Category Archives: Science

What does it mean to preserve nature in the Age of Humans?

By Ben A Minteer, Arizona State University and Stephen Pyne, Arizona State University

Is the Earth now spinning through the “Age of Humans?” More than a few scientists think so. They’ve suggested, in fact, that we modify the name of the current geological epoch (the Holocene, which began roughly 12,000 years ago) to the “Anthropocene.” It’s a term first put into wide circulation by Nobel-Prize winning atmospheric chemist Paul Crutzen in an article published in Nature in 2002. And it’s stirring up a good deal of debate, not only among geologists.

The idea is that we needed a new planetary marker to account for the scale of human changes to the Earth: extensive land transformation, mass extinctions, control of the nitrogen cycle, large-scale water diversion, and especially change of the atmosphere through the emission of greenhouse gases. Although naming geological epochs isn’t usually a controversial act, the Anthropocene proposal is radical because it means that what had been an environmental fixture against which people acted, the geological record, is now just another expression of the human presence.

It seems to be a particularly bitter pill to swallow for nature preservationists, heirs to the American tradition led by writers, scientists and activists such as John Muir, Aldo Leopold, David Brower, Rachel Carson and Edward Abbey. That’s because some have argued the traditional focus on the goal of wilderness protection rests on a view of “pristine” nature that is simply no longer viable on a planet hurtling toward nine billion human inhabitants.

Given this situation, we felt the time was ripe to explore the impact of the Anthropocene on the idea and practice of nature preservation. Our plan was to create a salon, a kind of literary summit. But we wanted to cut to the chase: What does it mean to “save American nature” in the age of humans?

We invited a distinguished group of environmental writers – scientists, philosophers, historians, journalists, agency administrators and activists – to give it their best shot. The essays appear in the new collection, After Preservation: Saving American Nature in the Age of Humans.

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Climate scientists need to produce more ‘actionable science’

John Upton writes: When a San Francisco panel began mulling rules about building public projects near changing shorelines, its self-described science translator, David Behar, figured he would just turn to the U.N.’s most recent climate assessment for guidance on future sea levels.

He couldn’t.

Nor could Behar, leader of the city utility department’s climate program, get what he needed from a 2012 National Research Council report dealing with West Coast sea level rise projections. A National Climate Assessment paper dealing with sea level rise didn’t seem to have what he needed, either. Even after reviewing two California government reports dealing with sea level rise, Behar says he had to telephone climate scientists and review a journal paper summarizing the views of 90 experts before he felt confident that he understood science’s latest projections for hazards posed by the onslaught of rising seas.

“You sometimes have to interview the authors of these reports to actually understand what they’re saying,” Behar said. “On the surface,” the assessments and reports that Behar turned to “all look like they’re saying different things,” he said. “But when you dive deeper — with the help of the authors, in most cases — they don’t disagree with one another very much.”

Governments around the world, from Madison, Wis., and New York City to the Obama Administration and the European Union have begun striving in recent years to adapt to the growing threats posed by climate change. But the burst of adaptation planning threatens to be hobbled by cultural and linguistic divides between those who practice science and those who prepare policy.[Continue reading…]

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How Yitang Zhang rose from obscurity and a disadvantaged youth to mathematical celebrity

Thomas Lin writes: As a boy in Shanghai, China, Yitang Zhang believed he would someday solve a great problem in mathematics. In 1964, at around the age of nine, he found a proof of the Pythagorean theorem, which describes the relationship between the lengths of the sides of any right triangle. He was 10 when he first learned about two famous number theory problems, Fermat’s last theorem and the Goldbach conjecture. While he was not yet aware of the centuries-old twin primes conjecture, he was already taken with prime numbers, often described as indivisible “atoms” that make up all other natural numbers.

But soon after, the anti-intellectual Cultural Revolution shuttered schools and sent him and his mother to the countryside to work in the fields. Because of his father’s troubles with the Communist Party, Zhang was also unable to attend high school. For 10 years, he worked as a laborer, reading books on math, history and other subjects when he could.

Not long after the revolution ended, Zhang, then 23, enrolled at Peking University and became one of China’s top math students. After completing his master’s at the age of 29, he was recruited by T. T. Moh to pursue a doctorate at Purdue University in Lafayette, Ind. But, promising though he was, after defending his dissertation in 1991 he could not find academic work as a mathematician.

In George Csicsery’s new documentary film Counting From Infinity, Zhang discusses his difficulties at Purdue and in the years that followed. He says his doctoral adviser never wrote recommendation letters for him. (Moh has written that Zhang did not ask for any.) Zhang admits that his shy, quiet demeanor didn’t help in building relationships or making himself known to the wider math community. During this initial job-hunting period, Zhang sometimes lived in his car, according to his friend Jacob Chi, music director of the Pueblo Symphony in Colorado. In 1992, Zhang began working at another friend’s Subway sandwich restaurant. For about seven years he worked odd jobs for various friends.

In 1999, at 44, Zhang caught a break. [Continue reading…]

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Stardust

Ray Jayawardhana writes: Joni Mitchell beat Carl Sagan to the punch. She sang “we are stardust, billion-year-old carbon” in her 1970 song “Woodstock.” That was three years before Mr. Sagan wrote about humans’ being made of “star-stuff” in his book “The Cosmic Connection” — a point he would later convey to a far larger audience in his 1980 television series, “Cosmos.”

By now, “stardust” and “star-stuff” have nearly turned cliché. But that does not make the reality behind those words any less profound or magical: The iron in our blood, the calcium in our bones and the oxygen we breathe are the physical remains — ashes, if you will — of stars that lived and died long ago.

That discovery is relatively recent. Four astrophysicists developed the idea in a landmark paper published in 1957. They argued that almost all the elements in the periodic table were cooked up over time through nuclear reactions inside stars — rather than in the first instants of the Big Bang, as previously thought. The stuff of life, in other words, arose in places and times somewhat more accessible to our telescopic investigations.

Since most of us spend our lives confined to a narrow strip near Earth’s surface, we tend to think of the cosmos as a lofty, empyrean realm far beyond our reach and relevance. We forget that only a thin sliver of atmosphere separates us from the rest of the universe. [Continue reading…]

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Too many worlds

Philip Ball writes: In July 2011, participants at a conference on the placid shore of Lake Traunsee in Austria were polled on what they thought the meeting was about. You might imagine that this question would have been settled in advance, but since the broad theme was quantum theory, perhaps a degree of uncertainty was to be expected. The title of the conference was ‘Quantum Physics and the Nature of Reality’. The poll, completed by 33 of the participating physicists, mathematicians and philosophers, posed a range of unresolved questions about the relationship between those two things, one of which was: ‘What is your favourite interpretation of quantum mechanics?’

The word ‘favourite’ speaks volumes. Isn’t science supposed to be decided by experiment and observation, free from personal preferences? But experiments in quantum physics have been obstinately silent on what it means. All we can do is develop hunches, intuitions and, yes, cherished ideas. Of these, the survey offered no fewer than 11 to choose from (as well as ‘other’ and ‘none’).

The most popular (supported by 42 per cent of the very small sample) was basically the view put forward by Niels Bohr, Werner Heisenberg and their colleagues in the early days of quantum theory. Today it is known as the Copenhagen Interpretation. More on that below. You might not recognise most of the other alternatives, such as Quantum Bayesianism, Relational Quantum Mechanics, and Objective Collapse (which is not, as you might suppose, just saying ‘what the hell’). Maybe you haven’t heard of the Copenhagen Interpretation either. But in third place (18 per cent) was the Many Worlds Interpretation (MWI), and I suspect you do know something about that, since the MWI is the one with all the glamour and publicity. It tells us that we have multiple selves, living other lives in other universes, quite possibly doing all the things that we dream of but will never achieve (or never dare). Who could resist such an idea?

Yet resist we should. We should resist not just because MWI is unlikely to be true, or even because, since no one knows how to test it, the idea is perhaps not truly scientific at all. Those are valid criticisms, but the main reason we should hold out is that it is incoherent, both philosophically and logically. There could be no better contender for Wolfgang Pauli’s famous put-down: it is not even wrong. [Continue reading…]

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Ancient planets are almost as old as the universe

New Scientist reports: The Old Ones were already ancient when the Earth was born. Five small planets orbit an 11.2 billion-year-old star, making them about 80 per cent as old as the universe itself. That means our galaxy started building rocky planets earlier than we thought.

“Now that we know that these planets can be twice as old as Earth, this opens the possibility for the existence of ancient life in the galaxy,” says Tiago Campante at the University of Birmingham in the UK.

NASA’s Kepler space telescope spotted the planets around an orange dwarf star called Kepler 444, which is 117 light years away and about 25 per cent smaller than the sun.

Orange dwarfs are considered good candidates for hosting alien life because they can stay stable for up to 30 billion years, compared to the sun’s 10 billion years, the time it takes these stars to consume all their hydrogen. For context, the universe is currently 13.8 billion years old.

Since, as far as we know, life begins by chance, older planets would have had more time to allow life to get going and evolve. But it was unclear whether planets around such an old star could be rocky – life would have a harder time on gassy planets without a solid surface. [Continue reading…]

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Trying to read scrolls that can’t be read

The Economist: In 1752 Camillo Paderni, an artist who had been put in charge of the growing pile of antiquities being dug up at Herculaneum, a seaside town near Naples, wrote to a certain Dr Mead, who then wrote to the Royal Society in London reporting that “there were found many volumes of papyrus but turned to a sort of charcoal, and so brittle, that being touched, it fell to ashes. Yet by His Majesty’s orders he made many trials to open them, but all to no purpose; excepting some scraps containing some words.”

The excavation at Herculaneum — which, like nearby Pompeii, was buried in 79AD under ash from Mount Vesuvius — had uncovered a literary time capsule. What came to be called the Villa of the Papyri contained a library of perhaps 2,000 books, the only such collection known to have been preserved from antiquity.

Actually reading these scrolls has, however, proved both tricky and destructive — until now. For a paper just published in Nature Communications, by Vito Mocella of the Institute for Microelectronics and Microsystems, in Naples, describes a way to decipher them without unrolling them.

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Did physics get sucked down a wormhole?

Bryan Appleyard writes: The greatest story of our time may also be the greatest mistake. This is the story of our universe from the Big Bang to now with its bizarre, Dickensian cast of characters – black holes, tiny vibrating strings, the warped space-time continuum, trillions of companion universes and particles that wink in and out of existence.

It is the story told by a long list of officially accredited geniuses from Isaac Newton to Stephen Hawking. It is also the story that is retold daily in popular science fiction from Star Trek to the latest Hollywood sci-fi blockbuster Interstellar. Thanks to the movies, the physicist standing in front of a vast blackboard covered in equations became our age’s symbol of genius. The universe is weird, the TV shows and films tell us, and almost anything can happen.

But it is a story that many now believe is pointless, wrong and riddled with wishful thinking and superstition.

“Stephen Hawking,” says philosopher Roberto Mangabeira Unger, “is not part of the solution, he is part of the problem.”

The equations on the blackboard may be the problem. Mathematics, the language of science, may have misled the scientists.

“The idea,” says physicist Lee Smolin, “that the truth about nature can be wrestled from pure thought through mathematics is overdone… The idea that mathematics is prophetic and that mathematical structure and beauty are a clue to how nature ultimately works is just wrong.”

And in an explosive essay published last week in the science journal Nature astrophysicists George Ellis and Joe Silk say that the wild claims of theoretical physicists are threatening the authority of science itself.

“This battle for the heart and soul of physics,” they write, “is opening up at a time when scientific results — in topics from climate change to the theory of evolution — are being questioned by some politicians and religious fundamentalists. Potential damage to public confidence in science and to the nature of fundamental physics needs to be contained by deeper dialogue between scientists and philosophers….The imprimatur of science should be awarded only to a theory that is testable. Only then can we defend science from attack.”

Unger and Smolin have also just gone into print with a monumental book – The Singular Universe and the Reality of Time – which systematically takes apart contemporary physics and exposes much of it as, in Unger’s words, “an inferno of allegorical fabrication.” The book says it is time to return to real science which is tested against nature rather than constructed out of mathematics. Physics should no longer be seen as the ultimate science, underwriting all others. The true queen of the sciences should be history – the biography of the cosmos. [Continue reading…]

Before any physicists stop by to question whether I really understand what a wormhole is, I will without hesitation make it clear: I have no idea. It just seems like a suitable metaphor — better, say, than rabbit hole.

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The Pillars of Creation

pillars-of-creation

NBC News: In celebration of its upcoming 25th anniversary in April, the Hubble Space Telescope has returned to the site of what may be its most famous image, the wispy columns of the Eagle Nebula, and produced a stunning new picture. “The Pillars of Creation,” located 6,500 light-years away in area M16 of the distant nebula, were photographed in visible and near-infrared light with the Hubble’s upgraded equipment, and the result is as astonishing now as the original was in 1995. Hubble went online in 1990.

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Thousands of Einstein documents now accessible online

The New York Times reports: They have been called the Dead Sea Scrolls of physics. Since 1986, the Princeton University Press and the Hebrew University of Jerusalem, to whom Albert Einstein bequeathed his copyright, have been engaged in a mammoth effort to study some 80,000 documents he left behind.

Starting on Friday, when Digital Einstein is introduced, anyone with an Internet connection will be able to share in the letters, papers, postcards, notebooks and diaries that Einstein left scattered in Princeton and in other archives, attics and shoeboxes around the world when he died in 1955.

The Einstein Papers Project, currently edited by Diana Kormos-Buchwald, a professor of physics and the history of science at the California Institute of Technology, has already published 13 volumes in print out of a projected 30. [Continue reading…]

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What is it like to be a bee?

honey-bee

In the minds of many humans, empathy is the signature of humanity and yet if this empathy extends further and includes non-humans we may be suspected of indulging in anthropomorphism — a sentimental projection of our own feelings into places where similar feelings supposedly cannot exist.

But the concept of anthropomorphism is itself a strange idea since it seems to invalidate what should be one of the most basic assumptions we can reasonably make about living creatures: that without the capacity to suffer, nothing would survive.

Just as the deadening of sensation makes people more susceptible to injury, an inability to feel pain would impede any creature’s need to avoid harm.

The seemingly suicidal draw of the moth to a flame is the exception rather than the rule. Moreover the insect is driven by a mistake, not a death wish. It is drawn towards the light, not the heat, oblivious that the two are one.

If humans indulge in projections about the feelings of others — human and non-human — perhaps we more commonly engage in negative projections: choosing to assume that feelings are absent where it would cause us discomfort to be attuned to their presence.

Our inclination is to avoid feeling too much and thus we construct neat enclosures for our concerns.

These enclosures shut out the feelings of strangers and then by extension seal away boundless life from which we have become even more estranged.

Heather Swan writes: It was a warm day in early spring when I had my first long conversation with the entomologist and science studies scholar Sainath Suryanarayanan. We met over a couple of hives I had recently inherited. One was thriving. Piles of dead bees filled the other. Parts of the comb were covered with mould and oozing something that looked like molasses.

Having recently attended a class for hobby beekeepers with Marla Spivak, an entomologist at the University of Minnesota, I was aware of the many different diseases to which bees are susceptible. American foulbrood, which was a mean one, concerned me most. Beekeepers recommended burning all of your equipment if you discovered it in your hives. Some of these bees were alive, but obviously in low spirits, and I didn’t want to destroy them unnecessarily. I called Sainath because I thought he could help me with the diagnosis.

Beekeeping, these days, is riddled with risks. New viruses, habitat loss, pesticides and mites all contribute to creating a deadly labyrinth through which nearly every bee must travel. Additionally, in 2004, mysterious bee disappearances began to plague thousands of beekeepers. Seemingly healthy bees started abandoning their homes. This strange disappearing act became known as colony collapse disorder (CCD).

Since then, the world has seen the decline of many other pollinating species, too. Because honeybees and other pollinators are responsible for pollinating at least one-third of all the food we eat, this is a serious problem globally. Diagnosing bee problems is not simple, but some answers are emerging. A ubiquitous class of pesticides called neonicotinoids have been implicated in pollinator decline, which has fuelled conversations among beekeepers, scientists, policy-makers and growers. A beekeeper facing a failing hive now has to consider not only the health of the hive itself, but also the health of the landscape around the hive. Dead bees lead beekeepers down a path of many questions. And some beekeepers have lost so many hives, they feel like giving up.

When we met at my troubled hives, Sainath brought his own hive tool and veil. He had already been down a path of many questions about bee deaths, one that started in his youth with a fascination for observing insects. When he was 14, he began his ‘Amateur Entomologist’s Record’, where he kept taxonomic notes on such things as wing textures, body shapes, colour patterns and behaviours. But the young scientist’s approach occasionally slipped to include his exuberance, describing one moment as ‘a stupefying experience!’ All this led him to study biology and chemistry in college, then to work on the behavioural ecology of paper wasps during his doctoral studies, and eventually to Minnesota to help Spivak investigate the role of pesticides in CCD.

Sainath had spent several years doing lab and field experiments with wasps and bees, but ultimately wanted to shift from traditional practices in entomology to research that included human/insect relationships. It was Sainath who made me wonder about the role of emotion in science – both in the scientists themselves and in the subjects of their experiments. I had always thought of emotion as something excised from science, but this was impossible for some scientists. What was the role of empathy in experimentation? How do we, with our human limitations, understand something as radically different from us as the honeybee? Did bees have feelings, too? If so, what did that mean for the scientist? For the science? [Continue reading…]

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Wonder and the ends of inquiry

Lorraine Daston writes: Science and wonder have a long and ambivalent relationship. Wonder is a spur to scientific inquiry but also a reproach and even an inhibition to inquiry. As philosophers never tire of repeating, only those ignorant of the causes of things wonder: the solar eclipse that terrifies illiterate peasants is no wonder to the learned astronomer who can explain and predict it. Romantic poets accused science of not just neutralizing wonder but of actually killing it. Modern popularizations of science make much of wonder — but expressions of that passion are notably absent in professional publications. This love-hate relationship between wonder and science started with science itself.

Wonder always comes at the beginning of inquiry. “For it is owing to their wonder that men both now begin and at first began to philosophize,” explains Aristotle; Descartes made wonder “the first of the passions,” and the only one without a contrary, opposing passion. In these and many other accounts of wonder, both soul and senses are ambushed by a puzzle or a surprise, something that catches us unawares and unprepared. Wonder widens the eyes, opens the mouth, stops the heart, freezes thought. Above all, at least in classical accounts like those of Aristotle and Descartes, wonder both diagnoses and cures ignorance. It reveals that there are more things in heaven and earth than have been dreamt of in our philosophy; ideally, it also spurs us on to find an explanation for the marvel.

Therein lies the paradox of wonder: it is the beginning of inquiry (Descartes remarks that people deficient in wonder “are ordinarily quite ignorant”), but the end of inquiry also puts an end to wonder. [Continue reading…]

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Beyond the Bell Curve, a new universal law

Natalie Wolchover writes: Imagine an archipelago where each island hosts a single tortoise species and all the islands are connected — say by rafts of flotsam. As the tortoises interact by dipping into one another’s food supplies, their populations fluctuate.

In 1972, the biologist Robert May devised a simple mathematical model that worked much like the archipelago. He wanted to figure out whether a complex ecosystem can ever be stable or whether interactions between species inevitably lead some to wipe out others. By indexing chance interactions between species as random numbers in a matrix, he calculated the critical “interaction strength” — a measure of the number of flotsam rafts, for example — needed to destabilize the ecosystem. Below this critical point, all species maintained steady populations. Above it, the populations shot toward zero or infinity.

Little did May know, the tipping point he discovered was one of the first glimpses of a curiously pervasive statistical law.

The law appeared in full form two decades later, when the mathematicians Craig Tracy and Harold Widom proved that the critical point in the kind of model May used was the peak of a statistical distribution. Then, in 1999, Jinho Baik, Percy Deift and Kurt Johansson discovered that the same statistical distribution also describes variations in sequences of shuffled integers — a completely unrelated mathematical abstraction. Soon the distribution appeared in models of the wriggling perimeter of a bacterial colony and other kinds of random growth. Before long, it was showing up all over physics and mathematics.

“The big question was why,” said Satya Majumdar, a statistical physicist at the University of Paris-Sud. “Why does it pop up everywhere?” [Continue reading…]

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Scientists got it wrong on gravitational waves. So what?

Philip Ball writes: It was announced in headlines worldwide as one of the biggest scientific discoveries for decades, sure to garner Nobel prizes. But now it looks likely that the alleged evidence of both gravitational waves and ultra-fast expansion of the universe in the big bang (called inflation) has literally turned to dust.

Last March, a team using a telescope called Bicep2 at the South Pole claimed to have read the signatures of these two elusive phenomena in the twisting patterns of the cosmic microwave background radiation: the afterglow of the big bang. But this week, results from an international consortium using a space telescope called Planck show that Bicep2’s data is likely to have come not from the microwave background but from dust scattered through our own galaxy.

Some will regard this as a huge embarrassment, not only for the Bicep2 team but for science itself. Already some researchers have criticised the team for making a premature announcement to the press before their work had been properly peer reviewed.

But there’s no shame here. On the contrary, this episode is good for science. [Continue reading…]

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Earth’s magnetic field polarity could flip sooner than expected

Scientific American reports: Earth’s magnetic field, which protects the planet from huge blasts of deadly solar radiation, has been weakening over the past six months, according to data collected by a European Space Agency (ESA) satellite array called Swarm.

The biggest weak spots in the magnetic field — which extends 370,000 miles (600,000 kilometers) above the planet’s surface — have sprung up over the Western Hemisphere, while the field has strengthened over areas like the southern Indian Ocean, according to the magnetometers onboard the Swarm satellites — three separate satellites floating in tandem.

The scientists who conducted the study are still unsure why the magnetic field is weakening, but one likely reason is that Earth’s magnetic poles are getting ready to flip, said Rune Floberghagen, the ESA’s Swarm mission manager. In fact, the data suggest magnetic north is moving toward Siberia.

“Such a flip is not instantaneous, but would take many hundred if not a few thousand years,” Floberghagen told Live Science. “They have happened many times in the past.”

Scientists already know that magnetic north shifts. Once every few hundred thousand years the magnetic poles flip so that a compass would point south instead of north. While changes in magnetic field strength are part of this normal flipping cycle, data from Swarm have shown the field is starting to weaken faster than in the past. Previously, researchers estimated the field was weakening about 5 percent per century, but the new data revealed the field is actually weakening at 5 percent per decade, or 10 times faster than thought. As such, rather than the full flip occurring in about 2,000 years, as was predicted, the new data suggest it could happen sooner. [Continue reading…]

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In a grain, a glimpse of the cosmos

Natalie Wolchover writes: One January afternoon five years ago, Princeton geologist Lincoln Hollister opened an email from a colleague he’d never met bearing the subject line, “Help! Help! Help!” Paul Steinhardt, a theoretical physicist and the director of Princeton’s Center for Theoretical Science, wrote that he had an extraordinary rock on his hands, one that he thought was natural but whose origin and formation he could not identify. Hollister had examined tons of obscure rocks over his five-decade career and agreed to take a look.

Originally a dense grain two or three millimeters across that had been ground down into microscopic fragments, the rock was a mishmash of lustrous metal and matte mineral of a yellowish hue. It reminded Hollister of something from Oregon called josephinite. He told Steinhardt that such rocks typically form deep underground at the boundary between Earth’s core and mantle or near the surface due to a particular weathering phenomenon. “Of course, all of that ended up being a false path,” said Hollister, 75. The more the scientists studied the rock, the stranger it seemed.

After five years, approximately 5,000 Steinhardt-Hollister emails and a treacherous journey to the barren arctic tundra of northeastern Russia, the mystery has only deepened. Today, Steinhardt, Hollister and 15 collaborators reported the curious results of a long and improbable detective story. Their findings, detailed in the journal Nature Communications, reveal new aspects of the solar system as it was 4.5 billion years ago: chunks of incongruous metal inexplicably orbiting the newborn sun, a collision of extraordinary magnitude, and the creation of new minerals, including an entire class of matter never before seen in nature. It’s a drama etched in the geochemistry of a truly singular rock. [Continue reading…]

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To understand turbulence we need the intuitive perspective of art

turbulence-leonardo

Philip Ball writes: When the German physicist Arnold Sommerfeld assigned his most brilliant student a subject for his doctoral thesis in 1923, he admitted that “I would not have proposed a topic of this difficulty to any of my other pupils.” Those others included such geniuses as Wolfgang Pauli and Hans Bethe, yet for Sommerfeld the only one who was up to the challenge of this subject was Werner Heisenberg.

Heisenberg went on to be a key founder of quantum theory and was awarded the 1932 Nobel Prize in physics. He developed one of the first mathematical descriptions of this new and revolutionary discipline, discovered the uncertainty principle, and together with Niels Bohr engineered the “Copenhagen interpretation” of quantum theory, to which many physicists still adhere today.

The subject of Heisenberg’s doctoral dissertation, however, wasn’t quantum physics. It was harder than that. The 59-page calculation that he submitted to the faculty of the University of Munich in 1923 was titled “On the stability and turbulence of fluid flow.”

Sommerfeld had been contacted by the Isar Company of Munich, which was contracted to prevent the Isar River from flooding by building up its banks. The company wanted to know at what point the river flow changed from being smooth (the technical term is “laminar”) to being turbulent, beset with eddies. That question requires some understanding of what turbulence is. Heisenberg’s work on the problem was impressive—he solved the mathematical equations of flow at the point of the laminar-to-turbulent change—and it stimulated ideas for decades afterward. But he didn’t really crack it—he couldn’t construct a comprehensive theory of turbulence.

Heisenberg was not given to modesty, but it seems he had no illusions about his achievements here. One popular story goes that he once said, “When I meet God, I am going to ask him two questions. Why relativity? And why turbulence? I really believe he will have an answer for the first.”

It is probably an apocryphal tale. The same remark has been attributed to at least one other person: The British mathematician and expert on fluid flow, Horace Lamb, is said to have hoped that God might enlighten him on quantum electrodynamics and turbulence, saying that “about the former I am rather optimistic.”

You get the point: turbulence, a ubiquitous and eminently practical problem in the real world, is frighteningly hard to understand. [Continue reading…]

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Have cosmologists lost their minds in the multiverse?

Luke Barnes and Geraint Lewis write: The recent BICEP2 observations – of swirls in the polarisation of the cosmic microwave background – have been proclaimed as many things, from evidence of the Big Bang and gravitational waves to something strange called the multiverse.

The multiverse theory is that our universe is but one of a vast, variegated ensemble of other universes. We don’t know how many pieces there are to the multiverse but estimates suggest there many be squillions of them.

But (if they exist) there has not been enough time since our cosmic beginning for light from these other universes to reach us. They are beyond our cosmic horizon and thus in principle unobservable.

How, then, can cosmologists say they have seen evidence of them?

Unobservable entities aren’t necessarily out-of-bounds for science. For example, protons and neutrons are made of subatomic particles called quarks. While they cannot be observed directly, their existence and properties are inferred from the way particles behave when smashed together.

But there is no such luxury with the multiverse. No signals from from other universes have or will ever bother our telescopes.

While there is some debate about what actually makes a scientific theory, we should at least ask if the multiverse theory is testable? Does it make predictions that we can test in a laboratory or with our telescopes? [Continue reading…]

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