If you are into Twitter (as I am), you might enjoy this: New Scientist challenged their readers to encompass the Big Bang into a Tweet. That means the description of the event that started everything that is needs to be 140 characters or less –and actually it was only 133 characters because to qualify, the Tweet had to include the #sci140 hashtag so the folks at New Scientist could gather them all together. Some went the complete science route by trying to summarize the physics (at least one person fit in the equation for Hubble’s Law), others quoted (“In the beginning the universe was created. This has made a lot of people very angry and has been widely regarded as a bad move.” — Douglas Adams), others took a religious bend, and still others described the event in how it might sound (boom, bang, kaboom or tweeeet). Here’s my favorite:
Timeless energy, / all dressed up, no place to go: / had to create space. / – #BigBang #haiku #sci140 – haiQ
God said delB=0 etc, & then light (sym breaking), separation light from darkness (recombination), man created from dirt (evolution) #sci140 – dmadance
#sci140 starburst, molecule, amino acid, protein, cell development, cell division, sex, technology, war, religion, OK magazine. – jonotrumpeto
@newscientist #sci140 Antimatter and matter duke it out. Matter wins 1 billion and one to 1 billion. The matter left expands and makes us. – zeroentropy
#sci140 A place for everything, and everything in one place. Then — kaboom, everything all over the place. – tui4
@newscientist The Big Bang: the moment the universe vanishes when extrapolating its expansion backwards into the past #sci140 – hubi1857
For t<0 some say there was no matter, others say it does not matter. For t>0 its a matter of life and death – as a matter of fact #sci140 – thebeerhunter
an argument between the 9th and 10th dimensions overspilled into the 1st, 2nd, 3rd and 4th. #sci140 – AlexStavrinides
The Big Bang: Basically a ballooning of bosons, belatedly bloating into our beautiful universe. Brought to you by the letter ‘B’. #sci140 – CoyoteTrax
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Einstein’s general theory of relativity describes gravity in terms of the geometry of both space and time. Far from a source of gravity, such as a star like our sun, space is “flat” and clocks tick at their normal rate. Closer to a source of gravity, however, clocks slow down and space is curved. But measuring this curvature of space is difficult. However, scientists have now used a continent-wide array of radio telescopes to make an extremely precise measurement of the curvature of space caused by the Sun’s gravity. This new technique promises to contribute greatly in studying quantum physics.
“Measuring the curvature of space caused by gravity is one of the most sensitive ways to learn how Einstein’s theory of General Relativity relates to quantum physics. Uniting gravity theory with quantum theory is a major goal of 21st-Century physics, and these astronomical measurements are a key to understanding the relationship between the two,” said Sergei Kopeikin of the University of Missouri.
Kopeikin and his colleagues used the National Science Foundation’s Very Long Baseline Array (VLBA) radio-telescope system to measure the bending of light caused by the Sun’s gravity to within one part in 30,000 3,333 (corrected by NRAO and updated here on 9/03/09 — see this link provided by Ned Wright of UCLA for more information on deflection and delay of light). With further observations, the scientists say their precision technique can make the most accurate measure ever of this phenomenon.
Bending of starlight by gravity was predicted by Albert Einstein when he published his theory of General Relativity in 1916. According to relativity theory, the strong gravity of a massive object such as the Sun produces curvature in the nearby space, which alters the path of light or radio waves passing near the object. The phenomenon was first observed during a solar eclipse in 1919.
Though numerous measurements of the effect have been made over the intervening 90 years, the problem of merging General Relativity and quantum theory has required ever more accurate observations. Physicists describe the space curvature and gravitational light-bending as a parameter called “gamma.” Einstein’s theory holds that gamma should equal exactly 1.0.
“Even a value that differs by one part in a million from 1.0 would have major ramifications for the goal of uniting gravity theory and quantum theory, and thus in predicting the phenomena in high-gravity regions near black holes,” Kopeikin said.
To make extremely precise measurements, the scientists turned to the VLBA, a continent-wide system of radio telescopes ranging from Hawaii to the Virgin Islands. The VLBA offers the power to make the most accurate position measurements in the sky and the most detailed images of any astronomical instrument available. Sun's Path in Sky in Front of Quasars, 2005. Credit: NRAO
The researchers made their observations as the Sun passed nearly in front of four distant quasars — faraway galaxies with supermassive black holes at their cores — in October of 2005. The Sun’s gravity caused slight changes in the apparent positions of the quasars because it deflected the radio waves coming from the more-distant objects.
The result was a measured value of gamma of 0.9998 +/- 0.0003, in excellent agreement with Einstein’s prediction of 1.0.
“With more observations like ours, in addition to complementary measurements such as those made with NASA’s Cassini spacecraft, we can improve the accuracy of this measurement by at least a factor of four, to provide the best measurement ever of gamma,” said Edward Fomalont of the National Radio Astronomy Observatory (NRAO). “Since gamma is a fundamental parameter of gravitational theories, its measurement using different observational methods is crucial to obtain a value that is supported by the physics community,” Fomalont added.
Kopeikin and Fomalont worked with John Benson of the NRAO and Gabor Lanyi of NASA’s Jet Propulsion Laboratory. They reported their findings in the July 10 issue of the Astrophysical Journal.
Artists concept of graviational waves. Credit: NASA
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The only way to know what the Universe was like at the moment of the Big Bang requires analysis of gravitational waves created when the Universe began. Scientists working with the Laser Interferometer Gravitational-Wave Observatory (LIGO) say their initial investigations of these gravitiation waves have turned up nothing. But that’s a good thing. Not detecting the waves provides constraints about the initial conditions of the universe, and narrows the field of where we actually do need to look in order to find them.
Much like it produced the cosmic microwave background, the Big Bang is believed to have created a flood of gravitational waves — ripples in the fabric of space and time. From our current understanding, gravitational waves are the only known form of information that can reach us undistorted from the beginnings of the Universe. They would be observed as a “stochastic” or random background, and would carry with them information about their violent origins and about the nature of gravity that cannot be obtained by conventional astronomical tools. The existence of the waves was predicted by Albert Einstein in 1916 in his general theory of relativity.
Analysis of data taken over a two-year period, from 2005 to 2007, yields that the stochastic background of gravitational waves has not yet been discovered. But the nondiscovery of the background, described in a new paper in the August 20 Nature, offers its own brand of insight into the universe’s earliest history.
“Since we have not observed the stochastic background, some of these early-universe models that predict a relatively large stochastic background have been ruled out,” said Vuk Mandic, assistant professor at the University of Minnesota and the head of the group that performed the analysis. “We now know a bit more about parameters that describe the evolution of the universe when it was less than one minute old.”
According to Mandic, the new findings constrains models of cosmic strings, objects that are proposed to have been left over from the beginning of the universe and subsequently stretched to enormous lengths by the universe’s expansion; the strings, some cosmologists say, can form loops that produce gravitational waves as they oscillate, decay, and eventually disappear.
“Since we have not observed the stochastic background, some of these early-universe models that predict a relatively large stochastic background have been ruled out,” said Mandic. “If cosmic strings or superstrings exist, their properties must conform with the measurements we made—that is, their properties, such as string tension, are more constrained than before.”
This is interesting, he says, “because such strings could also be so-called fundamental strings, appearing in string-theory models. So our measurement also offers a way of probing string-theory models, which is very rare today.”
The analysis used data collected from the LIGO interferometers in Hanford, Wash., and Livingston, La. Each of the L-shaped interferometers uses a laser split into two beams that travel back and forth down long interferometer arms. The two beams are used to monitor the difference between the two interferometer arm lengths.
The next phase of the project, called Advanced LIGO, will go online in 2014, and be 10 times more sensitive than the current instrument. It will allow scientists to detect cataclysmic events such as black-hole and neutron-star collisions at 10-times-greater distances.
The Nature paper is entitled “An Upper Limit on the Amplitude of Stochastic Gravitational-Wave Background of Cosmological Origin.”
When it comes to universes, perhaps one is enough after all.
Many theories in physics and cosmology require the existence of alternate, or parallel, universes. But Dr. Lee Smolin of the Perimeter Institute for Theoretical Physics in Waterloo, Canada, explains the flaws of theories that suggest our universe is just one of many, and which also perpetuate the notion that time does not exist. Smolin, author of the bestselling science book ‘The Trouble with Physics’ and a founding member of the Perimeter Institute, explains his views in the June issue of Physics World.
Smolin explains how theories describing a myriad of possible universes, or a “multiverse”, with many dimensions and particles and forces have become more popular in the last few years. However, through his work with the Brazilian philosopher Roberto Mangabeira Unger, Smolin believes that multiverse theories, which imply that time is not a fundamental concept, are “profoundly mistaken”.
Smolin says a timeless multiverse means our laws of physics can’t be determined from experiment. And he explains the unclear connection between fundamental laws, which are unique and applicable universally, and effective laws, which hold based on what we can actually observe.
Smolin suggests new principles that rethink the notion of physical law to apply to a single universe. These principles say there is only one universe; that all that is real is real in a moment, as part of a succession of moments; and that everything real in each moment is a process of change leading to future moments. As he explains, “If there is just one universe, there is no reason for a separation into laws and initial conditions, as we want a law to explain just one history of one universe.”
He hopes these principles will bring a fresh adventure in science.
If we accept there is only one universe and that time is a fundamental property of nature, then this opens up the possibility that the laws of physics evolve with time. As Smolin writes, “The notion of transcending our time-bound experiences in order to discover truths that hold timelessly is an unrealizable fantasy. When science succeeds, we do nothing of the sort; what we physicists really do is discover laws that hold in the universe we experience within time. This, I would claim, should be enough; anything beyond that is more a religious urge for transcendence than science.”
The warm colors in this diagram stand for strong correlations of the brightness ratios between two wavelengths and a Type Ia supernova's absolute magnitude. (Diagram colors are unrelated to those in the spectrum itself.) Wavelengths are in nanometers. The upper left triangle shows correlations with uncorrected magnitudes; at lower right are correlations using color-corrected data. Credit: Nearby Supernova Factory
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Cosmologists have found a new and quicker technique that establishes the intrinsic brightness of Type Ia supernovae more accurately than ever before. These exploding stars are the best standard candles for measuring cosmic distances and are the tools that made the discovery of dark energy possible. An international team has found a way to do the job of measuring stellar distances in just a single night as opposed to months of observations by simply measuring the ratio of the flux (visible power, or brightness) between two specific regions in the spectrum of a Type Ia supernova. With this new method, a supernova’s distance can be determined to better than 6 percent uncertainty.
Using classic methods, which are based on a supernova’s color and the shape of its light curve – the time it takes to reach maximum brightness and then fade away – the distance to Type Ia supernovae can be measured with a typical uncertainty of 8 to 10 percent. But obtaining a light curve takes up to two months of high-precision observations. The new method provides better correction with a single night’s full spectrum, which can be scheduled based on a much less precise light curve.
Members of the international Nearby Supernova Factory (SNfactory), a collaboration among the U.S. Department of Energy’s Lawrence Berkeley National Laboratory, a consortium of French laboratories, and Yale University, searched the spectra of 58 Type Ia supernovae in the SNfactory’s dataset and found the key spectroscopic ratio.
The new brightness-ratio correction appears to hold no matter what the supernova’s age or metallicity (mix of elements), its type of host galaxy, or how much it has been dimmed by intervening dust.
Team member Stephen Bailey from the Laboratory of Nuclear and High-Energy Physics (LPNHE) in Paris, France, says that the SNfactory’s library of high-quality spectra is what made his successful results possible. “Every supernova image the SNfactory takes is a full spectrum,” he says. “Our dataset is by far the world’s largest collection of excellent Type Ia time series, totaling some 2,500 spectra.”
The most accurate standardization factor Bailey found was the ratio between the 642-nanometer wavelength, in the red-orange part of the spectrum, and the 443-nanometer wavelength, in the blue-purple part of the spectrum. In his analysis he made no assumptions about the possible physical significance of the spectral features. Nevertheless he turned up multiple brightness ratios that were able to improve standardization over current methods applied to the same supernovae.
SNfactory member Rollin Thomas of Berkeley Lab’s Computational Research Division, who analyzes the physics of supernovae, says, “While the luminosity of a Type Ia supernova indeed depends on its physical features, it also depends on intervening dust. The 642/443 ratio somehow aligns those two factors, and it’s not the only ratio that does. It’s as if the supernova were telling us how to measure it.”
The Nearby Supernova Factory describes the discovery of the new standardization technique in an article in the forthcoming issue of the journal Astronomy & Astrophysics, and the abstract is available online.
The name “dark energy” is just a placeholder for the force — whatever it is — that is causing the Universe to expand. But astronomers are perhaps getting closer to understanding this force. New observations of several Cepheid variable stars by the Hubble Space Telescope has refined the measurement of the Universe’s present expansion rate to a precision where the error is smaller than five percent. The new value for the expansion rate, known as the Hubble constant, or H0 (after Edwin Hubble who first measured the expansion of the universe nearly a century ago), is 74.2 kilometers per second per megaparsec (error margin of ± 3.6). The results agree closely with an earlier measurement gleaned from Hubble of 72 ± 8 km/sec/megaparsec, but are now more than twice as precise.
The Hubble measurement, conducted by the SHOES (Supernova H0 for the Equation of State) Team and led by Adam Riess, of the Space Telescope Science Institute and the Johns Hopkins University, uses a number of refinements to streamline and strengthen the construction of a cosmic “distance ladder,” a billion light-years in length, that astronomers use to determine the universe’s expansion rate.
Hubble observations of the pulsating Cepheid variables in a nearby cosmic mile marker, the galaxy NGC 4258, and in the host galaxies of recent supernovae, directly link these distance indicators. The use of Hubble to bridge these rungs in the ladder eliminated the systematic errors that are almost unavoidably introduced by comparing measurements from different telescopes. Steps to the Hubble Constant. Credit: NASA, ESA, and A. Feild (STScI)
Riess explains the new technique: “It’s like measuring a building with a long tape measure instead of moving a yard stick end over end. You avoid compounding the little errors you make every time you move the yardstick. The higher the building, the greater the error.”
Lucas Macri, professor of physics and astronomy at Texas A&M, and a significant contributor to the results, said, “Cepheids are the backbone of the distance ladder because their pulsation periods, which are easily observed, correlate directly with their luminosities. Another refinement of our ladder is the fact that we have observed the Cepheids in the near-infrared parts of the electromagnetic spectrum where these variable stars are better distance indicators than at optical wavelengths.”
This new, more precise value of the Hubble constant was used to test and constrain the properties of dark energy, the form of energy that produces a repulsive force in space, which is causing the expansion rate of the universe to accelerate.
By bracketing the expansion history of the universe between today and when the universe was only approximately 380,000 years old, the astronomers were able to place limits on the nature of the dark energy that is causing the expansion to speed up. (The measurement for the far, early universe is derived from fluctuations in the cosmic microwave background, as resolved by NASA’s Wilkinson Microwave Anisotropy Probe, WMAP, in 2003.)
Their result is consistent with the simplest interpretation of dark energy: that it is mathematically equivalent to Albert Einstein’s hypothesized cosmological constant, introduced a century ago to push on the fabric of space and prevent the universe from collapsing under the pull of gravity. (Einstein, however, removed the constant once the expansion of the universe was discovered by Edwin Hubble.) Detail from NGC 3021. Credit: NASA, ESA, and A. Riess (STScI/JHU)
“If you put in a box all the ways that dark energy might differ from the cosmological constant, that box would now be three times smaller,” says Riess. “That’s progress, but we still have a long way to go to pin down the nature of dark energy.”
Though the cosmological constant was conceived of long ago, observational evidence for dark energy didn’t come along until 11 years ago, when two studies, one led by Riess and Brian Schmidt of Mount Stromlo Observatory, and the other by Saul Perlmutter of Lawrence Berkeley National Laboratory, discovered dark energy independently, in part with Hubble observations. Since then astronomers have been pursuing observations to better characterize dark energy.
Riess’s approach to narrowing alternative explanations for dark energy—whether it is a static cosmological constant or a dynamical field (like the repulsive force that drove inflation after the big bang)—is to further refine measurements of the universe’s expansion history.
Before Hubble was launched in 1990, the estimates of the Hubble constant varied by a factor of two. In the late 1990s the Hubble Space Telescope Key Project on the Extragalactic Distance Scale refined the value of the Hubble constant to an error of only about ten percent. This was accomplished by observing Cepheid variables at optical wavelengths out to greater distances than obtained previously and comparing those to similar measurements from ground-based telescopes.
The SHOES team used Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS) and the Advanced Camera for Surveys (ACS) to observe 240 Cepheid variable stars across seven galaxies. One of these galaxies was NGC 4258, whose distance was very accurately determined through observations with radio telescopes. The other six galaxies recently hosted Type Ia supernovae that are reliable distance indicators for even farther measurements in the universe. Type Ia supernovae all explode with nearly the same amount of energy and therefore have almost the same intrinsic brightness.
By observing Cepheids with very similar properties at near-infrared wavelengths in all seven galaxies, and using the same telescope and instrument, the team was able to more precisely calibrate the luminosity of supernovae. With Hubble’s powerful capabilities, the team was able to sidestep some of the shakiest rungs along the previous distance ladder involving uncertainties in the behavior of Cepheids.
Riess would eventually like to see the Hubble constant refined to a value with an error of no more than one percent, to put even tighter constraints on solutions to dark energy.
NICMOS Image of the GOODS North field. Credit: C Conselice, A Bluck, GOODS NICMOS Team.
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A new survey is revealing how the most massive galaxies formed in the early Universe, and the findings support the theory that Cold Dark Matter played a role. A team of scientists from six countries used the NICMOS near infrared camera on the Hubble Space Telescope to carry out the deepest ever survey of its type at near infrared wavelengths. Early results show that the most massive galaxies, which have masses roughly 10 times larger than the Milky Way, were involved in significant levels of galaxy mergers and interactions when the Universe was just 2-3 billion years old.
“As almost all of these massive galaxies are invisible in the optical wavelengths, this is the first time that most of them have been observed,” said Dr. Chris Conselice, who is the Principal Investigator for the survey. “To assess the level of interaction and mergers between the massive galaxies, we searched for galaxies in pairs, close enough to each other to merge within a given time-scale. While the galaxies are very massive and at first sight may appear fully formed, the results show that they have experienced an average of two significant merging events during their life-times.”
The results show that these galaxies did not form in a simple collapse in the early universe, but that their formation is more gradual over the course of the Universe’s evolution, taking about 5 billion years. NICMOS image of merging galaxies. Credit: C Conselice, A Bluck, GOODS NICMOS Team
“The findings support a basic prediction of the dominant model of the Universe, known as Cold Dark Matter,” said Conselice, “so they reveal not only how the most massive galaxies are forming, but also that the model that’s been developed to describe the Universe, based on the distribution of galaxies that we’ve observed overall, applies in its basic form to galaxy formation.”
The Cold Dark Matter theory is a refinement of the Big Bang theory, which includes the assumption that most of the matter in the Universe consists of material that cannot be observed by its electromagnetic radiation and hence is dark matter, while at the same time the particles making up this matter are slow and are thereforer cold.
The preliminary results are based on a paper led by PhD student Asa Bluck at the University of Nottingham, and were presented this week at the European Week of Astronomy and Space Science at the University of Hertfordshire.
The observations are part of the Great Observatories Origins Deep Survey (GOODS), a campaign that is using NASA’s Spitzer, Hubble and Chandra space telescopes together with ESA’s XMM Newton X-ray observatory to study the most distant Universe.
On April 7th, commands were sent to NASA’s exoplanet-hunting Kepler telescope to eject the 1.3×1.7 metre lens cap so the unprecedented mission could begin its hunt for Earth-like alien worlds orbiting distant stars. However, one UK astronomer won’t be using the Kepler data to detect the faint transits of rocky exoplanets in front of their host stars. He’ll be using it to monitor the light from a special class of variable star, and through the extreme precision of Kepler’s optics he will be joining an international team of collaborators to redefine the size of the Universe…
Kepler is carrying the largest camera ever launched into space. The camera has 42 charge-coupled devices (CCDs) to monitor the very slight changes in star brightness as an exoplanet passes in front of its host star. Considering the fact that it is hoped Kepler will detect exoplanets a little larger than our planet (known as super-Earths), the instrument is extremely sensitive. It is for this reason that not only exoplanet hunters are interested in using Kepler’s sensitive eye.
Using Kepler data, Dr Alan Penny, a researcher at the University of St Andrews will be joining a 200-strong team of astronomers to analyse the light not emitted from exoplanet-harbouring stars, but from a smaller group of variable stars that fluctuate in brightness with striking regularity and precision. These stars are Cepheid variables, also known as “standard candles” as they can be relied upon for their strong correlation between period of variability and absolute luminosity. This means that no matter where Cepheids are observed in galaxies or clusters, astronomers can always deduce the distance from the Earth to the Cepheid with great precision. The only thing limiting astronomers is the precision that can be attained by instrumentation, so when Kepler left Earth, carrying the most advanced and sensitive camera ever to be taken into space, Penny and his collaborators jumped at the chance to use Kepler to refine the measurement of the Universe.
“While Kepler is doing its exciting planet-hunting, we will be using its extreme precision to resolve a possible problem with our measurement of the size of the Universe,” said Penny. “These variable stars known as ‘Cepheids’ form the base of a series of steps by which we measure the distance to distant galaxies and, through them, we can measure the size of the Universe.”
Current estimates place the size of the Universe at 93 billion light years across, but Penny believes Kepler observations of a small selection of Cepheids may change this value by a few percent. When precision observations of a very precise stellar period-brightness relationship, it’s nice to be able to use the most precise instrument you can lay your hands on. However, our understanding of the “standard candles” themselves is very poor, and small-scale, dynamic changes on the star itself can go unnoticed on the ground. Kepler should shed some light on gaps in our knowledge of Cepheids as well as give us the best-yet measurement of the scale of our Universe.
“These Cepheid stars which get brighter and fainter by some tens of percent every ten to a hundred days are mostly understood. But recently it has become clear that our theories of what happens in the outer layers of these stars which cause the variations in brightness do not totally agree with what we see. The exquisite accuracy of Kepler in measuring star brightness, one hundred times better than we can do from the ground, means we can get such good measurements that we should be able to match theory with observation. Resolving the issue may only change estimates of the size of the Universe by a small amount, but we won’t rest easy until the problem is solved.” — Dr Alan Penny
The South Pole Telescope under the aurora australis (southern lights). Photo by Keith Vanderlinde
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During the next decade, cosmologists will attempt to observe the first moments of the Universe, hoping to prove a popular theory. They’ll be searching for extremely weak gravity waves to measure primordial light, looking for convincing evidence for the Cosmic Inflation Theory, which proposes that a random, microscopic density fluctuation in the fabric of space and time gave birth to the Universe in a hot big bang approximately 13.7 billion years ago. A new instrument called a polarimeter is being attached to the South Pole Telescope (SPT), which operates at submillimeter wavelengths, between microwaves and the infrared on the electromagnetic spectrum. Einstein’s theory of general relativity predicts that Cosmic Inflation should produce the weak gravity waves.
Inflation Theory proposes a period of extremely rapid and exponential expansion of the Universe during its first few moments prior to the more gradual Big Bang expansion, during which time the energy density of the universe was dominated by a cosmological constant-type of vacuum energy that later decayed to produce the matter and radiation that fill the Universe today.
In 1979, physicist Alan Guth proposed the Cosmic Inflation Theory, which also predicts the existence of an infinite number of universes. Unfortunately, cosmologists have no way of testing that particular prediction. The South Pole Telescope takes advantage of the clear, dry skies at the National Science Foundation’s South Pole Station to study the cosmic background radiation, the afterglow of the big bang. The SPT measures eight meters (26.4 feet) in diameter. Photo by Jeff McMahon
“Since these are separate universes, by definition that means we can never have any contact with them. Nothing that happens there has any impact on us,” said Scott Dodelson, a scientist at Fermi National Accelerator Laboratory and a Professor in Astronomy & Astrophysics at the University of Chicago.
But there is a way to probe the validity of cosmic inflation. The phenomenon would have produced two classes of perturbations. The first, fluctuations in the density of subatomic particles happen continuously throughout the universe, and scientists have already observed them.
“Usually they’re just taking place on the atomic scale. We never even notice them,” Dodelson said. But inflation would instantaneously stretch these perturbations into cosmic proportions. “That picture actually works. We can calculate what those perturbations should look like, and it turns out they are exactly right to produce the galaxies we see in the universe.”
The second class of perturbations would be gravity waves—Einsteinian distortions in space and time. Gravity waves also would get promoted to cosmic proportions, perhaps even strong enough for cosmologists to detect them with sensitive telescopes tuned to the proper frequency of electromagnetic radiation.
If the new polarimeter is sensitive enough, scientists should be able to detect the waves.
“If you detect gravity waves, it tells you a whole lot about inflation for our universe,” said John Carlstrom from the University of Chicago, who developed the new instrument. Carlstrom said detecting the waves would rule out various competing ideas for the origin of the universe. “There are fewer than there used to be, but they don’t predict that you have such an extreme, hot big bang, this quantum fluctuation, to start with,” he said. Nor would they produce gravity waves at detectable levels.
A simulation at this link portrays the distortions in space and time at the subatomic scale, the result of quantum fluctuations occurring continuously throughout the universe. Near the end of the simulation, cosmic inflation begins to stretch space-time to the cosmic proportions of the universe.
Cosmologists also use the SPT in their quest to solve the mystery of dark energy. A repulsive force, dark energy pushes the universe apart and overwhelms gravity, the attractive force exerted by all matter.
Dark energy is invisible, but astronomers are able to see its influence on clusters of galaxies that formed within the last few billion years. NASA’s Wilkinson Microwave Anisotropy Probe collected data that produced this chart of sound waves from the universe. Called a power spectrum, the chart plots the cosmic microwave background radiation as ripples of different sizes across the sky. The data are consistent with predictions of cosmic inflation theory. Courtesy of the WMAP Science Team
The SPT detects the cosmic microwave background (CMB) radiation, the afterglow of the big bang. Cosmologists have mined a fortune of data from the CMB, which represent the forceful drums and horns of the cosmic symphony. But now the scientific community has its ears cocked for the tones of a subtler instrument—gravitational waves—that underlay the CMB.
“We have these key components to our picture of the universe, but we really don’t know what physics produces any of them,” said Dodelson of inflation, dark energy and the equally mysterious dark matter. “The goal of the next decade is to identify the physics.”
The Universe 590 million years after the Big Bang. Credit: Alvaro Orsi, Institute for Computational Cosmology, Durham University.
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What did the Universe look like early in its history, only 500 million years after the Big Bang? Currently, we have no way of actually “looking” back that far with our telescopes, but cosmologists from Durham University in the UK have used a computer simulation to predict how the very early Universe would have appeared. The images portray the “Cosmic Dawn,” and calculate the formation of the first big galaxies. The simulation also attempts to discern the role that dark matter played in galaxy formation. “We are effectively looking back in time and by doing so we hope to learn how galaxies like our own were made and to understand more about dark matter,” said Alvaro Orsi, lead author of the study from Durham University’s Institute for Computational Cosmology (ICC). “The presence of dark matter is the key to building galaxies – without dark matter we wouldn’t be here today.”
In the images produced by the computer simulation, the green swirls represent dark matter, which the scientists say is an essential ingredient in galaxy formation, while the circles show the star formation rate in galaxies. The different color circles represent the varying luminosity of star formation with yellow being brightest. The top image portrays the Universe as it was 590 million years after the Big Bang, and the image below shows the Universe 1 billion years after the Big Bang, as star formation rates begin to ramp up. The Universe 1 billion years after the Big Bang. Credit: Alvaro Orsi, Institute for Computational Cosmology, Durham University.
The very first galaxies were created from the debris of massive stars which died explosively shortly after the beginning of the Universe. The Durham calculation predicts where these galaxies appear and how they evolve to the present day, over 13 billion years later. Although the galaxies today are bigger, they are not forming stars as quickly now as they were in the past. “Our research predicts which galaxies are growing through the formation of stars at different times in the history of the Universe and how these relate to the dark matter,” said co-author Dr. Carlton Baugh. “We give the computer what we think is the recipe for galaxy formation and we see what is produced which is then tested against observations of real galaxies.”
The massive simulation shows how structures grow in dark matter with a model showing how normal matter, such as gas, behaves to predict how galaxies grow. Gas feels the pull of gravity from dark matter and is heated up before cooling by releasing radiation and turning into stars. The simulation images show which galaxies are forming stars most vigorously at a given time. The image below shows the Universe 1.9 billion years after the Big Bang, a very active time of star formations in galaxies. The Universe 1.9 billion years after the Big Bang. Credit: Alvaro Orsi, Institute for Computational Cosmology, Durham University.
The calculations of the Durham team, supported by scientists at the Universidad Catolica in Santiago, Chile, can be tested against new observations reaching back to early stages in the history of the Universe almost one billion years after the Big Bang. Professor Keith Mason, Chief Executive of the Science and Technology Facilities Council, said: “Computational cosmology plays an important part in our understanding of the Universe. Not only do these simulations allow us to look back in time to the early Universe but they complement the work and observations of our astronomers.”
This image shows the Universe today, 13.6 billion years after the Big Bang. Galaxies are not forming stars as quickly now as they were in the past. The Universe today. Credit: Alvaro Orsi, Institute for Computational Cosmology, Durham University.
The team hopes that further study and simulations of effects of dark matter on galaxies will help astronomers learn more about what this ubiquitous substance is.
