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  • richardmitnick 12:18 pm on June 29, 2016 Permalink | Reply
    Tags: , , Perimeter Institute   

    From PI: “What We Know (And What We Don’t) About Dark Matter” 

    Perimeter Institute
    Perimeter Institute

    June 29, 2016

    Eamon O’Flynn
    Manager, Media Relations
    eoflynn@perimeterinstitute.ca
    (519) 569-7600 x5071

    Some of the most abundant stuff in the universe is also the most mysterious, but we may not be in the dark for long.

    The concept of dark matter is a mind-bender.

    It proposes that all the stuff we’re familiar with in the universe – planets, stars, galaxies, hippopotamuses – represent just a smidgen of what’s really out there, and that the universe is mostly populated by something else that we don’t yet understand.

    The existence of this abundant-but-elusive stuff is inferred by the gravitational sway it seems to exert on what we can see, and on the large-scale structure of the universe.

    So what is it? Well, we’re still largely in the dark, but much research aims to shed light on the matter.

    Here’s a look at what we know, and what we don’t, about one of the greatest mysteries in modern physics.

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    Check out Perimeter Institute’s educational resource, The Mystery of Dark Matter.

    3
    Watch an excerpt about Fritz Zwicky from a Perimeter Institute Public Lecture by Katherine Freese.

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    Weakly interacting massive particles (WIMPs) are a leading candidate for dark matter. Wimpzillas are, as the name implies, supermassive WIMPs. Other candidates include robust associations of massive baryonic objects (RAMBOs), gravitinos, and massive astrophysical compact halo objects (MACHOs). Less catchy, but equally intriguing, are the axion and the Kaluza-Klein particle.

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    Watch a public lecture by Perimeter researcher Kendrick Smith about what we have learned from the CMB.

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    Check out this Business Insider article on the physics of Super Mario World.

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    Watch “The Dark Side of the Universe,” a Perimeter Institute Public Lecture by Katherine Freese, delivered March 2, 2016.

    Access mp4 video here .

    See the full article here .

    Please help promote STEM in your local schools.

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    About Perimeter

    Perimeter Institute is the world’s largest research hub devoted to theoretical physics. The independent Institute was founded in 1999 to foster breakthroughs in the fundamental understanding of our universe, from the smallest particles to the entire cosmos. Research at Perimeter is motivated by the understanding that fundamental science advances human knowledge and catalyzes innovation, and that today’s theoretical physics is tomorrow’s technology. Located in the Region of Waterloo, the not-for-profit Institute is a unique public-private endeavour, including the Governments of Ontario and Canada, that enables cutting-edge research, trains the next generation of scientific pioneers, and shares the power of physics through award-winning educational outreach and public engagement.

     
  • richardmitnick 4:31 pm on June 17, 2016 Permalink | Reply
    Tags: Institute for Quantum Computing U Waterloo, Noncontextuality, Perimeter Institute, , , What does it mean to say the world is quantum?   

    From PI: “New Experiment Clarifies How The Universe Is Not Classical” 

    Perimeter Institute
    Perimeter Institute

    June 17, 2016
    Erin Bow

    “This is a great example of what’s possible when Perimeter and IQC work together. We can start with these exciting, abstract ideas and convert them to things we can actually do in our labs.”
    – Kevin Resch, Faculty member, Institute for Quantum Computing

    1
    From left to right: Matthew Pusey (Perimeter postdoctoral researcher), Kevin Resch (IQC and University of Waterloo faculty member), Robert Spekkens (Perimeter faculty member), and Michael Mazurek (University of Waterloo and IQC PhD student) interact in a quantum optics lab at the Institute for Quantum Computing. No image credit.

    Theorists from Perimeter and experimentalists from the Institute for Quantum Computing have found a new way to test whether the universe is quantum, a test that will have widespread applicability: they’ve proven the failure of noncontextuality in the lab.
    _______________________________________________________________________________________________________________________________________

    What does it mean to say the world is quantum? It’s a surprisingly difficult question to answer, and most casual discussions on the point are heavy on the hand-waving, with references to cats in boxes.

    If we are going to turn the quantum-ness of the universe to our advantage through technologies like quantum computing, our definition of what it means to be quantum – or, more broadly, what it means to be non-classical – needs to be more rigorous. That’s one of the aims of the field of quantum foundations, and the point of new joint research carried out by theorists at Perimeter and experimentalists at the University of Waterloo’s Institute for Quantum Computing (IQC).

    “We need to make precise the notion of non-classicality,” says Robert Spekkens, a faculty member at Perimeter, who led the work from the theoretical side. “We need to find phenomena that defy classical explanation, and then subject those phenomena to direct experimental tests.”

    One candidate for something that defies classical explanation is the failure of noncontextuality.

    “You can think of noncontextuality as the ‘if it walks like a duck’ principle,” says Matthew Pusey, a postdoctoral researcher at Perimeter who also worked on the project.

    As the saying has it, if something walks like a duck and quacks like a duck, it’s probably a duck. The principle of noncontextuality pushes that further, and says that if something walks like a duck and quacks like a duck and you can’t tell it apart from a duck in any experiment, not even in principle, then it must be a duck.

    Though noncontextuality is not something we often think about, it is a feature one would expect to hold in experiments. Indeed, it’s so intuitive that it seems silly to say it aloud: if you can’t tell two things apart, even in principle, then they’re the same. Makes sense, right?

    But in the quantum universe, it’s not quite true.

    Under quantum theory, two preparations of a system can return identical results in every conceivable test. But researchers run into trouble when they try to define exactly what those systems are doing. It turns out that in quantum mechanics, any model that assigns the systems well-defined properties requires them to be different. That’s a violation of the principle of noncontextuality.

    To understand what’s happening, imagine a yellow box that spits out a mix of polarized photons – half polarized horizontally and half polarized vertically. A different box – imagine it to be orange – spits out a different mix of photons, half polarized diagonally and half polarized anti-diagonally.

    Now measure the polarization of the photons from the yellow box and of the photons from the orange box. You can measure any polarization property you like, as much as you like. Because of the way the probabilities add up, the statistics of any measurement performed on photons from the yellow box are going to be identical to the statistics of the same measurement performed on photons from the orange box. In each case, the average polarization is always zero.

    “Those two kinds of boxes, according to quantum theory, cannot be distinguished,” says Spekkens. “All the measurements are going to see exactly the same thing.”

    You might think, following the principle of noncontextuality, that since the yellow and orange boxes produce indistinguishable mixes of photons, they can be described by the same probability distributions. They walk like ducks, so you can describe them both as ducks. But as it turns out, that doesn’t work.

    In a noncontextual world, the fact that the yellow-box photons and orange-box photons are indistinguishable would be explained in the natural way: by the fact that the probability distribution over properties are the same. But the quantum universe resists such explanations – it can be proven mathematically that those two mixtures of photons cannot be described by the same distribution of properties.

    “So that’s the theoretical result,” says Spekkens. “If quantum theory is right, then we can’t have a noncontextual model.”

    But can such a theoretical result be tested? Theorists from Perimeter and experimentalists from IQC set out to discover that very thing.

    Kevin Resch, a faculty member at IQC and the Department of Physics and Astronomy at the University of Waterloo, as well as a Perimeter Affiliate, worked on the project from the experimental end in his lab.

    “The original method of testing noncontextuality required two or more preparation procedures that give exactly the same statistics,” he says. “I would argue that that’s basically not possible, because no experiments are perfect. The method described in our paper allows contextuality tests to deal with these imperfections.”

    While previous attempts to test for the predicted failure of noncontextuality have had to resort to assuming things like noiseless measurements that are not achievable in practice, the Perimeter and IQC teams wanted to avoid such unrealistic assumptions. They knew they couldn’t eliminate all error, so they designed an experiment that could make meaningful tests of noncontextuality even in the presence of error.

    Pusey hit on a clever idea to fight statistical error with statistical inference. Ravi Kunjwal, a doctoral student at the Institute for Mathematical Sciences in Chennai, India, who was visiting at the time, helped define what a test of noncontextuality should look like operationally. Michael Mazurek, a doctoral student with Waterloo’s Department of Physics and Astronomy and IQC, built the experimental apparatus – single photon emitters and detectors, just as in the yellow-and-orange box example above – and ran the tests.

    “The interesting part of the experiment is that it looks really simple on paper,” says Mazurek. “But it wasn’t simple in practice. The analysis that we did and the standards that we held ourselves to required us to really get on top of the small systematic errors that are present in every experiment. Characterizing those errors and compensating for them was quite challenging.”

    At one point, Mazurek used half a roll of masking tape to keep optical fibres from moving around in response to tiny shifts in temperature. Nothing about this experiment was easy, and much of it can only be described with statistics and diagrams. But in the end, the team made it work.

    The result: an experiment that definitively shows the failure of noncontextuality. Like the pioneering work on Bell’s theorem, this research clarifies what it means for the world to be non-classical, and confirms that non-classicality experimentally.

    Importantly, and in contrast to previous tests of contextuality, this experiment renders its verdict without assuming any idealizations, such as noiseless measurements or statistics being exactly the same. This opens a new range of possibilities.

    Researchers in several fields are working to find “quantum advantages” – that is, things we can do if we harness the quantum-ness of the world that would not be possible in the classical world. Examples include quantum cryptography and quantum computation. Such advantages are the beams and girders of any future quantum technology we might be able to build. Noncontextuality can help researchers understand these quantum advantages.

    “We now know, for example, that for certain kinds of cryptographic tasks and computational tasks, the failure of noncontextuality is the resource,” says Spekkens.

    In other words, contextuality is the steel out of which the beams and girders are made.

    “This is a great example of what’s possible when Perimeter and IQC work together,” says Resch, Canada Research Chair in Optical Quantum Technologies. “We can start with these exciting, abstract ideas and convert them to things we can actually do in our labs.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    About Perimeter

    Perimeter Institute is a leading centre for scientific research, training and educational outreach in foundational theoretical physics. Founded in 1999 in Waterloo, Ontario, Canada, its mission is to advance our understanding of the universe at the most fundamental level, stimulating the breakthroughs that could transform our future. Perimeter also trains the next generation of physicists through innovative programs, and shares the excitement and wonder of science with students, teachers and the general public.

     
  • richardmitnick 3:27 pm on May 30, 2016 Permalink | Reply
    Tags: , Perimeter Institute, , , ,   

    From PI: “Bridging Two Roads of Physics” Women in Science 

    Perimeter Institute
    Perimeter Institute

    May 30, 2016
    Rose Simone

    Recent Perimeter research based on the holographic principle seeks new connections between general relativity and quantum field theory.

    Imagine driving along a road that traverses a beautiful landscape. Around every corner, there is a new vista of natural beauty to explore. Suddenly you come to a chasm.

    You can see a road on the other side, but how do you get there to complete the journey? You need a bridge.

    That’s the state of physics today, and Bianca Dittrich, Perimeter Institute researcher in mathematical physics and quantum gravity, is one of the people trying to build that bridge.

    1
    Bianca Dittrich

    On one side of the chasm is the road built by Albert Einstein’s theory of general relativity. It describes the force of gravity as the warping of spacetime by large masses such as planets and stars.

    On the other side is quantum field theory, our best description of interacting particles and the three other forces (the strong and weak nuclear forces and electromagnetism) operating at minuscule subatomic distances.

    The theories are incredibly successful in their respective realms, yet they are so different, both in formulation and conceptually, that it is difficult to bridge them.

    “Basically, we are trying to bridge all of the scales that we know,” Dittrich says. “That is what physics is about, but it is very hard. You need to bridge all of these scales by modelling the tiny scales, and show that this model actually does indeed describe reality as we know it at macroscopic scales.”

    In general relativity, spacetime is smooth and continuous. If you were to zoom in with a microscope to arbitrarily small distances, it should look the same as it does when you zoom out for the larger view. Quantum field theory, on the other hand, describes particles and forces that come as discrete “packets,” and spacetime would also have to be discrete and granular, like the pixels in a photograph.

    Scientists need a theory to describe the force of gravity at the quantum scale, and it must be consistent with the larger picture of general relativity. Building the bridge to a theory of quantum gravity is what occupies many physicists around the world today.

    It is easier said than done. If general relativity is scaled down to the quantum size, you start to get nonsensical “infinities” in the calculations. “Quantizing gravity sounds simple, in that it should be just the quantization of another force, besides the three forces (the non-gravitational forces) that were quantized decades ago,” Dittrich says. “But in fact it is a very hard and open problem.”

    There are many approaches to this longstanding problem. In loop quantum gravity, for example, physicists speak in terms of “spacetime atoms” linked together in a network like a fine mesh. This provides a model of what spacetime itself is made of.

    But in a recent paper*, “3D Holography: From Discretum to Continuum,” Dittrich and co-author Valentin Bonzom, now an assistant professor at Université Paris 13 who was previously a postdoctoral researcher at Perimeter Institute, tested a different approach, based on the holographic principle.

    The holographic principle says everything that happens in a given space can be explained in terms of information stored on the boundary of that space. (The principle takes its name from holograms, in which two-dimensional surfaces contain all the information needed to project a three-dimensional image.)

    A popular mathematical framework based on the holographic principle is known as the AdS/CFT correspondence. AdS is short for anti-de Sitter space, which describes a particular kind of geometry. Just like a bowling ball will stretch a rubber sheet, the elliptical shape of anti-de Sitter space can also stretch or contract, thus allowing it to describe gravity.

    CFT, meanwhile, is short for conformal field theory. Field theories are the language of quantum mechanics and can describe, for example, how an electrical field might change over space and time.

    The holographic principle applies because the AdS/CFT correspondence basically states that for every conformal field theory, there is a corresponding theory of gravity with one more dimension. So a two-dimensional CFT would correspond to a three-dimensional theory of gravity, for instance.

    But the holographic principle applies to infinitely large boundaries, and Dittrich and Bonzom wanted to see if it could also hold for finite boundaries, and for other types of geometries apart from AdS. This would then provide a more manageable way of describing a piece of spacetime, and understanding the microscopic details as they reconstruct the spacetime bulk.

    Working with a boundary without worrying too much about the bulk “very much simplifies the construction of a theory of quantum gravity,” Dittrich explains.

    They tested this in three spacetime dimensions, and “it turned out that the holographic principle indeed holds for finite boundaries, and we also obtained a very simple description of how to translate the boundary data into the geometry of the bulk,” she says.

    That this could be done in 3D was not too surprising, but the more challenging part will be extending this work into 4D space, Dittrich adds.

    Most theories of quantum gravity require the force of gravity to also be mediated by hypothetical particles called gravitons. If Dittrich can get her model to work in 4D, then she will have successfully taken it into a realm where gravitons exist. “Gravity can propagate through that spacetime,” Dittrich says.

    Dittrich has been on the physics road for some time. She grew up in Germany, reading a lot of popular books about science, as well as history and literature, and when she finished high school she considered various options, including areas such as geo-ecology.

    But she realized it was physics that could take her on the journey to the most complete understanding of nature. “If you want to understand why something works, the answer is in physics,” she says.

    Now, she is designing another bridge that will span that chasm between the two great roads and carry physicists to that more complete understanding of nature.

    *Science paper:
    3D holography: from discretum to continuum

    See the full article here .

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    About Perimeter

    Perimeter Institute is a leading centre for scientific research, training and educational outreach in foundational theoretical physics. Founded in 1999 in Waterloo, Ontario, Canada, its mission is to advance our understanding of the universe at the most fundamental level, stimulating the breakthroughs that could transform our future. Perimeter also trains the next generation of physicists through innovative programs, and shares the excitement and wonder of science with students, teachers and the general public.

     
  • richardmitnick 11:08 am on April 29, 2016 Permalink | Reply
    Tags: , , , Perimeter Institute, The Globe and Mail   

    From The Globe and Mail via PI: “‘Brilliant’ physicist to hold $8-million research chair at Perimeter Institute” 

    Perimeter Institute
    Perimeter Institute

    1

    Apr. 28, 2016
    IVAN SEMENIUK

    Long before the February press conference where physicists reported the first detection of gravitational waves from space – a major scientific achievement that made headlines around the world – Asimina Arvanitaki had arrived at a way to do the same thing with a far smaller and cheaper experiment involving a microscopic disk suspended by powerful lasers.

    The 36-year-old theorist, known to friends and colleagues as Mina, has become a specialist in thinking up novel approaches to some of of the deepest problems in fundamental physics. Her work is at the forefront of an emerging area of research that is sometimes called “the precision frontier” because it involves making exacting measurements of well-understood phenomena and looking for unexpected deviations from what theory predicts.

    “Most of these ideas you can actually build on a table,” said Dr. Arvanitaki.

    Now Dr. Arvanitaki will have more scope and resources to pursue her ideas as the latest recipient of an $8-million research chair at the Perimeter Institute for Theoretical Physics in Waterloo, Ont., where she has worked as a researcher since 2014.

    The new chair is noteworthy for a few reasons. In addition to representing an area of research that thrives on working off the beaten track, Dr. Arvanitaki will become the first female chair holder at the high-profile institute and the first to be supported by a funding source from outside Canada.

    The Stavros Niarchos Foundation, a philanthropic organization headquartered in Athens and associated with a shipping industry fortune, will cover half the cost of the chair with the remaining support coming from the Perimeter Institute.

    Greek heritage is evident in the title of the new position, dubbed the Aristarchus Chair in Theoretical Physics after the ancient philosopher from the Greek island of Samos who famously suggested that the Earth revolves around the sun, some 18 centuries before Nicolaus Copernicus.

    “His thinking implied the sun is exactly like the distant stars,” said Dr. Arvanitaki, who suggested the name for the inaugural chair.

    She added that by foreseeing that our solar system many not be unique in the universe, Aristarchus was also setting the stage for a far more contentious theory in current physics, which holds that our entire universe is just one of many.

    “It’s a very controversial idea. People hate it, but I find it fascinating,” Dr. Arvanitaki said.

    Raised in a small village in southern Greece, Dr. Arvanitaki was the child of two teachers and grew up with an appetite for learning. She recalls that at a young age she correctly calculated the time it takes light to travel from Earth to the sun – about eight minutes – and was stunned to realize that “we cannot know the ‘now’ of the sun.”

    Dr. Arvanitaki came to Perimeter after earning her PhD and doing postdoctoral work at Stanford University under Savas Dimopoulus, a widely respected theorist who also hails from Greece.

    “She’s one of the most brilliant young people I’ve ever met,” Dr. Dimopoulos said of his former student and collaborator.

    He added that intelligence alone was not enough for success in physics, and that one way Dr. Arvanitaki excels is in selecting problems to work on that lead to productive results.

    “You have to have good taste,” he said. “Or in her case, even inventing new directions and new ways to see very well-motivated ideas.”

    Dr. Arvanitaki said she was looking forward to bringing on more researchers and students to accelerate her efforts to explore new domains of physics, and was pleased at the prospect of doing it at the Perimeter Institute. “There’s something about this place – you feel it when you walk in the building – it’s intoxicating.”

    The Institute was established in 1999 by BlackBerry co-founder Mike Lazaridis and has since drawn substantial government support, including a $50-million investment over five years announced in the latest federal budget.

    Black holes merging Swinburne Astronomy Productions
    Black holes merging Swinburne Astronomy Productions

    See the full article here .

    Please help promote STEM in your local schools.

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    About Perimeter

    Perimeter Institute is a leading centre for scientific research, training and educational outreach in foundational theoretical physics. Founded in 1999 in Waterloo, Ontario, Canada, its mission is to advance our understanding of the universe at the most fundamental level, stimulating the breakthroughs that could transform our future. Perimeter also trains the next generation of physicists through innovative programs, and shares the excitement and wonder of science with students, teachers and the general public.

     
  • richardmitnick 10:10 am on April 21, 2016 Permalink | Reply
    Tags: , Perimeter Institute, , Three Ways Physics Could Help Save Humanity   

    From PI: “Three Ways Physics Could Help Save Humanity” 

    Perimeter Institute
    Perimeter Institute

    April 21, 2016

    Technology has put our global environment in crisis. Could it also provide the solution?

    PROBLEM: fossil fuels for power and transit
    SOLUTION: Superconductors

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    Fossil fuels generate most electricity, which is then transported through wires and cables – a process that loses between eight and 15 percent of the original power production. But exotic materials called superconductors could just save the day.
    Superconductors let electric current flow without resistance or loss, and allow movement with no friction. Today’s superconductors operate at extremely low temperatures and require supercooling. Creating – or finding – room-temperature superconductors is one of modern science’s great quests.

    High-temperature superconductors could be used to create extremely efficient rotating machines (think: steam-free turbines), and power networks with near-100-percent efficiency.

    They could also revolutionize transit. Magnetic levitation (maglev) trains already use supercooled superconducting magnets to levitate and propel the train floating above the tracks. High-temperature versions would do away with energy-guzzling cooling systems and pave the way for even-more-Earth-friendly commutes.

    Problem: Gravity and inertia
    Solution: Advanced materials

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    Many resources devoted to overcoming the effects of gravity and inertia also contribute to climate change. Just think of the fuel used simply to get heavy vehicles to move. Cue the arrival of, and excitement about, graphene.

    Graphene is a sheet of carbon just one atom thick, and it’s the strongest material in the world. (If it was the thickness of cling wrap, it would take the force of a large car to puncture it with a pencil.)

    Experimentalists are currently working towards creating a graphene-composite material that would replace steel in aircraft and other vehicles, making them significantly more fuel-efficient.

    But some theorists are looking even further afield. Graphene could prove strong enough to fabricate long-theorized space elevators. These elevators could tether a satellite to the Earth, turning the satellite into a base station for mining natural resources on asteroids, among other possibilities.

    Advanced quantum materials are also expected to significantly improve our ability to create and store energy, from high-efficiency solar panels to high-performance batteries.

    Problem: Humans
    Solution: Artificial intelligence

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    The Anthropocene is not an official epoch yet – the International Commission on Stratigraphy (the people who define geologic time scales) will decide this year whether to officially recognize it – but scientists have no doubt that human society has been, and continues to be, profoundly damaging to the Earth.

    So why not consider a non-human effort to ameliorate that impact? Powered by recent advances in neural networks and deep-learning algorithms, computers are becoming increasingly “human” in their abilities. (Google hit a milestone this year when its AlphaGo computer beat the world champion of the ancient Chinese board game of Go.)

    But artificial intelligence could do much more than play a mean board game. A combination of machine-learning algorithms and future supercomputer hardware – including quantum computers – could forge the new era of AI and help realize efficiencies in infrastructure design, conduct fundamental research projects, and even mediate arguments.

    ______________________________________________________________________________

    BUT THAT’S NOT ALL: The physics of chaos theory, quantum information, and next-generation supercomputing could also help scientists understand and predict climate change.

    According to Tim Palmer, the Oxford University Royal Society Research Professor in Climate Physics, the emerging concept of inexact supercomputing could provide a powerful approach to assessing the chaotic, uncertain nature of our climate system.
    Tune in on May 4 to watch the live webcast of Dr. Palmer’s Perimeter Public Lecture “Climate Change, Chaos, and Inexact Computing.”


    Access mp4 video here .

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    About Perimeter

    Perimeter Institute is a leading centre for scientific research, training and educational outreach in foundational theoretical physics. Founded in 1999 in Waterloo, Ontario, Canada, its mission is to advance our understanding of the universe at the most fundamental level, stimulating the breakthroughs that could transform our future. Perimeter also trains the next generation of physicists through innovative programs, and shares the excitement and wonder of science with students, teachers and the general public.

     
  • richardmitnick 3:39 pm on March 15, 2016 Permalink | Reply
    Tags: , , Innovation150, Perimeter Institute   

    From PI: “Perimeter heads nationwide partnership to ignite innovation for Canada’s 150th year” 

    Perimeter Institute
    Perimeter Institute

    March 15, 2016

    Five of Canada’s leading science outreach organizations will deliver Innovation150, a cross-country celebration of Canadian ingenuity, throughout 2017.

    Travelling science exhibitions, major city-wide festivals, and dynamic online experiences are among the year-long activities in Innovation150, a nationwide partnership announced this week in Halifax, Nova Scotia.

    Innovation150 is an interactive celebration of Canadian ingenuity that will offer opportunities for youth, families, and communities across the country to experience innovation first-hand.

    As a Signature Initiative of Canada 150, the Government of Canada’s sesquicentennial celebrations, Innovation150 will share Canadian innovations of the past and focus on the creative thinking and innovations that will drive our future.


    Access the mp4 video here .

    The Honourable Minister of Canadian Heritage Mélanie Joly unveiled the initiative today at Halifax’s Discovery Centre, where she announced $5,875,000 in funding for Innovation150 programming from the Government of Canada, through the Canada 150 Fund. Innovation150 is one of several Signature Initiatives planned to celebrate the country’s past, present, and future nationwide in 2017.

    “The Innovation150 project will highlight the innovation and creativity that represent us so well, and I am sure it will be able to inspire a whole generation of young Canadians,” said Minister Joly.

    “The festivities for the 150th anniversary of Confederation are a unique opportunity to promote and celebrate our outstanding talents in this fields of science, innovation, and culture.”

    Perimeter Institute leads a partnership of Canada’s top science outreach organizations to bring Innovation150 to life, including Actua, the Institute for Quantum Computing at the University of Waterloo, the Canadian Association of Science Centres, and the Canada Science and Technology Museums Corporation.

    “Canada’s greatest resource has always been the ingenuity of its people,” said Neil Turok, Director of Perimeter Institute.

    “Innovation and the brave pursuit of opportunities have always characterized us, from Indigenous peoples’ deeply rooted knowledge of this harsh, beautiful landscape to today’s increasingly urban, diverse, and progressive society. Through Innovation150, we will honour all the dreamers and doers that have made Canada innovative, and encourage future innovators – especially youth – to pursue ideas, inventions, and initiatives which will solve big problems and open new pathways for the world.”

    Art McDonald, winner of the 2015 Nobel Prize in Physics and Perimeter Institute Board member, served as an official Canada 150 Champion at the launch. McDonald said he hopes Innovation150 will show youth that “Canada can do things that will really have an impact on the world stage in innovation, science, and technology.”

    Innovation150 will provide Canadians of all ages with access to an integrated portfolio of exciting science, technology, engineering, and math-related activities, including:

    Power of Ideas National Tour – A highly engaging, travelling celebration that will feature an interactive science exhibit from Perimeter Institute where youth can explore the incredible power of the human mind, plus a speaker series, a MakerMobile from Actua, and in-classroom legacy resources – brought directly to 80 communities coast to coast to coast.
    MakerMobile – A moving maker space, produced by Actua, that will be full of exciting technology like 3D printers that will allow youth to experiment with hands-on learning and create their own innovations. Part of the Power of Ideas National Tour and in partnership with Actua’s national network, the MakerMobile will be focused on visiting remote and Indigenous communities and engaging youth that would otherwise not have access to these experiences.
    Quantum: The Exhibition – A fully bilingual, interactive, travelling exhibition sharing the wonders of the quantum world and the emerging quantum technologies that will shape our future. Quantum: The Exhibition will travel to science centres across Canada, launching at THEMUSEUM in downtown Kitchener in October 2016. For more information, visit quantumexhibit.ca.
    Innovation Celebration Festivals – Bringing together all travelling components, the Innovation150 Festivals will amplify the excitement of the Canada 150 celebrations and inspire curiosity and innovation through a full range of activities. Hosted by the nation’s leading science centres, these large-scale festivals will include activities to showcase innovation and engage entire communities.
    Innovation150 Digital Hub – This go-to digital showcase about Canadian thinkers and new concepts will be the online nexus for Innovation150 activities, with opportunities to explore stories of innovation, share new ideas for a brighter future, and participate in exciting contests to experience Canadian innovation firsthand.
    Public Awareness Campaign – Highlighting the past, present, and future of Canadian innovation, this national awareness campaign will engage youth, families, and communities with Innovation150 through integrated promotions, media engagement, and interactive online content.

    The program starts in Waterloo Region, Ontario, in October 2016 and then travels across Canada throughout 2017.

    “Innovation150 will engage Canadians of all ages in truly meaningful and enriching experiences that spark new ideas and build greater capacity for innovators of the future,” said Greg Dick, Director of Educational Outreach at Perimeter Institute.

    “This is vitally important to the success of Canada as a nation in an internationally competitive world where new knowledge and innovation will be key.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    About Perimeter

    Perimeter Institute is a leading centre for scientific research, training and educational outreach in foundational theoretical physics. Founded in 1999 in Waterloo, Ontario, Canada, its mission is to advance our understanding of the universe at the most fundamental level, stimulating the breakthroughs that could transform our future. Perimeter also trains the next generation of physicists through innovative programs, and shares the excitement and wonder of science with students, teachers and the general public.

     
  • richardmitnick 6:26 pm on January 19, 2016 Permalink | Reply
    Tags: , , , eLISA, , , Perimeter Institute   

    From PI: “Preparing for a cosmological challenge” 

    Perimeter Institute
    Perimeter Institute

    January 19, 2016
    Rose Simone

    Einstein’s theory of general relativity may soon be put to the ultimate test through measurements of a black hole’s shadow, say a pair of Perimeter researchers.
    __________________________________________________________________________________________________________________________________________
    Even though it is over 100 years old, Albert Einstein’s theory of general relativity is still a formidable prizefighter.

    The theory, which successfully describes gravity as a consequence of the curvature of spacetime itself, has withstood all the experimental tests that physicists have been able to throw at it over the decades.

    So now, to have any hope of challenging general relativity, they need to bring in a heavyweight. Enter the closest challenger: the smallish but still formidable 4.5-million- at the centre of our own Milky Way galaxy.

    The challenge will be assisted by the Event Horizon Telescope (EHT), a radio telescope array as large as the Earth, being configured to take precise images of the silhouette (or the shadow) of that black hole, known as Sagittarius A*.

    1
    Sag A*. This image was taken with NASA’s Chandra X-Ray Observatory. Ellipses indicate light echoes.

    NASA Chandra Telescope
    NASA/Chandra

    Event Horizon Telescope map
    EHT map

    Meanwhile, Tim Johannsen, a postdoctoral fellow at Perimeter Institute and the University of Waterloo, who works with Avery Broderick, an Associate Faculty member at Perimeter Institute jointly appointed at Waterloo, has led a group of researchers in calculating the measurements that will be used to determine whether general relativity really does stand up in the strong gravity regime of that black hole.

    3
    Perimeter postdoctoral researcher Tim Johannsen.

    4
    Perimeter Associate Faculty member Avery Broderick.

    Their paper was recently published in Physical Review Letters, along with an accessible synopsis of the work.

    When the images from the black hole come in and the measurements outlined in the recent paper are actually taken, it will be the first truly broad test of general relativity in the strong gravity regime.

    “That is very exciting and we expect to be able to do that within the next few years,” Johannsen says.

    Black holes are regions of spacetime, where gravity is so strong that not even light can escape once it has passed the threshold of no return − the event horizon. So as the name implies, they are dark.

    But owing to its immense gravity, the black hole pulls in vast quantities of dust and gas from surrounding stars. These accrete into a hot swirling plasma disk that illuminates the silhouette of the black hole. The EHT will be able to capture this, in images that will be historic firsts.

    A lot of physics will be done with the data gleaned from those images, but putting general relativity to the test is perhaps the most exciting challenge.

    General relativity has been fantastically successful. In every experiment that has been done to test how the sun and stars in our cosmos affect spacetime and exert gravitational pull on other objects, its predictions have held up.

    But the question is whether the theory will continue to hold up in a strong gravity environment, such as the surroundings of a black hole.

    Black holes are so massive and compact that the spacetime-warping effects, predicted by general relativity, would be more evident than around the sun or other stars. They are “orders of magnitude” different as gravitational environments go, Broderick says.

    “That means that this is terra incognita and we don’t know what we are going to find,” Broderick says. The EHT provides “an opportunity to begin probing in a critical way the non-linear nature of general relativity in the strong gravity regime.”

    This is important to physicists because even though general relativity has been enormously successful in explaining the cosmos that we can see, there are a number of difficulties with it. “It is not clear, for example, exactly how it should be combined with the quantum theory that we have, and in fact, it is very difficult to reconcile the two in a grand unification scheme,” Johannsen says.

    Moreover, there is the problem of the mysterious “dark energy” driving the accelerated expansion of spacetime, as well as the conundrum about the nature of “dark matter,” unseen mass theorized as an explanation for observed galaxy rotation rates that prevent galaxy clusters from flying apart. Physicists are hoping for some insights about general relativity in the strong gravity regime to make sense of these mysteries.

    Johannsen’s team has developed a way of checking how much the gravitational environment of this black hole might deviate from the theory of general relativity and other gravity theories.

    The paper sets constraints on the parameters of the size of the shadow to fit with general relativity. Other gravity models also propose modifications to the theory of general relativity, such as the Modified Gravity Theory (MOG) and the Randall-Sundrum-type braneworld model (RS2). The paper sets the constraints for the black hole to fit with these gravity models as well.

    “We have made the first realistic estimate of the high precision with which the EHT can detect the size of the shadow,”Johannsen says. “We show that such a measurement can be a precise test of general relativity.”

    A nice bonus from this work is that researchers will also get much more precise measurements of the mass of the black hole and its distance. “Sharpening the precision is great because that will enable us to get even more precise constraints on deviations from general relativity,” Johannsen adds.

    There are already good measurements of how far away Sagittarius A* is and how massive it is, based on other experiments that have looked at the motion of stars as they orbit the black hole, as well as of masers throughout the Milky Way, Johannsen explains. “People have been doing this for about 20 years.”

    This can be used to figure out what it should look like. But once the images from the EHT are available, it will be possible to check: “Do we get what we expect? Or do we get something else?” Johannsen says.

    Getting the measurements is really a matter of drawing a series of lines from the centre of the black hole image to the edge of its shadow. On the image, it looks like a pie shape with slices. Measuring the lines of each slice and calculating an average “gives us the angular radius of the shadow and then we know how big it is,” Johannsen says.

    6
    A reconstructed image of Sgr A* for an EHT observation at 230 GHz with a seven-station array.

    From the measurements of the size of the shadow, it is possible to see how closely the gravity in the black hole environment matches the predictions of general relativity and of other theories of gravity.

    “If general relativity is not correct, there can be significant change in the size. The shadow can also become asymmetric so that it is no longer circular, but egg-shaped, for example,” Johannsen says.

    Getting to the point of making these measurements will take a couple more years because at least seven or eight of the telescopes in the EHT array must be coordinated to get the data at the same time in a massive worldwide collaboration.

    The amount of raw data that has to be gathered to get the images is so enormous, it can’t even be transmitted over the internet.

    “These are humongous data sets. So they literally have to save all this data on hard drives and put them in a box and ship them,” Johannsen says.

    The hard drives get shipped to the MIT Haystack Observatory, which is the headquarters for the EHT. From there, the raw data is analyzed and the images are produced.

    After the images are produced, Johannsen gets to use his measurement technique to find out if general relativity is correct for the strong gravity environment around this black hole.

    This isn’t the only test of general relativity in the strong gravity regime in the works. There are other sophisticated experiments to detect, for example, the gravitational waves that are predicted by general relativity. But the prime experimental candidate to confirm the existence of gravitational waves would be the Evolved Laser Interferometer Space Antenna (eLISA), a space-based telescope with an estimated launch date of 2034.

    LISA graphic
    NASA LISA
    LISA

    The EHT will produce images in the next few years.

    If it turns out that the measurements yield what was expected and general relativity holds up, that would be interesting, “because Einstein had this theory 100 years ago, and then we will know that it is true,” Johannsen says.

    But if the challenger should prevail, and strong gravity does strike a blow to the theory of general relativity, “that would be big,” he adds.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    About Perimeter

    Perimeter Institute is a leading centre for scientific research, training and educational outreach in foundational theoretical physics. Founded in 1999 in Waterloo, Ontario, Canada, its mission is to advance our understanding of the universe at the most fundamental level, stimulating the breakthroughs that could transform our future. Perimeter also trains the next generation of physicists through innovative programs, and shares the excitement and wonder of science with students, teachers and the general public.

     
  • richardmitnick 9:32 pm on January 11, 2016 Permalink | Reply
    Tags: , , Perimeter Institute, The Sky is the Limit   

    From PI: “The sky as a limit” 

    Perimeter Institute
    Perimeter Institute

    January 11, 2016

    Eamon O’Flynn
    Manager, Media Relations
    eoflynn@perimeterinstitute.ca
    (519) 569-7600 x5071

    Perimeter researchers show how the largest possible structure – the curvature of the universe as a whole – can be used as a lens onto the smallest objects observable today, elementary particles.

    1
    Elliot Nelson (left) and Niayesh Afshordi. No image credit found.

    Perimeter Associate Faculty member Niayesh Afshordi and postdoctoral fellow Elliot Nelson recently won a third-place Buchalter Cosmology Prize for uncovering an entirely new way cosmology can shed light on the future of particle physics.

    1
    Hubble Goes to the eXtreme to Assemble Farthest-Ever View of the Universe

    Like photographers assembling a portfolio of best shots, astronomers have assembled a new, improved portrait of mankind’s deepest-ever view of the universe. Called the eXtreme Deep Field, or XDF, the photo was assembled by combining 10 years of NASA Hubble Space Telescope photographs taken of a patch of sky at the center of the original Hubble Ultra Deep Field.

    NASA Hubble Telescope
    NASA/ESA Hubble

    The XDF is a small fraction of the angular diameter of the full moon. The Hubble Ultra Deep Field is an image of a small area of space in the constellation Fornax, created using Hubble Space Telescope data from 2003 and 2004. By collecting faint light over many hours of observation, it revealed thousands of galaxies, both nearby and very distant, making it the deepest image of the universe ever taken at that time. The new full-color XDF image is even more sensitive, and contains about 5,500 galaxies even within its smaller field of view. The faintest galaxies are one ten-billionth the brightness of what the human eye can see. Magnificent spiral galaxies similar in shape to our Milky Way and the neighboring Andromeda Galaxy appear in this image, as do the large, fuzzy red galaxies where the formation of new stars has ceased. These red galaxies are the remnants of dramatic collisions between galaxies and are in their declining years. Peppered across the field are tiny, faint, more distant galaxies that were like the seedlings from which today’s magnificent galaxies grew. The history of galaxies — from soon after the first galaxies were born to the great galaxies of today, like our Milky Way — is laid out in this one remarkable image.

    Hubble pointed at a tiny patch of southern sky in repeat visits (made over the past decade) for a total of 50 days, with a total exposure time of 2 million seconds. More than 2,000 images of the same field were taken with Hubble’s two premier cameras: the Advanced Camera for Surveys [ACS] and the Wide Field Camera 3 [WFC3], which extends Hubble’s vision into near-infrared light.

    NASA Hubble ACS
    ACS

    NASA Hubble WFC3
    WFC3

    “The XDF is the deepest image of the sky ever obtained and reveals the faintest and most distant galaxies ever seen. XDF allows us to explore further back in time than ever before”, said Garth Illingworth of the University of California at Santa Cruz, principal investigator of the Hubble Ultra Deep Field 2009 (HUDF09) program.

    The universe is 13.7 billion years old, and the XDF reveals galaxies that span back 13.2 billion years in time. Most of the galaxies in the XDF are seen when they were young, small, and growing, often violently as they collided and merged together. The early universe was a time of dramatic birth for galaxies containing brilliant blue stars extraordinarily brighter than our sun. The light from those past events is just arriving at Earth now, and so the XDF is a “time tunnel into the distant past.” The youngest galaxy found in the XDF existed just 450 million years after the universe’s birth in the big bang.

    Before Hubble was launched in 1990, astronomers could barely see normal galaxies to 7 billion light-years away, about halfway across the universe. Observations with telescopes on the ground were not able to establish how galaxies formed and evolved in the early universe.

    Hubble gave astronomers their first view of the actual forms and shapes of galaxies when they were young. This provided compelling, direct visual evidence that the universe is truly changing as it ages. Like watching individual frames of a motion picture, the Hubble deep surveys reveal the emergence of structure in the infant universe and the subsequent dynamic stages of galaxy evolution.

    The infrared vision of NASA’s planned James Webb Space Telescope [JWST] will be aimed at the XDF.

    NASA Webb Telescope
    JWST

    The Webb telescope will find even fainter galaxies that existed when the universe was just a few hundred million years old. Because of the expansion of the universe, light from the distant past is stretched into longer, infrared wavelengths. The Webb telescope’s infrared vision is ideally suited to push the XDF even deeper, into a time when the first stars and galaxies formed and filled the early “dark ages” of the universe with light.
    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Md., conducts Hubble science operations. STScI is operated by the Association of Universities for Research in Astronomy, Inc., in Washington.
    Date 29 June 2012
    Photographer NASA; ESA; G. Illingworth, D. Magee, and P. Oesch, University of California, Santa Cruz; R. Bouwens, Leiden University; and the HUDF09 Team

    2
    Andromeda Galaxy. Adam Evans

    Their work begins with the knowledge that space is flat. While there are local wrinkles, they are wrinkles in a flat space, not wrinkles in curved space. The universe as a whole is within one percent of flat.

    The problem is that it shouldn’t be. The vacuum of space is not empty; it is filled with fields that may be weak but cannot be zero – nothing quantum can ever be zero, because quantum things wiggle. According to general relativity, such fluctuations should cause spacetime to curve. In fact, a straightforward calculation of how much the vacuum should curve predicts a universe so tightly wound that the moon would not fit inside it.

    Cosmologists have typically worked around this problem – that the universe should be curved, but looks flat – by assuming there is some antigravity that exactly offsets the tendency of the vacuum to curve. This set of off-base predictions and unlikely corrections is known as the cosmological constant problem, and it has been dogging cosmology for more than half a century.

    In this paper, Nelson and Afshordi make no attempt to solve it, but where other cosmologists invoked an offsetting constant and moved on, Nelson and Afshordi went on to ask one more question: Does adding such a constant to cancel the vacuum’s energy guarantee a flat spacetime? Their answer: not quite.

    The vacuum is still filled with quantum fields, and it is the nature of quantum fields to fluctuate. Even if they are perfectly offset such that their average value is zero, they will still fluctuate around that zero point. Those fluctuations should (again) cause space to curve – just not as much.

    In this scenario, the amount of curve created by the known fields – the electromagnetic field, for example, or the Higgs field – is too small to be measured, and is therefore allowed. But any unknown field would have to be weak enough that its fluctuations would not cause an observable curve in the universe. This sets a maximum energy for unknown fields.

    A theoretical maximum on a theoretical field may not sound groundbreaking – but the work opens a new window in an unexpected place: particle physics.

    A particle, quantum mechanics teaches us, is just an excitation of a field. A photon is an excitation of the electric field, for example, and the newly discovered Higgs boson is an excitation of Higgs field. It’s roughly similar to the way a wave is an excitation of the ocean. And just as the height of a breaking wave can tell us something about the depth of the water, the mass of a particle depends on the strength of its corresponding field.

    New kinds of quantum fields are often associated with proposals to extend the Standard Model of particle physics.

    5
    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    If Afshordi and Nelson are right, and there can be no such fields whose fluctuations have enough energy to noticeably curve space, there can be no unknown particles with a mass of more than 35 TeV. The authors predict that if there are new fields and particles associated with an extension to the Standard Model, they will be below that range.

    For generations, particle physics has made progress from the bottom up: building more and more powerful colliders to create – then spot and study – heavier and heavier particles. It is as if we started from the ground floor and built up, discovering more particles at higher altitudes as we went. What Nelson and Afshordi have done is lower the sky.

    There is a great deal of debate in particle physics about whether we should build increasingly powerful accelerators to search for heavier unknown particles. Right now, the most powerful accelerator in the world, the Large Hadron Collider [LHC], runs at a top energy of about 14 TeV; a proposed new super accelerator in China would run at about 100 TeV.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    As this debate unfolds, this new work could be particularly useful in helping experimentalists decide which energy levels – which skyscraper heights – are the most interesting.

    The sky does indeed have a limit, this research suggests – and we are about to hit it.

    Read the original prize-winning paper from by Afshordi and Nelson

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    About Perimeter

    Perimeter Institute is a leading centre for scientific research, training and educational outreach in foundational theoretical physics. Founded in 1999 in Waterloo, Ontario, Canada, its mission is to advance our understanding of the universe at the most fundamental level, stimulating the breakthroughs that could transform our future. Perimeter also trains the next generation of physicists through innovative programs, and shares the excitement and wonder of science with students, teachers and the general public.

     
  • richardmitnick 4:12 pm on January 2, 2016 Permalink | Reply
    Tags: , , , Perimeter Institute,   

    From PI Via Daily Galaxy: “The Big Bang was a Mirage from a Collapsing Higher-Dimensional Star” February 2015 but Very Interesting 

    Daily Galaxy
    The Daily Galaxy

    Perimeter Institute
    Perimeter Institute
    Perimeter Institute bloc

    February 14, 2015 [Just brought forward – again]
    No writer credit

    Temp 1

    Big Bang was a mirage from collapsing higher-dimensional star, theorists propose. While the recent [ESA]Planck results “prove that inflation is correct”, they leave open the question of how inflation happened.

    ESA Planck
    ESA/Planck

    A new The study could help to show how inflation was triggered by the motion of the Universe through a higher-dimensional reality.
    The event horizon of a black hole — the point of no return for anything that falls in — is a spherical surface. In a higher-dimensional universe, a black hole could have a three-dimensional event horizon, which could spawn a whole new universe as it forms.

    It could be time to bid the Big Bang bye-bye. Cosmologists have speculated that the Universe formed from the debris ejected when a four-dimensional star collapsed into a black hole — a scenario that would help to explain why the cosmos seems to be so uniform in all directions.

    Cosmic Background Radiation Planck
    CMB per Planck

    The standard Big Bang model tells us that the Universe exploded out of an infinitely dense point, or singularity. But nobody knows what would have triggered this outburst: the known laws of physics cannot tell us what happened at that moment.

    “For all physicists know, dragons could have come flying out of the singularity,” says Niayesh Afshordi, an astrophysicist at the Perimeter Institute for Theoretical Physics in Waterloo, Canada.

    It is also difficult to explain how a violent Big Bang would have left behind a Universe that has an almost completely uniform temperature, because there does not seem to have been enough time since the birth of the cosmos for it to have reached temperature equilibrium.

    To most cosmologists, the most plausible explanation for that uniformity is that, soon after the beginning of time, some unknown form of energy made the young Universe inflate at a rate that was faster than the speed of light. That way, a small patch with roughly uniform temperature would have stretched into the vast cosmos we see today. But Afshordi notes that “the Big Bang was so chaotic, it’s not clear there would have been even a small homogenous patch for inflation to start working on”.

    In a paper posted last week on the arXiv preprint server1, Afshordi and his colleagues turn their attention to a proposal made in 2000 by a team including Gia Dvali, a physicist now at the Ludwig Maximilians University in Munich, Germany. In that model, our three-dimensional (3D) Universe is a membrane, or brane, that floats through a ‘bulk universe’ that has four spatial dimensions.

    Ashfordi’s team realized that if the bulk universe contained its own four-dimensional (4D) stars, some of them could collapse, forming 4D black holes in the same way that massive stars in our Universe do: they explode as supernovae, violently ejecting their outer layers, while their inner layers collapse into a black hole.

    In our Universe, a black hole is bounded by a spherical surface called an event horizon. Whereas in ordinary three-dimensional space it takes a two-dimensional object (a surface) to create a boundary inside a black hole, in the bulk universe the event horizon of a 4D black hole would be a 3D object — a shape called a hypersphere. When Afshordi’s team modelled the death of a 4D star, they found that the ejected material would form a 3D brane surrounding that 3D event horizon, and slowly expand.

    The authors postulate that the 3D Universe we live in might be just such a brane — and that we detect the brane’s growth as cosmic expansion. “Astronomers measured that expansion and extrapolated back that the Universe must have begun with a Big Bang — but that is just a mirage,” says Afshordi.

    The model also naturally explains our Universe’s uniformity. Because the 4D bulk universe could have existed for an infinitely long time in the past, there would have been ample opportunity for different parts of the 4D bulk to reach an equilibrium, which our 3D Universe would have inherited.

    The picture has some problems, however. Earlier this year, the European Space Agency’s Planck space observatory released data that mapped the slight temperature fluctuations in the cosmic microwave background — the relic radiation that carries imprints of the Universe’s early moments. The observed patterns matched predictions made by the standard Big Bang model and inflation, but the black-hole model deviates from Planck’s observations by about 4%. Hoping to resolve the discrepancy, Afshordi says that his is now refining its model.

    Despite the mismatch, Dvali praises the ingenious way in which the team threw out the Big Bang model. “The singularity is the most fundamental problem in cosmology and they have rewritten history so that we never encountered it,” he says. Whereas the Planck results “prove that inflation is correct”, they leave open the question of how inflation happened, Dvali adds. The study could help to show how inflation is triggered by the motion of the Universe through a higher-dimensional reality, he says.

    Nature doi:10.1038/nature.2013.13743

    See the full article here .

    Please help promote STEM in your local schools

    stem

    STEM Education Coalition

     
  • richardmitnick 2:59 pm on December 4, 2015 Permalink | Reply
    Tags: , Perimeter Institute, ,   

    From PI: “Unveiling the Turbulent Times of a Dying Star” 

    Perimeter Institute
    Perimeter Institute

    November 26, 2015

    Eamon O’Flynn
    Manager, Media Relations
    eoflynn@perimeterinstitute.ca
    (519) 569-7600 x5071

    Running sophisticated simulations on a powerful supercomputer, an international research team has glimpsed the unique turbulence that fuels stellar explosions.

    2
    Supercomputer visualization of the toroidal magnetic field in a collapsed, massive star, showing how in a span of 10 milliseconds the rapid differential rotation revs up the stars magnetic field to a million billion times that of our sun (yellow is positive, light blue is negative). Red and blue represent weaker positive and negative magnetic fields, respectively. Credit: Robert R. Sisneros (NCSA) and Philipp Mösta.

    When a dying star goes supernova, it explodes with such ferocity that it outshines the entire galaxy in which it lived, spewing material and energy across unimaginable distances at near-light speed.

    In some cases, these cosmic cataclysms defy expectations, blasting not symmetrically in all directions – as an exploding firework might – but instead launching two narrow beams, known as jets, in opposite directions.

    Temp 1

    Understanding how these jets are created is a vexing challenge, but an international research team has recently employed powerful computer simulations to sleuth out some answers.

    The team – led by Philipp Mösta (NASA Einstein Fellow at UC Berkeley), with Caltech researchers Christian Ott, David Radice and Luke Roberts, Perimeter Institute computational scientist Erik Schnetter, and Roland Haas of the Max-Planck Institute for Gravitational Physics – published their findings Nov. 30 in Nature.

    Their work sheds light on an explosive chain reaction that creates jets and, over time, helps create the structure of the universe as we know it.

    “We were looking for the basic mechanism, the core engine, behind how a collapsing star could lead to the formation of jets,” said Schnetter, who designed computer programs for the simulations employed by the research team to model dying stars.

    That core engine, the team discovered, is a highly turbulent place. Any turbulent system – like an aging car with a deteriorating suspension on a bumpy road – is bound to get progressively more chaotic. In certain types of supernovae, that turbulence is caused by what is known as magnetorotational instability – a type of rapid change within the magnetic field of a spinning system, like some stars.


    Supercomputer visualization of the toroidal magnetic field in a collapsed, massive star, showing how in a span of 10 milliseconds the rapid differential rotation revs up the stars magnetic field to a million billion times that of our sun (yellow is positive, light blue is negative). Red and blue represent weaker positive and negative magnetic fields, respectively. Simulations and visualization by Philipp Mösta.

    Prior to the work of Schnetter and colleagues, this instability was believed to be a possible driver of jet-formation in supernovae, but the evidence to support that belief was scant.

    Uncovering such evidence, Schnetter says, required a something of a scientific perfect storm.

    “You need to have the right people, with the right expertise and the right chemistry between them, you need to have the right understanding of physics and mathematics and computer science, and in the end you need the computer hardware that can actually run the experiment.”

    They assembled the right people and found the computational horsepower they needed at the University of Urbana-Champaign in Illinois.

    The team used Blue Waters, one of the world’s most powerful supercomputers, to run simulations of supernovae explosions – simulations so complex that no typical computer could handle the number-crunching required. On Blue Waters, the simulations provided an unprecedented glimpse into the extreme magnetic forces at play in stellar explosions.

    3
    Cray Blue Waters supercomputer

    The 3D simulations revealed an inverse cascade of magnetic energy in the core of spinning stars, which builds up with enough intensity to launch jets from the stellar poles.

    Though the simulations do not take into account every chaotic variable inside a real supernova, they achieve a new level of understanding that will drive follow-up research with more specialized simulations.

    Deepening our understanding of supernova explosions is an ongoing process, Schnetter says, and one that may help us better understand the origins of – to borrow a phrase from Douglas Adams – life, the universe, and everything.

    The formation of galaxies, stars, and even life itself are fundamentally connected to energy and matter blasted outward in exploding stars. Even our own Sun, which supports all life on our planet, is known to be the descendent of earlier supernovae.

    So the study of stellar explosions is, Schnetter says, deeply connected to some of the most fundamental questions humans can ask about the universe. A nice bonus, he adds, is that supernovae are also really awesome explosions.

    “These are some of the most powerful events in the universe,” he says. “Who wouldn’t want to know more about that?”


    Supercomputer visualization of the toroidal magnetic field in a collapsed, massive star, showing how in a span of 10 milliseconds the rapid differential rotation revs up the star’s magnetic field to a million billion times that of our sun (yellow is positive, light blue is negative). Red and blue represent weaker positive and negative magnetic fields, respectively. From left to right are shown: 500m, 200m, 100m, and 50m simulations. Simulations and visualization by Philipp Mösta.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    About Perimeter

    Perimeter Institute is a leading centre for scientific research, training and educational outreach in foundational theoretical physics. Founded in 1999 in Waterloo, Ontario, Canada, its mission is to advance our understanding of the universe at the most fundamental level, stimulating the breakthroughs that could transform our future. Perimeter also trains the next generation of physicists through innovative programs, and shares the excitement and wonder of science with students, teachers and the general public.

     
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