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  • richardmitnick 11:19 am on August 8, 2019 Permalink | Reply
    Tags: , , , Big Bang Science, , , , , ,   

    From Johns Hopkins University via Science Alert: “Fascinating New Study Claims Dark Matter May Be Older Than The Big Bang” 

    Johns Hopkins
    From Johns Hopkins University

    via

    ScienceAlert

    Science Alert

    8 AUG 2019
    MICHELLE STARR

    1
    A simulated map of dark matter. (Tom Abel & Ralf Kaehler/KIPAC/SLAC/AMNH)

    Dark matter might well be the biggest mystery in the Universe. We know there’s something out there making things move faster than they should. But we don’t know what it is, and we sure as heck don’t know where it came from.

    According to a new paper [below], the origins of dark matter may be more peculiar than we know. Perhaps, they were particles that appeared in a very brief period of time, just fractions of fractions of a second, before the Big Bang.

    This doesn’t just suggest a new connection between particle physics and astronomy; if this hypothesis holds, it could indicate a new way to search for the mysterious stuff.

    “If dark matter consists of new particles that were born before the Big Bang, they affect the way galaxies are distributed in the sky in a unique way,” said astronomer and physicist Tommi Tenkanen of Johns Hopkins University.

    “This connection may be used to reveal their identity and make conclusions about the times before the Big Bang too.”

    It’s all tangled up with the order of events at the beginning of the Universe, which in itself is a pretty murky period of time.

    We think there was something called the Big Bang – although precisely what that entailed is still being debated. And we think there was something called cosmic inflation, a very brief period of time – a fraction of a second so small we don’t have a name for it – in which the Universe blew up like a balloon.

    Inflation

    4
    Alan Guth, from Highland Park High School and M.I.T., who first proposed cosmic inflation

    HPHS Owls

    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex MittelmannColdcreation

    Alan Guth’s notes:

    Alan Guth’s original notes on inflation

    3
    (Drbogdan/Yinweichen/Wikimedia Commons)

    It seems more generally accepted that this occurred between around 10^-36 and 10^-32 seconds after the Big Bang. That model of inflation looks like the image above.

    But some scientists think it happened just before the Big Bang, in which case the Big Bang is the name given to the conditions in the Universe right at the end of inflation.

    At this stage we just have no way of knowing. As Harvard-Smithsonian theoretical physicist Avi Loeb said earlier this year, “the current situation for inflation is that it’s such a flexible idea, it cannot be falsified experimentally.” He was talking about whether or not cosmic inflation actually happened (also a matter of debate), but the statement works for the timing of the whoompf, too.

    Dark matter – which, according to our calculations, makes up around 80 percent of the matter in the Universe – is sometimes considered to be a product of the Big Bang.

    But “if dark matter were truly a remnant of the Big Bang, then in many cases researchers should have seen a direct signal of dark matter in different particle physics experiments already,” Tenkanen states.

    Instead, his mathematical modelling suggests that dark matter could have been a product of cosmic inflation. It’s not the first time this idea has been proposed, but Tenkanen has provided the maths that support it.

    And, if cosmic inflation occurred before the Big Bang, dark matter could have been around before the rest of the stuff in the primordial Universe Soup.

    This suggests that scalar particles could lead us to dark matter. These are particles with a spin of zero, and the inflaton theory – whereby a scalar field drove cosmic inflation – suggests that they were produced in abundance during this eyeblink of time.

    So far, we’ve only ever detected one scalar particle, the Higgs boson.

    Peter Higgs


    CERN CMS Higgs Event


    CERN ATLAS Higgs Event

    But that wouldn’t be able to tell us much about dark matter in and of itself anyway.

    “While this type of dark matter is too elusive to be found in particle experiments, it can reveal its presence in astronomical observations,” Tenkanen said.

    “We will soon learn more about the origin of dark matter when the Euclid satellite is launched in 2022.

    ESA/Euclid spacecraft

    It’s going to be very exciting to see what it will reveal about dark matter and if its findings can be used to peak into the times before the Big Bang.”

    It’s all highly theoretical stuff, but it’s about as good a lead as any on the mysterious matter that’s playing a key role in shaping our Universe. It’ll be fascinating to see how the search for dark matter plays out in the coming decade.

    The research has been published in Physical Review Letters.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Johns Hopkins Campus

    The Johns Hopkins University opened in 1876, with the inauguration of its first president, Daniel Coit Gilman. “What are we aiming at?” Gilman asked in his installation address. “The encouragement of research … and the advancement of individual scholars, who by their excellence will advance the sciences they pursue, and the society where they dwell.”

    The mission laid out by Gilman remains the university’s mission today, summed up in a simple but powerful restatement of Gilman’s own words: “Knowledge for the world.”

    What Gilman created was a research university, dedicated to advancing both students’ knowledge and the state of human knowledge through research and scholarship. Gilman believed that teaching and research are interdependent, that success in one depends on success in the other. A modern university, he believed, must do both well. The realization of Gilman’s philosophy at Johns Hopkins, and at other institutions that later attracted Johns Hopkins-trained scholars, revolutionized higher education in America, leading to the research university system as it exists today.

     
  • richardmitnick 11:25 am on March 27, 2019 Permalink | Reply
    Tags: , , , Big Bang Science, Big Bounce, , ,   

    From Harvard-Smithsonian Center for Astrophysics: “What Happened Before the Big Bang?” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    CfA the Big Bounce before the Big Bang

    March 25, 2019

    Peter Reuell
    Harvard Staff Writer
    preuell@fas.harvard.edu

    Tyler Jump
    Public Affairs
    Center for Astrophysics | Harvard & Smithsonian
    +1 617-495-7462
    tyler.jump@cfa.harvard.edu

    Peter Edmonds
    Public Affairs
    Center for Astrophysics | Harvard & Smithsonian
    +1 617-571-7279
    pedmonds@cfa.harvard.edu

    A team of scientists has proposed a powerful new test for inflation, the theory that the universe dramatically expanded in size in a fleeting fraction of a second right after the Big Bang.

    Inflation

    4
    Alan Guth, from Highland Park High School and M.I.T., who first proposed cosmic inflation

    HPHS Owls

    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex MittelmannColdcreation

    Alan Guth’s notes:
    5

    Their goal is to give insight into a long-standing question: what was the universe like before the Big Bang?

    Although cosmic inflation is well known for resolving some important mysteries about the structure and evolution of the universe, other very different theories can also explain these mysteries. In some of these theories, the state of the universe preceding the Big Bang – the so-called primordial universe – was contracting instead of expanding, and the Big Bang was thus a part of a Big Bounce.

    To help decide between inflation and these other ideas, the issue of falsifiability – that is, whether a theory can be tested to potentially show it is false – has inevitably arisen. Some researchers, including Avi Loeb of the Center for Astrophysics | Harvard & Smithsonian (CfA) in Cambridge, Mass., have raised concerns about inflation, suggesting that its seemingly endless adaptability makes it all but impossible to properly test.

    “Falsifiability should be a hallmark of any scientific theory. The current situation for inflation is that it’s such a flexible idea, it cannot be falsified experimentally,” Loeb said. “No matter what value people measure for some observable attribute, there are always some models of inflation that can explain it.”

    Now, a team of scientists led by the CfA’s Xingang Chen, along with Loeb, and Zhong-Zhi Xianyu of the Physics Department of Harvard University, have applied an idea they call a “primordial standard clock” [see paper below] to the non-inflationary theories, and laid out a method that may be used to falsify inflation experimentally. The study appears in Physical Review Letters as an Editors’ Suggestion.

    In an effort to find some characteristic that can separate inflation from other theories, the team began by identifying the defining property of the various theories – the evolution of the size of the primordial universe.

    “For example, during inflation, the size of the universe grows exponentially,” Xianyu said. “In some alternative theories, the size of the universe contracts. Some do it very slowly, while others do it very fast.

    “The attributes people have proposed so far to measure usually have trouble distinguishing between the different theories because they are not directly related to the evolution of the size of the primordial universe,” he continued. “So, we wanted to find what the observable attributes are that can be directly linked to that defining property.”

    The signals generated by the primordial standard clock can serve such a purpose. That clock is any type of heavy elementary particle in the primordial universe. Such particles should exist in any theory and their positions should oscillate at some regular frequency, much like the ticking of a clock’s pendulum.

    The primordial universe was not entirely uniform. There were tiny irregularities in density on minuscule scales that became the seeds of the large-scale structure observed in today’s universe. This is the primary source of information physicists rely on to learn about what happened before the Big Bang. The ticks of the standard clock generated signals that were imprinted into the structure of those irregularities. Standard clocks in different theories of the primordial universe predict different patterns of signals, because the evolutionary histories of the universe are different.

    “If we imagine all of the information we learned so far about what happened before the Big Bang is in a roll of film frames, then the standard clock tells us how these frames should be played,” Chen explained. “Without any clock information, we don’t know if the film should be played forward or backward, fast or slow, just like we are not sure if the primordial universe was inflating or contracting, and how fast it did so. This is where the problem lies. The standard clock put time stamps on each of these frames when the film was shot before the Big Bang, and tells us how to play the film.”

    The team calculated how these standard clock signals should look in non-inflationary theories, and suggested how they should be searched for in astrophysical observations. “If a pattern of signals representing a contracting universe were found, it would falsify the entire inflationary theory,” Xianyu said.

    The success of this idea lies with experimentation. “These signals will be very subtle to detect,” Chen said, “and so we may have to search in many different places. The cosmic microwave background radiation is one such place, and the distribution of galaxies is another. We have already started to search for these signals and there are some interesting candidates already, but we need more data.”

    CMB per ESA/Planck

    Cosmic Background Radiation per Planck

    ESA/Planck 2009 to 2013

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    Many future galaxy surveys, such as US-lead LSST, European’s Euclid and the newly approved project by NASA, SphereX, are expected to provide high quality data that can be used toward the goal.

    LSST


    LSST Camera, built at SLAC



    LSST telescope, currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.


    LSST Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova

    ESA/Euclid spacecraft

    NASA’s SPHEREx Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer depiction

    This paper is available in Physical Review Letters. A related previous work can be found in Journal of Cosmology and Astroparticle Physics

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
  • richardmitnick 1:31 pm on January 30, 2019 Permalink | Reply
    Tags: , Big Bang Science, BNL Relativistic Heavy Ion Collider (RHIC), , Brookhaven STAR collaboration, , , ,   

    From Lehigh University: “Big Bang Query” 

    From Lehigh University

    Mapping how a mysterious liquid became all matter

    The leading theory about how the universe began is the Big Bang, which says that 14 billion years ago the universe existed as a singularity, a one-dimensional point, with a vast array of fundamental particles contained within it. Extremely high heat and energy caused it to inflate and then expand into the cosmos as we know it?and, the expansion continues to this day.

    The initial result of the Big Bang was an intensely hot and energetic liquid that existed for mere microseconds that was around 10 billion degrees Fahrenheit (5.5 billion Celsius). This liquid contained nothing less than the building blocks of all matter. As the universe cooled, the particles decayed or combined giving rise to…well, everything.

    Quark-gluon plasma (QGP) is the name for this mysterious substance so called because it was made up of quarks — the fundamental particles — and gluons, which physicist Rosi J. Reed describes as “what quarks use to talk to each other.”

    Quark gluon plasma. Duke University

    Scientists like Reed, an assistant professor in Lehigh University’s Department of Physics whose research includes experimental high-energy physics, cannot go back in time to study how the Universe began. So they re-create the circumstances, by colliding heavy ions, such as Gold, at nearly the speed of light, generating an environment that is 100,000 times hotter than the interior of the sun. The collision mimics how quark-gluon plasma became matter after the Big Bang, but in reverse: the heat melts the ions’ protons and neutrons, releasing the quarks and gluons hidden inside them.

    There are currently only two operational accelerators in the world capable of colliding heavy ions — and only one in the U.S.: Brookhaven National Lab’s Relativistic Heavy Ion Collider (RHIC). It is about a three-hour drive from Lehigh, in Long Island, New York.


    BNL RHIC Campus



    BNL/RHIC

    Reed is part of the STAR Collaboration , an international group of scientists and engineers running experiments on the Solenoidal Tracker at RHIC (STAR). The STAR detector is massive and is actually made up of many detectors. It is as large as a house and weighs 1,200 tons. STAR’s specialty is tracking the thousands of particles produced by each ion collision at RHIC in search of the signatures of quark-gluon plasma.

    BNL/RHIC Star Detector

    “When running experiments there are two ‘knobs’ we can change: the species — such as gold on gold or proton on proton — and the collision energy,” says Reed. “We can accelerate the ions differently to achieve different energy-to-mass ratio.”

    Using the various STAR detectors, the team collides ions at different collision energies. The goal is to map quark-gluon plasma’s phase diagram, or the different points of transition as the material changes under varying pressure and temperature conditions. Mapping quark-gluon plasma’s phase diagram is also mapping the nuclear strong force, otherwise known as Quantum Chromodynamics (QCD), which is the force that holds positively charged protons together.

    “There are a bunch of protons and neutrons in the center of an ion,” explains Reed. “These are positively charged and should repel, but there’s a ‘strong force’ that keeps them together? strong enough to overcome their tendency to come apart.”

    Understanding quark-gluon plasma’s phase diagram, and the location and existence of the phase transition between the plasma and normal matter is of fundamental importance, says Reed.

    “It’s a unique opportunity to learn how one of the four fundamental forces of nature operates at temperature and energy densities similar to those that existed only microseconds after the Big Bang,” says Reed.

    Upgrading the RHIC detectors to better map the “strong force”

    The STAR team uses a Beam Energy Scan (BES) to do the phase transition mapping. During the first part of the project, known as BES-I, the team collected observable evidence with “intriguing results.” Reed presented these results at the 5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan in Hawaii in October 2018 in a talk titled: “Testing the quark-gluon plasma limits with energy and species scans at RHIC.”

    However, limited statistics, acceptance, and poor event plane resolution did not allow firm conclusions for a discovery. The second phase of the project, known as BES-II, is going forward and includes an improvement that Reed is working on with STAR team members: an upgrade of the Event Plan Detector. Collaborators include scientists at Brookhaven as well as at Ohio State University.

    The STAR team plans to continue to run experiments and collect data in 2019 and 2020, using the new Event Plan Detector. According to Reed, the new detector is designed to precisely locate where the collision happens and will help characterize the collision, specifically how “head on” it is.

    “It will also help improve the measurement capabilities of all the other detectors,” says Reed.

    The STAR collaboration expects to run their next experiments at RHIC in March 2019.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Lehigh University is an American private research university in Bethlehem, Pennsylvania. It was established in 1865 by businessman Asa Packer. Its undergraduate programs have been coeducational since the 1971–72 academic year. As of 2014, the university had 4,904 undergraduate students and 2,165 graduate students. Lehigh is considered one of the twenty-four Hidden Ivies in the Northeastern United States.

    Lehigh has four colleges: the P.C. Rossin College of Engineering and Applied Science, the College of Arts and Sciences, the College of Business and Economics, and the College of Education. The College of Arts and Sciences is the largest, which roughly consists of 40% of the university’s students.The university offers a variety of degrees, including Bachelor of Arts, Bachelor of Science, Master of Arts, Master of Science, Master of Business Administration, Master of Engineering, Master of Education, and Doctor of Philosophy.

    Lehigh has produced Pulitzer Prize winners, Fulbright Fellows, members of the American Academy of Arts & Sciences and of the National Academy of Sciences, and National Medal of Science winners.

     
  • richardmitnick 10:43 am on February 7, 2018 Permalink | Reply
    Tags: Big Bang Science, , ,   

    From The Atlantic Magazine: “The Big Bang May Have Been One of Many” 

    Atlantic Magazine

    The Atlantic Magazine

    Feb 6, 2018
    Natalie Wolchover

    1
    davidope / Quanta Magazine

    Our universe could be expanding and contracting eternally.

    Humans have always entertained two basic theories about the origin of the universe. “In one of them, the universe emerges in a single instant of creation (as in the Jewish-Christian and the Brazilian Carajás cosmogonies),” the cosmologists Mario Novello and Santiago Perez Bergliaffa noted in 2008. In the other, “the universe is eternal, consisting of an infinite series of cycles (as in the cosmogonies of the Babylonians and Egyptians).” The division in modern cosmology “somehow parallels that of the cosmogonic myths,” Novello and Perez Bergliaffa wrote.

    In recent decades, it hasn’t seemed like much of a contest. The Big Bang theory, standard stuff of textbooks and television shows, enjoys strong support among today’s cosmologists. The rival eternal-universe picture had the edge a century ago, but it lost ground as astronomers observed that the cosmos is expanding and that it was small and simple about 14 billion years ago. In the most popular modern version of the theory, the Big Bang began with an episode called “cosmic inflation”—a burst of exponential expansion during which an infinitesimal speck of space-time ballooned into a smooth, flat, macroscopic cosmos, which expanded more gently thereafter.

    With a single initial ingredient (the “inflaton field”), inflationary models reproduce many broad-brush features of the cosmos today. But as an origin story, inflation is lacking; it raises questions about what preceded it and where that initial, inflaton-laden speck came from. Undeterred, many theorists think the inflaton field must fit naturally into a more complete, though still unknown, theory of time’s origin.

    But in the past few years, a growing number of cosmologists have cautiously revisited the alternative. They say the Big Bang might instead have been a Big Bounce. Some cosmologists favor a picture in which the universe expands and contracts cyclically like a lung, bouncing each time it shrinks to a certain size, while others propose that the cosmos only bounced once—that it had been contracting, before the bounce, since the infinite past, and that it will expand forever after. In either model, time continues into the past and future without end.

    With modern science, there’s hope of settling this ancient debate. In the years ahead, telescopes could find definitive evidence for cosmic inflation. During the primordial growth spurt—if it happened—quantum ripples in the fabric of space-time would have become stretched and later imprinted as subtle swirls in the polarization of ancient light called the cosmic microwave background [CMB].

    CMB per ESA/Planck


    ESA/Planck

    Current and future telescope experiments are hunting for these swirls. If they aren’t seen in the next couple of decades, this won’t entirely disprove inflation (the telltale swirls could simply be too faint to make out), but it will strengthen the case for bounce cosmology, which doesn’t predict the swirl pattern.

    Already, several groups are making progress at once. Most significantly, in the last year, physicists have come up with two new ways that bounces could conceivably occur. One of the models, described in a paper that will appear in the Journal of Cosmology and Astroparticle Physics, comes from Anna Ijjas of Columbia University, extending earlier work with her former adviser, the Princeton University professor and high-profile bounce cosmologist Paul Steinhardt. More surprisingly, the other new bounce solution, accepted for publication in Physical Review D, was proposed by Peter Graham, David Kaplan, and Surjeet Rajendran, a well-known trio of collaborators who mainly focus on particle-physics questions and have no previous connection to the bounce-cosmology community. It’s a noteworthy development in a field that’s highly polarized on the bang-vs.-bounce question.

    The question gained renewed significance in 2001, when Steinhardt and three other cosmologists argued that a period of slow contraction in the history of the universe could explain its exceptional smoothness and flatness, as witnessed today, even after a bounce—with no need for a period of inflation.

    The universe’s impeccable plainness, the fact that no region of sky contains significantly more matter than any other and that space is breathtakingly flat as far as telescopes can see, is a mystery. To match its present uniformity, experts infer that the cosmos, when it was one centimeter across, must have had the same density everywhere to within one part in 100,000. But as it grew from an even smaller size, matter and energy ought to have immediately clumped together and contorted space-time. Why don’t our telescopes see a universe wrecked by gravity?

    “Inflation was motivated by the idea that that was crazy to have to assume the universe came out so smooth and not curved,” says the cosmologist Neil Turok, the director of the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, and a coauthor of the 2001 paper [Physical Review D] on cosmic contraction with Steinhardt, Justin Khoury, and Burt Ovrut.

    In the inflation scenario, the centimeter-size region results from the exponential expansion of a much smaller region—an initial speck measuring no more than a trillionth of a trillionth of a centimeter across. As long as that speck was infused with an inflaton field that was smooth and flat, meaning its energy concentration didn’t fluctuate across time or space, the speck would have inflated into a huge, smooth universe like ours. Raman Sundrum, a theoretical physicist at the University of Maryland, says the thing he appreciates about inflation is that “it has a kind of fault tolerance built in.” If, during this explosive growth phase, there was a buildup of energy that bent space-time in a certain place, the concentration would have quickly inflated away. “You make small changes against what you see in the data and you see the return to the behavior that the data suggests,” Sundrum says.

    However, where exactly that infinitesimal speck came from, and why it came out so smooth and flat itself to begin with, no one knows. Theorists have found many possible ways to embed the inflaton field into string theory., a candidate for the underlying quantum theory of gravity. So far, there’s no evidence for or against these ideas.

    Cosmic inflation also has a controversial consequence. The theory—which was pioneered in the 1980s by Alan Guth, Andrei Linde, Aleksei Starobinsky, and (of all people) Steinhardt, almost automatically leads to the hypothesis that our universe is a random bubble in an infinite, frothing multiverse sea. Once inflation starts, calculations suggest that it keeps going forever, only stopping in local pockets that then blossom into bubble universes like ours. The possibility of an eternally inflating multiverse suggests that our particular bubble might never be fully understandable on its own terms, since everything that can possibly happen in a multiverse happens infinitely many times. The subject evokes gut-level disagreement among experts. Many have reconciled themselves to the idea that our universe could be just one of many; Steinhardt calls the multiverse “hogwash.”

    This sentiment partly motivated his and other researchers’ about-face on bounces. “The bouncing models don’t have a period of inflation,” Turok says. Instead, they add a period of contraction before a Big Bounce to explain our uniform universe. “Just as the gas in the room you’re sitting in is completely uniform because the air molecules are banging around and equilibrating,” he says, “if the universe was quite big and contracting slowly, that gives plenty of time for the universe to smooth itself out.”

    Although the first contracting-universe models were convoluted and flawed, many researchers became convinced of the basic idea that slow contraction can explain many features of our expanding universe. “Then the bottleneck became literally the bottleneck—the bounce itself,” Steinhardt says. As Ijjas puts it, “The bounce has been the showstopper for these scenarios. People would agree that it’s very interesting if you can do a contraction phase, but not if you can’t get to an expansion phase.”

    Bouncing isn’t easy. In the 1960s, the British physicists Roger Penrose and Stephen Hawking proved a set of so-called “singularity theorems” showing that, under very general conditions, contracting matter and energy will unavoidably crunch into an immeasurably dense point called a singularity. These theorems make it hard to imagine how a contracting universe in which space-time, matter, and energy are all rushing inward could possibly avoid collapsing all the way down to a singularity—a point where Albert Einstein’s classical theory of gravity and space-time breaks down and the unknown quantum-gravity theory rules. Why shouldn’t a contracting universe share the same fate as a massive star, which dies by shrinking to the singular center of a black hole?

    Both of the newly proposed bounce models exploit loopholes in the singularity theorems—ones that, for many years, seemed like dead ends. Bounce cosmologists have long recognized that bounces might be possible if the universe contained a substance with negative energy (or other sources of negative pressure), which would counteract gravity and essentially push everything apart. They’ve been trying to exploit this loophole since the early 2000s, but they always found that adding negative-energy ingredients made their models of the universe unstable, because positive- and negative-energy quantum fluctuations could spontaneously arise together, unchecked, out of the zero-energy vacuum of space. In 2016, the Russian cosmologist Valery Rubakov and colleagues even proved a “no-go” [JCAP] theorem that seemed to rule out a huge class of bounce mechanisms on the grounds that they caused these so-called “ghost” instabilities.

    Then Ijjas found a bounce mechanism that evades the no-go theorem. The key ingredient in her model is a simple entity called a “scalar field,” which, according to the idea, would have kicked into gear as the universe contracted and energy became highly concentrated. The scalar field would have braided itself into the gravitational field in a way that exerted negative pressure on the universe, reversing the contraction and driving space-time apart—without destabilizing everything. Ijjas’ paper “is essentially the best attempt at getting rid of all possible instabilities and making a really stable model with this special type of matter,” says Jean-Luc Lehners, a theoretical cosmologist at the Max Planck Institute for Gravitational Physics in Germany who has also worked on bounce proposals.

    What’s especially interesting about the two new bounce models is that they are “non-singular,” meaning the contracting universe bounces and starts expanding again before ever shrinking to a point. These bounces can therefore be fully described by the classical laws of gravity, requiring no speculations about gravity’s quantum nature.

    Graham, Kaplan, and Rajendran, of Stanford University, Johns Hopkins University and UC Berkeley, respectively, reported their non-singular bounce idea on the scientific preprint site ArXiv.org in September 2017. They found their way to it after wondering whether a previous contraction phase in the history of the universe could be used to explain the value of the cosmological constant—a mystifyingly tiny number that defines the amount of dark energy infused in the space-time fabric, energy that drives the accelerating expansion of the universe.

    In working out the hardest part—the bounce—the trio exploited a second, largely forgotten loophole in the singularity theorems. They took inspiration from a characteristically strange model of the universe proposed by the logician Kurt Gödel in 1949, when he and Einstein were walking companions and colleagues at the Institute for Advanced Study in Princeton, New Jersey. Gödel used the laws of general relativity to construct the theory of a rotating universe, whose spinning keeps it from gravitationally collapsing in much the same way that Earth’s orbit prevents it from falling into the sun. Gödel especially liked the fact that his rotating universe permitted “closed time-like curves,” essentially loops in time, which raised all sorts of Gödelian riddles. To his dying day, he eagerly awaited evidence that the universe really is rotating in the manner of his model. Researchers now know it isn’t; otherwise, the cosmos would exhibit alignments and preferred directions. But Graham and company wondered about small, curled-up spatial dimensions that might exist in space, such as the six extra dimensions postulated by string theory. Could a contracting universe spin in those directions?

    magine there’s just one of these curled-up extra dimensions, a tiny circle found at every point in space. As Graham puts it, “At each point in space there’s an extra direction you can go in, a fourth spatial direction, but you can only go a tiny little distance and then you come back to where you started.” If there are at least three extra compact dimensions, then, as the universe contracts, matter and energy can start spinning inside them, and the dimensions themselves will spin with the matter and energy. The vorticity in the extra dimensions can suddenly initiate a bounce. “All that stuff that would have been crunching into a singularity, because it’s spinning in the extra dimensions, it misses—sort of like a gravitational slingshot,” Graham says. “All the stuff should have been coming to a single point, but instead it misses and flies back out again.”

    he paper has attracted attention beyond the usual circle of bounce cosmologists. Sean Carroll, a theoretical physicist at the California Institute of Technology, is skeptical but called the idea “very clever.” He says it’s important to develop alternatives to the conventional inflation story, if only to see how much better inflation appears by comparison—especially when next-generation telescopes come online in the early 2020s looking for the telltale swirl pattern in the sky caused by inflation. “Even though I think inflation has a good chance of being right, I wish there were more competitors,” Carroll says. Sundrum, the Maryland physicist, feels similarly. “There are some questions I consider so important that even if you have only a 5 percent chance of succeeding, you should throw everything you have at it and work on them,” he says. “And that’s how I feel about this paper.”

    As Graham, Kaplan, and Rajendran explore their bounce and its possible experimental signatures, the next step for Ijjas and Steinhardt, working with Frans Pretorius of Princeton, is to develop computer simulations. (Their collaboration is supported by the Simons Foundation, which also funds Quanta Magazine.) Both bounce mechanisms also need to be integrated into more complete, stable cosmological models that would describe the entire evolutionary history of the universe.

    Beyond these non-singular bounce solutions, other researchers are speculating about what kind of bounce might occur when a universe contracts all the way to a singularity—a bounce orchestrated by the unknown quantum laws of gravity, which replace the usual understanding of space and time at extremely high energies. In forthcoming work, Turok and collaborators plan to propose a model in which the universe expands symmetrically into the past and future away from a central, singular bounce. Turok contends that the existence of this two-lobed universe is equivalent to the spontaneous creation of electron-positron pairs, which constantly pop in and out of the vacuum. “Richard Feynman pointed out that you can look at the positron as an electron going backward in time,” he says. “They’re two particles, but they’re really the same; at a certain moment in time they merge and annihilate.” He added, “The idea is a very, very deep one, and most likely the Big Bang will turn out to be similar, where a universe and its anti-universe were drawn out of nothing, if you like, by the presence of matter.”

    It remains to be seen whether this universe/anti-universe bounce model can accommodate all observations of the cosmos, but Turok likes how simple it is. Most cosmological models are far too complicated in his view. The universe “looks extremely ordered and symmetrical and simple,” he says. “That’s very exciting for theorists, because it tells us there may be a simple—even if hard-to-discover—theory waiting to be discovered, which might explain the most paradoxical features of the universe.”

    See the full article here .

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  • richardmitnick 4:29 pm on October 15, 2017 Permalink | Reply
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    From Goddard: “NASA’s James Webb Space Telescope and the Big Bang: A Short Q&A with Nobel Laureate Dr. John Mather” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    Oct. 11, 2017
    Maggie Masetti
    NASA’s Goddard Space Flight Center

    1
    Dr. John Mather, a Nobel laureate and the senior project scientist for NASA’s James Webb Space Telescope. Credits: NASA/Chris Gunn

    Q: What is the Big Bang?

    A: The Big Bang is a really misleading name for the expanding universe that we see. We see an infinite universe with distant galaxies all rushing away from each other.

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    The name Big Bang conveys the idea of a firecracker exploding at a time and a place — with a center. The universe doesn’t have a center, at least not one we can find. The Big Bang happened everywhere at once and was a process happening in time, not a point in time. We know this because 1) we see galaxies rushing away from each other, not from a central point; 2) we see the heat that was left over from early times, and that heat uniformly fills the universe; and 3) we can calculate and imagine what the universe was like when the parts were much closer together, and the calculations match everything we can see.

    Q: Can we see the Big Bang?

    A: No, the Big Bang itself is not something we can see.

    Q: What can we see?

    A: We can see the heat radiation that was there when the universe was young. We see this heat as it was about 380,000 years after the expansion of the universe began 13.8 billion years ago (which is what we refer to as the Big Bang). This heat covers the entire sky and fills the universe. (In fact it still does.) We were able to map it with satellites we (NASA and ESA) built called the Cosmic Background Explorer (COBE), the Wilkinson Microwave Anisotropy Probe (WMAP), and Planck. The universe at this point was extremely smooth, with only tiny ripples in temperature.

    Cosmic Infrared Background, Credit: Michael Hauser (Space Telescope Science Institute), the COBE/DIRBE Science Team, and NASA

    NASA/COBE

    1
    All-sky image of the infant universe, created from nine years of data from the Wilkinson Microwave Anisotropy Probe (WMAP).
    Credits: NASA/WMAP Science Team

    NASA/WMAP

    CMB per ESA/Planck


    ESA/Planck

    Q: I heard the James Webb Space Telescope will see back further than ever before. What will Webb see?

    NASA/ESA/CSA Webb Telescope annotated

    A: COBE, WMAP, and Planck all saw further back than Webb, though it’s true that Webb will see farther back than Hubble.

    NASA/ESA Hubble Telescope

    Webb was designed not to see the beginnings of the universe, but to see a period of the universe’s history that we have not seen yet.

    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex MittelmannColdcreation

    Specifically, we want to see the first objects that formed as the universe cooled down after the Big Bang. That time period is perhaps hundreds of millions of years later than the one COBE, WMAP, and Planck were built to see. We think that the tiny ripples of temperature they observed were the seeds that eventually grew into galaxies. We don’t know exactly when the universe made the first stars and galaxies — or how for that matter. That is what we are building Webb to help answer.

    Q: Why can’t Hubble see the first stars and galaxies forming?

    A: The only way we can see back to the time when these objects were forming is to look very far away. Hubble isn’t big enough or cold enough to see the faint heat signals of these objects that are so far away.

    Q: Why do we want to see the first stars and galaxies forming?

    A: The chemical elements of life were first produced in the first generation of stars after the Big Bang. We are here today because of them — and we want to better understand how that came to be! We have ideas, we have predictions, but we don’t know. One way or another the first stars must have influenced our own history, beginning with stirring up everything and producing the other chemical elements besides hydrogen and helium. So if we really want to know where our atoms came from, and how the little planet Earth came to be capable of supporting life, we need to measure what happened at the beginning.

    Dr. John Mather is the senior project scientist for the James Webb Space Telescope. Dr. Mather shares the 2006 Nobel Prize for Physics with George F. Smoot of the University of California for their work using the COBE satellite to measure the heat radiation from the Big Bang.

    The James Webb Space Telescope, the scientific complement to NASA’s Hubble Space Telescope, will be the premier space observatory of the next decade. Webb is an international project led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).

    For more information about the Webb telescope, visit: http://www.webb.nasa.gov or http://www.nasa.gov/webb

    See the full article here.

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    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.


    NASA/Goddard Campus

     
  • richardmitnick 1:08 pm on October 12, 2017 Permalink | Reply
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    From Ethan Siegel: “Inflation Isn’t Just Science, It’s The Origin Of Our Universe” 

    From Ethan Siegel

    Oct 12, 2017

    1
    The stars and galaxies we see today didn’t always exist, and the farther back we go, the closer to an apparent singularity the Universe gets, but there is a limit to that extrapolation. To go all the way back, we need a modification to the Big Bang: cosmological inflation. Image credit: NASA, ESA, and A. Feild (STScI).

    “There’s no obvious reason to assume that the very same rare properties that allow for our existence would also provide the best overall setting to make discoveries about the world around us. We don’t think this is merely coincidental.” -Guillermo Gonzalez

    In order to be considered a scientific theory, there are three things your idea needs to do. First off, you have to reproduce all of the successes of the prior, leading theory. Second, you need to explain a new phenomenon that isn’t presently explained by the theory you’re seeking to replace. And third, you need to make a new prediction that you can then go out and test: where your new idea predicts something entirely different or novel from the pre-existing theory. Do that, and you’re science. Do it successfully, and you’re bound to become the new, leading scientific theory in your area. Many prominent physicists have recently come out against inflation, with some claiming that it isn’t even science. But the facts say otherwise. Not only is inflation science, it’s now the leading scientific theory about where our Universe comes from.

    2
    The expanding Universe, full of galaxies and the complex structure we observe today, arose from a smaller, hotter, denser, more uniform state. But even that initial state had its origins, with cosmic inflation as the leading candidate for where that all came from. Image credit: C. Faucher-Giguère, A. Lidz, and L. Hernquist, Science 319, 5859 (47).

    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex MittelmannColdcreation

    The Big Bang was first confirmed in the 1960s, with the observation of the Cosmic Microwave Background [CMB].

    Cosmic Microwave Background NASA/WMAP

    NASA/WMAP

    CMB per ESA/Planck

    ESA/Planck

    Since that first detection of the leftover glow, predicted from an early, hot, dense state, we’ve been able to validate and confirm the Big Bang’s predictions in a number of important ways. The large-scale structure of the Universe is consistent with having formed from a nearly-uniform past state, under the influence of gravity over billions of years. The Hubble expansion and the temperature in the distant past is consistent with an expanding, cooling Universe filled with matter and energy of various types. The abundances of hydrogen, helium, lithium, and their various isotopes matches the predictions from an early, hot, dense state. And the blackbody spectrum of the Big Bang’s leftover glow matches our observations precisely.

    3
    The light from the cosmic microwave background and the pattern of fluctuations from it gives us one way to measure the Universe’s curvature. To the best of our measurements, to within 1 part in about 400, the Universe is perfectly spatially flat. Image credit: Smoot Cosmology Group / Lawrence Berkeley Labs.

    But there are a number of things that we observe that the Big Bang doesn’t explain. The fact that the Universe is the same exact temperature in all directions, to better than 99.99%, is an observational fact without a theoretical cause. The fact that the Universe, in all directions, appears to be spatially flat (rather than positively or negatively curved), is another true fact without an explanation. And the fact that there are no leftover high-energy relics, like magnetic monopoles, is a curiosity that we wouldn’t expect if the Universe began from an arbitrarily hot, dense state.

    In other words, the implication is that despite all of the Big Bang’s successes, it doesn’t explain everything about the origin of the Universe. Either we can look at these unexplained phenomena and conjecture, “maybe the Universe was simply born this way,” or we can look for an explanation that meets our requirements for a scientific theory. That’s exactly what Alan Guth did in 1979, when he first stumbled upon the idea of cosmological inflation.

    4
    Alan Guth, Highland Park High School and M.I.T., who first proposed cosmic inflation

    HPHS Owls

    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex MittelmannColdcreation

    5
    Alan Guth’s notes. http://www.bestchinanews.com/Explore/4730.html

    The big idea of cosmic inflation was that the matter-and-radiation-filled Universe, the one that has been expanding and cooling for billions of years, arose from a very different state that existed prior to what we know as our observable Universe. Instead of being filled with matter-and-radiation, space was full of vacuum energy, which caused it to expand not just rapidly, but exponentially, meaning the expansion rate doesn’t fall with time as long as inflation goes on. It’s only when inflation comes to an end that this vacuum energy gets converted into matter, antimatter, and radiation, and the hot Big Bang results.

    5
    This illustration shows regions where inflation continues into the future (blue), and where it ends, giving rise to a Big Bang and a Universe like ours (red X). Note that this could go back indefinitely, and we’d never know. Image credit: E. Siegel / Beyond The Galaxy.

    It was generally recognized that inflation, if true, would solve those three puzzles that the Big Bang could only posit as initial conditions: the horizon (temperature), flatness (curvature), and monopole (lack-of-relics) problems. In the early-to-mid 1980s, lots of work went into meeting that first criteria: reproducing the successes of the Big Bang. The key was to arrive at an isotropic, homogeneous Universe with conditions that matched what we observed.

    6
    he two simplest classes of inflationary potentials, with chaotic inflation (L) and new inflation (R) shown. Image credit: E. Siegel / Google Graph.

    After a few years, we had two generic classes of models that worked:

    “New inflation” models, where vacuum energy starts off at the top of a hill and rolls down it, with inflation ending when the ball rolls into the valley, and
    “Chaotic inflation” models, where vacuum energy starts out high on a parabola-like potential, rolling into the valley to end inflation.

    Both of these classes of models reproduced the successes of the Big Bang, but also made a number of similar, quite generic predictions for the observable Universe. They were as follows:

    7
    The earliest stages of the Universe, before the Big Bang, are what set up the initial conditions that everything we see today has evolved from. Image credit: E. Siegel, with images derived from ESA/Planck and the DoE/NASA/ NSF interagency task force on CMB research.

    1. The Universe should be nearly perfectly flat. Yes, the flatness problem was one of the original motivations for it, but at the time, we had very weak constraints. 100% of the Universe could be in matter and 0% in curvature; 5% could be matter and 95% could be curvature, or anywhere in between. Inflation, quite generically, predicted that 100% needed to be “matter plus whatever else,” but curvature should be between 0.01% and 0.0001%. This prediction has been validated by our ΛCDM model, where 5% is matter, 27% is dark matter and 68% is dark energy; curvature is constrained to be 0.25% or less. As observations continue to improve, we may, in fact, someday be able to measure the non-zero curvature predicted by inflation.

    2. There should be an almost scale-invariant spectrum of fluctuations. If quantum physics is real, then the Universe should have experienced quantum fluctuations even during inflation. These fluctuations should be stretched, exponentially, across the Universe. When inflation ends, these fluctuations should get turned into matter and radiation, giving rise to overdense and underdense regions that grow into stars and galaxies, or great cosmic voids. Because of how inflation proceeds in the final stages, the fluctuations should be slightly greater on either small scales or large scales, depending on the model of inflation, which means there should be a slight departure from perfect scale invariance. If scale invariance were exact, a parameter we call n_s would equal 1; n_s is observed to be 0.96, and wasn’t measured until WMAP in the 2000s.

    3. There should be fluctuations on scales larger than light could have traveled since the Big Bang. This is another consequence of inflation, but there’s no way to get a coherent set of fluctuations on large scales like this without something stretching them across cosmic distances. The fact that we see these fluctuations in the cosmic microwave background and in the large-scale structure of the Universe — and didn’t know about them until the COBE and WMAP satellites in the 1990s and 2000s — further validates inflation.

    NASA/COBE

    Cosmic Infrared Background, Credit: Michael Hauser (Space Telescope Science Institute), the COBE/DIRBE Science Team, and NASA

    4. These quantum fluctuations, which translate into density fluctuations, should be adiabatic. Fluctuations could have come in different types: adiabatic, isocurvature, or a mixture of the two. Inflation predicted that these fluctuations should have been 100% adiabatic, which should leave unique signatures in both the cosmic microwave background and the Universe’s large-scale structure. Observations bear out that yes, in fact, the fluctuations were adiabatic: of constant entropy everywhere.

    5. There should be an upper limit, smaller than the Planck scale, to the temperature of the Universe in the distant past. This is also a signature that shows up in the cosmic microwave background: how high a temperature the Universe reached at its hottest. Remember, if there were no inflation, the Universe should have gone up to arbitrarily high temperatures at early times, approaching a singularity. But with inflation, there’s a maximum temperature that must be at energies lower than the Planck scale (~10^19 GeV). What we see, from our observations, is that the Universe achieved temperatures no higher than about 0.1% of that (~10^16 GeV) at any point, further confirming inflation. This is an even better solution to the monopole problem than the one initially envisioned by Guth.

    6. And finally, there should be a set of primordial gravitational waves, with a particular spectrum. Just as we had an almost perfectly scale-invariant spectrum of density fluctuations, inflation predicts a spectrum of tensor fluctuations in General Relativity, which translate into gravitational waves. The magnitude of these fluctuations are model-dependent on inflation, but the spectrum has a set of unique predictions. This sixth prediction is the only one that has not been verified observationally in any way.

    7
    The contribution of gravitational waves left over from inflation to the B-mode polarization of the Cosmic Microwave background has a known shape, but its amplitude is dependent on the specific model of inflation. These B-modes from gravitational waves from inflation have not yet been observed. Image credit: Planck science team.

    On all three counts — of reproducing the successes of the non-inflationary Big Bang, of explaining observations that the Big Bang cannot, and of making new predictions that can be (and, in large number, have been) verified — inflation undoubtedly succeeds as science. It does so in a way that other theories which only give rise to non-observable predictions, such as string theory, does not. Yes, when critics talk about inflation and mention a huge amount of model-building, that is a problem; inflation is a theory in search of a single, unique, definitive model. It’s true that you can contrive as complex a model as you want, and it’s virtually impossible to rule them out.

    8
    A variety of inflationary models and the scalar and tensor fluctuations predicted by cosmic inflation. Note that the observational constraints leave a huge variety of inflationary models as still valid. Image credit: Kamionkowski and Kovetz, ARAA, 2016, via http://lanl.arxiv.org/abs/1510.06042.

    But that is not a flaw inherent to the theory of inflation; it is an indicator that we don’t yet know enough about the mechanics of inflation to discern which models have the features our Universe requires. It is an indicator that the inflationary paradigm itself has limits to its predictive power, and that a further advance will be necessary to move the needle forward. But simply because inflation isn’t the ultimate answer to everything doesn’t mean it isn’t science. Rather, it’s exactly in line with what science has always shown itself to be: humanity’s best toolkit for understanding the Universe, one incremental improvement at a time.

    See the full article here .

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    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 1:00 pm on June 17, 2017 Permalink | Reply
    Tags: , Big Bang Science, ,   

    From phys.org: “No Universe without Big Bang” 

    physdotorg
    phys.org

    June 15, 2017

    1
    Credit: J.-L. Lehners (Max Planck Institute for Gravitational Physics)

    According to Einstein’s theory of relativity, the curvature of spacetime was infinite at the big bang. In fact, at this point all mathematical tools fail, and the theory breaks down. However, there remained the notion that perhaps the beginning of the universe could be treated in a simpler manner, and that the infinities of the big bang might be avoided. This has indeed been the hope expressed since the 1980s by the well-known cosmologists James Hartle and Stephen Hawking with their “no-boundary proposal”, and by Alexander Vilenkin with his “tunnelling proposal”. Now scientists at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI) in Potsdam and at the Perimeter Institute in Canada have been able to use better mathematical methods to show that these ideas cannot work.

    One of the principal goals of cosmology is to understand the beginning of our universe. Data from the Planck satellite mission shows that 13.8 billion years ago the universe consisted of a hot and dense soup of particles. Since then the universe has been expanding. This is the main tenet of the hot big bang theory, but the theory fails to describe the very first stages themselves, as the conditions were too extreme. Indeed, as we approach the big bang, the energy density and the curvature grow until we reach the point where they become infinite.

    As an alternative, the “no-boundary” and “tunneling” proposals assume that the tiny early universe arose by quantum tunnelling from nothing, and subsequently grew into the large universe that we see. The curvature of spacetime would have been large, but finite in this beginning stage, and the geometry would have been smooth – without boundary (see Fig. 1, left panel). This initial configuration would replace the standard big bang. However, for a long time the true consequences of this hypothesis remained unclear. Now, with the help of better mathematical methods, Jean-Luc Lehners, group leader at the AEI, and his colleagues Job Feldbrugge and Neil Turok at Perimeter Institute, managed to define the 35 year old theories in a precise manner for the first time, and to calculate their implications [Physical Review D]. The result of these investigations is that these alternatives to the big bang are no true alternatives. As a result of Heisenberg’s uncertainty relation, these models do not only imply that smooth universes can tunnel out of nothing, but also irregular universes. In fact, the more irregular and crumpled they are, the more likely (see Fig. 1, right panel). “Hence the “no-boundary proposal” does not imply a large universe like the one we live in, but rather tiny curved universes that would collapse immediately”, says Jean-Luc Lehners, who leads the “theoretical cosmology” group at the AEI.

    Hence one cannot circumvent the big bang so easily. Lehners and his colleagues are now trying to figure out what mechanism could have kept those large quantum fluctuations in check under the most extreme circumstances, allowing our large universe to unfold.

    The big bang, in its complicated glory, retains all its mystery.

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 12:44 pm on February 20, 2017 Permalink | Reply
    Tags: , Big Bang Science, ,   

    From ALMA via ESO: “ALMA’s Hole in the Universe” 

    ALMA Array

    ALMA

    20 February 2017
    No writer credit

    1
    Credit: ALMA (ESO/NAOJ/NRAO)/T. Kitayama (Toho University, Japan)/ESA/Hubble & NASA

    The events surrounding the Big Bang were so cataclysmic that they left an indelible imprint on the fabric of the cosmos. We can detect these scars today by observing the oldest light in the Universe. As it was created nearly 14 billion years ago, this light — which exists now as weak microwave radiation and is thus named the cosmic microwave background (CMB) — has now expanded to permeate the entire cosmos, filling it with detectable photons.

    CMB per ESA/Planck
    CMB per ESA/Planck

    The CMB can be used to probe the cosmos via something known as the Sunyaev-Zel’dovich (SZ) effect, which was first observed over 30 years ago. We detect the CMB here on Earth when its constituent microwave photons travel to us through space. On their journey to us, they can pass through galaxy clusters that contain high-energy electrons. These electrons give the photons a tiny boost of energy. Detecting these boosted photons through our telescopes is challenging but important — they can help astronomers to understand some of the fundamental properties of the Universe, such as the location and distribution of dense galaxy clusters.

    This image shows the first measurements of the thermal Sunyaev-Zel’dovich effect from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile (in blue). Astronomers combined data from ALMA’s 7- and 12-metre antennas to produce the sharpest possible image. The target was one of the most massive known galaxy clusters, RX J1347.5–1145, the centre of which shows up here in the dark “hole” in the ALMA observations. The energy distribution of the CMB photons shifts and appears as a temperature decrease at the wavelength observed by ALMA, hence a dark patch is observed in this image at the location of the cluster.

    See the full article here .

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    The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

    ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

    NRAO Small

    ESO 50 Large

    NAOJ

     
  • richardmitnick 4:49 pm on February 12, 2017 Permalink | Reply
    Tags: Big Bang Science, , oscillon,   

    From U Basel: “Ancient Signals From the Early Universe” 

    u-basel-bloc

    U Basel

    February 12, 2017
    No writer credit

    2
    The animation shows a computer simulation of an oscillon, a strong localized fluctuation of the inflaton field of the early universe. According to the calculations of Prof. Stefan Antusch and his team, oscillons produced a characteristic peak in the otherwise broad spectrum of gravitational waves. © Department of Physics, University of Basel

    For the first time, theoretical physicists from the University of Basel in Switzerland have calculated the signal of specific gravitational wave sources that emerged fractions of a second after the Big Bang. The source of the signal is a long-lost cosmological phenomenon called “oscillon”. The journal Physical Review Letters has published the results.

    Although Albert Einstein had already predicted the existence of gravitational waves, their existence was not actually proven until fall 2015, when highly sensitive detectors received the waves formed during the merging of two black holes. Gravitational waves are different from all other known waves. As they travel through the universe, they shrink and stretch the space-time continuum; in other words, they distort the geometry of space itself. Although all accelerating masses emit gravitational waves, these can only be measured when the mass is extremely large, as is the case with black holes or supernovas.

    Gravitational waves transport information from the Big Bang

    However, gravitational waves not only provide information on major astrophysical events of this kind but also offer an insight into the formation of the universe itself. In order to learn more about this stage of the universe, Prof. Stefan Antusch and his team from the Department of Physics at the University of Basel are conducting research into what is known as the stochastic background of gravitational waves. This background consists of gravitational waves from a large number of sources that overlap with one another, together yielding a broad spectrum of frequencies. The Basel-based physicists calculate predicted frequency ranges and intensities for the waves, which can then be tested in experiments.

    A highly compressed universe

    Shortly after the Big Bang, the universe we see today was still very small, dense, and hot. “Picture something about the size of a football,” Antusch explains. The whole universe was compressed into this very small space, and it was extremely turbulent. Modern cosmology assumes that at that time the universe was dominated by a particle known as the inflaton and its associated field.

    Oscillons generate a powerful signal

    The inflaton underwent intensive fluctuations, which had special properties. They formed clumps, for example, causing them to oscillate in localized regions of space. These regions are referred to as oscillons and can be imagined as standing waves. “Although the oscillons have long since ceased to exist, the gravitational waves they emitted are omnipresent – and we can use them to look further into the past than ever before,” says Antusch.

    Using numerical simulations, the theoretical physicist and his team were able to calculate the shape of the oscillon’s signal, which was emitted just fractions of a second after the Big Bang. It appears as a pronounced peak in the otherwise rather broad spectrum of gravitational waves. “We would not have thought before our calculations that oscillons could produce such a strong signal at a specific frequency,” Antusch explains. Now, in a second step, experimental physicists must actually prove the signal’s existence using detectors.

    Original article

    Stefan Antusch, Francesco Cefalà, and Stefano Orani
    Gravitational Waves from Oscillons after Inflation
    Physical Review Letters (2017), doi: 10.1103/PhysRevLett.118.011303

    See the full article here .

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    u-basel-campus

    Purposes

    The University of Basel fosters the development of critically thinking and tolerant individuals who are capable of taking initiative and taking on responsibility. It is the aim of the University to enable these individuals to deepen their knowledge and field-specific academic training and further education.

    Through research and teaching, the University imparts the insights past down over the ages in addition to producing new knowledge. It is guided by the principle of meaningfulness and purpose rather than feasibility.

    The University is aware of the duties arising from knowledge, fulfilling these duties through critical reflection and the services it provides. It takes its own position concerning problems facing society.

    The University realizes its aims by taking responsibility with respect to future generations, the society that supports them, the international academic community and the culture that is passed down from generation to generation.

     
  • richardmitnick 4:51 pm on August 23, 2016 Permalink | Reply
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    From Symmetry: “Five facts about the Big Bang” 

    Symmetry Mag

    Symmetry

    08/23/16
    Matthew R. Francis

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    Illustration by Sandbox Studio, Chicago with Corinne Mucha

    Inflationary Universe. NASA/WMAP
    Inflationary Universe. NASA/WMAP

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey
    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    It’s the cornerstone of cosmology, but what is it all about?

    Astronomers Edwin Hubble and Milton Humason in the early 20th century discovered that galaxies are moving away from the Milky Way. More to the point: Every galaxy is moving away from every other galaxy on average, which means the whole universe is expanding. In the past, then, the whole cosmos must have been much smaller, hotter and denser.

    That description, known as the Big Bang model, has stood up against new discoveries and competing theories for the better part of a century. So what is this “Big Bang” thing all about?

    The Big Bang happened everywhere at once.

    The universe has no center or edge, and every part of the cosmos is expanding. That means if we run the clock backward, we can figure out exactly when everything was packed together—13.8 billion years ago. Because every place we can map in the universe today occupied the same place 13.8 billion years ago, there wasn’t a location for the Big Bang: Instead, it happened everywhere simultaneously.

    The Big Bang may not describe the actual beginning of everything.

    “Big Bang” broadly refers to the theory of cosmic expansion and the hot early universe. However, sometimes even scientists will use the term to describe a moment in time—when everything was packed into a single point. The problem is that we don’t have either observations or theory that describes that moment, which is properly (if clumsily) called the “initial singularity.”

    The initial singularity is the starting point for the universe we observe, but there might have been something that came before.

    The difficulty is that the very hot early cosmos and the rapid expansion called “inflation” that likely happened right after the singularity wiped out most—if not all—of the information about any history that preceded the Big Bang. Physicists keep thinking of new ways to check for signs of an earlier universe, and though we haven’t seen any of them so far, we can’t rule it out yet.

    The Big Bang theory explains where all the hydrogen and helium in the universe came from.

    In the 1940s, Ralph Alpher and George Gamow calculated that the early universe was hot and dense enough to make virtually all the helium, lithium and deuterium (hydrogen with a neutron attached) present in the cosmos today; later research showed where the primordial hydrogen came from. This is known as “Big Bang nucleosynthesis,” and it stands as one of the most successful predictions of the theory. The heavier elements (such as oxygen, iron and uranium) were formed in stars and supernova explosions.

    The best evidence for the Big Bang is in the form of microwaves. Early on, the whole universe was dense enough to be completely opaque. But at a time roughly 380,000 years after the Big Bang, expansion spread everything out enough to make the universe transparent.

    The light released from this transition, known as the cosmic microwave background (CMB), still exists.

    Cosmic Microwave Background per ESA/Planck
    Cosmic Microwave Background per ESA/Planck

    It was first observed in the 1960s by Arno Penzias and Robert Wilson.

    Big Ear, Arno Penzias and Robert Wilson, AT&T, Holmdel, NJ USA
    Big Ear, Arno Penzias and Robert Wilson, AT&T, Holmdel, NJ USA

    That discovery cemented the Big Bang theory as the best description of the universe; since then, observatories such WMAP and Planck have used the CMB to tell us a lot about the total structure and content of the cosmos.

    One of the first people to think scientifically about the origin of the universe was a Catholic priest.

    In addition to his religious training and work, Georges Lemaître was a physicist who studied the general theory of relativity and worked out some of the conditions of the early cosmos in the 1920s and ’30s.

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    His preferred metaphors for the origin of the universe were “cosmic egg” and “primeval atom,” but they never caught on, which is too bad, because …

    It seems nobody likes the name “Big Bang.”

    Until the 1960s, the idea of a universe with a beginning was controversial among physicists. The name “Big Bang” was actually coined by astronomer Fred Hoyle, who was the leading proponent of an alternative theory, where universe continues forever without a beginning.

    His shorthand for the theory caught on, and now we’re kind of stuck with it. Calvin and Hobbes’ attempt to get us to adopt “horrendous space kablooie” has failed so far.

    The Big Bang is the cornerstone of cosmology, but it’s not the whole story. Scientists keep refining the theory of the universe, motivated by our observation of all the weird stuff out there. Dark matter (which holds galaxies together) and dark energy (which makes the expansion of the universe accelerate) are the biggest mysteries that aren’t described by the Big Bang theory by itself.

    Our view of the universe, like the cosmos itself, keeps evolving as we discover more and more new things. But rather than fading away, our best explanation for why things are the way they are has remained—the fire at the beginning of the universe.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
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