KentuckyFC (1144503) writes "The halting problem is to determine whether an arbitrary computer program, once started, will ever finish running or whether it will continue forever. In 1936, Alan Turing famously showed that there is no general algorithm that can solve this problem. Now a group of computer scientists and ethicists have used the halting problem to tackle the question of how a weaponised robot could decide to kill a human. Their trick is to reformulate the problem in algorithmic terms by considering an evil computer programmer who writes a piece of software on which human lives depend. The question is whether the software is entirely benign or whether it can ever operate in a way that ends up killing people. In general, a robot could never decide the answer to this question. As a result, autonomous robots should never be designed to kill or harm humans, say the authors, even though various lethal autonomous robots are already available. One curious corollary is that if the human brain is a Turing machine, then humans can never decide this issue either, a point that the authors deliberately steer well clear of."
KentuckyFC (1144503) writes "During the Chinese New Year earlier this year, some 3.6 billion people travelled across China making it the largest seasonal migration on Earth. These kinds of mass movements have always been hard to study in detail. But the Chinese web services company Baidu has managed it using a mapping app that tracked the location of 200 million smartphone users during the New Year period. The latest analysis of this data shows just how vast this mass migration is. For example, over 2 million people left the Guandong province of China and returned just a few days later--that's equivalent to the entire population of Chicago upping sticks. The work shows how easy it is to track the movement of large numbers of people with current technology--assuming they are willing to allow their data to be used in this way."
KentuckyFC (1144503) writes "Back in 1947, a pair of physicists demonstrated that when a beam of light reflects off a surface, the point of reflection can shift forward when parts of the beam interfere with each other. 60 years later, another group of physicists discovered that this so-called Goos-Hanchen effect could sometimes be negative so the point of reflection would back towards the source rather than away from it. They even suggested that if the negative effect could be made big enough, it could cancel out the forward movement of the light. In other words, the light would become trapped at a single location. Now, physicists have demonstrated this effect for the first time using light reflected of a sheet of silica. The trick they've employed is to place a silicon diffraction grating in contact with the silica to make the interference effect large enough to counteract the forward motion of the light. And by using several gratings with different spacings, they've trapped an entire rainbow. The light can be easily released by removing the grating. Until now, it has only been possible to trap light efficiently inside Bose Einstein Condensate at temperatures close to absolute zero. The new technique could be used as a cheap optical buffer or memory, making it an enabling technology for purely optical computing."
KentuckyFC (1144503) writes "It's 20 years since the FDA approved the Flavr Savr tomato for human consumption, the first genetically engineered food to gain this status. Today, roughly 85 per cent of corn and 90 per cent of soybeans produced in the US are genetically modified. So it's easy to imagine that the scientific debate over the safety of genetically modified organisms has been largely settled. Not for Nassim Nicholas Taleb, author of The Black Swan and several academic colleagues who say that the risks have been vastly underestimated. They say that genetically modified organisms threaten harm on a global scale, both to ecosystems and to human health. That's different from many conventional risks that threaten harm on a local scale, like nuclear energy for example. They argue that this global threat means that the precautionary principle ought to be applied to severely limit the way genetically modified organisms can be used."
KentuckyFC (1144503) writes "Earth's closest white dwarf is called van Maanen 2 and sits 14 light years from here. It was discovered by the Dutch astronomer Adriaan van Maanen in 1917, but it was initially hard to classify. That's because its spectra contains lots of heavy elements alongside hydrogen and helium, the usual components of a white dwarf photosphere. In recent years, astronomers have discovered many white dwarfs with similar spectra and shown that the heavy elements come from asteroids raining down onto the surface of the stars. It turns out that all these white dwarfs are orbited by a large planet and an asteroid belt. As the planet orbits, it perturbs the rocky belt causing asteroids to collide and spiral in towards their parent star. This process is so common that astronomers now use the heavy element spectra as a marker for the presence of extrasolar planets. And a re-analysis of van Maanen's work shows that, in hindsight, he was the first to discover the tell-tale signature of extrasolar planets almost a century ago."
KentuckyFC (1144503) writes "One way to explore the link between quantum mechanics and general relativity is to study the physics that occurs on a small scale in highly curved spacetimes. However, these conditions only occur in the most extreme environments such as at the edge of black holes or in the instants after the Big Bang. But now one physicist has described how it is possible to create curved spacetime in an ordinary quantum optics lab. The idea is based on optical lattices which form when a pair of lasers interfere to create an eggbox-like interference pattern. When ultracold atoms are dropped into the lattice, they become trapped like ping pong balls in an eggbox. This optical trapping technique is common in labs all over the world. However, the ultracold atoms do not stay at a fixed location in the lattice because they can tunnel from one location to another. This tunnelling is a form of movement through the lattice and can be controlled by changing the laser parameters to make tunneling easier or more difficult. Now one physicists has shown that on a large scale, the tunneling motion of atoms through the lattice is mathematically equivalent to the motion of atoms in a quantum field in a flat spacetime. And that means it is possible to create a formal analogue of a curved spacetime by changing the laser parameters across the lattice. Varying the laser parameters over time even simulates the behaviour of gravitational waves. Creating this kind of curved spacetime in the lab won't reveal any new physics but it will allow researchers to study the behaviour of existing laws under these conditions for the first time. That's not been possible even in theory because the equations that describe these behaviours are so complex that they can only be solved in the simplest circumstances."
KentuckyFC (1144503) writes "Machine learning algorithms use a training dataset to learn how to recognise features in images and use this 'knowledge' to spot the same features in new images. The computational complexity of this task is such that the time required to solve it increases in polynomial time with the number of images in the training set and the complexity of the "learned" feature. So it's no surprise that quantum computers ought to be able to rapidly speed up this process. Indeed, a group of theoretical physicists last year designed a quantum algorithm that solves this problem in logarithmic time rather than polynomial, a significant improvement. Now, a Chinese team has successfully implemented this artificial intelligence algorithm on a working quantum computer, for the first time. The information processor is a standard nuclear magnetic resonance quantum computer capable of handling 4 qubits. The team trained it to recognise the difference between the characters '6' and '9' and then asked it to classify a set of handwritten 6s and 9s accordingly, which it did successfully. The team say this is the first time that this kind of artificial intelligence has ever been demonstrated on a quantum computer and opens the way to the more rapid processing of other big data sets--provided, of course, that physicists can build more powerful quantum computers."
KentuckyFC (1144503) writes "Since 2001, crowdfunding sites have raised almost $3 billion and in 2012 alone, successfully funded more than 1 million projects. But while many projects succeed, far more fail. The reasons for failure are varied and many but one of the most commonly cited is the inability to match a project with suitable investors. Now a group of researchers from Yahoo Labs and the University of Cambridge have mined data from Kickstarter to discover how investors choose projects to back. They studied over 1000 projects in the US funded by over 80,000 investors. They conclude that there are two types of backers: occasional investors who tend to back arts-related projects, probably because of some kind of social connection to the proposers; and frequent investors who have a much more stringent set of criteria. Frequent investors tend to fund projects that are well-managed, have high pledging goals, are global, grow quickly, and match their interests. The team is now working on a website that will create a list of the Twitter handles of potential investors given the URL of a Kickstarter project"
KentuckyFC (1144503) writes "Photons have many properties such as their frequency, momentum, spin and orbital angular momentum. But when it comes to quantum teleportation, physicists have only ever been able to to transmit one of these properties at a time. So the possibility of teleporting a complete quantum object has always seemed a distant dream. Now a team of Chinese physicists has worked out how to teleport more than one quantum property. The team has demonstrated it by teleporting both the spin and orbital angular momentum of single photons simultaneously. They point out that there is no reason in principle why the technique cannot be generalised to include other properties as well, such as a photon's frequency, momentum and so on. That's an important step towards teleporting complex quantum objects in their entirety, such as atoms, molecules and perhaps even small viruses."
KentuckyFC (1144503) writes "The human visual system has evolved to recognise people in almost any pose under a vast range of lighting conditions. But abstract art pushes this ability to its limits by distorting the human form. In particular, Cubism seeks to represent three-dimensional objects on a two-dimensional plane by juxtaposing snapshots from different angles. The result is that a Cubist picture contains many ‘fragments of perception’ of the same object. That's why it is often hard for people to recognise the human figures that these pictures contain. Now a group of computer scientists have tested how computer vision algorithms fare at the task of spotting human figures in Cubist art. They compared a variety of different algorithms against humans in trying to spot human figures in 218 Cubist paintings by Picasso. Humans easily outperform all the algorithms at this task. But some algorithms were much better than others. The most successful were based on so-called "deformable parts models" that recognise human figures by looking for body parts rather than the entire form. Interestingly, the team says this backs up various studies by neuroscientists suggesting that the human brain works in a similar way."
KentuckyFC (1144503) writes "One way of predicting the future is to study data about events in the past and build a statistical model that generates the same pattern of data. Statisticians can then use the model to generate data about the future. Now one statistician has taken this art to new heights by predicting the content of the soon-to-be published novels in the Song of Ice and Fire series by George R R Martin. The existing five novels are the basis of the hit TV series Game of Thrones. Each chapter in the existing books is told from the point of view of one of the characters. So far, 24 characters have starred in this way. The statistical approach uses the distribution of characters in chapters in the first five books to predict the distribution in the forthcoming novels. The results suggest that several characters will not appear at all and also throw light on whether one important character is dead or not, following an ambiguous story line in the existing novels. However, the model also serves to highlight the shortcomings of purely statistical approaches. For example, it does not 'know' that characters who have already been killed off are unlikely to appear in future chapters. Neither does it allow for new characters that might appear. Nevertheless, this statistical approach to literature could introduce the process of mathematical modelling to more people than any textbook."
KentuckyFC (1144503) writes "Back in the 1970s, the astronauts from Apollos 12. 14. 15 and 16 set up an array of seismometers on the lunar surface to listen for moonquakes. This array sent back data until 1977 when NASA switched it off. Now astrophysicists are using this lunar seismic data in the hunt for gravitational waves. The idea is that gravitational waves must squeeze and stretch the Moon as they pass by and that at certain resonant frequencies, this could trigger the kind of seismic groans that the array ought to have picked up. However, the data shows no evidence of activity at the relevant frequencies. That's important because it has allowed astronomers to put the strongest limits yet on the strength of gravitational waves in this part of the universe. Earlier this year, the same team used a similar approach with terrestrial seismic data to strengthen the existing limits by 9 orders of magnitude. The lunar data betters this by yet another order of magnitude because there is no noise from sources such as oceans, the atmosphere and plate tectonics. The work shows that good science on gravitational waves can be done without spending the hundreds of millions of dollars for bespoke gravitational wave detectors, such as LIGO, which have yet to find any evidence of the waves either."
KentuckyFC (1144503) writes "Underwater vehicles have never matched the extraordinary agility of marine creatures. While many types of fish can travel at speeds of up to 10 body lengths per second, a nuclear sub can manage a less than half a body length per second. Now a team of researchers has copied a trick used by octopuses to build an underwater robot capable of matching the agility of marine creatures. This trick is the way an octopus expands the size of its head as it fills with water and then squirts it out to generate propulsion. The team copied this by building a robot with a flexible membrane that also expands as it fills with water. The fluid then squirts out through a rear-facing nozzle as the membrane contracts. To the team's surprise, the robot reached speeds of 10 body lengths per second with a peak acceleration of 14 body lengths per second squared. That's unprecedented in an underwater vehicle of this kind. What's more, the peak force experienced by the robot was 30 per cent greater than the thrust generated by the jet. The team think they know why and say the new technique could be used to design bigger subs capable of even more impressive octopus-like feats."
KentuckyFC (1144503) writes "It's not just star systems and galaxies that have habitable zones--regions where conditions are suitable for life to evolve. Astrophysicists have now identified the entire universe's habitable zones. Their approach starts by considering the radiation produced by gamma ray bursts in events such as the death of stars and the collisions between black holes and so on. Astrobiologists have long known that these events are capable of causing mass extinctions by stripping a planet of its ozone layer and exposing the surface to lethal levels of radiation. The likelihood of being hit depends on the density of stars, which is why the centre of galaxies are thought to be inhospitable to life. The new work focuses on the threat galaxies pose to each other, which turns out to be considerable when they are densely packed together. Astronomers know that the distribution of galaxies is a kind of web-like structure with dense knots of them connected by filaments interspersed with voids where galaxies are rare. The team says that life-friendly galaxies are most likely to exist in the low density regions of the universe in the voids and filaments of the cosmic web. The Milky Way is in one of these low density regions with Andromeda too far away to pose any threat. But conditions might not be so life friendly in our nearest knot of galaxies called the Virgo supercluster."
KentuckyFC (1144503) writes "A growing number of police forces around the world are using data on past crimes to predict the likelihood of crimes in the future. These predictions can be made more accurate by combining crime data with local demographic data about the local population. However, this data is time consuming and expensive to collect and so only updated rarely. Now a team of data experts have shown how combing crime data with data collected from mobile phones can make the prediction of future crimes even more accurate. The team used an anonymised dataset of O2 mobile phone users in the London metropolitan area during December 2012 and January 2013. They then used a small portion of the data to train a machine learning algorithm to find correlations between this and local crime statistics in the same period. Finally, they used the trained algorithm to predict future crime rates in the same areas. Without the mobile phone data, the predictions have an accuracy of 62 per cent. But the phone data increases this accuracy significantly to almost 70 per cent. What's more, the data is cheap to collect and can be gathered in more or less real time. Whether the general population would want their data used in this way is less clear but either way, Minority Report-style policing is looking less far-fetched than when the film appeared in 2002."