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  • richardmitnick 5:45 pm on August 12, 2014 Permalink | Reply
    Tags: , , , Cosmic Microwave Background, ,   

    From SPACE.com: “Planck’s Mystery Cosmic ‘Cold Spot’ May Be an Error” 

    space-dot-com logo

    SPACE.com

    August 12, 2014
    Ian O’Neill

    The European Planck space telescope detects very faint primordial radiation that was generated after the Big Bang — when the universe was only 380,000 years old. By creating a cosmic map of the slight variations in this cosmic microwave background (CMB) radiation — variations known as “anisotropies” — cosmologists have been able to gain some clue as to the structure of the Universe nearly 14 billion years ago.

    cmb planck
    he European Space Agency’s Planck space telescope mapped the cosmic microwave background.
    Credit: ESA and the Planck Collaboration

    However, several anomalies in the CMB map have confused the scientific community; some mysterious features mapped by Planck don’t agree with established theory as to how the Cosmos works. Is there some exotic new cosmology at play? Or are these features simply observational error?

    Cosmologists in Switzerland and France have now shown that many of these features disappear from the map when observational data is processed differently, potentially erasing features like the mysterious CMB “cold spot.”

    One of the more exotic explanations for the cold spot is that it could be observational evidence for the “multiverse“— a hypothesis with roots in superstring theory where our universe exists in an ocean of other universes — and the cold spot is caused by a neighboring universe pushing up against ours. Unfortunately, the feature might not even be real.

    “Using new techniques to separate the foreground light from the background, and taking into account effects like the motion of our Galaxy, we found that most of the claimed anomalies we studied, like the cold spot, stop being problematic,” said lead researcher Anaïs Rassat, of the Ecole Polytechnique Fédérale de Lausanne, Switzerland.

    ANALYSIS: Will Science Burst the Multiverse’s Bubble?

    Rassat’s team’s work has been published today (Aug. 4) in the Journal of Cosmology and Astroparticle Physics.

    When mapping such faint radiation that has been traveling through space-time for billions of years, it is difficult to separate the primordial signal from other microwave sources. Our galaxy, for example, swamps the universal vista with microwaves and, as we live inside the galactic disk, our microwave view is dominated by Milky Way emissions. It’s a thick cosmic fog that needs to be subtracted.

    Through complex algorithms and foreground emission subtraction techniques, these extraneous microwave sources can be effectively removed. But Rassat’s team gave the data another pass, correcting for the motion of our galaxy and other impacts such as gravitational interference and distortions in the radiation itself.

    Although this study appears to have corrected for previously overlooked effects in Planck observations, some anomalies remain in the data, leaving room for some of the more exotic hypotheses about the origin and nature of our universe. But as for Planck’s “cold spot,” that mystery might be down to observational error and not something real.

    See the full article here.

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  • richardmitnick 11:18 am on July 11, 2014 Permalink | Reply
    Tags: , , , , Cosmic Microwave Background, , South Pole Telescope   

    From BBC- “Cosmic inflation: BICEP2 and Planck to share data” 

    BBC

    3 July 2014
    Jonathan Amos

    spt
    The BICEP2 telescope studied a small patch of sky in detail above the South Pole

    Scientists on rival projects looking for evidence that the early Universe underwent a super-expansion are in discussion about working together.

    The negotiations between the US-led BICEP2 group and Europe’s Planck Collaboration are at an early stage.

    BICEP2 announced in March that its South Pole telescope had found good evidence for “cosmic inflation“.

    South Pole Telescope
    South Pole Telescope

    Cosmic Background Radiation Planck
    CMB from Planck

    But to be sure, it needs the best data on factors that confound its research – data that Planck has been compiling.

    If the two teams come to an arrangement, it is more likely they will hammer down the uncertainties.

    “We’re still discussing the details but the idea is to exchange data between the two teams and eventually come out with a joint paper,” Dr Jan Tauber, the project scientist on the European Space Agency’s Planck satellite, told BBC News.

    This paper, hopefully, would be published towards the end of the year, he added.

    dust
    Foreground dust per Planck

    The question of whether the BICEP2 team did, or did not, identify a signal on the sky for inflation has gripped the science world for weeks.

    The group used an extremely sensitive detector in its Antarctic telescope to study light coming to Earth from the very edge of the observable Universe – the famous Cosmic Microwave Background (CMB) radiation.
    Planck artist impression The Planck satellite was launched in 2009 to map the Cosmic Microwave Background

    BICEP2 looked for swirls in the polarisation of the light.

    This pattern in the CMB’s directional quality is a fundamental prediction of inflation – the idea that there was an ultra-rapid expansion of space just fractions of a second after the Big Bang.

    The twists, known as B-modes, are an imprint of the waves of gravitational energy that would have accompanied the violent growth spurt.

    But this primordial signal – if it exists – is expected to be extremely delicate, and a number of independent scientists have expressed doubts about the American team’s finding. And the BICEP2 researchers themselves lowered their confidence in the detection when they formally published their work in a Physical Review Letters paper last month.

    At issue is the role played by foreground dust in our galaxy.

    Nearby spinning grains can produce an identical polarisation pattern, and this effect must be removed to get an unambiguous view of the primordial, background signal.

    The BICEP2 team used every piece of dust information it could source on the part of the sky it was observing above Antarctica.

    What it lacked, however, was access to the dust data being compiled by the Planck space telescope, which has mapped the microwave sky at many more frequencies than BICEP2.

    This allows it to more easily characterise the dust and discern its confounding effects.
    Dust Planck released dust information close to the galactic plane in May

    In May, the Planck Collaboration published dust polarisation information gathered close to the galaxy’s centre – where the grains are most abundant.

    In a few weeks’ time, the Planck team plans to release further information detailing galactic dust in high latitude regions, including the narrow patch of the southern sky examined by BICEP2.

    And then, in late October, the Planck Collaboration is expected to say something about whether it can detect primordial B-modes.

    As Dr Tauber explained, Planck’s approach to the problem is a different one to BICEP2’s.

    “Planck’s constraints on primordial B-modes will come from looking at the whole sky with relatively low sensitivity as compared to BICEP2,” he said.

    “But because we can look at the whole sky, it makes up for some of that [lower sensitivity] at least. On the other hand, we have to deal with the foregrounds – we can’t ignore them at all.

    “At the same time, we will work together with BICEP2 so that we can contribute our data to improve the overall assessment of foregrounds and the Cosmic Microwave Background.

    “We hope to start working with them very soon, and if all goes well then we can maybe publish in the same timeframe as our main result [at the end of October].”

    See the full article here.


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  • richardmitnick 2:17 pm on April 1, 2014 Permalink | Reply
    Tags: , , , , Cosmic Microwave Background, , , ,   

    From Symmetry: “The oldest light in the universe” 

    [I know that I have covered this topic before, but Symmetry's article is the very best that I have seen.]

    April 01, 2014
    Lori Ann White

    The Cosmic Microwave Background, leftover light from the big bang, carries a wealth of information about the universe—for those who can read it.

    Fifty years ago, two radio astronomers [Arno Penzias and Robert Wilson, both Nobel Laureates] from Bell Labs discovered a faint, ever-present hum in their [radio] telescope that they couldn’t identify. After ruling out radio broadcasts, radar signals, a too-warm receiver and even droppings from pigeons nesting inside the scope, they realized they’d found a soft cosmic static that originated from beyond our galaxy. Indeed, it seemed to fill all of space.

    Fast-forward five decades, and the static has a well-known name: the cosmic microwave background, or CMB. Far from a featureless hum, these faint, cold photons, barely energetic enough to boost a thermometer above absolute zero, have been identified as the afterglow of the big bang.

    Cosmic Microwave Background Planck
    Cosmic Microwave Background from ESA/Planck

    ESA Planck
    ESA/Planck

    This light—the oldest ever observed—offers a baby picture of the very early universe. How early? The most recent result, announced on Saint Patrick’s Day 2014 by the researchers of the BICEP2 experiment, used extremely faint signals imprinted on CMB photons to reach back to the first trillionth of a trillionth of a trillionth of a second after the big bang—almost more of a cosmic sonogram than a baby picture. This image offered the first direct evidence for the era of cosmic inflation, when space itself ballooned outward in a turbocharged period of expansion.

    BICEP 2
    BICEP2 at the South Pole Telescope

    keck
    BICEP / Keck Array; The BICEP2 detector array under a microscope
    The BICEP2 telescope at the South Pole uses novel technology developed at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. The focal plane shown here is an array of devices that use superconductivity to gather, filter, detect, and amplify polarized light from the cosmic microwave background — relic radiation left over from the Big Bang that created our universe. The microscope is showing a close-up view of one of the 512 pixels on the focal plane, displayed on the screen in the background. Each pixel is made from a printed antenna that collects polarized millimeter-wavelength radiation, with a filter that selects the wavelengths to be detected. A sensitive detector is fabricated on a thin membrane created through a process called micro-machining. The antennas and filters on the focal plane are made from superconducting materials. An antenna is seen on the close-up shot in the background with the green meandering lines. The detector uses a superconducting film as a sensitive thermometer to detect the heat from millimeter-wave radiation that was collected by the antenna and dissipated at the detector. A detector is seen on the close-up shot in the background to the right of the pink square. Finally, a tiny electrical current from the sensor is measured with amplifiers on the focal plane called SQUIDs (Superconducting QUantum Interference Devices), developed at National Institute of Standards and Technology, Boulder, Colo. The amplifiers are the rectangular chips on the round focal plane. The focal planes are manufactured using optical lithography techniques, similar to those used in the industrial production of integrated circuits for computers.

    CMB photons have more to tell us. Combined with theoretical models of cosmic growth and evolution, ongoing studies will expand this view of the very early universe while also looking forward in time. The goal is to create an entire album chronicling the growth of the universe from the very moments of its birth to today.

    Further studies promise clear insight into which of the many different models of inflation shaped our universe, and can also help us understand dark matter, dark energy and the mass of the neutrino—if researchers can read the CMB in enough detail.

    That’s not easy, though, because the afterglow has faded. During its epic 13-billion-year-plus journey, light that originally blazed through the universe has stretched with space itself, its waves growing billions of times longer and cooler and quieter.

    Relic radiation

    The Standard Model of Cosmology says that about 13.8 billion years ago, the universe was born from an unimaginably hot, dense state. Before a single second had ticked away, cosmic inflation [first proposed by Dr. Alan Guth, M.I.T.] increased the volume of the universe by an amount that varies according to the particular model, but always features a 10 followed by about 30 to 80 zeroes.

    smc

    When inflation hit the brakes, leftover energy from that expansion created many of the particles we see around us today: gluons, quarks, photons, electrons and their bigger brethren, muons and taus, and neutrinos. Primordial photons scattered off free-floating electrons, bouncing around inside the gas cloud that was the universe. Hundreds of thousands of years later, the cosmic cloud of particles cooled enough that single protons and helium nuclei could capture the electrons they needed to form neutral hydrogen and helium. This rounded up the free electrons, clearing the fog and releasing the photons. The universe began to shine.

    These photons are the cosmic microwave background. Although now weak, they are everywhere; CMB photons bathe the Earth—and every other star, planet, black hole and hunk of rock in the universe—in their cold light.

    Cosmic sonograms

    The latest big discovery coaxed from CMB data peeks back into the earliest moments of the universe.

    Using cutting-edge sensors, the BICEP2 telescope located at the South Pole detected a type of signal that has been predicted at one strength or another by every version of inflation theory out there: a type of polarization to the CMB light called “B-mode polarization.”

    According to the theories, tiny variations in the energy of the pre-inflation universe caused primordial gravitational waves—ripples in the fabric of space-time—that ballooned outward with inflation. Even before they became the CMB, photons interacted with these ripples, causing the photons’ wavelengths to take on a slight twist. It was this twist that the BICEP2 collaboration measured as a swirling polarization pattern.

    “BICEP2 clearly detected B-mode polarization at precisely the angular scales predicted by inflation,” says Chao-Lin Kuo, one of four principal investigators on the experiment. “This is an incredible combination of big theoretical ideas, teamwork, focus and cutting-edge technologies. The development of mass-produced superconducting polarization detectors and quantum current sensors made a real difference to our success in getting to B-modes first.”

    A discovery of this magnitude calls for further confirmation—not of the signals, which were very clear, but of their inflationary origin. If it holds, the B-mode polarization signals will also give scientists more details about the inflationary event that took place. For example, it can tell us about the energy scale of the universe—essentially the amount of energy poured into the instant of inflation. The BICEP2 result puts this at about 1016 billion electronvolts. For comparison, the Large Hadron Collider’s most powerful proton beams smash together at 104 billion electronvolts—a number with 12 fewer zeros than the first.

    Such information can help scientists determine which of the many different models of inflation actually describes the beginning of our universe. To Walt Ogburn, a postdoctoral researcher at Stanford University and a member of the BICEP2 team, the first view of primordial B-mode polarization does more than turn inflationary theory into fact: It breaks through into uncharted territory in high-energy physics. “What drove inflation is not in the Standard Model,” Ogburn says. By definition, proof of inflation offers evidence that there’s something more out there that’s not yet discovered, and that something big we don’t yet fully understand helped drive the evolution of the early universe.

    Baby picture

    The detection of B-mode polarization is the latest in a long string of scientific discoveries base on information coaxed from these scarce, faint photons.

    The first successes in probing the CMB came almost two decades after it was identified. Beginning with Relikt-1, a Soviet satellite-based experiment launched in 1983, and continuing all the way up to the present, a variety of balloons and satellites have mapped the temperature of the CMB. They found it was 2.7 kelvin across the whole of the sky, with only small, scattered variations in temperature of about one part in 100,000.

    In that temperature map cosmologists saw the image of the infant universe.

    “We’ve learned an enormous amount from the temperature [patterns],” says Lyman Page, also a cosmologist at Princeton. Page was one of the original researchers on what, until this year, was probably the best-known CMB instrument, the Wilkinson Microwave Anisotropy Probe [WMAP]. He now focuses on the Atacama Cosmology Telescope, and few people know more about how to make the CMB give up its secrets.

    ACT Telescope
    Princeton ACT

    Page explains that both the overall sameness of the temperature and the pattern of these minor variations told cosmologists that when the universe began, it was compact enough to be in thermal equilibrium: a dense, nearly featureless plasma of immense energies. But within that plasma, quantum fluctuations caused tiny variations in energy density.

    Then, during cosmic inflation, space grew enormously in all directions. This magnified the variations like an inflating balloon expands ink spots sprayed on it into larger and larger blotches.

    This is the same process that generated the gravitational waves imaged by BICEP2. The gravitational waves left telltale swirling polarization patterns in the CMB without doing much else. However, the dense areas—“blotches” on the otherwise smooth map of the sky—became important seeds of all structures in the universe.

    They grew and cooled, morphed from variations in energy density to variations in matter density. The denser regions attracted more matter as the universe continued to expand, eventually building up large-scale structures we see stitched across the universe today.

    When combined with other theories and measurements, Page says, the temperature variations provide strong evidence that our universe began with the big bang. They have also helped cosmologists improve estimates for how much dark matter and dark energy existed in the early universe (and likely still exist today), and backed the notion that the geometry of the universe is flat.

    “The CMB is really a beautiful signal,” says the University of Chicago’s John Carlstrom, who, like Page, is an expert in extracting information from a few faint photons. He leads the South Pole Telescope project, which uses several instruments mounted on a telescope not too far from BICEP2, to learn more about the CMB. The signal, he continues, offers “very precise measurements of conditions at recombination,” which is the name given to the time when the CMB photons escaped from the primordial cloud of cooling plasma.

    South Pole Telescope
    South Pole Telescope

    These temperature maps—in combination with the primordial B-mode signals detected by BICEP2—cover a time period from a tiny fraction of a second after the birth of the universe to about 380,000 years after that. In the coming years, cosmologists want to expand that picture to include everything that’s happened in the more than 13 billion years since recombination. Many predictions exist for what happened during this huge span of time, but scientists need rock-solid empirical data to compare their theoretical models against.

    map
    BICEP2 revealed a faint but distinctive twist in the polarization pattern of the CMB. Here the lines represent polarization; the red and blue shading show the degree of the clockwise and counter-clockwise twist. Courtesy of: BICEP2

    Filling in the photo album

    CMB photons have more important information to offer, and a new generation of experiments is listening to what they have to say. Situated mostly on the high, dry, cold deserts of the South Pole and the Atacama Plateau in Chile, or in high-flying balloons that rise above much of the atmosphere, new instruments use the CMB to refine our knowledge of how the universe has evolved.

    As the CMB photons traveled through the universe, they were pulled this way and that by gravity, bearing witness to everything that happened on their way from the beginning to now. Using these photons as messengers, the new instruments are helping scientists carefully tease out the story of what the photons saw along their journey.

    Interactions with the hot gas that surrounded and infused galaxy clusters, for example, left a mark on some of the photons in the form of a tiny boost in energy, which is detectable as a very slight adjustment to the temperature map.

    The new instruments also measure a different type of B-mode polarization, added to the CMB photons long after inflation. This type of twist occurs when the photons brush up against the gravity of large-scale cosmic structures comprising both regular matter and dark matter, and it was detected for the first time just last year by SPTpol, a polarization-sensitive microwave camera mounted on the South Pole Telescope.

    SPTpol
    SPTpol

    Taken together, these measurements of tiny temperature differences and polarization can help scientists map matter distributions over time and improve estimates of how much of the universe is made up of dark matter versus the normal matter we see in stars and planets. It can also help tease apart the difference between expansion due to the momentum left from the big bang and expansion due to dark energy. This will yield an accurate four-dimensional map of the universe, revealing the movement of matter through space and time.

    Further measurements are poised to reveal more information about the contributions to our cosmos of a tiny particle with big implications: the neutrino. Its mass is currently not known to any respectable precision, yet this number is of great importance to predictions regarding the neutrinos’ influence on the growing universe.

    Experiments so far have seen three types of neutrinos [electron neutrinos, muon neutrinos and tau neutrinos, yet some theories predict a fourth type, called a sterile neutrino, as well.

    “Neutrinos are the second most plentiful particle in the universe—after photons,” says Bradford Benson, a scientist at Fermilab and a member of the SPTpol team. “The total mass of all the neutrinos in the universe should at least equal the mass of all the stars.”

    When the universe was smaller, that neutrino mass could have had a significant influence on the universe’s developing structure. As the universe expanded, two things happened: Clumps of heavier, slower-moving particles grew even bigger by pulling in more matter, while the light, speedy neutrinos escaped; and space expanded while the number of neutrinos stayed the same such that, as their density decreased, their gravitational influence decreased as well.

    As they traveled among the growing cosmic structures, the CMB photons recorded these changes in the relative density of neutrinos. Scientists are now mining this record to determine how the influence of neutrinos has evolved over time, and can use the information to estimate their mass. Combined with CMB measurements of dark matter and expansion due to dark energy, scientists expect this research to refine their view of the universe past and present, revealing how matter and energy interacted in the early universe to make the universe we see today.

    Old light, new science

    Using the CMB to discover primordial gravitational waves has been a tremendous step forward. “What’s truly amazing is that the CMB may still hide more secrets even after we found the holy grail,” says Kuo, referring to BICEP2’s discovery.

    Temperature maps, scattered photons and twisted light still have more to tell us. Over the next decade, CMB measurements are poised to help us understand the immense forces of the big bang, illuminate the physics of the early universe and explain the matter and energy we see around us today.

    “Having this signal has helped turn cosmology into a precision science,” Carlstrom says. “We’ve gone from being told, ‘You guys don’t really know what you’re measuring’ to having inde-pendent measurements with levels of precision that rival particle physics.”

    And the benefits are only set to increase. “The study of the CMB is a fantastic field, a very rich field,” Page says. “The microwave background is still going to be a useful tool in 20 years.”

    That’s not bad for a few frigid photons.

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.



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  • richardmitnick 12:15 pm on March 25, 2014 Permalink | Reply
    Tags: , , , , Cosmic Microwave Background, ,   

    From Berkeley Lab: “Setting a Trap for Gravity Waves” 


    Berkeley Lab

    March 18, 2014
    Paul Preuss paul_preuss@lbl.gov

    In 1996 Uros Seljak was a postdoc at Harvard, contemplating ways to extract information from the cosmic microwave background (CMB). The distribution of anisotropies, slight temperature differences, in the CMB had much to say about the large-scale structure of the universe. If it were also possible to detect the polarization of the CMB itself, however, a much wider window would be opened – polarization could even reveal the tracks of gravitational waves.

    Cosmic Background RadiationXMM Newton
    CMB from ESA/Planck

    Gravitational waves are distortions of space on a small scale, and have no consequence for the large-scale structure of the universe,” says Seljak, now a professor of physics and astronomy at UC Berkeley and a faculty scientist in Berkeley Lab’s Physics Division. “Both result from perturbations during inflation, but the seeds of large-scale structure are described by a scalar field, and gravitational waves by a tensor field.”

    Cosmologists already assumed that inflation theory was essentially correct: virtually instantaneous expansion after the big bang explained how regions of the universe never otherwise in contact had in fact started from the same initial conditions. Here was a way to test inflation directly.

    Seljak posted a paper to arXiv (soon published in the Astrophysical Journal), becoming the first to predict how polarization could be used to find CMB tensor signals, including gravitational waves. Marc Kamionkowski, Arthur Kosowsky, and Albert Stebbins of Fermilab independently posted their similar proposal shortly thereafter. In further work with Matias Zaldarriaga, Seljak named the E and B modes of CMB polarization, borrowing the symbols for light’s electric and magnetic fields – scalar fields produce E-mode polarization; a gravitational tensor field can produce both.

    Fast forward to the year 2000, when Adrian Lee, a professor of astrophysics at UC Berkeley and faculty scientist in the Lab’s Physics Division, came up with the idea of suspending the recently invented transition-edge sensor bolometer(TES), creating what he describes as “a trampoline that heats up when an energy pulse lands on it” – the more energy, the bigger the reaction.

    Lee integrated suspended TESs with other functions in flat chips suitable for the focal planes of CMB telescopes. He proposed just such a telescope, the POLARBEAR experiment, initiated with support from Berkeley Lab’s Laboratory Directed Research and Development (LDRD). BICEP2 and many other CMB telescopes also use versions of these focal-plane chips.

    BICEP 2
    BICEP2 at the South Pole Telescope

    On Monday, March 17, 2014, the BICEP2 collaboration grabbed the brass ring: first detection of B-mode polarization from gravitational waves, thus first direct evidence of inflation – a signal far stronger than most scientists had expected.

    “We look forward to working with BICEP2 to refine their measurements,” says Lee. “Until now, the best evidence for inflation was a slight ‘tilt’ in the CMB scalar field. POLARBEAR’s higher resolution could detect a similar tilt in the tensor field, a double confirmation of inflation.”

    Among the many implications of the large B-mode signal, says Seljak: “It may force us in the direction of string theory. It also fits in with models of continuing inflation that produce multiple universes.”

    Berkeley Lab has played an important part in opening the cosmic frontier to even wider vistas.

    See the full article here.

    A U.S. Department of Energy National Laboratory Operated by the University of California

    University of California Seal

    DOE Seal


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  • richardmitnick 9:24 am on March 20, 2014 Permalink | Reply
    Tags: , , , , Cosmic Microwave Background, , , ,   

    From M.I.T.: “3 Questions: Alan Guth on new insights into the ‘Big Bang’” 

    March 19, 2014
    Steve Bradt, MIT News Office

    Earlier this week, scientists announced that a telescope observing faint echoes of the so-called “Big Bang” had found evidence of the universe’s nearly instantaneous expansion from a mere dot into a dense ball containing more than 1090 particles. This discovery, using the BICEP2 telescope at the South Pole, provides the first strong evidence of “cosmic inflation” at the birth of our universe, when it expanded billions of times over.

    BICEP Telescope
    BICEP2 Telescope at South Pole

    The theory of cosmic inflation was first proposed in 1980 by Alan Guth, now the Victor F. Weisskopf Professor of Physics at MIT. Inflation has become a cornerstone of Big Bang cosmology, but until now it had remained a theory without experimental support. Guth discussed the significance of the new BICEP2 results with MIT News.

    ag
    Dr. Alan Guth

    Q: Can you explain the theory of cosmic inflation that you first put forth in 1980?

    A: I usually describe inflation as a theory of the “bang” of the Big Bang: It describes the propulsion mechanism that drove the universe into the period of tremendous expansion that we call the Big Bang. In its original form, the Big Bang theory never was a theory of the bang. It said nothing about what banged, why it banged, or what happened before it banged.

    The original Big Bang theory was really a theory of the aftermath of the bang. The universe was already hot and dense, and already expanding at a fantastic rate. The theory described how the universe was cooled by the expansion, and how the expansion was slowed by the attractive force of gravity.

    Inflation proposes that the expansion of the universe was driven by a repulsive form of gravity. According to [Isaac] Newton, gravity is a purely attractive force, but this changed with [Albert] Einstein and the discovery of general relativity. General relativity describes gravity as a distortion of spacetime, and allows for the possibility of repulsive gravity.

    Modern particle theories strongly suggest that at very high energies, there should exist forms of matter that create repulsive gravity. Inflation, in turn, proposes that at least a very small patch of the early universe was filled with this repulsive-gravity material. The initial patch could have been incredibly small, perhaps as small as 10-24 centimeter, about 100 billion times smaller than a single proton. The small patch would then start to exponentially expand under the influence of the repulsive gravity, doubling in size approximately every 10-37 second. To successfully describe our visible universe, the region would need to undergo at least 80 doublings, increasing its size to about 1 centimeter. It could have undergone significantly more doublings, but at least this number is needed.

    During the period of exponential expansion, any ordinary material would thin out, with the density diminishing to almost nothing. The behavior in this case, however, is very different: The repulsive-gravity material actually maintains a constant density as it expands, no matter how much it expands! While this appears to be a blatant violation of the principle of the conservation of energy, it is actually perfectly consistent.

    This loophole hinges on a peculiar feature of gravity: The energy of a gravitational field is negative. As the patch expands at constant density, more and more energy, in the form of matter, is created. But at the same time, more and more negative energy appears in the form of the gravitational field that is filling the region. The total energy remains constant, as it must, and therefore remains very small.

    It is possible that the total energy of the entire universe is exactly zero, with the positive energy of matter completely canceled by the negative energy of gravity. I often say that the universe is the ultimate free lunch, since it actually requires no energy to produce a universe.

    At some point the inflation ends because the repulsive-gravity material becomes metastable. The repulsive-gravity material decays into ordinary particles, producing a very hot soup of particles that form the starting point of the conventional Big Bang. At this point the repulsive gravity turns off, but the region continues to expand in a coasting pattern for billions of years to come. Thus, inflation is a prequel to the era that cosmologists call the Big Bang, although it of course occurred after the origin of the universe, which is often also called the Big Bang.

    Q: What is the new result announced this week, and how does it provide critical support for your theory?

    A: The stretching effect caused by the fantastic expansion of inflation tends to smooth things out — which is great for cosmology, because an ordinary explosion would presumably have left the universe very splotchy and irregular. The early universe, as we can see from the afterglow of the cosmic microwave background (CMB) radiation, was incredibly uniform, with a mass density that was constant to about one part in 100,000.

    CMB Planck ESA
    Cosmic Microwave Background

    ESA Planck
    ESA/Planck

    The tiny nonuniformities that did exist were then amplified by gravity: In places where the mass density was slightly higher than average, a stronger-than-average gravitational field was created, which pulled in still more matter, creating a yet stronger gravitational field. But to have structure form at all, there needed to be small nonuniformities at the end of inflation.

    In inflationary models, these nonuniformities — which later produce stars, galaxies, and all the structure of the universe — are attributed to quantum theory. Quantum field theory implies that, on very short distance scales, everything is in a state of constant agitation. If we observed empty space with a hypothetical, and powerful, magnifying glass, we would see the electric and magnetic fields undergoing wild oscillations, with even electrons and positrons popping out of the vacuum and then rapidly disappearing. The effect of inflation, with its fantastic expansion, is to stretch these quantum fluctuations to macroscopic proportions.

    The temperature nonuniformities in the cosmic microwave background were first measured in 1992 by the COBE satellite, and have since been measured with greater and greater precision by a long and spectacular series of ground-based, balloon-based, and satellite experiments. They have agreed very well with the predictions of inflation. These results, however, have not generally been seen as proof of inflation, in part because it is not clear that inflation is the only possible way that these fluctuations could have been produced.

    NASA COBE satellite
    NASA/COBE

    The stretching effect of inflation, however, also acts on the geometry of space itself, which according to general relativity is flexible. Space can be compressed, stretched, or even twisted. The geometry of space also fluctuates on small scales, due to the physics of quantum theory, and inflation also stretches these fluctuations, producing gravity waves in the early universe.

    The new result, by John Kovac and the BICEP2 collaboration, is a measurement of these gravity waves, at a very high level of confidence. They do not see the gravity waves directly, but instead they have constructed a very detailed map of the polarization of the CMB in a patch of the sky. They have observed a swirling pattern in the polarization (called “B modes”) that can be created only by gravity waves in the early universe, or by the gravitational lensing effect of matter in the late universe.

    But the primordial gravity waves can be separated, because they tend to be on larger angular scales, so the BICEP2 team has decisively isolated their contribution. This is the first time that even a hint of these primordial gravity waves has been detected, and it is also the first time that any quantum properties of gravity have been directly observed.

    Q: How would you describe the significance of these new findings, and your reaction to them?

    A: The significance of these new findings is enormous. First of all, they help tremendously in confirming the picture of inflation. As far as we know, there is nothing other than inflation that can produce these gravity waves. Second, it tells us a lot about the details of inflation that we did not already know. In particular, it determines the energy density of the universe at the time of inflation, which is something that previously had a wide range of possibilities.

    By determining the energy density of the universe at the time of inflation, the new result also tells us a lot about which detailed versions of inflation are still viable, and which are no longer viable. The current result is not by itself conclusive, but it points in the direction of the very simplest inflationary models that can be constructed.

    Finally, and perhaps most importantly, the new result is not the final story, but is more like the opening of a new window. Now that these B modes have been found, the BICEP2 collaboration and many other groups will continue to study them. They provide a new tool to study the behavior of the early universe, including the process of inflation.

    When I (and others) started working on the effect of quantum fluctuations in the early 1980s, I never thought that anybody would ever be able to measure these effects. To me it was really just a game, to see if my colleagues and I could agree on what the fluctuations would theoretically look like. So I am just astounded by the progress that astronomers have made in measuring these minute effects, and particularly by the new result of the BICEP2 team. Like all experimental results, we should wait for it to be confirmed by other groups before taking it as truth, but the group seems to have been very careful, and the result is very clean, so I think it is very likely that it will hold up.

    See the full article here.


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  • richardmitnick 12:17 pm on March 19, 2014 Permalink | Reply
    Tags: , , , Cosmic Microwave Background, , ,   

    From Fermilab: “From quantum to cosmos” 


    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    Wednesday, March 19, 2014

    ch
    Craig Hogan, head of the Center for Particle Astrophysics, wrote this column.

    On Monday morning, cosmologists around the world felt a wave of ecstasy as they learned of a breathtaking discovery: a particular pattern of light coming from the early universe, imprinted on the cosmic expansion during its first moments. It feels like a love letter from Mother Nature has invited us to share her deepest secrets.

    CMB Planck ESA
    Cosmic Background from ESA/Planck

    All forms of matter and energy come in quanta — the “particles” of particle physics. For the first time, we have now detected a quantum behavior of space and time. The new result invokes an interplay among all the scales of physical universe, from the smallest to largest, from the beginning to the present day. It spectacularly confirms many of the “inner space/outer space” connections pioneered over several decades by Fermilab’s astrophysics theory group. This includes the amazing idea that quantum fluctuations can be amplified to enormous size by cosmic expansion and lead not only to gravitational waves, but ultimately to the formation of all cosmic structures, including galaxies, stars, planets and life.

    The now discovered polarization of cosmic background light displays a faint but distinctive pattern of swirls that can be created only by an extraordinarily exotic process known as inflation, a stretching of space-time (gravitational waves), caused by its own subatomic, quantum fluctuations. This unique signature reaches us intact across all the vast stretches of space since the beginning of time and can now be studied in precise detail.

    The discovery, published in this paper, came sooner than anyone expected. Theorists, including Fermilab’s Albert Stebbins, proposed long ago the possibility of isolating the distinctive swirling signature used to make the discovery, but everyone was surprised this week that the signal in the real universe is so strong. The implications for cosmology are immediate and profound. We now know far more reliably what conditions were during the cosmic inflation that created our expansion; for example, the new data directly measures how fast things were expanding back then. We can now delve much more concretely into the new physics that governs cosmic origins and how it connects to the unification of the Standard Model particles and forces studied at the Tevatron and the LHC. Cosmic polarization experiments may even provide real data addressing the quantum system underlying unification of the Standard Model with gravity — the “theory of everything.”

    sm
    The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    Fermilab Tevatron
    Tevatron

    CERN LHC
    Inside the LHC

    The discovery was inspired by theory but propelled in recent years by new transformational technology, in particular, a new generation of sensors being developed at Argonne, Berkeley, Jet Propulsion Laboratory and NIST. Large focal plane arrays of antennas are fabricated on silicon wafers, together with superconducting detectors that achieve quantum-noise-limited performance. In experiments, they are deployed in advanced telescopes at the world’s best site for peering deep into space, the South Pole.

    The newly discovered effect is strong enough to confirm soon with other experiments, perhaps even using data already obtained. The next step will be to improve the quality of the measurements with a larger area of sky, more frequency bands and higher angular resolution. That will require larger focal planes with more detection elements and a larger telescope.

    We are already developing this next-generation experiment. It will use the world’s leading facility for cosmic background studies, the South Pole Telescope (SPT). As part of a new joint effort with Argonne, the University of Chicago and other partners, Fermilab is playing a central role in developing and building the new SPT-3G cryogenic camera system, an order of magnitude more capable than that currently deployed. Over the next two years, the system will be assembled, integrated and tested at Fermilab by a team led by Brad Benson, using many of the facilities previously developed for the Dark Energy Camera and the QUIET polarization experiment, before being shipped to the South Pole.

    South Pole Telescope
    South Pole Telescope

    Fermilab DECam
    DECam

    Plans are also under way for an even more ambitious fourth-generation cosmic microwave background polarization experiment, by a larger consortium of national labs and universities. A recent APS Community Summer Study (“Snowmass“) report, co-led by Fermilab’s Scott Dodelson, identified such an experiment, in synergy with other surveys, as a unique opportunity to study many aspects of new physics, including neutrino masses, new relativistic species (so-called dark radiation) and dark energy. A study group proposes to expand CMB polarization capabilities by another order of magnitude beyond SPT-3G, including the addition of more telescopes to access more of the sky not visible from the South Pole. The new discovery extends and enriches the science reach of this enterprise to a new and deeper level — one we had hardly dared to dream about until this week.

    See the full article here.

    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics.


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  • richardmitnick 1:17 pm on August 7, 2013 Permalink | Reply
    Tags: , , Cosmic Microwave Background, , , , ,   

    From Berkeley Lab: “First Hundred Thousand Years of Our Universe” 


    Berkeley Lab

    August 07, 2013
    Lynn Yarris (510) 486-5375 lcyarris@lbl.gov

    “To understand the mysteries of our universe, scientists are trying to go back as far they can to the Big Bang. A new analysis of cosmic microwave background (CMB) radiation data by researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) has taken the furthest look back through time yet – 100 years to 300,000 years after the Big Bang – and provided tantalizing new hints of clues as to what might have happened.

    first
    First 100,000 years

    cmr
    Planck image

    ‘We found that the standard picture of an early universe, in which radiation domination was followed by matter domination, holds to the level we can test it with the new data, but there are hints that radiation didn’t give way to matter exactly as expected,’ says Eric Linder, a theoretical physicist with Berkeley Lab’s Physics Division and member of the Supernova Cosmology Project. ‘There appears to be an excess dash of radiation that is not due to CMB photons.’

    Our knowledge of the Big Bang and the early formation of the universe stems almost entirely from measurements of the CMB, primordial photons set free when the universe cooled enough for particles of radiation and particles of matter to separate. These measurements reveal the CMB’s influence on the growth and development of the large-scale structure we see in the universe today.”

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    Eric Linder is a theoretical physicist with Berkeley Lab’s Physics Division and member of the Supernova Cosmology Project. (Photo by Roy Kaltschmidt)

    Linder, working with Alireza Hojjati and Johan Samsing, who were then visiting scientists at Berkeley Lab, analyzed the latest satellite data from the European Space Agency’s Planck mission and NASA’s Wilkinson Microwave Anisotropy Probe (WMAP), which pushed CMB measurements to higher resolution, lower noise, and more sky coverage than ever before.

    ‘With the Planck and WMAP data we’re really pushing back the frontier and looking further back in the history of the universe, to regions of high energy physics we previously could not access,’ Linder says. ‘While our analysis shows the CMB photon relic afterglow of the Big Bang being followed mainly by dark matter as expected, there was also a deviation from the standard that hints at relativistic particles beyond CMB light.’

    Linder says the prime suspects behind these relativistic particles are ‘wild’ versions of neutrinos, the phantomlike subatomic particles that are the second most populous residents (after photons) of today’s universe. The term ‘wild’ is used to distinguish these primordial neutrinos from those expected within particle physics and being observed today. Another suspect is dark energy, the anti-gravitational force that accelerates our universe’s expansion. Again, however, this would be from the dark energy we observe today.

    ‘Early dark energy is a class of explanations for the origin of cosmic acceleration that arises in some high energy physics models,’ Linder says. ‘While conventional dark energy, such as the cosmological constant, are diluted to one part in a billion of total energy density around the time of the CMB’s last scattering, early dark energy theories can have 1-to-10 million times more energy density.’

    Linder says early dark energy could have been the driver that seven billion years later caused the present cosmic acceleration. Its actual discovery would not only provide new insight into the origin of cosmic acceleration, but perhaps also provide new evidence for string theory and other concepts in high energy physics.

    ‘New experiments for measuring CMB polarization that are already underway, such as the POLARBEAR and SPTpol telescopes, will enable us to further explore primeval physics,’ Linder says.

    Linder, Hojjati and Samsing are the authors of a paper describing these results in the journal Physical Review Letters titled New Constraints on the Early Expansion History of the Universe. Hojjati is now with the Institute for the Early Universe in South Korea, and Samsing is with the DARK Cosmology Centre in Denmark.”

    See the full article here.

    A U.S. Department of Energy National Laboratory Operated by the University of California

    University of California Seal

    DOE Seal


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