Space and astronomy news
One of the greatest mysteries is how the Universe began — and also how and why does it appear to be ever-expanding? CERN physicist Tom Whyntie shows how cosmologists and particle physicists are exploring these questions by replicating the heat, energy, and activity of the first few seconds of our Universe, from right after the Big Bang.
Today, we see an unobstructed view of the cosmos in all directions. But, a time existed near the Big Bang when the space between galaxies was an opaque fog where nothing could be seen. And according to two University of Michigan researchers, rare Green Pea galaxies, discovered in 2007, could offer clues into a pivotal step, called reionization, in the Universe’s evolution when space became transparent.
Reionization occurred just a few million years after the Big Bang. During this time, the first stars were beginning to blaze forth and galaxies. Astronomers believe these massive stars blasted the early universe with high-energy ultraviolet light. The UV light interacted with the neutral hydrogen gas it met, scraping off electrons and leaving behind a plasma of negatively charged electrons and positively charged hydrogen ions.
“We think this is what happened but when we looked at galaxies nearby, the high-energy radiation doesn’t appear to make it out. There’s been a push to find some galaxies that show signs of radiation escaping,” Anne Jaskot, a doctoral student in astronomy, says in a press release.
In findings released in the current edition of the Astrophysical Journal, Jaskot and Sally Oey, an associate professor of astronomy, the astronomers focused on six of the most intensely star-forming Green Pea galaxies between one billion and five billion light-years from Earth. The galaxies are compact and closely resemble early galaxies. The objects are thought to be a type of Luminous Blue Compact Galaxy, a type of starburst galaxy where stars are forming at prodigious rates. They were discovered in 2007 by volunteers with the citizen science project Galaxy Zoo. Named “peas” because of their fuzzy green appearance, the galaxies are very small. Scientists estimate that they are no larger than about 16,000 light-years across making them about the size of the Large Magellanic Cloud, a irregular galaxy near our Milky Way Galaxy.
Using data from the Sloan Digital Sky Survey, Jaskot and Oey studied the emission lines from the galaxies to determine how much light was absorbed. Emission lines tell astronomers not only what elements are present in the stars but also much about the intervening space. By studying this interaction, the researchers determined that the galaxies produced more radiation than observed, meaning some must have escaped.
“An analogy might be if you have a tablecloth and you spill something on it. If you see the cloth has been stained all the way to the edges, there’s a good chance it also spilled onto the floor,” Jaskot said. “We’re looking at the gas like the tablecloth and seeing how much light it has absorbed. It has absorbed a lot of light. We’re seeing that the galaxy is saturated with it and there’s probably some extra that spilled off the edges.”
Behind every modern tale of cosmological discovery is the supercomputer that made it possible. Such was the case with the announcement yesterday from the European Space Agencies’ Planck mission team which raised the age estimate for the universe to 13.82 billion years and tweaked the parameters for the amounts dark matter, dark energy and plain old baryonic matter in the universe.
Planck built upon our understanding of the early universe by providing us the most detailed picture yet of the cosmic microwave background (CMB), the “fossil relic” of the Big Bang first discovered by Penzias & Wilson in 1965. Planck’s discoveries built upon the CMB map of the universe observed by the Wilkinson Microwave Anisotropy Probe (WMAP) and serves to further validate the Big Bang theory of cosmology.
But studying the tiny fluctuations in the faint cosmic microwave background isn’t easy, and that’s where Hopper comes in. From its L2 Lagrange vantage point beyond Earth’s Moon, Planck’s 72 onboard detectors observe the sky at 9 separate frequencies, completing a full scan of the sky every six months. This first release of data is the culmination of 15 months worth of observations representing close to a trillion overall samples. Planck records on average of 10,000 samples every second and scans every point in the sky about 1,000 times.
That’s a challenge to analyze, even for a supercomputer. Hopper is a Cray XE6 supercomputer based at the Department of Energy’s National Energy Research Scientific Computing center (NERSC) at the Lawrence Berkeley National Laboratory in California. Named after computer scientist and pioneer Grace Hopper, the supercomputer has a whopping 217 terabytes of memory running across 153,216 computer cores with a peak performance of 1.28 petaflops a second. Hopper placed number five on a November 2010 list of the world’s top supercomputers. (The Tianhe-1A supercomputer at the National Supercomputing Center in Tianjin China was number one at a peak performance of 4.7 petaflops per second).
One of the main challenges for the team sifting through the flood of CMB data generated by Planck was to filter out the “noise” and bias from the detectors themselves.
“It’s like more than just bugs on a windshield that we want to remove to see the light, but a storm of bugs all around us in every direction,” said Planck project scientist Charles Lawrence. To overcome this, Hopper runs simulations of how the sky would appear to Planck under different conditions and compares these simulations against observations to tease out data.
“By scaling up to tens of thousands of processors, we’ve reduced the time it takes to run these calculations from an impossible 1,000 years to a few weeks,” said Berkeley lab and Planck scientist Ted Kisner.
But the Planck mission isn’t the only data that Hopper is involved with. Hopper and NERSC were also involved with last year’s discovery of the final neutrino mixing angle. Hopper is also currently involved with studying wave-plasma interactions, fusion plasmas and more. You can see the projects that NERSC computers are tasked with currently on their site along with CPU core hours used in real time. Maybe a future descendant of Hopper could give Deep Thought of Hitchhiker’s Guide to the Galaxy fame competition in solving the answer to Life, the Universe, and Everything.
Also, a big congrats to Planck and NERSC researchers. Yesterday was a great day to be a cosmologist. At very least, perhaps folks won’t continue to confuse the field with cosmetology… trust us, you don’t want a cosmologist styling your hair!
Hubble mosaic of massive galaxy cluster MACS J0717.5+3745, thought to be connected by a filament of dark matter. Credit: NASA, ESA, Harald Ebeling (University of Hawaii at Manoa) & Jean-Paul Kneib (LAM)
Even though teams of scientists around the world are at this very moment hot on the trail of dark matter — the “other stuff” that the Universe is made of and supposedly accounts for nearly 80% of the mass that we can’t directly observe (yet) — and trying to quantify exactly how so-called “dark energy” drives its ever-accelerating expansion, perhaps one answer to these ongoing mysteries is maybe they don’t exist at all.
This is precisely what one astronomer is suggesting in a recent paper, submitted Dec. 3 to Astrophysical Journal Letters.
In a paper titled “An expanding universe without dark matter and dark energy” (arXiv:1212.1110) Pierre Magain, a professor at Belgium’s Institut d’Astrophysique et de Géophysique, proposes that the expansion of the Universe could be explained without the need for enigmatic material and energy that, to date, has yet to be directly measured.
In addition, Magain’s proposal puts a higher age to the Universe than what’s currently accepted. With a model that shows a slower expansion rate during the early Universe than today, Magain’s calculations estimate its age to be closer to 15.4 – 16.5 billion years old, adding a couple billion more candles to the cosmic birthday cake.
The benefit to a slightly older Universe, Magain posits, is that it’s not so uncannily close to the apparent age of the most distant galaxies recently found — such as MACS0647-JD, which is 13.3 billion light-years away and thus (based on current estimates, see graphic at right) must have formed when the Universe was a mere 420 million years old.
Read more: Now Even Further: Ancient Galaxy is Latest Candidate for Most Distant
Using accepted physics of how time behaves based on Einstein’s theory of general relativity — namely, how the passage of time is relative to the position and velocity of the viewer (as well as the intensity of the gravitational field the viewer is within) — Magain’s model allows for an observer located within the Universe to potentially be experiencing a different rate of time than a hypothetical viewer located outside the Universe. Not to be so metaphysical as to presume that there are external observers of our Universe but merely to say that an external point would be a fixed one against which one could benchmark a varying passage of time inside the Universe, Magain calls this universal relativity.
A viewer experiencing universal relativity would, Magain claims, always measure the curvature of the Universe to be equal to zero. This is what’s currently observed, a “flatness problem” that Magain insinuates is strangely coincidental.
By attributing an expanding Universe to dark energy and the high velocities of stars along the edges of galaxies (as well as the motions of galaxy clusters themselves) to dark matter, we may be introducing ad hoc elements to the Universe, says Magain. Instead, he proposes his “more economical” model — which uses universal relativity — explains these apparently accelerating, increasingly expanding behaviors… and gives a bigger margin of time between the Big Bang and the formation of the first galactic structures.
Read more: First Images in a New Hunt for Dark Energy
There’s quite a bit of math involved, and since I never claimed to understand physics equations you can check out the original paper here.
While intriguing, the bottom line is that dark energy and dark matter have still managed to elude science, existing just outside the borders of what can be observed (although the gravitational lensing effects of what’s thought to be dark matter filaments have been observed by Hubble) and Magain’s paper is merely putting another idea onto the table — one that, while he recognizes needs further testing and relies upon very specific singular parameters, doesn’t depend upon invisible, unobservable and mysteriously dark “stuff”. Whether it belongs on the table or not will be up to other astrophysicists to decide.
Prof. Magain’s research was supported by ESA and the Belgian Science Policy Office.
At right: Artist’s impression of dark matter (h/t to Steve Nerlich)
Note: this is “just” a submitted paper and has not been selected for publication yet. Any hypotheses proposed are those of the author and are not endorsed by this site. (Personally I like dark matter. It’s fascinating stuff… even if we can’t see it. Want an astrophysicist’s viewpoint on the existence of dark matter? Check out Ethan Siegel’s blog response here.)
From the initial expansion of the Big Bang to the birth of the Moon, from the timid scampering of the first mammals to the rise — and fall — of countless civilizations, this fascinating new video by melodysheep (aka John D. Boswell) takes us on a breathless 90-second tour through human history — starting from the literal beginnings of space and time itself. It’s as imaginative and powerful as the most gripping Hollywood trailer… and it’s even inspired by a true story: ours.
Enjoy!
(Video by melodysheep, creator of the Symphony of Science series.)
Albert Einstein’s revolutionary general theory of relativity describes gravity as a curvature in the fabric of spacetime. Mathematicians at University of California, Davis have come up with a new way to crinkle that fabric while pondering shockwaves.
“We show that spacetime cannot be locally flat at a point where two shockwaves collide,” says Blake Temple, professor of mathematics at UC Davis. “This is a new kind of singularity in general relativity.”
Temple and his collaborators study the mathematics of how shockwaves in a perfect fluid affect the curvature of spacetime. Their new models prove that singularities appear at the points where shock waves collide. Vogler’s mathematical models simulated two shockwaves colliding. Reintjes followed up with an analysis of the equations that describe what happens when the shockwaves cross. He dubbed the singularity created a “regularity singularity.”
“What is surprising,” Temple told Universe Today, “is that something as mundane as the interaction of waves could cause something as extreme as a spacetime singularity — albeit a very mild new kind of singularity. Also surprising is that they form in the most fundamental equations of Einstein’s theory of general relativity, the equations for a perfect fluid.”
The results are reported in two papers by Temple with graduate students Moritz Reintjes and Zeke Vogler in the journal Proceedings of the Royal Society A.
Einstein revolutionized modern physics with his general theory of relativity published in 1916. The theory in short describes space as a four-dimensional fabric that can be warped by energy and the flow of energy. Gravity shows itself as a curvature of this fabric. “The theory begins with the assumption that spacetime (a 4-dimensional surface, not 2 dimensional like a sphere), is also “locally flat,” Temple explains. “Reintjes’ theorem proves that at the point of shockwave interaction, it [spacetime] is too “crinkled” to be locally flat.”
We commonly think of a black hole as being a singularity which it is. But this is only part of the explanation. Inside a black hole, the curvature of spacetime becomes so steep and extreme that no energy, not even light, can escape. Temple says that a singularity can be more subtle where just a patch of spacetime cannot be made to look locally flat in any coordinate system.
“Locally flat” refers to space that appears to be flat from a certain perspective. Our view of the Earth from the surface is a good example. Earth looks flat to a sailor in the middle of the ocean. It’s only when we move far from the surface that the curvature of the Earth becomes apparent. Einstein’s theory of general relativity begins with the assumption that spacetime is also locally flat. Shockwaves create an abrupt change, or discontinuity, in the pressure and density of a fluid. This creates a jump in the curvature of spacetime but not enough to create the “crinkling” seen in the team’s models, Temple says.
The coolest part of the finding for Temple is that everything, his earlier work on shockwaves during the Big Bang and the combination of Vogler’s and Reintjes’ work, fits together.
There is so much serendipity,” says Temple. “This is really the coolest part to me.
I like that it is so subtle. And I like that the mathematical field of shockwave theory, created to address problems that had nothing to do with General Relativity, has led us to the discovery of a new kind of spacetime singularity. I think this is a very rare thing, and I’d call it a once in a generation discovery.”
While the model looks good on paper, Temple and his team wonder how the steep gradients in spacetime at a “regularity singularity” could cause larger than expected effects in the real world. General relativity predicts gravity waves might be produced by the collision of massive objects, such as black holes. “We wonder whether an exploding stellar shock wave hitting an imploding shock at the leading edge of a collapse, might stimulate stronger than expected gravity waves,” Temple says. “This cannot happen in spherical symmetry, which our theorem assumes, but in principle it could happen if the symmetry were slightly broken.”
Image caption: Artist rendition of the unfurling of spacetime at the beginning of the Big Bang. John Williams/TerraZoom
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Astronomers from Arizona State University have grabbed an image of a dim, distant galaxy, seeing it as it looked only 800 million years after the birth of the Universe. Visible above as a green blob in the center of a false-color image acquired with the Magellan Telescopes at the Las Campanas Observatory in Chile, the galaxy is seen in its infancy and, at 13 billion light-years away, is one of the ten most distant objects ever discovered.
The galaxy, designated LAEJ095950.99+021219.1, was detected by light emitted by ionized hydrogen using the Magellan Telescopes’ IMACS (Inamori-Magellan Areal Camera & Spectrograph) instrument, built at the Carnegie Institute in Washington. In order to even find such a remote object — whose existence had already been suspected — the team had to use a special narrow-band filter on the IMACS instrument designed to isolate specific wavelengths of light.
“Young galaxies must be observed at infrared wavelengths and this is not easy to do using ground-based telescopes, since the Earth’s atmosphere itself glows and large detectors are hard to make,” said team leader Sangeeta Malhotra, an associate professor at ASU who helped develop the technique.
“As time goes by, these small blobs which are forming stars, they’ll dance around each other, merge with each other and form bigger and bigger galaxies. Somewhere halfway through the age of the universe they start looking like the galaxies we see today – and not before.”
– Sangeeta Malhotra, ASU professor
LAEJ095950.99+021219.1 is seen at a redshift of 7, putting it farther away than any other objects previously discovered using the narrow-band technique.
(What is redshift? Watch “How To Measure The Universe” here.)
“We have used this search to find hundreds of objects at somewhat smaller distances. We have found several hundred galaxies at redshift 4.5, several at redshift 6.5, and now at redshift 7 we have found one,” said James Rhoads, associate professor at ASU and research team leader.
“This image is like a baby picture of this galaxy, taken when the universe was only 5 percent of its current age. Studying these very early galaxies is important because it helps us understand how galaxies form and grow.”
So why does LAEJ095950.99+021219.1 not look much like the galaxies we’re used to seeing in images?
Malhotra explains: “Somewhere halfway through the age of the universe they start looking like the galaxies we see today – and not before. Why, how, when, where that happens is a fairly active area of research.”
The team’s NSF-funded research was published in Astrophysical Journal Letters. Read more on Phys.Org News here.
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Astronomers and students from the University of Minnesota hoping to search for radiation left over from the Big Bang instead spent the past few days looking for their telescope – a 6,000 lb (2729 kg) behemoth of a science experiment. Just how does a telescope that big go missing? You could ask the truck driver who was supposed to deliver it to a NASA facility in Palestine, Texas, but he’s not talking and police in Texas won’t press charges against him. But the good news is that the missing telescope has been found – sitting at a truck wash — after a frantic cross-country search.
The telescope is a high-tech irreplaceable piece of equipment that is 22 ft high 15 ft wide (6.5 X 4.5 meters). It is designed to detect radiation from the Big Bang and it took fifteen people 8 years to build. The telescope will be shipped to Antarctica, where it will be attached to a giant balloon in December and sent 110,000 feet (33,500 meters) into the atmosphere.
Last Friday, a Minnesota trucking company sent off one of their trucks with telescope inside. But by Monday there was no word from the trucker and the scientists started to panic when the truck didn’t show up at the NASA facility. Calls to the trucker went unanswered. The owner of the trucking company sent his son to Dallas to search for the truck and the driver. Their only clue was a credit card charge at a Dallas truck stop.
The son found the driver, asleep in the cab of the truck, but the trailer, with the precious cargo inside, was nowhere to be seen.
The driver said he left the trailer at a hotel parking lot, but when the searchers arrived, it wasn’t there. More searching, and the trucker clammed up and wouldn’t provide any more clues or reasons for why he didn’t deliver his cargo.
Finally another employee of the trucking company found the trailer sitting at a truck wash in Dallas.
“If they would not have found that particular trailer at that time, maybe half a day or a day later someone would have stolen it and taken it for metal or just for scrap,” said physics professor Shaul Hanany, the project’s lead researcher.
NASA unpacked the crate Thursday morning and said the telescope was unharmed and is in great shape.
The owner of the trucking company said sometimes they do have trouble with drivers, but he has never had anything like this happen, especially with such a unique instrument. He wondered, why couldn’t the driver be hauling a load of potato chips instead of something that will solve the mysteries of the Universe?
The driver has been fired, and the telescope will head to Antarctica as planned.
Source: Minnesota Public Radio
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Is there any place in space which hasn’t been affected by time? The answer is yes. Thanks to some very awesome research, the W. M. Keck Observatory and a team of scientists have recently located two clumps of primordial gas which may very well have had its origin within minutes of the Big Bang.
How do we know these gas clouds are so special? In this case, they are simply too disseminated to enable stellar birth and contain no heavy metals which would support it. These diaphanous regions are pure hydrogen and helium… along with a heavier isotope, deuterium. This combination could mean the two billion year old regions are pure – never involved in the star-forming process. An exciting discovery? You bet. The clouds could have possibly survived in an unchanged state – giving us a look at what may have occurred at the dawn of time.
“Despite decades of effort to find anything metal-free in the universe, Nature has previously set a limit to enrichment at no less than one-thousandth that found in the Sun,” said astronomer J. Xavier Prochaska of the University of California Observatories-Lick Observatory, U.C. Santa Cruz. “These clouds are at least 10 times lower than that limit and are the most pristine gas discovered in our universe.”
Prochaska is part of the Keck team and has coauthored a paper reporting on the discovery with Michele Fumagalli of the U.C. Santa Cruz and John O’Meara of Saint Michael’s College in Vermont. “We’ve searched carefully for oxygen, carbon, nitrogen and silicon – the things that are found on Earth and the Sun in abundance,” Fumagalli said. “We don’t find a trace of anything other than hydrogen and deuterium.”
According to the Keck Observatory news release exactly how they can detect dark, cold, diffuse gas about 12 billion light-years away is a story in itself.
“In this case we actually have to do a bit of a trick,” Prochaska explained. “We study the gas in silhouette.” A more distant quasar provides the light for this. The quasar light shines though the gas and the elements in the gas absorb very specific wavelengths of light, which can only be found by splitting the light into very detailed spectra to reveal the dark lines of missing light.
In other words, said Fumagalli, “All of the analysis is on the light we didn’t get.” The clouds absorb only a small fraction of the quasar light that makes it to Earth. “But the signatures of hydrogen absorption are obvious, so there’s no doubt there’s a lot of gas there.”
While some folks might not get excited over the location of immaculate gases, astronomers think differently. This revelation supports their theories of what may have occurred within moments after the Big Bang and what formed at the time of nucleosynthesis. It’s a look back at when hydrogen, helium, lithium and boron originated.
“That theory has been very well tested at Keck as regards to hydrogen and its isotope deuterium,” said O’Meara. “One of the conundrums of that previous work, however, is that the gas also showed at least trace amounts of oxygen and carbon. The clouds that we have discovered are the first to match the full predictions of BBN.”
What’s more, Keck’s two 10-meter optical/infrared telescopes have shown us what the early universe may have been like. This is the very first time that science has been able to peer into regions where no metals have influenced the environment and no stars have formed.
“What excites me about this discovery is that there is an almost a range of 1,000,000 in the metallicity in gases at that time in the universe,” said Fumagalli. In other words, there were places like our Solar system – where metals are very abundant – and there were also places very unlike today, where metals were still virtually non-existent and the gases were unchanged since almost the beginning of time.”
Original Story Source: Keck Observatory News Release. For Further Reading: Detection of Pristine Gas Two Billion Years After the Big Bang.
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Welcome back to the third, and last, installment of Cosmology 101. So far, we’ve covered the history of the universe up to the present moment. But what happens next? How will our universe end? And how can we be so sure that this is how the story unfolded?
Robert Frost once wrote, “Some say the world will end in fire; some say in ice.” Likewise, some scientists have postulated that the universe could die either a dramatic, cataclysmic death – either a “Big Rip” or a “Big Crunch” – or a slower, more gradual “Big Freeze.” The ultimate fate of our cosmos has a lot to do with its shape. If the universe were open, like a saddle, and the energy density of dark energy increased without bound, the expansion rate of the cosmos would eventually become so great that even atoms would be torn apart – a Big Rip. Conversely, if the universe were closed, like a sphere, and gravity’s strength trumped the influence of dark energy, the outward expansion of the cosmos would eventually come to a halt and reverse, collapsing on itself in a Big Crunch.
Despite the poetic beauty of fire, however, current observations favor an icy end to our universe – a Big Freeze. Scientists believe that we live in a spatially flat universe whose expansion is accelerating due to the presence of dark energy; however, the total energy density of the cosmos is most likely less than or equal to the so-called “critical density,” so there will be no Big Rip. Instead, the contents of the universe will eventually drift prohibitively far away from each other and heat and energy exchange will cease. The cosmos will have reached a state of maximum entropy, and no life will be able to survive. Depressing and a bit anti-climactic? Perhaps. But it probably won’t be perceptible until the universe is at least twice its current age.
At this point you might be screaming, “How do we know all this? Isn’t it all just rampant speculation?” Well, first of all, we know without a doubt that the universe is expanding. Astronomical observations consistently demonstrate that light from distant stars is always redshifted relative to us; that is, its wavelength has been stretched due to the expansion of the cosmos. This leads to two possibilities when you wind back the clock: either the expanding universe has always existed and is infinite in age, or it began expanding from a smaller version of itself at a specific time in the past and thus has a fixed age. For a long time, proponents of the Steady State Theory endorsed the former explanation. It wasn’t until Arno Penzias and Robert Wilson discovered the cosmic microwave background in 1965 that the big bang theory became the most accepted explanation for the origin of the universe.
Why? Something as large as our cosmos takes quite a while to cool completely. If the universe did, in fact, began with the kind of blistering energies that the big bang theory predicts, astronomers should still see some leftover heat today. And they do: a uniform 3K glow evenly dispersed at every point in the sky. Not only that – but WMAP and other satellites have observed tiny inhomogeneities in the CMB that precisely match the initial spectrum of quantum fluctuations predicted by the big bang theory.
What else? Take a look at the relative abundances of light elements in the universe. Remember that during the first few minutes of the cosmos’ young life, the ambient temperature was high enough for nuclear fusion to occur. The laws of thermodynamics and the relative density of baryons (i.e. protons and neutrons) together determine exactly how much deuterium (heavy hydrogen), helium and lithium could be formed at this time. As it turns out, there is far more helium (25%!) in our current universe than could be created by nucleosynthesis in the center of stars. Meanwhile, a hot early universe – like the one postulated by the big bang theory – gives rise to the exact proportions of light elements that scientists observe in the universe today.
But wait, there’s more. The distribution of large-scale structure in the universe can be mapped extremely well based solely on observed anisotropies in the CMB. Moreover, today’s large-scale structure looks very different from that at high redshift, implying a dynamic and evolving universe. Additionally, the age of the oldest stars appears to be consistent with the age of the cosmos given by the big bang theory. Like any theory, it has its weaknesses – for instance, the horizon problem or the flatness problem or the problems of dark energy and dark matter; but overall, astronomical observations match the predictions of the big bang theory far more closely than any rival idea. Until that changes, it seems as though the big bang theory is here to stay.