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  • richardmitnick 9:11 am on May 8, 2019 Permalink | Reply
    Tags: "Two Neutron Stars Collided Near the Solar System Billions of Years Ago", , , “This means that in each of us we would find an eyelash worth of these elements mostly in the form of iodine which is essential to life”, , Columbia University, , This single cosmic event close to our solar system gave birth to 0.3 percent of the Earth’s heaviest elements including gold platinum and uranium., University of Florida   

    From Columbia University: “Two Neutron Stars Collided Near the Solar System Billions of Years Ago” 

    Columbia U bloc

    From Columbia University

    May 07, 2019
    Carla Cantor
    212-854-5276
    carla.cantor@columbia.edu.

    Columbia University and University of Florida astrophysicists find signs of cosmic event that created elements that sent gold and silver to Earth.

    Merging neutron stars. Image Credit: Mark Garlick, University of Warwick.

    Astrophysicists Szabolcs Márka at Columbia University and Imre Bartos (GSAS’12) at the University of Florida have identified a violent collision of two neutron stars 4.6 billion years ago as the likely source of some of the most coveted matter on Earth.

    This single cosmic event, close to our solar system, gave birth to 0.3 percent of the Earth’s heaviest elements, including gold, platinum and uranium.

    “This means that in each of us we would find an eyelash worth of these elements, mostly in the form of iodine, which is essential to life,” Bartos said.

    The researchers’ report their findings in the May 2 issue of Nature.

    Meteorites forged in the early solar system carry the traces of radioactive isotopes. As these isotopes decay, they act as “clocks” that can be used to reconstruct the time they were created, Márka said.

    To arrive at their conclusion, Bartos and Márka compared the composition of meteorites to numerical simulations of the Milky Way. They found that a single neutron-star collision could have occurred about 100 million years before the formation of Earth, in our own neighborhood, about 1,000 light years from the gas cloud that eventually formed the Solar System.

    The Milky Way galaxy itself is 100,000 light years in diameter, or 100 times the distance of this cosmic event from the cradle of Earth. “If a comparable event happened today at a similar distance from the solar system, the ensuing radiation could outshine the entire night sky,” Márka said.

    The researchers believe that their study provides insight into a uniquely consequential event in our planetary history. “It sheds bright light on the processes involved in the origin and composition of our solar system, and will initiate a new type of quest within disciplines, such as chemistry, biology and geology, to solve the cosmic puzzle,” Bartos said.

    “Our results address a fundamental quest of humanity: Where did we come from and where are we going?” Márka said. “It is very difficult to describe the tremendous emotions we felt when we realized what we had found and what it means for the future as we search for an explanation of our place in the universe.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Columbia U Campus

    Columbia University was founded in 1754 as King’s College by royal charter of King George II of England. It is the oldest institution of higher learning in the state of New York and the fifth oldest in the United States.

     
  • richardmitnick 12:34 pm on April 8, 2019 Permalink | Reply
    Tags: "Carbon Lurking in Deep Ocean Threw Ancient Climate Switch, A key Atlantic Ocean current system that today once again is slowing, , , , Columbia University, , Lamont-Doherty Earth Observatory, Say Researchers", Slowdown of Atlantic Circulation Sent Planet Into Deep Freeze, State of the Planet, The researchers reached their findings by analyzing cores of deep-sea sediments taken in the south and north Atlantic   

    From Columbia University: “Carbon Lurking in Deep Ocean Threw Ancient Climate Switch, Say Researchers” 

    Columbia U bloc

    From Columbia University

    April 8, 2019
    Kevin Krajick

    Slowdown of Atlantic Circulation Sent Planet Into Deep Freeze.

    A million years ago, a longtime pattern of alternating glaciations and warm periods dramatically changed, when ice ages suddenly became longer and more intense. Scientists have long suspected that this was connected to the slowdown of a key Atlantic Ocean current system that today once again is slowing. A new study of sediments from the Atlantic bottom directly links this slowdown with a massive buildup of carbon dragged from the air into the abyss. With the system running at full speed, this carbon would have percolated back into the air fairly quickly, but during this period it just stagnated in the depths. This suggests that the carbon draw down cooled the planet—the opposite of the greenhouse effect we are seeing now, as humans pump carbon into the atmosphere. But if the current keeps slowing now, we should not expect it to help us out by storing our emissions; possibly to the contrary. The study, led by researchers at Columbia University’s Lamont-Doherty Earth Observatory, appears this week in the journal Nature Geoscience.

    The scientists targeted a system of currents called the Atlantic meridional overturning circulation, or AMOC. Flowing northward near the surface, it transports warm, salty water from near the equator into the latitudes near Greenland and northern Europe. Here, it hits colder water from the Arctic, becomes denser and sinks into the abyss, taking with it large amounts of carbon absorbed from the atmosphere. The deep water then circles back south, where much of it re-merges in the Southern Ocean, to release carbon back to the air. The journey takes place over decades to centuries.

    A 2014 study [Science] by Lamont-Doherty scientists Steven Goldstein and Leopoldo Pena–both of whom also are coauthors of the new study–showed that this current system abruptly slowed around 950,000 years ago. The new study shows that this slowdown correlated directly with a huge buildup of carbon in the deep Atlantic, and corresponding decline of carbon in the air. This event was the apparent trigger for a series of ice ages that came every 100,000 years, versus previous ones that occurred about every 40,000 years, and which built up less ice than those that came later. Scientists call this turning point the Mid-Pleistocene Transition, and the new pattern has persisted right through the last ice age, which ended about 15,000 years ago. Exactly why the pattern has continued no one knows, but the study clearly demonstrates that the carbon missing from the air ended up in the ocean, and had a powerful effect on climate.

    2
    The Atlantic meridional overturning circulation, seen here in simplified form, brings warm water northward (red arrows) until it reaches the region around Greenland and northern Europe. Here, it sinks and travels southward (yellow arrows). Much of the water re-emerges in the Southern Ocean. (Courtesy Francesco Muschitiello/Lamont-Doherty Earth Observatory)

    “It’s a one-to-one relationship. It was like flipping a switch,” said lead author Jesse Farmer, who did the work while a PhD. student at Lamont-Doherty. “It shows us that there’s an intimate relationship between the amount of carbon stored in the ocean, and what the climate is doing.”

    The researchers reached their findings by analyzing cores of deep-sea sediments taken in the south and north Atlantic, where ancient deep waters passed by and left chemical clues about their contents in the shells of microscopic creatures. Their analysis confirmed the 2014 study showing that the AMOC weakened to an extent not seen before, around 950,000 years ago, and for an unusually long time. Because of this, the deep water collected about 50 billion tons more carbon than it had during previous glaciations—equivalent to about one third of the human emissions that all the world’s oceans have so far absorbed today. (For context, the oceans today absorb roughly a quarter of what we emit; land and vegetation take up a third. The rest stays in the air.)

    In the warm period leading up to this event, the atmosphere had held about 280 parts per million carbon; with the slowdown, airborne carbon dioxide went down to 180 ppm, as measured by ice cores. Atmospheric carbon had sunk during previous glaciations as well, but from 280 ppm down only to about 210 ppm. (Because of human emissions during the past two centuries, this normal repeating 280 ppm warm-era figure has become obsolete; atmospheric carbon is now up to about 410 ppm.)

    3
    Left: Before about 950,000 years ago, waters reached the deep Atlantic Ocean from the north (black arrows) and south (purple arrows). Right: Using data from two sediment cores (yellow stars), scientists showed that a weakening of the northern-sourced circulation (thinner black arrows) after that led to more carbon storage in the Atlantic. Under a weaker circulation, more of the deep Atlantic water was sourced from the south. (Jesse Farmer)

    At some point, the current woke up again, and things warmed for a while before dropping back into another similarly extreme ice age, after 100,000 years. “There are lots of ideas about what caused these changes to happen, but it’s hard to say what the trigger was,” said Bärbel Hönisch, Farmer’s advisor and coauthor of the study. “There are several different screws you could imagine turning, and lots of loose screws.”

    One idea, espoused by Goldstein’s group [Science] among others: In the north, repeated build-ups of glaciers ultimately scrape everything on land down to bedrock. Subsequent glaciers are then able to stick fast to the bedrock and bulk up even more, before discharging icebergs into the ocean. This introduces more freshwater to mix with the AMOC, making it less dense and eventually unable to sink. On the other end, ice would also grow in Antarctica and discharge more icebergs, which would make the ocean waters colder and less salty, thus encouraging the growth of more sea ice. This, theoretically, would cap the surface and keep deep water from rising and releasing its carbon. But if this is indeed the way it works, it is not clear what starts or ends any of the processes; it is a chicken-and-egg kind of question.

    The strength of the AMOC is believed to fluctuate naturally, but it appears to have weakened by an unusual 15 percent since the mid-20th century. No one is sure what is behind that, or what effects it might produce if the slowdown continues. Another Lamont-Doherty study [Nature] last month showed that a slowdown around 13,000 years ago, at the tail end of the last ice age, was followed 400 years later by an intense cold snap that lasted centuries.

    “We have to be careful about drawing parallels with that,” said Farmer, now a postdoctoral researcher at Princeton University. “We see a similar weakening today, and one might say, ‘Great! Ocean circulation is going to save us from warming climate!’ But that’s not correct, because of the way different parts of the climate system talk to each other.” Farmer said that if the AMOC continues weakening now, it is probable that less carbon-laden water will sink in the north, at the same time, in the Southern Ocean, any carbon already arriving in the deep water will likely keep bubbling up without any problem. The result: carbon will continue to build in the air, not the ocean.

    The researchers point out that the AMOC is only part of a much larger system of global circulation that connects all the oceans—the so-called Great Ocean Conveyor, a term coined by the late Lamont-Doherty scientist Wallace Broecker, who laid the groundwork for much of the current research. Much less is known about the carbon dynamics of the Indian and Pacific, which together dwarf the Atlantic, so there are many missing pieces to the puzzle. Ongoing research at Lamont-Doherty is aimed at building carbon chronologies of those other waters in the next few years.

    The study was also coauthored by Laura Haynes, Heather Ford, Maureen Raymo, Maria Jaume-Seguí, Steven Goldstein, Maayan Yehudai and Joohee Kim, all of Lamont-Doherty; Dirk Kroon, Simon Jung and Dave Bell of the University of Edinburgh; and Leopoldo Pena of the University of Barcelona.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Columbia U Campus

    Columbia University was founded in 1754 as King’s College by royal charter of King George II of England. It is the oldest institution of higher learning in the state of New York and the fifth oldest in the United States.

     
  • richardmitnick 11:15 am on March 12, 2019 Permalink | Reply
    Tags: "Scientists Track Deep History of Planets' Motions and Effects on Earth's Climate", , , Columbia University, , ,   

    From Columbia University: “Scientists Track Deep History of Planets’ Motions, and Effects on Earth’s Climate” 

    Columbia U bloc

    From Columbia University

    March 4, 2019
    Kevin Krajick

    Newly Forming Map of Chaos in the Solar System.

    1
    Geologist Paul Olsen at Arizona’s Petrified Forest National Park, where 200 million-year-old rocks are helping reveal the long-ago motions of other planets. (Kevin Krajick/Earth Institute)

    Scientists have long posited that periodic swings in Earth’s climate are driven by cyclic changes in the distribution of sunlight reaching our surface. This is due to cyclic changes in how our planet spins on its axis, the ellipticity of its orbit, and its orientation toward the sun — overlapping cycles caused by subtle gravitational interplays with other planets, as the bodies whirl around the sun and by each other like gyrating hula-hoops.

    But planetary paths change over time, and that can change the cycles’ lengths. This has made it challenging for scientists to untangle what drove many ancient climate shifts. And the problem gets ever more difficult the further back in time you go; tiny changes in one planet’s motion may knock others’ askew — at first slightly, but as eons pass, these changes resonate against each other, and the system morphs in ways impossible to predict using even the most advanced math. In other words, it’s chaos out there. Up to now, researchers are able to calculate the relative motions of the planets and their possible effects on our climate with reasonable reliability back only about 60 million years — a relative eyeblink in the 4.5 billion-plus life of Earth.

    This week, in a new paper in the Proceedings of the National Academy of Sciences, a team of researchers has pushed the record way back, identifying key aspects of the planets’ motions from a period around 200 million years ago. The team is led by geologist and paleontologist Paul Olsen of Columbia University’s Lamont-Doherty Earth Observatory. Last year, by comparing periodic changes in ancient sediments drilled from Arizona and New Jersey, Olsen and colleagues identified a 405,000-year cycle in Earth’s orbit that apparently has not changed at all over at least the last 200 million years — a kind of metronome against which all other cycles can be measured. Using those same sediments in the new paper, they now have identified a cycle that started out lasting 1.75 million years, but is now operating every 2.4 million years. This, they say, allows them to extrapolate long-term changes in the paths of Jupiter and the inner planets (Mercury, Venus and Mars), the bodies most likely to affect our own orbit.

    Olsen’s ultimate aim: to use Earth’s rocks to create what he calls a “Geological Orrery” — a record of climatic changes on Earth that can be extrapolated back into a larger map of solar system motions over hundreds of millions of years. He says it would open a window not just onto our own climate, but the evolution of the solar system itself, including the possible existence of past planets, and its possible interactions with invisible dark matter.

    We spoke with Olsen about the Geological Orrery, his work, and the new paper.

    Most people have probably never even heard the word “orrery.” What is it, and how does it fit with our evolving understanding of celestial mechanics?

    In the early 1800s, mathematician Pierre-Simon de Laplace took Newton’s laws of gravitation and planetary motion and published his idea that it should be possible to develop a single great equation that would allow all the universe to be modeled. With only knowledge of the present, all the past and future could be known. This idea is embodied in the orrery, a mechanical model of the solar system. Clockwork mechanisms like this for predicting eclipses and the like go back to the ancient Greeks, but it’s now clear the problem is far more complicated, and interesting.

    We’ve since discovered that the solar system not a clockwork. It is in fact chaotic over long time scales, so Laplace’s grand equation was a mirage. This means you cannot unpack its history from calculations or models, no matter how precise, because the motions of the real solar system are incredibly sensitive. Varying any factor even a tiniest bit results in a different outcome after millions of years — even what the major asteroids, or minor planets, such as Ceres and Vesta, are doing. One of my coauthors, Jacques Laskar, has shown that computations can project forward or backward only 60 million years. After that, the predictions become utterly unreliable. Since Earth is about 4.6 billion years old, this means that only about 1.6 percent of its past or future orbit can be predicted. Over billions of years, the best calculations reveal many possible terrific events, such as one of the inner planets falling into the sun or being ejected from the solar system. Maybe even that Earth and Venus could collide one day. We can’t tell if any of these actually happened, or might happen in the future. So we need some other method to limit the possibilities.

    2
    View looking east toward the U.S. East Coast, Oct. 7, 2015, when the three planets most influential to Earth’s orbit lined up with the Moon. Lower left near Earth’s horizon, Jupiter (greenish); slightly higher, Mars (reddish); slightly higher and to right, Venus (bright white); and the Moon. On Earth’s surface, lights of the New York-Philadelphia metro region trace the area where scientists took rock cores revealing these planets’ motions. Inspired by a photo taken by U.S. astronaut Scott Kelly. (Painting by Paul Olsen; acrylic on clay board, digitally modified)

    So, what is the “Geological Orrery?” Are you trying again to boil everything down to one equation, or is this something different?

    The Geological Orrery is the opposite of an equation or model. It’s designed to provide a precise and accurate history of the solar system. We get that history right here on Earth, from the history of our climates, which is recorded in the geological record, especially in large, long-lived lakes.

    Earth’s orbit and axis orientation are constantly changing because they are being deformed by the gravitational attractions of other bodies. These changes affect the distribution of sunlight hitting our surface, which in turn affects climate, and the kinds of sediments that are deposited. That gives us the geological record of solar system behavior.

    Many scientists have used sediments to determine the effects of orbital deformations. That’s how we know that the ice ages of the last few million years were paced by them. Some researchers have tried to go back much further in time. What is new here is the systematic approach of taking rock cores spanning tens of millions of years, looking at the cyclical sedimentary record of climate and accurately dating those changes over multiple sites. That allows us to capture the full range of solar system-driven deformations of our orbit and axis over long time periods.

    3
    A mechanical orrery presented in 1713 by English inventor John Rowley to Charles Boyle, the Fourth Earl of Orrery — origin of the modern name. (Engraving from The Universal Magazine, 1749)

    What are the rocks telling you about how such cyclic changes affect our climate?

    With two major coring experiments to date, we’ve we learned that changes in tropical climates from wet to dry during the time of early dinosaurs, from about 252 to 199 million years ago, were paced by orbital cycles lasting about 20,000, 100,000 and 400,000 years. On top of that is a much longer cycle of about 1.75 million years. The shorter cycles are about the same today, but the 1.75 million year cycle is way off —it’s 2.4 million years today. We think the difference is caused by a gravitational dance between Earth and Mars. This difference is the fingerprint of solar system chaos. No existing set of models or calculations precisely duplicates these data.

    How far do you think we’re going to get with this problem during your lifetime?

    Next step is to combine our two finished coring experiments with cores taken at high latitudes. While our core data do a really good job of mapping some aspects of planetary orbits, they tell us nothing about others. For those, we need a core from an ancient lake above the paleo-Arctic or Antarctic circles. Such deposits exist in what are now China and Australia. We also would like to include deposits that extend the record up 20 million years or so towards the present, and another low-latitude core that we can precisely date. With those, we would be able to determine what if any changes have taken place in that Mars-Earth gravitational dance. That would be a full proof of concept of the Geological Orrery. I plan to certainly be around for that.

    4
    Digital elevation map of sediment strata formed on a lake bottom some 220 million years ago, near present day Flemington, N.J. The lakebed was later tilted so that its cross section now faces the sky. Purple sections are ridges — remains of hard, compressed sediments formed when climate was wet and the lake deep; alternating greenish sections are lower areas made of eroded-out softer sediments from dryer times. Each pair represents 405,000 years. Groups of ridges in lower part of image manifest a separate 1.7 million-year cycle that has today grown to 2.4 million years. Thee 40-square-mile area is dissected by parts of the modern Raritan and Neshanic rivers (blue). (LIDAR image by U.S. Geological Survey; digital colorization by Paul Olsen)

    Your paper mentions that this work might offer insights into the evolution of the solar system — maybe the even wider universe.

    If all this works out, we could plan the grand mission to use the Geological Orrery for at least the rest of the time between 60 and 190 million years age. This mission would be expensive by geology standards, because rock coring is expensive. But the results would have far-reaching implications. For sure we would have data to produce high-quality climate models for Earth. And there is no doubt we would have the parameters for past climates on Mars or other rocky planets. But more excitingly and more speculative is the possibility of exploring how we might need to tweak gravity theory, or test some controversial theories, such as the possible existence of a plane of dark matter in our galaxy that our solar system passes through periodically.

    We’re talking deep time here. Does this have any application to questions about modern-day climate change?

    It does have relevance to the present. in addition to the way climate is tuned to our orbit, it’s also affected by the amount of carbon dioxide in the air. Now we’re heading into a time when CO2 levels may be as high as they were 200 million years ago, early dinosaur times. This gives us a potential way to see how all the factors interact. It also has resonance with our search for life on Mars, or for habitable exoplanets.

    The paper is coauthored by Jacques Laskar, Observatoire de Paris; Dennis Kent and Sean Kinney, Lamont-Doherty Earth Observatory; David Reynolds, ExxonMobil Exploration; Jingeng Sha, Nanjing Institute of Geology and Paleontology; and Jessica Whiteside, University of Southampton.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Columbia U Campus

    Columbia University was founded in 1754 as King’s College by royal charter of King George II of England. It is the oldest institution of higher learning in the state of New York and the fifth oldest in the United States.

     
  • richardmitnick 7:44 am on August 14, 2018 Permalink | Reply
    Tags: , Columbia University, , , String theory-not even wrong   

    From Columbia University via physicsworld.com: “Not Even Wrong” 

    Columbia U bloc

    From Columbia University

    via

    physicsworld
    physicsworld.com

    1

    August 13, 2018
    woit

    In recent weeks string theory has been again getting a lot of press attention, because of claims that new progress is being made in the study of the relation of string theory and the real world, via the study of the “swampland”. This is a very old story, and I’ve often written about it here. I just added a new category, so anyone who wants to can go follow it by clicking on the Swampland category of posts.

    Recent press coverage of this includes an article by Clara Moskowitz at Scientific American, entitled String Theory May Create Far Fewer Universes Than Thought. This motivated Avi Loeb to write his own Scientific American piece highlighting the dangers of string theory speculation unmoored to any possible experimental test, which appeared as Theoretical Physics is Pointless without Experimental Tests. Loeb reports:

    “…There is a funny anecdote related to the content of this commentary. In my concluding remarks at the BHI conference we held at Harvard in May 2018, I recommended boarding a futuristic spacecraft directed at the nearest black hole to experimentally test the validity of string theory near the singularity. Nima Arkani-Hamed commented that he suspects I have an ulterior motive for sending string theorists into a black hole. For the video of this exchange, see

    https://www.youtube.com/watch?v=WdFkbsPFQi0

    Last week Natalie Wolchover reported on this controversy, with an article that appeared at Quanta magazine as Dark Energy May Be Incompatible With String Theory and at The Atlantic as The Universe as We Understand It May Be Impossible (The Atlantic headline writer misidentifies “we” as “string theorists”).

    Wolchover accurately explains part of this story as a conflict between string theorists over whether certain solutions (such as the KKLT solution and the rest of the so-called “string theory landscape”) to string theory really exist. Vafa argues they may not exist, since the proposed solutions are complicated and “Usually in physics, we have simple examples of general phenomena.” In response Eva Silverstein argues:

    “…They [Vafa and others] essentially just speculate that those things don’t exist, citing very limited and in some cases highly dubious analyses….”

    On Twitter, Jim Baggott explains the problem

    “Let’s be clear. This is not a ‘test’ of string theory. There is no ‘evidence’ here. This is yet another conjecture that ‘might be true’, on which there is no consensus in the string theory community.”

    and points to an earlier tweet thread of his about this. Sabine Hossenfelder replies with the comment that

    “…The landscape itself is already a conjecture build on a conjecture, the latter being strings to begin with. So: conjecture strings, then conjecture the landscape (so you don’t have to admit the theory isn’t unique), then conjecture the swampland because it’s still not working….”

    The Simons Center summer workshop this year has been devoted to Recent Developments in the Swampland, videos are here (this was also the case in 2006, see here). Next month in Madrid a conference will be devoted to Vistas over the Swampland, and I’m sure many more such gatherings are planned.

    Unfortunately I think the fundamental problem here somehow never gets clearly explained: String theorists don’t actually have a theory, what they have is an approximation to an unknown theory supposed to be valid in certain limits, and a list of properties they would like the unknown theory to have. If this is all you have, there’s no way to distinguish when you’re on dry land (a solution to string theory) from when you’re in the swamp (a non-solution to string theory). Different string theorists can generate different opinions, conjectures and speculations about whether some location is swamp or dry land, but in the absence of an actual theory, no one can tell who is right and who is wrong. I don’t know why Vafa back in 2005 chose “Swampland” as the metaphor for this subject, but it’s an unfortunately apt one: string theorists are stuck in a swamp, with no way of getting out since they can’t tell what’s dry land and what isn’t.

    [I do not normally “poach” a blog post, especially wordpress material, but there was no other way to get this out]

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Columbia U Campus

    Columbia University was founded in 1754 as King’s College by royal charter of King George II of England. It is the oldest institution of higher learning in the state of New York and the fifth oldest in the United States.

     
  • richardmitnick 11:54 am on August 13, 2018 Permalink | Reply
    Tags: , , , Columbia University, , , Physicists Say There Could Be a Strange Source of 'Negative Gravity' All Around Us, ,   

    From Columbia University: “Physicists Say There Could Be a Strange Source of ‘Negative Gravity’ All Around Us” 

    Columbia U bloc

    From Columbia University

    via

    Science Alert

    13 AUG 2018
    FIONA MACDONALD

    1
    (Valerie Loiseleux/iStock)

    The macro world as we know it is governed by Newton’s laws of motion and gravity – what goes up, must come down.

    But a team of physicists from Columbia University have put forward a theoretical paper that turns this idea on its head. They say there might actually be particles with negative mass – which under gravity, move up, instead of down – and they’re all around us.

    According to their paper, it’s not any weird subatomic particle that has these properties, but the particles of sound we hear and produce every day – phonons – that are rebelling against the force of gravity.

    So far, so strange, right? After all, sound isn’t even a physical object, so how can the force of gravity have any impact on it?

    This paradox is at the heart of the new hypothesis – what if, the researchers say, sound waves actually did carry mass. Negative mass. And that negative mass created its own tiny negative gravitational fields that push them up instead of down.

    It sounds pretty wild, but there are three things to keep in mind here.

    First, and most importantly, this paper is purely theoretical – that means the researchers have simply put forward a hypothesis and performed some detailed calculations based on how we know the world words, and shown that, in theory, this could be true.

    That’s not to say they’ve found any physical evidence sound waves carry negative mass as yet, they’ve simply shown that if it was the case, it wouldn’t break anything else in physics.

    The second qualifier is that the paper has only been published on the pre-print site arXiv ahead of peer review. So we need to see some independent verification of these numbers before we get too carried away.

    Now keeping those first two in mind, the third thing you need to know is that this idea isn’t actually that insane.

    No, really. Bear with us, because there is some logical precedent that’s gone into the hypothesis.

    For starters, we know that negative mass particles exist – and they do move against a force in the opposite direction than you’d expect.

    Just last year researchers created negative mass fluid in the lab for the first time, and when pushed, it accelerated backwards instead of forwards.

    Okay, so negative mass particles might be real. But sound waves aren’t actually particles, are they?

    Sound waves move through matter and causes vibrations in the molecules around it, which results in those vibrations being passed on and hitting our eardrums so we can hear.

    But although they’re not particles in the traditional sense, sounds waves can be described mathematically as particles, called phonons.

    Still, it’s previously been thought that these phonons couldn’t be affected by gravity – or have an effect on gravity – because they don’t carry mass.

    But earlier research by the team’s leader, Alberto Nicolis, which was published in Physical Review Letters B in May, provided some experimental evidence that this might not be the case – at least not under extreme conditions.

    The experiment was conducted in zero-temperature superfluids, which are a strange type of fluid that flow with no resistance at all at temperatures close to absolute zero.

    Under those conditions, Nicolis and his team reported seeing phonons’ trajectories bend upwards, seemingly in opposition to the effect of gravity.

    “In a gravitational field phonons slowly accelerate in the opposite direction that you would expect, say, a brick to fall,” one of the team, Rafael Krichevsky, told Live Science.

    The effect is too small to measure with existing technology, and there are also other potential explanations for this trajectory that have nothing to do with gravity.

    But Nicolis’ latest paper builds on the idea that the phonons were generating some type of negative gravitational field.

    They propose that “the (tiny) effective gravitational mass of the phonon generates a (tiny) gravitational field. And the source of this gravitational field travels with the phonon,” the team writes on arXiv.

    “Thus, in a very physical sense, the phonon carries (negative) mass.”

    Now, we’re not going to go into all the calculations carried out because they’re pretty intense (you can read all about them in the paper).

    But in short, the team was able to show mathematically that classical sound waves could carry mass – and not just in superfluids or the quantum world, but in real-world settings.

    “We showed that, contrary to common belief, sound waves carry gravitational mass, in a standard Newtonian sense: they are affected by gravity, but they also source gravity,” the team concludes.

    They also outline ways we could experimentally test this idea going forward.

    And that’s important, not only because it could shift our fundamental understanding of the sound waves that exist in the world all around us all the time.

    But also because this effect could impact the behaviour of other objects in the Universe – like neutron stars, which have incredibly dense cores where sound waves move at nearly the speed of light.

    A lot more research is needed, but it’s definitely an intriguing hypothesis to build on.

    The paper has been published and can be read in full on arXiv.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    stem

    Stem Education Coalition

    Columbia U Campus

    Columbia University was founded in 1754 as King’s College by royal charter of King George II of England. It is the oldest institution of higher learning in the state of New York and the fifth oldest in the United States.

     
  • richardmitnick 2:39 pm on May 28, 2018 Permalink | Reply
    Tags: , Columbia University, , , , The hunt for Dark Natter, , XENON1T at Gran Sasso   

    From Columbia University The XENON1T experiment via interactions.org: “XENON1T probes deeper into Dark Matter WIMPs, with 1300 kg of cold Xe atoms” 

    Columbia U bloc

    From Columbia University

    interactions.org

    XENON1T at Gran Sasso LABORATORI NAZIONALI del GRAN SASSO, located in the Abruzzo region of central Italy

    Results from XENON1T, the world’s largest and most sensitive detector dedicated to a direct search for Dark Matter in the form of Weakly Interacting Massive Particles (WIMPs), are reported today (Monday, 28th May) by the spokesperson, Prof. Elena Aprile of Columbia University, in a seminar at the hosting laboratory, the INFN Laboratori Nazionali del Gran Sasso (LNGS), in Italy.

    The international collaboration of more than 165 researchers from 27 institutions, has successfully operated XENON1T, collecting an unprecedentedly large exposure of about 1 tonne x year with a 3D imaging liquid xenon time projection chamber. The data are consistent with the expectation from background, and place the most stringent limit on spin-independent interactions of WIMPs with ordinary matter for a WIMP mass higher than 6 GeV/c². The sensitivity achieved with XENON1T is almost four orders of magnitude better than that of XENON10, the first detector of the XENON Dark Matter project, which has been hosted at LNGS since 2005. Steadily increasing the fiducial target mass from the initial 5 kg to the current 1300 kg, while simultaneously decreasing the background rate by a factor 5000, the XENON collaboration has continued to be at the forefront of Dark Matter direct detection, probing deeper into the WIMP parameter space.

    WIMPs are a class of Dark Matter candidates which are being frantically searched with experiments at the Large Hadron Collider, in space, and on Earth. Even though about a billion WIMPs are expected to cross a surface of one square meter per second on Earth, they are extremely difficult to detect. Results from XENON1T show that WIMPs, if they indeed comprise the Dark Matter in our galaxy, will result in a rare signal, so rare that even the largest detector built so far cannot see it directly. XENON1T is a cylindrical detector of approximately one meter height and diameter, filled with liquid xenon at -95 °C, with a density three times that of water. In XENON1T, the signature of a WIMP interaction with xenon atoms is a tiny flash of scintillation light and a handful of ionization electrons, which themselves are turned into flashes of light. Both light signals are simultaneously recorded with ultra-sensitive photodetectors, giving the energy and 3D spatial information on an event-by-event basis.

    2
    XENON1T installation in the underground hall of Laboratori Nazionali del Gran Sasso. The three story building houses various auxiliary systems. The cryostat containing the LXeTPC is located inside the large water tank next to the building. Photo by Roberto Corrieri and Patrick De Perio.

    In developing this unique type of detector to search for a rare WIMP signal, many challenges had to be overcome; first and foremost the reduction of the overwhelmingly large background from many sources, from radioactivity to cosmic rays. Today, XENON1T is the largest Dark Matter experiment with the lowest background ever measured, counting a mere 630 events in one year and one tonne of xenon in the energy region of interest for a WIMP search. The search results, submitted to Physical Review Letters, are based on 1300 kg out of the total 2000 kg active xenon target and 279 days of data, making it the first WIMP search with a noble liquid target exposure of 1.0 tonne x year. Only two background events were expected in the innermost, cleanest region of the detector, but none were detected, setting the most stringent limit on WIMPs with masses above 6 GeV/c² to date. XENON1T continues to acquire high-quality data and the search will continue until it will be upgraded with a larger mass detector, being developed by the collaboration. With another factor of four increase in fiducial target mass, and ten times less background rate, XENONnT will be ready in 2019 for a new exploration of particle Dark Matter at a level of sensitivity nobody imagined when the project started in 2002.

    The international collaboration of more than 165 researchers from 27 institutions, has successfully operated XENON1T, collecting an unprecedentedly large exposure of about 1 tonne x year with a 3D imaging liquid xenon time projection chamber.

    Columbia University, New York, USA
    PI and Spokesperson of XENON: Elena Aprile

    Istituto Nazionale di Fisica Nucleare, Laboratori Nazionale del Gran Sasso, l’Aquila, Italy
    PI: Walter Fulgione

    Istituto Nazionale di Fisica Nucleare, Torino, Italy
    PI: Giancarlo Trinchero

    Johannes Gutenberg University, Mainz, Germany
    PI: Uwe Oberlack

    Max-Planck-Institut für Kernphysik, Heidelberg, Germany
    PI: Manfred Lindner

    Nikhef & GRAPPA/University of Amsterdam, the Netherlands
    PI: Patrick Decowski

    Purdue University, West Lafayette, USA
    PI: Rafael Lang

    Rensselaer Polytechnic Institute, Troy, USA
    PI: Ethan Brown

    Rice University, Houston, USA
    PI: Petr Shagin

    Subatech, Nantes, France
    PI: Dominique Thers

    University of Bern, Switzerland
    PI: Marc Schumann

    Istituto Nazionale di Fisica Nucleare Bologna and University of Bologna, Italy
    PI: Gabriella Sartorelli

    University of California, Los Angeles, USA
    PI: Hanguo Wang

    University of California, San Diego, USA
    PI: Kaixuan Ni

    University of Chicago, USA
    PI: Luca Grandi

    University of Coimbra, Portugal
    PI: José Matias-Lopes

    University of Münster, Germany
    PI: Christian Weinheimer

    University of Zürich, Switzerland
    PI: Laura Baudis

    Weizmann Institute of Science, Rehovot, Israel
    PI: Ranny Budnik

    NYU Abu Dhabi, United Arab Emirates
    PI: Francesco Arneodo

    Stockholm University, Sweden
    PI: Jan Conrad

    The data are consistent with the expectation from background, and place the most stringent limit on spin-independent interactions of WIMPs with ordinary matter for a WIMP mass higher than 6 GeV/c². The sensitivity achieved with XENON1T is almost four orders of magnitude better than that of XENON10, the first detector of the XENON Dark Matter project, which has been hosted at LNGS since 2005. Steadily increasing the fiducial target mass from the initial 5 kg to the current 1300 kg, while simultaneously decreasing the background rate by a factor 5000, the XENON collaboration has continued to be at the forefront of Dark Matter direct detection, probing deeper into the WIMP parameter space.

    WIMPs are a class of Dark Matter candidates which are being frantically searched with experiments at the Large Hadron Collider, in space, and on Earth. Even though about a billion WIMPs are expected to cross a surface of one square meter per second on Earth, they are extremely difficult to detect. Results from XENON1T show that WIMPs, if they indeed comprise the Dark Matter in our galaxy, will result in a rare signal, so rare that even the largest detector built so far cannot see it directly. XENON1T is a cylindrical detector of approximately one meter height and diameter, filled with liquid xenon at -95 °C, with a density three times that of water. In XENON1T, the signature of a WIMP interaction with xenon atoms is a tiny flash of scintillation light and a handful of ionization electrons, which themselves are turned into flashes of light. Both light signals are simultaneously recorded with ultra-sensitive photodetectors, giving the energy and 3D spatial information on an event-by-event basis.

    See the full article here .


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    Stem Education Coalition

    Columbia U Campus

    Columbia University was founded in 1754 as King’s College by royal charter of King George II of England. It is the oldest institution of higher learning in the state of New York and the fifth oldest in the United States.

     
  • richardmitnick 3:03 pm on January 4, 2018 Permalink | Reply
    Tags: , , Climate Change Will Displace Millions of People. Where Will They Go?, Columbia University,   

    From Columbia: “Climate Change Will Displace Millions of People. Where Will They Go?” 

    Columbia U bloc

    Columbia University

    January 4, 2018
    Tiffany Challe

    1
    Islands like Barbuda may seem like paradise now, but they face many challenges from climate change in the future. Photo: Tiffany Challe

    Barbuda, the sister island of Antigua, is a small, low-lying Caribbean island. Most of its 1,700 residents lived in Codrington, the central location for stores and schools. The town is also the location for the Barbuda Research Complex, where I attended sustainability field school in 2013.

    What makes this island so unique? The beauty of the natural beaches untouched by tourism developments, the rich vegetation, diverse wildlife, fascinating archaeological sites and the people of Barbuda. During my three-week stay there, it became clear to me that Barbudans were a proud, happy and resilient people. Their community identity is heavily steeped in their food culture, which forges their intricate relationship with the environment. This entry in my field journal captures their spirit: “I admire how Barbudans respect and use all their resources on the island and understand their environment.” Their livelihoods and culture center on fishing, hunting and farming. However, climate change has altered the island’s food system and therefore their livelihoods. Droughts and rising seas that encroach on freshwater supplies are causing crop yields to decline, and Barbudans must increasingly rely on expensive imported foods.

    Hurricane Irma hit Barbuda in September and decimated most of the island – 95 percent of the buildings and infrastructure were destroyed. One person died and countless animals were killed by debris or separated from their owners. For the first time in 300 years, the island was rendered uninhabitable. All the residents were evacuated and temporarily relocated to Antigua, where they still remain today. Barbudans are eager to return to the island, as they have a strong sense of place-based identity. Rebuilding efforts are currently under way, though funds are sorely lacking and a bitter dispute over land rights has ensued. This story illustrates tragedy for the islanders, who are at the front lines of climate change.

    2
    This Somalian family left their village after a drought killed most of their livestock. Climate change could make droughts like these more common and more severe, causing many to flee their homes. Photo: Oxfam East Africa, Flickr

    And they’re not the only ones. This year, hurricane season hit U.S. coastal communities and islands in the Caribbean at an alarming scale, causing massive infrastructure damage and loss of life. Meanwhile, wildfires are wreaking havoc in Southern California. These natural disasters are influenced by a warming climate. As the sea level rises and average temperatures continue to increase, these disasters will become more frequent and intense. Climate change is expected to displace millions of people in the coming decades, and countries will increasingly have to grapple with this issue.

    When disaster strikes, what happens to the communities in harm’s way? Where do the displaced people stay? Will they be able to return to their homes in areas that climate change may have rendered unlivable? Experts from Columbia University discussed these challenges and more at a recent event hosted by the Earth Institute.

    Climate scientist Radley Horton from the Lamont-Doherty Earth Observatory moderated the panel. The speakers included: Lisa Dale, a lecturer in the undergraduate program in Sustainable Development; Alex de Sherbinin, a geographer at the Center for International Earth Science Information Network; and Michael Gerrard, director of the Sabin Center for Climate Change Law at Columbia Law School. The event was part of the Earth Institute’s Climate Adaptation Initiative—a three-year project to enhance Columbia’s impact on sustainability problem-solving. One of the themes of this initiative is climate-induced retreat to safer areas.

    Where Will Climate Migrants Go?

    Some experts estimate that climate change could force between 150 and 300 million people to find a new place to live by the middle of this century, though there is considerable uncertainty about the amount. Finding suitable locations to house them will be a significant impediment. As Michael Gerrard explained, “part of the problem is scale. If we’re talking about millions of people having to be on the move, it just doesn’t work.”

    In the U.S., there are very few habitable places that aren’t already occupied by homes, businesses, or agriculture, or preserved as park lands or forests. Meanwhile, rural areas would provide few opportunities for migrants to find employment and rebuild their lives.

    Instead, Gerrard suggested moving people from high-risk areas to cities whose populations are shrinking, such as Detroit, Michigan. He sees cities’ potential for vertical development, energy-efficient buildings, and public transportation as a way to sustainably host climate migrants.

    The 1951 Refugee Convention defines a protected refugee as someone who leaves his or her home country due to racial, religious, or social persecution, or reasonable fear of such persecution. These refugees have the right to seek asylum and protection from participating members of the United Nations (though these countries are not obligated to take them in). However, people displaced by climate change do not fit this definition. At the international level, there is no legal mechanism in place to protect climate migrants’ rights and to ensure assistance from other countries. In terms of cross-border migration, Gerrard said, “there is no international law that compels a country to take in people from other countries; it’s wholly voluntary.”

    When Should Climate Migration Happen?

    Once a major disaster strikes with little or no warning, victims can become ‘distressed’ migrants—people who have lost their homes and are forced to flee with nothing but the shirts on their backs.

    A better scenario would be to resettle people outside of at-risk areas before disaster strikes. That way, people would have some degree of choice in where to go and what to bring.

    However, Alex de Sherbinin pointed out that the U.S. government has no policy mechanism designed to relocate people before a disaster strikes.

    Not only does relocating people cost money, but governments miss out on tax revenues if land is left empty. “This is why there is an impetus to build up and grow in vulnerable coastal zones,” said de Sherbinin.

    But it’s not impossible to be proactive about climate migration. China has ‘ecological migration,’ a relocation program designed to anticipate future disasters. The government has resettled large communities from rural areas damaged by climate change, industrialization, and other problems. The program is partly an effort to reduce dust storms produced by agriculture. It works out economically because it was no longer financially tenable for the Chinese government to support these communities in rural areas.

    Where Would the Money Come From?

    Michael Gerrard views carbon pricing as an ideal solution to funding climate relocation. Displacement by sea level rise, hurricanes, and wildfires is, as he put it, “a negative externality of burning fossil fuels, so if you were to build that into the price and pay for some of this through a price on carbon, you would generate a whole lot of money that way.” In this scenario, the money paid by carbon emitters could help fund climate relocation while creating a major economic incentive to move away from fossil fuels.

    The panelists agreed that countries also need to be forward-looking. In order to avoid the US’ reactive disaster planning, we must plan ahead for future damage and associated costs from natural disasters when thinking about how to manage the retreat from at-risk areas.

    Unfortunately, U.S. disaster response is typically reactive instead of proactive. Lisa Dale explained how, much like flood planning, the federal fire budget is backward-looking. “The U.S. Forest Service’s annual budget is based on the last 10 years of fire costs,” she said, “so they are always estimating too low.” Meanwhile, the cost of suppressing fire has grown substantially, she added.

    A more progressive approach would lead to better management of funds to add protective measures against climate-related catastrophes, build resilience, and in extreme cases relocate at-risk communities.

    With a lack of finance, policy, and legal frameworks, managed retreat will be a huge challenge in the United States. So it is no wonder that developing nations are not receiving the financial and technical assistance they so desperately need to recover from disasters and to rebuild in a climate-resilient way. Gerrard pointed out that the U.S. is “one of the richest places on the planet and we’re struggling to come up with resources to fund it.”

    Changing Climate, Changing Cultures

    For climate relocation to work, governments need to care and commit to international responsibility and burden-sharing. However, in the current global political context of fear of terrorism, an increased refugee influx into Europe, and an overall rise of xenophobia, countries are more likely to opt for stricter policies on cross-border migration. Rex Tillerson announced on December 3 that the U.S. is pulling out of the Global Compact for Migration, arguing (falsely, in Gerrard’s view) that it was a threat to U.S. sovereignty.

    “There is such an anti-immigrant fervor that it’s hard to imagine the U.S. in the short-term taking in large numbers of people,” Gerrard said.

    According to Alex de Sherbinin, framing migration as a useful adaptation (and life- and cost-saving strategy), rather than a retreat, can encourage governments to take actions to support migration.

    On the other hand, there is a human cost to any kind of permanent relocation: The threat of losing one’s cultural heritage, particularly in native communities on coastal areas and islands such as Barbuda. Many islanders have a deep attachment to their homeland, which is inextricably linked to their culture and traditions.

    Gaston Browne, the prime minister of Antigua and Barbuda, is pushing for tourism development and land ownership to regenerate Barbuda’s economy and reduce the island’s reliance on Antigua. The Barbuda Land Act of 2007 formally recognized that citizens communally own Barbuda’s land—a practice dating back hundreds of years—and must consent to major developments. In its place, Browne proposes to institute a system in which Barbudans can buy their plots for $1, opening up the possibility of securing bank loans for reconstruction. Many people and representatives in the Barbuda Council are opposed to this new system, as it would threaten their culture and would potentially open up their island to foreign investment and development.

    As Alex de Sherbinin noted, “rebuilding homes is one thing, but also rebuilding communities and allowing the tissue of community to reform requires funds to facilitate.”

    There is a lot of work ahead of us to solve the climate migration issue, and as Michael Gerrard pointed out, “it’s really a question of trying to find sufficient humanity.”

    A video of the event, Climate Change Impacts: Relocation to Safer Ground, can be found here [1 hour lecture].

    See the full article here .

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    Columbia University was founded in 1754 as King’s College by royal charter of King George II of England. It is the oldest institution of higher learning in the state of New York and the fifth oldest in the United States.

     
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