Domain: quantamagazine.org
Stories and comments across the archive that link to quantamagazine.org.
Stories · 43
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A Suite of Digital Cryptography Tools, Released Today, Has Been Mathematically Proven To Be Completely Secure and Free of Bugs (quantamagazine.org)
By making programming more mathematical, a community of computer scientists is hoping to eliminate the coding bugs that can open doors to hackers, spill digital secrets and generally plague modern society. From a report: Now a set of computer scientists has taken a major step toward this goal with the release today of EverCrypt, a set of digital cryptography tools. The researchers were able to prove -- in the sense that you can prove the Pythagorean theorem -- that their approach to online security is completely invulnerable to the main types of hacking attacks that have felled other programs in the past. "When we say proof, we mean we prove that our code can't suffer these kinds of attacks," said Karthik Bhargavan, a computer scientist at Inria in Paris who worked on EverCrypt.
EverCrypt was not written the way most code is written. Ordinarily, a team of programmers creates software that they hope will satisfy certain objectives. Once they finish, they test the code. If it accomplishes the objectives without showing any unwanted behavior, the programmers conclude that the software does what it's supposed to do. Yet coding errors often manifest only in extreme "corner cases" -- a perfect storm of unlikely events that reveals a critical vulnerability. Many of the most damaging hacking attacks in recent years have exploited just such corner cases. -
Extreme CO2 Levels Could Trigger Clouds 'Tipping Point' and 8C of Global Warming (carbonbrief.org)
If atmospheric CO2 levels exceed 1,200 parts per million (ppm), it could push the Earth's climate over a "tipping point", finds a new study. This would see clouds that shade large part of the oceans start to break up. From a report: According to the new paper published in the journal Nature Geoscience, this could trigger a massive 8C rise in global average temperatures -- in addition to the warming from increased CO2. The only similar example of rapid warming at this magnitude in the Earth's recent history is the Paleo-Eocene Thermal Maximum 55m years ago, when global temperatures increased by 5-8C and drove widespread extinction of species on both the oceans and land.
However, scientists not involved in the research caution that the results are still speculative and that other complicating factors could influence if or when a tipping point is reached. The threshold identified by the researchers -- a 1,200ppm concentration of atmospheric CO2 -- is three times current CO2 concentrations. If fossil fuel use continues to rapidly expand over the remainder of the century, it is possible levels could get that high. The Representative Concentration Pathways 8.5 scenario (RCP8.5), a very high emissions scenario examined by climate scientists, has the Earth's atmosphere reaching around 1,100ppm by the year 2100. But this would require the world to massively expand coal use and eschew any climate mitigation over the rest of this century. Further reading: A state-of-the-art supercomputer simulation indicates that a feedback loop between global warming and cloud loss can push Earth's climate past a disastrous tipping point in as little as a century. -
How Nature Defies Math in Keeping Ecosystems Stable (quantamagazine.org)
Paradoxically, the abundance of tight interactions among living species usually leads to disasters in ecological models. New analyses hint at how nature seemingly defies the math. Veronique Greenwood, writing for Quantamagazine: Behind the beautiful facade of a rainforest, a savanna or a placid lake is a world teeming with contests and partnerships. Species are competing for space, consuming one another for resources, taking advantage of one another's talents, and brokering trades of nutrients. But there's something funny about this picture. When ecologists try to model ecosystems using math, they tend to find that the more interactions there are among species, the more unstable the system. For a simple ecosystem model to be stable, all the interactions among its species must be in perfect harmony. Maintaining that balancing act gets much harder, however, as the number of coupled species and the strengths of their interactions rise: Any disturbance or imbalance for one couple ripples outward and sows chaos throughout the network.
Bring in mutualisms, relationships in which species contribute directly to each other's survival, and things can really fly off the handle. Pairs of organisms that live off each other sometimes do so well in the mathematical simulations -- thriving exponentially in extreme cases, in what Robert May, the theoretical ecology pioneer, once called "an orgy of mutual benefaction" -- that everything else can go extinct. It seems unlikely that real ecosystems are quite this flimsy. In a new paper in Nature Communications, a pair of theoretical ecologists at the University of Illinois explored more precisely how the give-and-take in mutualism affects ecosystem stability and how, under the right conditions, it might contribute to it. Their result joins previous work in suggesting how real-world communities manage to be more resilient than the models imply. -
Mystery Math Whiz and Novelist Advance Permutation Problem (quantamagazine.org)
A new proof from the Australian science fiction writer Greg Egan and a 2011 proof anonymously posted online are now being hailed as significant advances on a puzzle mathematicians have been studying for at least 25 years. Erica Klarreich, writing for Quanta Magazine: On September 16, 2011, an anime fan posted a math question to the online bulletin board 4chan about the cult classic television series The Melancholy of Haruhi Suzumiya . Season one of the show, which involves time travel, had originally aired in nonchronological order, and a re-broadcast and a DVD version had each further rearranged the episodes. Fans were arguing online about the best order to watch the episodes, and the 4chan poster wondered: If viewers wanted to see the series in every possible order, what is the shortest list of episodes they'd have to watch? In less than an hour, an anonymous person offered an answer -- not a complete solution, but a lower bound on the number of episodes required. The argument, which covered series with any number of episodes, showed that for the 14-episode first season of Haruhi, viewers would have to watch at least 93,884,313,611 episodes to see all possible orderings. "Please look over [the proof] for any loopholes I might have missed," the anonymous poster wrote.
The proof slipped under the radar of the mathematics community for seven years -- apparently only one professional mathematician spotted it at the time, and he didn't check it carefully. But in a plot twist last month, the Australian science fiction novelist Greg Egan proved a new upper bound on the number of episodes required. Egan's discovery renewed interest in the problem and drew attention to the lower bound posted anonymously in 2011. Both proofs are now being hailed as significant advances on a puzzle mathematicians have been studying for at least 25 years. Mathematicians quickly verified Egan's upper bound, which, like the lower bound, applies to series of any length. Then Robin Houston, a mathematician at the data visualization firm Kiln, and Jay Pantone of Marquette University in Milwaukee independently verified the work of the anonymous 4chan poster. Now, Houston and Pantone, joined by Vince Vatter of the University of Florida in Gainesville, have written up the formal argument. In their paper, they list the first author as "Anonymous 4chan Poster." -
Machine Learning Confronts the Elephant in the Room (quantamagazine.org)
A visual prank exposes an Achilles' heel of computer vision systems: Unlike humans, they can't do a double take. From a report: In a new study [PDF], computer scientists found that artificial intelligence systems fail a vision test a child could accomplish with ease. "It's a clever and important study that reminds us that 'deep learning' isn't really that deep," said Gary Marcus, a neuroscientist at New York University who was not affiliated with the work. The result takes place in the field of computer vision, where artificial intelligence systems attempt to detect and categorize objects. They might try to find all the pedestrians in a street scene, or just distinguish a bird from a bicycle (which is a notoriously difficult task). The stakes are high: As computers take over critical tasks like automated surveillance and autonomous driving, we'll want their visual processing to be at least as good as the human eyes they're replacing.
It won't be easy. The new work accentuates the sophistication of human vision -- and the challenge of building systems that mimic it. In the study, the researchers presented a computer vision system with a living room scene. The system processed it well. It correctly identified a chair, a person, books on a shelf. Then the researchers introduced an anomalous object into the scene -- an image of an elephant. The elephant's mere presence caused the system to forget itself: Suddenly it started calling a chair a couch and the elephant a chair, while turning completely blind to other objects it had previously seen.
"There are all sorts of weird things happening that show how brittle current object detection systems are," said Amir Rosenfeld, a researcher at York University in Toronto and co-author of the study along with his York colleague John Tsotsos and Richard Zemel of the University of Toronto. Researchers are still trying to understand exactly why computer vision systems get tripped up so easily, but they have a good guess. It has to do with an ability humans have that AI lacks: the ability to understand when a scene is confusing and thus go back for a second glance. -
Titans of Mathematics Clash Over Epic Proof of ABC Conjecture (quantamagazine.org)
Two mathematicians have found what they say is a hole at the heart of a proof that has convulsed the mathematics community for nearly six years. Quanta Magazine: In a report [PDF] posted online Thursday, Peter Scholze of the University of Bonn and Jakob Stix of Goethe University Frankfurt describe what Stix calls a "serious, unfixable gap" within a mammoth series of papers by Shinichi Mochizuki, a mathematician at Kyoto University who is renowned for his brilliance. Posted online in 2012, Mochizuki's papers supposedly prove the abc conjecture, one of the most far-reaching problems in number theory. Despite multiple conferences dedicated to explicating Mochizuki's proof, number theorists have struggled to come to grips with its underlying ideas. His series of papers, which total more than 500 pages, are written in an impenetrable style, and refer back to a further 500 pages or so of previous work by Mochizuki, creating what one mathematician, Brian Conrad of Stanford University, has called "a sense of infinite regress."
Between 12 and 18 mathematicians who have studied the proof in depth believe it is correct, wrote Ivan Fesenko of the University of Nottingham in an email. But only mathematicians in "Mochizuki's orbit" have vouched for the proof's correctness, Conrad commented in a blog discussion last December. "There is nobody else out there who has been willing to say even off the record that they are confident the proof is complete." Nevertheless, wrote Frank Calegari of the University of Chicago in a December blog post, "mathematicians are very loath to claim that there is a problem with Mochizuki's argument because they can't point to any definitive error." That has now changed. In their report, Scholze and Stix argue that a line of reasoning near the end of the proof of "Corollary 3.12" in Mochizuki's third of four papers is fundamentally flawed. The corollary is central to Mochizuki's proposed abc proof. "I think the abc conjecture is still open," Scholze said. "Anybody has a chance of proving it." -
Titans of Mathematics Clash Over Epic Proof of ABC Conjecture (quantamagazine.org)
Two mathematicians have found what they say is a hole at the heart of a proof that has convulsed the mathematics community for nearly six years. Quanta Magazine: In a report [PDF] posted online Thursday, Peter Scholze of the University of Bonn and Jakob Stix of Goethe University Frankfurt describe what Stix calls a "serious, unfixable gap" within a mammoth series of papers by Shinichi Mochizuki, a mathematician at Kyoto University who is renowned for his brilliance. Posted online in 2012, Mochizuki's papers supposedly prove the abc conjecture, one of the most far-reaching problems in number theory. Despite multiple conferences dedicated to explicating Mochizuki's proof, number theorists have struggled to come to grips with its underlying ideas. His series of papers, which total more than 500 pages, are written in an impenetrable style, and refer back to a further 500 pages or so of previous work by Mochizuki, creating what one mathematician, Brian Conrad of Stanford University, has called "a sense of infinite regress."
Between 12 and 18 mathematicians who have studied the proof in depth believe it is correct, wrote Ivan Fesenko of the University of Nottingham in an email. But only mathematicians in "Mochizuki's orbit" have vouched for the proof's correctness, Conrad commented in a blog discussion last December. "There is nobody else out there who has been willing to say even off the record that they are confident the proof is complete." Nevertheless, wrote Frank Calegari of the University of Chicago in a December blog post, "mathematicians are very loath to claim that there is a problem with Mochizuki's argument because they can't point to any definitive error." That has now changed. In their report, Scholze and Stix argue that a line of reasoning near the end of the proof of "Corollary 3.12" in Mochizuki's third of four papers is fundamentally flawed. The corollary is central to Mochizuki's proposed abc proof. "I think the abc conjecture is still open," Scholze said. "Anybody has a chance of proving it." -
Fields Medals Awarded To 4 Mathematicians (nytimes.com)
Every four years, at an international gathering of mathematicians, the subject's youngest and brightest are honored with the Fields Medal, often described as the Nobel Prize of mathematics. The New York Times: This year's recipients, announced on Wednesday at the International Congress of Mathematicians in Rio de Janeiro, include one of the youngest ever: Peter Scholze, a professor of mathematics at the University of Bonn who is 30 years old. Two weeks ago, Peter Woit, a professor at Columbia University who blogs about mathematics and physics, was among those who anticipated that Dr. Scholze would receive the medal. Dr. Woit said Dr. Scholze was "by far the most talented arithmetic geometer of his generation." By custom, Fields medals are bestowed to mathematicians 40 years old or younger. That means Dr. Scholze would have still been eligible for another two rounds of medals. The medal, first awarded in 1936, was conceived by John Charles Fields, a Canadian mathematician. The youngest winner, Jean-Pierre Serre in 1954, was 27. The other Fields medalists this year are Caucher Birkar, 40, of the University of Cambridge in England; Alessio Figalli, 34, of the Swiss Federal Institute of Technology in Zurich; and Akshay Venkatesh, 36, of the Institute for Advanced Study in Princeton and Stanford University in California. Peter Scholze's award cites "the revolution that he launched in arithmetic geometry," the study of shapes that arise from the rational-number solutions to polynomial equations (like xy3 + x2 = 1 or x2 â" y3z = 3). More about him here. As a mathematician, Caucher Birkar has helped bring order to the infinite variety of polynomial equations -- those equations that consist of different variables raised to various powers. No two equations are exactly alike, but Birkar has helped reveal that many can be neatly categorized into a small number of families. [As a reader pointed out, Birkar's award was stolen within minutes of him receiving it.] UPDATE (8/4/18): Organizers have announced they'll provide an identical replacement medal.
Once a classics student with no particular affinity for mathematics, Alessio Figalli has gone on to shake the venerable mathematical discipline of analysis, which concerns the properties of certain types of equations. Figalli's results have provided a refined mathematical understanding of everything from the shape of crystals to weather patterns, to the way ice melts in water. Akshay Venkatesh, a former prodigy who struggled with the genius stereotype, has won a Fields Medal for his "profound contributions to an exceptionally broad range of subjects in mathematics." -
Fields Medals Awarded To 4 Mathematicians (nytimes.com)
Every four years, at an international gathering of mathematicians, the subject's youngest and brightest are honored with the Fields Medal, often described as the Nobel Prize of mathematics. The New York Times: This year's recipients, announced on Wednesday at the International Congress of Mathematicians in Rio de Janeiro, include one of the youngest ever: Peter Scholze, a professor of mathematics at the University of Bonn who is 30 years old. Two weeks ago, Peter Woit, a professor at Columbia University who blogs about mathematics and physics, was among those who anticipated that Dr. Scholze would receive the medal. Dr. Woit said Dr. Scholze was "by far the most talented arithmetic geometer of his generation." By custom, Fields medals are bestowed to mathematicians 40 years old or younger. That means Dr. Scholze would have still been eligible for another two rounds of medals. The medal, first awarded in 1936, was conceived by John Charles Fields, a Canadian mathematician. The youngest winner, Jean-Pierre Serre in 1954, was 27. The other Fields medalists this year are Caucher Birkar, 40, of the University of Cambridge in England; Alessio Figalli, 34, of the Swiss Federal Institute of Technology in Zurich; and Akshay Venkatesh, 36, of the Institute for Advanced Study in Princeton and Stanford University in California. Peter Scholze's award cites "the revolution that he launched in arithmetic geometry," the study of shapes that arise from the rational-number solutions to polynomial equations (like xy3 + x2 = 1 or x2 â" y3z = 3). More about him here. As a mathematician, Caucher Birkar has helped bring order to the infinite variety of polynomial equations -- those equations that consist of different variables raised to various powers. No two equations are exactly alike, but Birkar has helped reveal that many can be neatly categorized into a small number of families. [As a reader pointed out, Birkar's award was stolen within minutes of him receiving it.] UPDATE (8/4/18): Organizers have announced they'll provide an identical replacement medal.
Once a classics student with no particular affinity for mathematics, Alessio Figalli has gone on to shake the venerable mathematical discipline of analysis, which concerns the properties of certain types of equations. Figalli's results have provided a refined mathematical understanding of everything from the shape of crystals to weather patterns, to the way ice melts in water. Akshay Venkatesh, a former prodigy who struggled with the genius stereotype, has won a Fields Medal for his "profound contributions to an exceptionally broad range of subjects in mathematics." -
Fields Medals Awarded To 4 Mathematicians (nytimes.com)
Every four years, at an international gathering of mathematicians, the subject's youngest and brightest are honored with the Fields Medal, often described as the Nobel Prize of mathematics. The New York Times: This year's recipients, announced on Wednesday at the International Congress of Mathematicians in Rio de Janeiro, include one of the youngest ever: Peter Scholze, a professor of mathematics at the University of Bonn who is 30 years old. Two weeks ago, Peter Woit, a professor at Columbia University who blogs about mathematics and physics, was among those who anticipated that Dr. Scholze would receive the medal. Dr. Woit said Dr. Scholze was "by far the most talented arithmetic geometer of his generation." By custom, Fields medals are bestowed to mathematicians 40 years old or younger. That means Dr. Scholze would have still been eligible for another two rounds of medals. The medal, first awarded in 1936, was conceived by John Charles Fields, a Canadian mathematician. The youngest winner, Jean-Pierre Serre in 1954, was 27. The other Fields medalists this year are Caucher Birkar, 40, of the University of Cambridge in England; Alessio Figalli, 34, of the Swiss Federal Institute of Technology in Zurich; and Akshay Venkatesh, 36, of the Institute for Advanced Study in Princeton and Stanford University in California. Peter Scholze's award cites "the revolution that he launched in arithmetic geometry," the study of shapes that arise from the rational-number solutions to polynomial equations (like xy3 + x2 = 1 or x2 â" y3z = 3). More about him here. As a mathematician, Caucher Birkar has helped bring order to the infinite variety of polynomial equations -- those equations that consist of different variables raised to various powers. No two equations are exactly alike, but Birkar has helped reveal that many can be neatly categorized into a small number of families. [As a reader pointed out, Birkar's award was stolen within minutes of him receiving it.] UPDATE (8/4/18): Organizers have announced they'll provide an identical replacement medal.
Once a classics student with no particular affinity for mathematics, Alessio Figalli has gone on to shake the venerable mathematical discipline of analysis, which concerns the properties of certain types of equations. Figalli's results have provided a refined mathematical understanding of everything from the shape of crystals to weather patterns, to the way ice melts in water. Akshay Venkatesh, a former prodigy who struggled with the genius stereotype, has won a Fields Medal for his "profound contributions to an exceptionally broad range of subjects in mathematics." -
Fields Medals Awarded To 4 Mathematicians (nytimes.com)
Every four years, at an international gathering of mathematicians, the subject's youngest and brightest are honored with the Fields Medal, often described as the Nobel Prize of mathematics. The New York Times: This year's recipients, announced on Wednesday at the International Congress of Mathematicians in Rio de Janeiro, include one of the youngest ever: Peter Scholze, a professor of mathematics at the University of Bonn who is 30 years old. Two weeks ago, Peter Woit, a professor at Columbia University who blogs about mathematics and physics, was among those who anticipated that Dr. Scholze would receive the medal. Dr. Woit said Dr. Scholze was "by far the most talented arithmetic geometer of his generation." By custom, Fields medals are bestowed to mathematicians 40 years old or younger. That means Dr. Scholze would have still been eligible for another two rounds of medals. The medal, first awarded in 1936, was conceived by John Charles Fields, a Canadian mathematician. The youngest winner, Jean-Pierre Serre in 1954, was 27. The other Fields medalists this year are Caucher Birkar, 40, of the University of Cambridge in England; Alessio Figalli, 34, of the Swiss Federal Institute of Technology in Zurich; and Akshay Venkatesh, 36, of the Institute for Advanced Study in Princeton and Stanford University in California. Peter Scholze's award cites "the revolution that he launched in arithmetic geometry," the study of shapes that arise from the rational-number solutions to polynomial equations (like xy3 + x2 = 1 or x2 â" y3z = 3). More about him here. As a mathematician, Caucher Birkar has helped bring order to the infinite variety of polynomial equations -- those equations that consist of different variables raised to various powers. No two equations are exactly alike, but Birkar has helped reveal that many can be neatly categorized into a small number of families. [As a reader pointed out, Birkar's award was stolen within minutes of him receiving it.] UPDATE (8/4/18): Organizers have announced they'll provide an identical replacement medal.
Once a classics student with no particular affinity for mathematics, Alessio Figalli has gone on to shake the venerable mathematical discipline of analysis, which concerns the properties of certain types of equations. Figalli's results have provided a refined mathematical understanding of everything from the shape of crystals to weather patterns, to the way ice melts in water. Akshay Venkatesh, a former prodigy who struggled with the genius stereotype, has won a Fields Medal for his "profound contributions to an exceptionally broad range of subjects in mathematics." -
The Peculiar Math That Could Underlie the Laws of Nature (quantamagazine.org)
xanthos writes: A fascinating article in Quanta magazine introduces us to Cohl Furey and the eight dimensional mathematics called octonions that she is using to model the interactions of strong and electromagnetic forces.
"Proof surfaced in 1898 that the reals, complex numbers, quaternions and octonions are the only kinds of numbers that can be added, subtracted, multiplied and divided. The first three of these "division algebras" would soon lay the mathematical foundation for 20th-century physics, with real numbers appearing ubiquitously, complex numbers providing the math of quantum mechanics, and quaternions underlying Albert Einstein's special theory of relativity. This has led many researchers to wonder about the last and least-understood division algebra. Might the octonions hold secrets of the universe?"
"In her most recent published paper she consolidated several findings to construct the full Standard Model symmetry group for a single generation of particles, with the math producing the correct array of electric charges and other attributes for an electron, neutrino, three up quarks, three down quarks and their anti-particles. The math also suggests a reason why electric charge is quantized in discrete units -- essentially, because whole numbers are." -
A New World's Extraordinary Orbit Points to Planet Nine (wired.com)
In early 2016, two planetary scientists declared that a ghost planet is hiding in the depths of the solar system, well beyond the orbit of Pluto. Their claim, which they made based on the curious orbits of distant icy worlds, quickly sparked a race to find this so-called Planet Nine -- a planet that is estimated to be about 10 times the mass of Earth. From a report: Now, astronomers are reporting that they have spotted another distant world -- perhaps as large as a dwarf planet -- whose orbit is so odd that it is likely to have been shepherded by Planet Nine. The object confirms a specific prediction made by Konstantin Batygin and Michael Brown, the astronomers at the California Institute of Technology who first argued for Planet Nine's existence. "It's not proof that Planet Nine exists," said David Gerdes, an astronomer at the University of Michigan and a co-author on the new paper. "But I would say the presence of an object like this in our solar system bolsters the case for Planet Nine."
Gerdes and his colleagues spotted the new object in data from the Dark Energy Survey, a project that probes the acceleration in the expansion of the universe by surveying a region well above the plane of the solar system. This makes it an unlikely tool for finding objects inside the solar system, since they mostly orbit within the plane. But that is exactly what makes the new object unique: Its orbit is tilted 54 degrees with respect to the plane of the solar system. It's something Gerdes did not expect to see. Batygin and Brown, however, predicted it. The rocky body is being described as 2015 BP519. Quanta magazine has more details. -
How Einstein Lost His Bearings, and With Them, General Relativity (quantamagazine.org)
Kevin Hartnett, writing for Quanta magazine: Albert Einstein released his general theory of relativity at the end of 1915. He should have finished it two years earlier. When scholars look at his notebooks from the period, they see the completed equations, minus just a detail or two. "That really should have been the final theory," said John Norton, an Einstein expert and a historian of science at the University of Pittsburgh. But Einstein made a critical last-second error that set him on an odyssey of doubt and discovery -- one that nearly cost him his greatest scientific achievement. The consequences of his decision continue to reverberate in math and physics today.
Here's the error. General relativity was meant to supplant Newtonian gravity. This meant it had to explain all the same physical phenomena Newton's equations could, plus other phenomena that Newton's equations couldn't. Yet in mid-1913, Einstein convinced himself, incorrectly, that his new theory couldn't account for scenarios where the force of gravity was weak -- scenarios that Newtonian gravity handled well. "In retrospect, this is just a bizarre mistake," said Norton. To correct this perceived flaw, Einstein thought he had to abandon what had been one of the central features of his emerging theory. Einstein's field equations -- the equations of general relativity -- describe how the shape of space-time evolves in response to the presence of matter and energy. To describe that evolution, you need to impose on space-time a coordinate system -- like lines of latitude and longitude -- that tells you which points are where. Another interesting read on Quanta: Why Stephen Hawking's Black Hole Puzzle Keeps Puzzling. -
How Einstein Lost His Bearings, and With Them, General Relativity (quantamagazine.org)
Kevin Hartnett, writing for Quanta magazine: Albert Einstein released his general theory of relativity at the end of 1915. He should have finished it two years earlier. When scholars look at his notebooks from the period, they see the completed equations, minus just a detail or two. "That really should have been the final theory," said John Norton, an Einstein expert and a historian of science at the University of Pittsburgh. But Einstein made a critical last-second error that set him on an odyssey of doubt and discovery -- one that nearly cost him his greatest scientific achievement. The consequences of his decision continue to reverberate in math and physics today.
Here's the error. General relativity was meant to supplant Newtonian gravity. This meant it had to explain all the same physical phenomena Newton's equations could, plus other phenomena that Newton's equations couldn't. Yet in mid-1913, Einstein convinced himself, incorrectly, that his new theory couldn't account for scenarios where the force of gravity was weak -- scenarios that Newtonian gravity handled well. "In retrospect, this is just a bizarre mistake," said Norton. To correct this perceived flaw, Einstein thought he had to abandon what had been one of the central features of his emerging theory. Einstein's field equations -- the equations of general relativity -- describe how the shape of space-time evolves in response to the presence of matter and energy. To describe that evolution, you need to impose on space-time a coordinate system -- like lines of latitude and longitude -- that tells you which points are where. Another interesting read on Quanta: Why Stephen Hawking's Black Hole Puzzle Keeps Puzzling. -
Two Stars Collided And Solved Half of Astronomy's Problems. Now What? (fivethirtyeight.com)
"It's hard to overstate the enormous leap forward that astronomy took on August 17, 2017," reports an article shared by schwit1: On that day, astronomers bore witness to the titanic collision of two neutron stars, the densest things in the universe besides black holes. In the collision's wake, astronomers answered multiple major questions that have dominated their field for a generation. They solved the origin of gamma-ray bursts, mysterious jets of hardcore radiation that could potentially roast Earth. They glimpsed the forging of heavy metals, like gold and platinum. They measured the rate at which the expansion of the universe is accelerating. They caught light at the same time as gravitational waves, confirmation that waves move at the speed of light. And there was more, and there is much more yet to come from this discovery... "Now it's a question of, do we have the right instrumentation for doing all the follow-up work?" said Edo Berger, an astronomer at Harvard who studies explosive cosmic events. "Do we have the right telescopes? What's going to happen when we have not just one event, but one a month, or one a week -- how do we deal with that flood...?"
The August 17 gravitational wave gave astronomers a glimpse at an entirely different universe. For most of history, they've studied stars and galaxies, which seem static and unchanging from the vantage point of human timescales... But GW170817 revealed a universe alive, pulsating with creation and destruction on human timescales... [T]he event itself unfolded in less than three human-designated weeks. This faster timescale is "pushing the way astronomy is done," Berger said... In space, the Fermi space telescope glimpsed a burst of gamma radiation. Within an hour, astronomers made six independent discoveries of a bright, fast-fading flash: A new phenomenon called a kilonova... Nine days later, X-rays streamed in, and after 16 days, radio waves arrived, too. Each type of information tells astronomers something different. Richard O'Shaughnessy, an astronomer at the Rochester Institute of Technology, describes the discovery as a "Rosetta stone for astronomy."
"What this has done is provide one event that unites all these different threads of astronomy at once," he said. "Like, all our dreams have come true, and they came true now..." Thanks to the August 17 event, astronomers now know what to look for. Soon, they will be able to sift through an embarrassment of neutron-star mergers and other phenomena... And they are talking about how to turn their eyes to the sky, at a moment's notice, the next time the universe throws something big their way. "It's a wonderful time, it's a terrifying time," O'Shaughnessy said. "I can't really capture the wonder and the horror and glee and happiness." -
Two Stars Collided And Solved Half of Astronomy's Problems. Now What? (fivethirtyeight.com)
"It's hard to overstate the enormous leap forward that astronomy took on August 17, 2017," reports an article shared by schwit1: On that day, astronomers bore witness to the titanic collision of two neutron stars, the densest things in the universe besides black holes. In the collision's wake, astronomers answered multiple major questions that have dominated their field for a generation. They solved the origin of gamma-ray bursts, mysterious jets of hardcore radiation that could potentially roast Earth. They glimpsed the forging of heavy metals, like gold and platinum. They measured the rate at which the expansion of the universe is accelerating. They caught light at the same time as gravitational waves, confirmation that waves move at the speed of light. And there was more, and there is much more yet to come from this discovery... "Now it's a question of, do we have the right instrumentation for doing all the follow-up work?" said Edo Berger, an astronomer at Harvard who studies explosive cosmic events. "Do we have the right telescopes? What's going to happen when we have not just one event, but one a month, or one a week -- how do we deal with that flood...?"
The August 17 gravitational wave gave astronomers a glimpse at an entirely different universe. For most of history, they've studied stars and galaxies, which seem static and unchanging from the vantage point of human timescales... But GW170817 revealed a universe alive, pulsating with creation and destruction on human timescales... [T]he event itself unfolded in less than three human-designated weeks. This faster timescale is "pushing the way astronomy is done," Berger said... In space, the Fermi space telescope glimpsed a burst of gamma radiation. Within an hour, astronomers made six independent discoveries of a bright, fast-fading flash: A new phenomenon called a kilonova... Nine days later, X-rays streamed in, and after 16 days, radio waves arrived, too. Each type of information tells astronomers something different. Richard O'Shaughnessy, an astronomer at the Rochester Institute of Technology, describes the discovery as a "Rosetta stone for astronomy."
"What this has done is provide one event that unites all these different threads of astronomy at once," he said. "Like, all our dreams have come true, and they came true now..." Thanks to the August 17 event, astronomers now know what to look for. Soon, they will be able to sift through an embarrassment of neutron-star mergers and other phenomena... And they are talking about how to turn their eyes to the sky, at a moment's notice, the next time the universe throws something big their way. "It's a wonderful time, it's a terrifying time," O'Shaughnessy said. "I can't really capture the wonder and the horror and glee and happiness." -
'To Live Your Best Life, Do Mathematics' (quantamagazine.org)
Excerpts from an article on Quanta Magazine, rearranged for clarity and space: Math conferences don't usually feature standing ovations, but Francis Su received one last month in Atlanta. In his talk he framed mathematics as a pursuit uniquely suited to the achievement of human flourishing, a concept the ancient Greeks called eudaimonia, or a life composed of all the highest goods. Su talked of five basic human desires that are met through the pursuit of mathematics: play, beauty, truth, justice and love. Su opened his talk with the story of Christopher, an inmate serving a long sentence for armed robbery who had begun to teach himself math from textbooks he had ordered. After seven years in prison, during which he studied algebra, trigonometry, geometry and calculus, he wrote to Su asking for advice on how to continue his work. After Su told this story, he asked the packed ballroom at the Marriott Marquis, his voice breaking: "When you think of who does mathematics, do you think of Christopher?" If mathematics is a medium for human flourishing, it stands to reason that everyone should have a chance to participate in it. But in his talk Su identified what he views as structural barriers in the mathematical community that dictate who gets the opportunity to succeed in the field -- from the requirements attached to graduate school admissions to implicit assumptions about who looks the part of a budding mathematician. When Su finished his talk, the audience rose to its feet and applauded, and many of his fellow mathematicians came up to him afterward to say he had made them cry. [...] Mathematics builds skills that allow people to do things they might otherwise not have been able to do or experience. If I learn mathematics and I become a better thinker, I develop perseverance, because I know what it's like to wrestle with a hard problem, and I develop hopefulness that I will actually solve these problems. And some people experience a kind of transcendent wonder that they're seeing something true about the universe. That's a source of joy and flourishing. -
Are Flawed Languages Creating Bad Software? (techcrunch.com)
"Most software, even critical system software, is insecure Swiss cheese held together with duct tape, bubble wrap, and bobby pins..." writes TechCrunch. An anonymous reader quotes their article: Everything is terrible because the fundamental tools we use are, still, so flawed that when used they inevitably craft terrible things... Almost all software has been bug-ridden and insecure for so long that we have grown to think that this is the natural state of code. This learned helplessness is not correct. Everything does not have to be terrible...
Vast experience has shown us that it is unrealistic to expect programmers to write secure code in memory-unsafe languages...as an industry, let's at least set a trajectory. Let's move towards writing system code in better languages, first of all -- this should improve security and speed. Let's move towards formal specifications and verification of mission-critical code.
Their article calls for LangSec testing, and applauds the use of languages like Go and Rust over memory-unsafe languages like C. "Itâ(TM)s not just systemd, not just Linux, not just software; the whole industry is at fault." -
How Richard Feynman's Diagrams Almost Saved Space (quantamagazine.org)
An anonymous Slashdot reader shares a fond remembrance of Richard Feynman written by Nobel prize-winner Frank Wilczek, describing not only the history of dark energy and field theory, but how Feynman's influential diagrams "embody a deep shift in thinking about how the universe is put together... a beautiful new way to think about fundamental processes". Richard Feynman looked tired when he wandered into my office. It was the end of a long, exhausting day in Santa Barbara, sometime around 1982... I described to Feynman what I thought were exciting if speculative new ideas such as fractional spin and anyons. Feynman was unimpressed, saying: "Wilczek, you should work on something real..."
Looking to break the awkward silence that followed, I asked Feynman the most disturbing question in physics, then as now: "There's something else I've been thinking a lot about: Why doesn't empty space weigh anything?"
Feynman replied "I once thought I had that one figured out. It was beautiful..." then launched into a "surreal" monologue about how "there's nothing there!" But Wilczek remembers that "The calculations that eventually got me a Nobel Prize in 2004 would have been literally unthinkable without Feynman diagrams, as would my calculations that established a route to production and observation of the Higgs particle." His article culminates with a truly beautiful supercomputer-generated picture showing gluon field fluctuations as we now understand them today, and demonstrating the kind of computer-assisted calculations which in coming years "will revolutionize our quantitative understanding of nuclear physics over a broad front." -
Mapping The Brain To Build Better Machines (quantamagazine.org)
An anonymous reader quotes a report from Quanta Magazine: An ambitious new program, funded by the federal government's intelligence arm, aims to bring artificial intelligence more in line with our own mental powers. Three teams composed of neuroscientists and computer scientists will attempt to figure out how the brain performs these feats of visual identification, then make machines that do the same. "Today's machine learning fails where humans excel," said Jacob Vogelstein, who heads the program at the Intelligence Advanced Research Projects Activity (IARPA). "We want to revolutionize machine learning by reverse engineering the algorithms and computations of the brain." By the end of the five-year IARPA project, dubbed Machine Intelligence from Cortical Networks (Microns), researchers aim to map a cubic millimeter of cortex. That tiny portion houses about 100,000 neurons, 3 to 15 million neuronal connections, or synapses, and enough neural wiring to span the width of Manhattan, were it all untangled and laid end-to-end. -
New Clues To How the Brain Maps Time (quantamagazine.org)
An anonymous reader sends this excerpt from Quanta Magazine: Our brains have an extraordinary ability to monitor time. A driver can judge just how much time is left to run a yellow light; a dancer can keep a beat down to the millisecond. But exactly how the brain tracks time is still a mystery. Researchers have defined the brain areas involved in movement, memory, color vision and other functions, but not the ones that monitor time. Indeed, our neural timekeeper has proved so elusive that most scientists assume this mechanism is distributed throughout the brain, with different regions using different monitors to keep track of time according to their needs.
Over the last few years, a handful of researchers have compiled growing evidence that the same cells that monitor an individual's location in space also mark the passage of time. This suggests that two brain regions — the hippocampus and the entorhinal cortex, both famous for their role in memory and navigation — can also act as a sort of timer. -
How Computer Scientists Cracked a 50-Year-Old Math Problem (quantamagazine.org)
An anonymous reader writes: Over the decades, the Kadison-Singer problem had wormed its way into a dozen distant areas of mathematics and engineering, but no one seemed to be able to crack it. The question "defied the best efforts of some of the most talented mathematicians of the last 50 years," wrote Peter Casazza and Janet Tremain of the University of Missouri in Columbia, in a 2014 survey article.
As a computer scientist, Daniel Spielman knew little of quantum mechanics or the Kadison-Singer problem's allied mathematical field, called C*-algebras. But when Gil Kalai, whose main institution is the Hebrew University of Jerusalem, described one of the problem's many equivalent formulations, Spielman realized that he himself might be in the perfect position to solve it. "It seemed so natural, so central to the kinds of things I think about," he said. "I thought, 'I've got to be able to prove that.'" He guessed that the problem might take him a few weeks.
Instead, it took him five years. In 2013, working with his postdoc Adam Marcus, now at Princeton University, and his graduate student Nikhil Srivastava, now at the University of California, Berkeley, Spielman finally succeeded. Word spread quickly through the mathematics community that one of the paramount problems in C*-algebras and a host of other fields had been solved by three outsiders — computer scientists who had barely a nodding acquaintance with the disciplines at the heart of the problem. -
The Information Theory of Life (quantamagazine.org)
An anonymous reader writes with this story about Michigan State University Professor Cristop Adami and his quest to answer how life arose with mathematics. From the Quanta story: "Christoph Adami does not know how life got started, but he knows a lot of other things. His main expertise is in information theory, a branch of applied mathematics developed in the 1940s for understanding information transmissions over a wire. Since then, the field has found wide application, and few researchers have done more in that regard than Adami, who is a professor of physics and astronomy and also microbiology and molecular genetics at Michigan State University. He takes the analytical perspective provided by information theory and transplants it into a great range of disciplines, including microbiology, genetics, physics, astronomy and neuroscience. Lately, he's been using it to pry open a statistical window onto the circumstances that might have existed at the moment life first clicked into place.
To do this, he begins with a mental leap: Life, he argues, should not be thought of as a chemical event. Instead, it should be thought of as information. The shift in perspective provides a tidy way in which to begin tackling a messy question. In the following interview, Adami defines information as 'the ability to make predictions with a likelihood better than chance,' and he says we should think of the human genome — or the genome of any organism — as a repository of information about the world gathered in small bits over time through the process of evolution. The repository includes information on everything we could possibly need to know, such as how to convert sugar into energy, how to evade a predator on the savannah, and, most critically for evolution, how to reproduce or self-replicate." -
The Mutant Genes Behind the Black Death
An anonymous reader writes: Each year, 4 million people visit Yosemite National Park in California. Most bring back photos, postcards and an occasional sunburn. But two unlucky visitors this summer got a very different souvenir. They got the plague. This quintessential medieval disease, caused by the bacterium Yersinia pestis and transmitted most often by fleabites, still surfaces in a handful of cases each year in the western United States, according to the Centers for Disease Control and Prevention. Its historical record is far more macabre. The plague of Justinian from 541 to 543 decimated nearly half the population in the Mediterranean, while the Black Death of the Middle Ages killed one in every three Europeans.
Now researchers are beginning to reveal a surprising genetic history of the plague. A rash of discoveries show how just a small handful of genetic changes — an altered protein here, a mutated gene there — can transform a relatively innocuous stomach bug into a pandemic capable of killing off a large fraction of a continent.
The most recent of these studies, published in June, found that the acquisition of a single gene named pla gave Y. pestis the ability to cause pneumonia, causing a form of plague so lethal that it kills essentially all of those infected who don't receive antibiotics. In addition, it is also among the most infectious bacteria known. "Yersinia pestis is a pretty kick-ass pathogen," said Paul Keim, a microbiologist at Northern Arizona University in Flagstaff. "A single bacterium can cause disease in mice. It's hard to get much more virulent than that." -
Tracing the Limits of Computation
An anonymous reader writes: For more than 40 years, researchers had been trying to find a better way to compare two arbitrary strings of characters, such as the long strings of chemical letters within DNA molecules. The most widely used algorithm is slow and not all that clever: It proceeds step-by-step down the two lists, comparing values at each step. If a better method to calculate this "edit distance" could be found, researchers would be able to quickly compare full genomes or large data sets, and computer scientists would have a powerful new tool with which they could attempt to solve additional problems in the field.
Yet in a paper presented at the ACM Symposium on Theory of Computing, two researchers from the Massachusetts Institute of Technology put forth a mathematical proof that the current best algorithm was "optimal" — in other words, that finding a more efficient way to compute edit distance was mathematically impossible. But researchers aren't quite ready to record the time of death. One significant loophole remains. The impossibility result is only true if another, famously unproven statement called the strong exponential time hypothesis (SETH) is also true. -
Cryptographers Brace For Quantum Revolution
Tokolosh writes: An article in Scientific American discusses the actions needed to address the looming advent of quantum computing and its ability to crack current encryption schemes. Interesting tidbits from the article: "'I'm genuinely worried we're not going to be ready in time,' says Michele Mosca, co-founder of the Institute for Quantum Computing (IQC) at the University of Waterloo..." and "Intelligence agencies have also taken notice. On August 11, the US National Security Agency (NSA) revealed its intention to transition to quantum-resistant protocols when it released security recommendations to its vendors and clients." Another concern is "intercept now, decrypt later", which presumably refers to the giant facility in Utah.In related news, an anonymous reader points out that the NSA has updated a page on its website, announcing plans to shift the encryption of government and military data from current cryptographic schemes to new ones that can resist an attack by quantum computers. -
John Conway: All Play and No Work For a Genius
An anonymous reader points out Quanta's spotlight piece on mathematician John Conway, whose best known mathematical contribution is probably his "Game of Life," which has inspired many a screensaver and more than a few computer science careers. From the article: Based at Princeton University, though he found fame at Cambridge (as a student and professor from 1957 to 1987), John Horton Conway, 77, claims never to have worked a day in his life. Instead, he purports to have frittered away reams and reams of time playing. Yet he is Princeton's John von Neumann Professor in Applied and Computational Mathematics (now emeritus). He's a fellow of the Royal Society. And he is roundly praised as a genius. "The word 'genius' gets misused an awful lot," said Persi Diaconis, a mathematician at Stanford University. "John Conway is a genius. And the thing about John is he'll think about anything. He has a real sense of whimsy. You can't put him in a mathematical box." -
New Genes May Arise From Junk DNA
An anonymous reader writes: Junk DNA (or noncoding DNA) is a term for section of a DNA strand that doesn't actually do much. Huge tracts of the human genome consist of junk DNA, and researchers are now finding that it may be more useful than previously thought. "For most of the last 40 years, scientists thought that [gene duplication] was the primary way new genes were born — they simply arose from copies of existing genes. The old version went on doing its job, and the new copy became free to evolve novel functions. Certain genes, however, seem to defy that origin story. They have no known relatives, and they bear no resemblance to any other gene. ... But in the past few years, a once-heretical explanation has quickly gained momentum — that many of these orphans arose out of so-called junk DNA." -
The Connoisseur of Number Sequences
An anonymous reader writes: 75-year-old Neil Sloane is considered by many to be one of the most influential mathematicians of our time, not because of the theorems he's proved, but because of his creation: The Online Encyclopedia of Integer Sequences (OEIS). Quanta Magazine reports: "This giant repository, which celebrated its 50th anniversary last year, contains more than a quarter of a million different sequences of numbers that arise in different mathematical contexts, such as the prime numbers (2, 3, 5, 7, 11 ) or the Fibonacci sequence (0, 1, 1, 2, 3, 5, 8, 13 ). What's the greatest number of cake slices that can be made with n cuts? Look up sequence A000125 in the OEIS. How many chess positions can be created in n moves? That's sequence A048987. The number of ways to arrange n circles in a plane, with only two crossing at any given point, is A250001. That sequence just joined the collection a few months ago. So far, only its first four terms are known; if you can figure out the fifth, Sloane will want to hear from you." -
Newfound Bacteria Expand Tree of Life
An anonymous reader writes: It used to be that to find new forms of life, all you had to do was take a walk in the woods. Now it's not so simple. The most conspicuous organisms have long since been cataloged and fixed on the tree of life, and the ones that remain undiscovered don't give themselves up easily. You could spend all day by the same watering hole with the best scientific instruments and come up with nothing. Maybe it's not surprising, then, that when discoveries do occur, they sometimes come in torrents. Find a different way of looking, and novel forms of life appear everywhere. A team of microbiologists based at the University of California, Berkeley, recently figured out one such new way of detecting life. At a stroke, their work expanded the number of known types — or phyla — of bacteria by nearly 50 percent, a dramatic change that indicates just how many forms of life on earth have escaped our notice so far. -
New Letters Added To the Genetic Alphabet
An anonymous reader writes with this excerpt from Quanta Magazine: [A]fter decades of work, [organic chemist Steven] Benner's team has synthesized artificially enhanced DNA that functions much like ordinary DNA, if not better. In two papers published in the Journal of the American Chemical Society last month, the researchers have shown that two synthetic nucleotides called P and Z fit seamlessly into DNA's helical structure, maintaining the natural shape of DNA. Moreover, DNA sequences incorporating these letters can evolve just like traditional DNA, a first for an expanded genetic alphabet. In fact, the article continues, these new nucleotides can actually outperform their natural counterparts: "When challenged to evolve a segment that selectively binds to cancer cells, DNA sequences using P and Z did better than those without." -
How Dinosaurs Shrank and Became Birds
An anonymous reader writes: Discoveries have shown that bird-specific features like feathers began to emerge long before the evolution of birds, indicating that birds simply adapted a number of pre-existing features to a new use. And recent research suggests that a few simple changes — among them the adoption of a more babylike skull shape into adulthood — likely played essential roles in the final push to bird-hood. Not only are birds much smaller than their dinosaur ancestors, they closely resemble dinosaur embryos. Adaptations such as these may have paved the way for modern birds' distinguishing features, namely their ability to fly and their remarkably agile beaks. The work demonstrates how huge evolutionary changes can result from a series of small evolutionary steps. -
Studying the Roots of Individuality
An anonymous reader sends an article from Quanta Magazine about research into individuality — how behavior varies (or doesn't) when genetics and environment are as similar as possible. Scientists are taking various strains of fruit fly that are genetically almost identical (the result of extreme inbreeding) and raising them alone in environments that are exact copies of each other. Then they run the fruit flies through a series of decision-making tests to see how varied their responses are. Some fruit fly strains show a high degree of variance for tasks like navigating a maze. Other strains show almost no variance, suggesting there's a genetic component to individuality. The scientists also found that manipulating a certain set of neurons in the fruit flies's brains could increase the variation in choices they make. One theory suggests that evolution tends to select for genes that increase individuality by making it more difficult for predators to predict what the prey will do next. -
Wormholes Untangle a Black Hole Paradox
An anonymous reader writes: Like initials carved in a tree, ER = EPR, as the new idea is known, is a shorthand that joins two ideas proposed by Einstein in 1935. One involved the paradox implied by what he called "spooky action at a distance" between quantum particles (the EPR paradox, named for its authors, Einstein, Boris Podolsky and Nathan Rosen). The other showed how two black holes could be connected through far reaches of space through "wormholes" (ER, for Einstein-Rosen bridges). At the time that Einstein put forth these ideas — and for most of the eight decades since — they were thought to be entirely unrelated.
But if ER = EPR is correct, the ideas aren't disconnected — they're two manifestations of the same thing. And this underlying connectedness would form the foundation of all space-time. Quantum entanglement — the action at a distance that so troubled Einstein — could be creating the "spatial connectivity" that "sews space together," according to Leonard Susskind, a physicist at Stanford University and one of the idea's main architects. Without these connections, all of space would "atomize," according to Juan Maldacena, a physicist at the Institute for Advanced Study in Princeton, N.J., who developed the idea together with Susskind. "In other words, the solid and reliable structure of space-time is due to the ghostly features of entanglement," he said. What's more, ER = EPR has the potential to address how gravity fits together with quantum mechanics. -
Concerns of an Artificial Intelligence Pioneer
An anonymous reader writes: In January, the British-American computer scientist Stuart Russell drafted and became the first signatory of an open letter calling for researchers to look beyond the goal of merely making artificial intelligence more powerful. "We recommend expanded research aimed at ensuring that increasingly capable AI systems are robust and beneficial," the letter states. "Our AI systems must do what we want them to do." Thousands of people have since signed the letter, including leading artificial intelligence researchers at Google, Facebook, Microsoft and other industry hubs along with top computer scientists, physicists and philosophers around the world. By the end of March, about 300 research groups had applied to pursue new research into "keeping artificial intelligence beneficial" with funds contributed by the letter's 37th signatory, the inventor-entrepreneur Elon Musk.
Russell, 53, a professor of computer science and founder of the Center for Intelligent Systems at the University of California, Berkeley, has long been contemplating the power and perils of thinking machines. He is the author of more than 200 papers as well as the field's standard textbook, Artificial Intelligence: A Modern Approach (with Peter Norvig, head of research at Google). But increasingly rapid advances in artificial intelligence have given Russell's longstanding concerns heightened urgency. -
Magician Turned Professor Talks About the Math Behind Shuffling Cards
An anonymous reader writes with this story about magician and professor of mathematics and statistics at Stanford University Persi Diaconis. "Now a professor of mathematics and statistics at Stanford University, Diaconis has employed his intuition about cards, which he calls 'the poetry of magic,' in a wide range of settings. Once, for example, he helped decode messages passed between inmates at a California state prison by using small random 'shuffles' to gradually improve a decryption key. He has also analyzed Bose-Einstein condensation — in which a collection of ultra-cold atoms coalesces into a single 'superatom' — by envisioning the atoms as rows of cards moving around. This makes them 'friendly,' said Diaconis, whose speech still carries the inflections of his native New York City. 'We all have our own basic images that we translate things into, and for me cards were where I started.' In 1992, Diaconis famously proved — along with the mathematician Dave Bayer of Columbia University — that it takes about seven ordinary riffle shuffles to randomize a deck. Over the years, Diaconis and his students and colleagues have successfully analyzed the effectiveness of almost every type of shuffle people use in ordinary life." -
Strange Stars Pulse To the Golden Mean
An anonymous reader sends this excerpt from an article at Quanta Magazine: What struck John Learned about the blinking of KIC 5520878, a bluish-white star 16,000 light-years away, was how artificial it seemed. Learned, a neutrino physicist at the University of Hawaii, Mnoa, has a pet theory that super-advanced alien civilizations might send messages by tickling stars with neutrino beams, eliciting Morse code-like pulses. "It's the sort of thing tenured senior professors can get away with," he said. The pulsations of KIC 5520878, recorded recently by NASA's Kepler telescope, suggested that the star might be so employed.
A "variable" star, KIC 5520878 brightens and dims in a six-hour cycle, seesawing between cool-and-clear and hot-and-opaque. Overlaying this rhythm is a second, subtler variation of unknown origin; this frequency interplays with the first to make some of the star's pulses brighter than others. In the fluctuations, Learned had identified interesting and, he thought, possibly intelligent sequences, such as prime numbers (which have been floated as a conceivable basis of extraterrestrial communication). He then found hints that the star's pulses were chaotic. But when Learned mentioned his investigations to a colleague, William Ditto, last summer, Ditto was struck by the ratio of the two frequencies driving the star's pulsations. "I said, 'Wait a minute, that's the golden mean.'" -
Game Theory Calls Cooperation Into Question
An anonymous reader sends this excerpt from Quanta Magazine: The physicist Freeman Dyson and the computer scientist William Press, both highly accomplished in their fields, have found a new solution to a famous, decades-old game theory scenario called the prisoner's dilemma, in which players must decide whether to cheat or cooperate with a partner. The prisoner's dilemma has long been used to help explain how cooperation might endure in nature. After all, natural selection is ruled by the survival of the fittest, so one might expect that selfish strategies benefiting the individual would be most likely to persist. But careful study of the prisoner's dilemma revealed that organisms could act entirely in their own self-interest and still create a cooperative community.
Press and Dyson's new solution to the problem, however, threw that rosy perspective into question (abstract). It suggested the best strategies were selfish ones that led to extortion, not cooperation.
[Theoretical biologist Joshua] Plotkin found the duo's math remarkable in its elegance. But the outcome troubled him. Nature includes numerous examples of cooperative behavior. For example, vampire bats donate some of their blood meal to community members that fail to find prey. Some species of birds and social insects routinely help raise another's brood. Even bacteria can cooperate, sticking to each other so that some may survive poison. If extortion reigns, what drives these and other acts of selflessness?" -
Quantum Computing Without Qubits
An anonymous reader shares this interview with quantum computing pioneer Ivan Deutsch. "For more than 20 years, Ivan H. Deutsch has struggled to design the guts of a working quantum computer. He has not been alone. The quest to harness the computational might of quantum weirdness continues to occupy hundreds of researchers around the world. Why hasn't there been more to show for their work? As physicists have known since quantum computing's beginnings, the same characteristics that make quantum computing exponentially powerful also make it devilishly difficult to control. The quantum computing 'nightmare' has always been that a quantum computer's advantages in speed would be wiped out by the machine's complexity. Yet progress is arriving on two main fronts. First, researchers are developing unique quantum error-correction techniques that will help keep quantum processors up and running for the time needed to complete a calculation. Second, physicists are working with so-called analog quantum simulators — machines that can't act like a general-purpose computer, but rather are designed to explore specific problems in quantum physics. A classical computer would have to run for thousands of years to compute the quantum equations of motion for just 100 atoms. A quantum simulator could do it in less than a second." -
Machine Learning Reveals Genetic Controls
An anonymous reader writes with this quote from Quanta Magazine: Most genetic research to date has focused on just 1 percent of the genome — the areas that code for proteins. But new research, published today in Science, provides an initial map for the sections of the genome that orchestrate this protein-building process. "It's one thing to have the book — the big question is how you read the book," said Brendan Frey, a computational biologist at the University of Toronto who led the new research (abstract).
For example, researchers can use the model to predict what will happen to a protein when there’s a mistake in part of the regulatory code. Mutations in splicing instructions have already been linked to diseases such as spinal muscular atrophy, a leading cause of infant death, and some forms of colorectal cancer. In the new study, researchers used the trained model to analyze genetic data from people afflicted with some of those diseases. The scientists identified some known mutations linked to these maladies, verifying that the model works. They picked out some new candidate mutations as well, most notably for autism.
One of the benefits of the model, Frey said, is that it wasn’t trained using disease data, so it should work on any disease or trait of interest. The researchers plan to make the system publicly available, which means that scientists will be able to apply it to many more diseases. -
A Common Logic To Seeing Cats and the Cosmos
An anonymous reader sends this excerpt from Quanta Magazine: "Using the latest deep-learning protocols, computer models consisting of networks of artificial neurons are becoming increasingly adept at image, speech and pattern recognition — core technologies in robotic personal assistants, complex data analysis and self-driving cars. But for all their progress training computers to pick out salient features from other, irrelevant bits of data, researchers have never fully understood why the algorithms or biological learning work.
Now, two physicists have shown that one form of deep learning works exactly like one of the most important and ubiquitous mathematical techniques in physics, a procedure for calculating the large-scale behavior of physical systems such as elementary particles, fluids and the cosmos. The new work, completed by Pankaj Mehta of Boston University and David Schwab of Northwestern University, demonstrates that a statistical technique called "renormalization," which allows physicists to accurately describe systems without knowing the exact state of all their component parts, also enables the artificial neural networks to categorize data as, say, "a cat" regardless of its color, size or posture in a given video.
"They actually wrote down on paper, with exact proofs, something that people only dreamed existed," said Ilya Nemenman, a biophysicist at Emory University. -
Dwarf Galaxies Dim Hopes of Dark Matter
An anonymous reader writes Once again, a shadow of a signal that scientists hoped would amplify into conclusive evidence of dark matter has instead flatlined, repeating a maddening refrain in the search for the invisible, omnipresent particles. The Fermi Large Area Telescope (LAT) failed to detect the glow of gamma rays emitted by annihilating dark matter in miniature "dwarf" galaxies that orbit the Milky Way, scientists reported Friday at a meeting in Nagoya, Japan. The hint of such a glow showed up in a Fermi analysis last year, but the statistical bump disappeared as more data accumulated. "We were obviously somewhat disappointed not to see a signal," said Matthew Wood, a postdoctoral researcher at Stanford University who was centrally involved the Fermi-LAT collaboration's new analysis, in an email.