrobiologists have worked out how this will look to distant observers watching the biosignature in our atmosphere. They say the first major effect of warming, about 1 billion years from now, will be a dramatic drop in atmospheric carbon dioxide as the oceans absorb more of it. That's bad news for trees and plants, which need carbon dioxide for photosynthesis, so they begin to die off. Since plants produce oxygen, atmospheric levels of oxygen will also drop, killing off the animals. Roughly 2 billion years from now, the only living things on Earth will be microbes. However, methane levels will have risen dramatically, caused by decaying plant matter. And decaying animals will release a gas called methanethiol, which breaks down into ethane, which ought to be visible too. Finally, they calculate that about 3 billion years from now, the oceans will boil and Earth will be a barren planet with little if any biosignature at all. But all this is not just a subject of morbid fascination. With the next generation of space telescopes, astronomers should see similar biosignatures on Earth-like planets around other stars that are also beyond their sell-by dates. So we'll be able to watch them die off first." -
Network Scientists Discover the 'Dark Corners' of the Internet
KentuckyFC writes "Network theorists have always simulated the spread of information through the internet using the same models epidemiologists use to study the spread of disease. Now Chinese scientists say this isn't quite right--it's easy to infect everybody you meet with a disease but it's much harder to inform all your contacts of a particular piece of information. So they've redone the conventional network simulations assuming that people only ever transmit messages to a certain fraction of their friends. And their results throw up a surprise. In these models, there are always individuals or clusters of individuals who are unreachable. These people never receive the information and make up a kind of underclass who eke out an information-poor existence in a few dark corners of the network. That has implications for organizations aiming to spread ideas who will have to think more carefully about how to reach people in these dark corners. That includes marketers and advertisers hoping to sell products and services but also agencies hoping to spread different kinds of messages such as safety-related information. It also raises the interesting prospect of individuals seeking out the dark corners of the internet, perhaps to preserve their privacy or perhaps for more nefarious reasons." -
How Safe Is Cycling?
theodp writes "With new bike sharing programs all the rage, spending tens of millions of dollars to make city streets more bike friendly with hundreds of miles of bike lanes has become a priority for bike-loving mayors like NYC's Michael Bloomberg and Chicago's Rahm Emanuel. 'You cannot be for a startup, high-tech economy and not be pro-bike,' claimed Emanuel, who credited bike-sharing and bike lanes for attracting Google and Motorola Mobility to downtown Chicago. Now, with huge bike-sharing contracts awarded and programs underway, the NY Times asks the big question, How Safe Is Cycling? Because bike accidents rarely make front page news and are likely to be dramatically underreported, it's hard to say, concludes the NYT's Gina Kolata. UCSF trauma surgeon Dr. Rochelle Dicker, who studied hospital and police records for 2,504 bicyclists treated at San Francisco General Hospital, told Kolata,'Lots of my colleagues do not want to ride after seeing these [city biking] injuries.' On the other hand, Andy Pruitt, the founder of the Boulder Center for Sports Medicine and an avid lifelong cyclist, said the dangers were overstated, noting he's only broken his collarbone twice and hip once in four decades of long-distance cycling. So, is cycling safe, especially in the city? And is it OK to follow Mayor Emanuel's lead and lose the helmet?" -
First Experimental Evidence That Time Is an Emergent Quantum Phenomenon
KentuckyFC writes "One of the great challenges in physics is to unite the theories of quantum mechanics and general relativity. But all attempts to do this all run into the famous 'problem of time' — the resulting equations describe a static universe in which nothing ever happens. In 1983, theoreticians showed how this could be solved if time is an emergent phenomenon based on entanglement, the phenomenon in which two quantum particles share the same existence. An external, god-like observer always sees no difference between these particles compared to an external objective clock. But an observer who measures one of the pair — and so becomes entangled with it--can immediately see how it evolves differently from its partner. So from the outside the universe appears static and unchanging, while objects that are entangled within it experience the maelstrom of change. Now quantum physicists have performed the first experimental test of this idea by measuring the evolution of a pair of entangled photons in two different ways. An external god-like observer sees no difference while an observer who measures one particle and becomes entangled with it does see the change. In other words, the experiment shows how time is an emergent phenomenon based on entanglement, in which case the contradiction between quantum mechanics and general relativity seems to melt away." -
Physicist Unveils a 'Turing Test' For Free Will
KentuckyFC writes "The problem of free will is one of the great unsolved puzzles in science, not to mention philosophy, theology, jurisprudence and so on. The basic question is whether we are able to make decisions for ourselves or whether the outcomes are predetermined and the notion of choice is merely an illusion. Now a leading theoretical physicist has outlined a 'Turing Test' for free will and says that while simple devices such as thermostats cannot pass, more complex ones like iPhones might. The test is based on an extension of Turing's halting problem in computer science. This states that there is no general way of knowing how an algorithm will finish, other than to run it. This means that when a human has to make a decision, there is no way of knowing in advance how it will end up. In other words, the familiar feeling of not knowing the final decision until it is thought through is a necessary feature of the decision-making process and why we have the impression of free will. This leads to a simple set of questions that forms a kind of Turing test for free will. These show how simple decision-making devices such as thermostats cannot believe they have free will while humans can. A more interesting question relates to decision-makers of intermediate complexity, such as a smartphone. As the author puts it, this 'seems to possess all the criteria required for free will, and behaves as if it has it.'" -
Black Death Predated 'Small World' Effect, Say Network Theorists
KentuckyFC writes "Epidemiologists know that modern diseases can spread almost simultaneously in different parts of the planet because an individual who becomes infected in Hong Kong, for example, can infect friends in New York the following day. This is known as the small world effect. It is the same property that allows any individual to link to another individual anywhere in the world in just a few steps. But in the 14th century, the Black Death spread in a very different way, moving slowly across Europe at a rate of about 2 kilometers a day. Now network theorists have simulated this spread and say it is only possible if the number of long distances travelers in those days was vanishingly small. In other words, people in medieval society were linked almost exclusively to others nearby and so did not form a small world network. That raises an interesting question. If society in 14th century Europe was not a small world but today's society is, when did the change occur? The researchers say the finger of blame points to the invention of railways and steamships which allowed large numbers of people, and the diseases they carried, to travel long distances for the first time." -
US Nuclear Weapons Lab Discovers How To Suppress the Casimir Force
KentuckyFC writes "One of the frustrating problems with microelectromechanical (MEM) devices is that the machinery can sometimes stick fast, causing them to stop working. One of the culprits is the Casimir effect — an exotic force that pushes metallic sheets together when they are separated by tiny distances. Now physicists at the Los Alamos National Laboratory in New Mexico have worked out and demonstrated how to suppress the Casimir force. The trick is to create a set of deep grooves and ridges in the surface of one sheet so that the other only comes close to the tips of the ridges. These tips have a much smaller surface area than the flat sheet and so generate much less force. That could help prevent stiction in future MEMs devices. But why would a nuclear weapons lab be interested? MEM devices are invulnerable to electromagnetic pulse weapons that fry transistor-based switches, and so could be used as on-off switches for nuclear devices." -
When Does the Universe Compute?
KentuckyFC writes "The idea that every physical event is a computation has spread like wildfire through science. That has triggered an unprecedented interest in unconventional computing such as quantum computing, DNA computing and even the ability of a single-celled organism, called slime mold, to solve mazes. However, that may need to change now that physicists have worked out a formal way of distinguishing between systems that compute and those that don't. One key is the ability to encode and decode information. 'Without the encode and decode steps, there is no computation; there is simply a physical system undergoing evolution,' they say. That means computers must be engineered systems based on well understood laws of physics that can be used to predict the outcome of an abstract evolution. So slime mold fails the test while most forms of quantum computation pass." -
Data Mining Reveals the Emotional Differences In Emails From Men and Women
KentuckyFC writes "Sentiment analysis relies on vast databases of common words which are marked as positive, negative or neutral and associated with one of the eight fundamental emotions: joy, trust, fear, surprise, sadness, discuss, anger and anticipation. It is then a straightforward matter to search Tweets, novels and even fairy tales to see what emotions appear. Now, researchers have carried out the first large-scale study of sentiment in workplace emails. They examined the emotions associated with words in over 30,000 emails and analyzed the emotional differences between messages sent by men and women. It turns out that women use more cheerful words in emails than men, that men use more fear words, especially when communicating with other men, and that both men and women are far more likely to use anticipation words when emailing a member of the opposite sex. The same researchers say they are developing a Google app that will allow users to track their own emotions towards the people they correspond with in Gmail. And they plan to make a public call for volunteers willing to share their data for research purposes." -
Voyager 1 May Be Caught Inside an Interstellar Flux Transfer Event
KentuckyFC writes "Last month, NASA declared that Earth's most distant probe had finally left the Solar System. But the announcement may now turn out to be premature. It was prompted by a dramatic increase in the density of plasma in the region of space the spacecraft is now in. However, there has been no change in the local magnetic field, which is what astrophysicists would expect if Voyager had entered interstellar space. Instead, space scientists think the probe may be caught inside a magnetic portal known as an interstellar flux transfer event. This occurs when the magnetic fields from two different objects briefly become connected through a tube-like magnetic structure. This process happens between the Earth and Sun's magnetic field about every eight minutes, so similar events are expected between the Sun's field and the interstellar field. This magnetic tube would allow particles in from outside the Solar System, increasing the density of plasma, while maintaining the same magnetic field. If so, Voyager 1 hasn't yet left the Solar System after all." -
Text Analyzer Reveals Emotional 'Temperature' of Novels and Fairy Tales
KentuckyFC writes "Stories are a powerful channel for communicating emotions. But while they have been studied in detail by generations of critics, there is little in the way of objective tools for analyzing and comparing their emotional content. That looks set to change thanks to one data mining researcher who has applied the process of sentiment analysis to novels and fairy tales that have been digitized on Project Gutenburg and the Google Books Corpus. The results show the density of emotions in different parts of a story and how the emotional 'temperature' changes throughout the tale. For example, this guy has used the technique to compare the emotional content of the entire collection of the Brothers Grimm fairy tales to reveal that the darkest story is a tale called Gambling Hansel; clearly a lesson to us all." -
Wealth In Africa Mapped Using Mobile Phone Data
KentuckyFC writes "The remarkable growth of mobile phone use is transforming many parts of Africa. In Sudan and Gabon, more than half of all adults use their phones to transfer money, the activist website Ushahidi used text messages to map post-election violence in Kenya in 2008 and in Nigeria, mobile music services are a multi-million dollar industry. Now demographers have used the way people purchase airtime to map wealth in Cote d'Ivoire on Africa's west coast. They analysed a dataset from one of the country's largest mobile operators containing caller IDs, the cell towers used for each call and the time and amount of all airtime purchases. The researchers say an individual's airtime buying habits are a good proxy for his or her income. As a result, they were able to to map wealth across the entire country. Their map clearly shows the wealthy cities such as Abidjan, the largest seaport in West Africa. But it also shows an unexpectedly wealthy region in the conflict-ridden area that borders Liberia. This wealth probably arises from illegal activities on the border, such as drug, arms and human trafficking, they conclude." -
"Ballooning" Spiders Use Electrostatic Forces To Generate Lift
KentuckyFC writes "Many types of small spider release threads into the air which then lift and carry them significant distances. Biologists have found them at altitudes of up to 4 km. The conventional thinking is that the threads catch thermal air currents which then carry them away but this does not explain how spiders perform their trick even when there is little or no wind. Now one physicist says the explanation is the atmosphere's natural electric field which has an average downward-pointing magnitude of 120 Volts per metre. He calculates that a strand of silk need only gain a negative charge of around 30 nanoCoulombs to lift a spider. That explains how the spiders take off on windless days, how they reach such great heights and how several strands can lift heavier spiders of up to 100 milligrams." -
"Synthetic Tracking" Makes It Possible to Find Millions of Near Earth Asteroids
KentuckyFC writes "Astronomers think that near-Earth Asteroids the size of apartment blocks number in the millions. And yet they spot new ones at the rate of only about 30 a year because these objects are so faint and fast moving. Now astronomers at the Jet Propulsion Laboratory have developed a technique called synthetic tracking for dramatically speeding up asteroid discovery. Insteads of long exposures in which near-Earth asteroids show up as faint streaks, the new technique involves taking lots of short exposures and adding them together in a special automated way. The trick is to shift each image so that the pixels that record the asteroid are superimposed on top of each other. The result is an image in which the asteroid is sharp point of light against a background of star streaks. They say synthetic tracking has the capability to spot 80 new near Earth asteroids each night using a standard 5 metre telescope. That'll be handy for spotting rocks heading our way before they get too close and for identifying targets for NASA's future asteroid missions." -
True Size of the Shadow Banking System Revealed (Spoiler: Humongous)
KentuckyFC writes "The banking system is closely regulated and monitored by central banks and other government agencies. But it has become common practice for banks to get around this by doing business in ways that don't show up on conventional balance sheets. This so-called shadow banking system is thought to be huge, but nobody knows exactly how big. Now three econophysicists have discovered that the size distribution of the world's largest financial firms significantly differs from the size distribution of smaller ones or indeed non-financial firms. And they hypothesize that the difference is the result of the hidden transactions that make up the shadow banking system. By this new measure, the shadow banking system has grown dramatically since the financial crisis and was worth over $100 trillion in 2012, significantly more than had been thought and more even than the GDP of the entire planet. Nothing to worry about, then." -
Black Holes Grow By Eating Quantum Foam
An anonymous reader writes "The discovery that even the most distant galaxies have supermassive black holes at their cores is a puzzle for astrophysicists. These objects must have formed relatively soon after the Big Bang. But if a galaxy is only a billion years old and contains a black hole that is a billion times more massive than the Sun, how did it get so big, so quickly? Now one cosmologist says he has the answer: black holes feed off the quantum foam that makes up the fabric of spacetime. This foam is 'nourishing' because it contains quantum black holes that can contribute to the black hole's growth. This idea leads to a prediction: that the supermassive black hole at the center of the Milky Way must also be growing in this way and at a rate that we should be able to measure. Just watch out for the burps." -
Humans Choose Friends With Similar DNA
KentuckyFC writes "The study of social networks has long shown that people tend to pick friends who are similar to them — birds of a feather stick together (PDF). Now a study of the genomes of almost 2000 Americans has found that those who are friends also share remarkable genetic similarities. 'Pairs of friends are, on average, as genetically similar to one another as fourth cousins,' the study concludes. By contrast, strangers share few genetic similarities. The result seems to confirm a 30-year-old theory that a person's genes causes them to seek out circumstances that are compatible with their phenotype. If that's the case, then people with similar genes should end up in similar environments and so be more likely to become friends." -
Surveillance Story Turns Into a Warning About Employer Monitoring
rtfa-troll writes "The story from yesterday about the Feds monitoring Google searches has turned into a warning about how work place surveillance could harm you. It turns out that Michele Catalano's husband's boss tipped off the police after finding 'suspicious' searches (including 'pressure cooker bombs') in his old work computer's search history. Luckily for the Catalanos, who even allowed a search of their house when they probably didn't have to, it seems the policemen and FBI agents were professional and friendly. Far from being imperiled by a SWAT raid, Catalano spoke to some men in black cars who were polite and even mentioned to Catalano that 99 times out of 100, these tip-offs come to nothing. Perhaps the lesson is to be a bit more careful about your privacy, so that what you do on the internet remains between you and the professionals at the NSA." -
YouTube Removes Video of Reactions To Being Videoed
theodp writes "To follow-up on an earlier Slashdot post, GeekWire reports that YouTube has removed Surveillance Camera Man's latest video of people's sometimes-violent reactions to being videoed, citing its policy of prohibiting content designed to harass, threaten or bully ("This video has been removed as a violation of YouTube's policy prohibiting content designed to harass, bully or threaten"). In a neat coincidence, the YouTube ban comes just after similar complaints were lodged against Google Glass. 'Some people also seem to feel threatened by Google Glass,' Philip De Cortes wrote in Google Glass Will Fail. 'They wonder if they're being recorded, and they feel like the tool could be used against them in some way.'" -
Mitigating Password Re-Use From the Other End
An anonymous reader writes "Jen Andre, software engineer and co-founder of Threat Stack, writes about the problem of password breaches in the wake of the LivingSocial hack. She notes that the problem here is longstanding — it's easy for LivingSocial to force password resets, but impossible to get users to create different passwords for each site they visit. We've tried education, and it's failed. Andre suggests a different approach: building out better auditing infrastructure. 'We, as an industry, need a standard for auditing that allows us to reliably track and record authentication events. Since authentication events are relatively similar across any application, I think this could be accomplished easily with a simple JSON-based common protocol and webhooks. ... [It] could even be a hosted service that learns based on my login behaviors and only alerts me when it thinks a login entry is suspicious— kind of how Gmail will alert if I am logging in from a strange location. Because these audit entries are stored on a third-party box, if a certain web application is compromised, it won't have access to alter its audit log history since it lives somewhere else.'"