Universe Today » Cosmology

Early Galaxy Pinpoints Reionization Era

Nancy Atkinson — Fri, 06 Nov 2009 19:17:46 +0000

Astronomers looking to pinpoint when the reionozation of the Universe took place have found some of the earliest galaxies about 800 million years after the Big Bang. 22 early galaxies were found using a method that looks for far-away redshifting sources that disappear or "drop-out" at a specific wavelength. The age of one galaxy was confirmed by a characteristic neutral hydrogen signature at 787 million years after the Big Bang. The finding is the first age-confirmation of a so-called dropout galaxy at that distant time and pinpoints when the reionization epoch likely began.
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New CMB Measurements Support Standard Model

Nicholos Wethington — Wed, 04 Nov 2009 15:31:10 +0000

New measurements of the cosmic microwave background (CMB) – the leftover light from the Big Bang – lend further support the Standard Cosmological Model and the existence of dark matter and dark energy, limiting the possibility of alternative models of the Universe. Researchers from Stanford University and Cardiff University produced a detailed map of the composition and structure of matter as it would have looked shortly after the Big Bang, which shows that the Universe would not look as it does today if it were made up solely of 'normal matter'.(...)
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If We Live in a Multiverse, How Many Are There?

Nancy Atkinson — Thu, 15 Oct 2009 15:12:08 +0000

Theoretical physics has brought us the notion that our single universe is not necessarily the only game in town. Satellite data from WMAP, along with string theory and its 11- dimensional hyperspace idea has produced the concept of the multiverse, where the Big Bang could have produced many different universes instead of a single uniform universe. The idea has gained popularity recently, so it was only a matter of time until someone asked the question of how many multiverses could possibly exist. The number, according to two physicists, could be "humongous."
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Planck First Light

Nancy Atkinson — Thu, 17 Sep 2009 14:03:39 +0000

Strips of the sky measured by Planck. Credit: ESA

One of the newest telescopes in space, the Planck spacecraft, recently completed its "first light" survey which began on August 13. Astronomers say the initial data, gathered from Planck's vantage point at the L2 point in space, is excellent. Planck is studying the Cosmic Microwave Background, looking for variations in temperature that are about a million times smaller than one degree. This is comparable to measuring from Earth the body heat of a rabbit sitting on the Moon.
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What! No Parallel Universe? Cosmic Cold Spot Just Data Artifact

Nancy Atkinson — Wed, 16 Sep 2009 14:18:27 +0000

Rats! Another perplexing space mystery solved by science. New analysis of the famous "cold spot" in the cosmic microwave background reveals, and confirms, actually, that the spot is just an artifact of the statistical methods used to find it. That means there is no supervoid lurking in the CMB, and no parallel universe lying just beyond the edge of our own. What fun is that?
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Post tags: CMB, Cold Spot, Cosmology, WMAP

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The Big Bang Writ Little

Nancy Atkinson — Fri, 11 Sep 2009 14:26:28 +0000

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:

@newscientist < ∞ #sci140 yanikproulx

A fun exercise in brevity.

Here's the rest of their top 10:

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New Way to Measure Curvature of Space Could Unite Gravity Theory

Nancy Atkinson — Tue, 01 Sep 2009 23:10:10 +0000

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.
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New Limits on Gravitational Waves From the Big Bang

Nancy Atkinson — Wed, 19 Aug 2009 18:48:30 +0000

Artists concept of graviational waves. Credit: NASA

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.
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What If There Is Only One Universe?

Brian Ventrudo — Thu, 04 Jun 2009 23:28:24 +0000

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.

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Cosmologists Improve on Standard Candles Measurement

Nancy Atkinson — Tue, 19 May 2009 16:55:22 +0000

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.
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Astronomers Closing in on Dark Energy with Refined Hubble Constant

Nancy Atkinson — Thu, 07 May 2009 14:39:32 +0000

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.
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New Hubble Survey Supports Cold Dark Matter in Early Universe

Nancy Atkinson — Thu, 23 Apr 2009 20:09:35 +0000

NICMOS Image of the GOODS North field. Credit: C Conselice, A Bluck, GOODS NICMOS Team.

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.
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Kepler Will Be Used to Measure the Size of the Universe

Ian O'Neill — Tue, 14 Apr 2009 10:30:59 +0000

Artist's rendering of the Kepler Mission (NASA)

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…
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Cosmologists Search for Gravity Waves to Prove Inflation Theory

Nancy Atkinson — Mon, 16 Feb 2009 15:19:35 +0000

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.
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Cosmologists Look Back to Cosmic Dawn

Nancy Atkinson — Wed, 11 Feb 2009 01:49:35 +0000

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."
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Next-Generation Telescope Gets Team

Anne Minard — Sun, 08 Feb 2009 02:26:58 +0000

Astronomy organizations in the United States, Australia and Korea have signed on to build the largest ground-based telescope in the world – unless another team gets there first. The Giant Magellan Telescope, or GMT, will have the resolving power of a single 24.5-meter (80-foot) primary mirror, which will make it three times more powerful than any of the Earth's existing ground-based optical telescopes. Its domestic partners include the Carnegie Institution for Science, Harvard University, the Smithsonian Institution, Texas A & M University, the University of Arizona, and the University of Texas at Austin. Although the telescope has been in the works since 2003, the formal collaboration was announced Friday.
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Space Telescope of the Future: SIM

Nancy Atkinson — Tue, 20 Jan 2009 14:52:57 +0000

Artist's concept of the current mission configuration. Credit: JPL

Two of the hottest and most engaging topics in space and astronomy these days are 1.) exoplanets – planets orbiting other stars – and 2.) dark matter—that unknown stuff that seemingly makes up a considerable portion of our universe. There's a spacecraft currently in development that could help answer our questions about whether there really are other Earth-like planets out there, as well as provide clues to the nature of dark matter. The spacecraft is called SIM – the Space Interferometry Mission. "We'll be looking for other Earths around other stars," said Stephen Edberg, System Scientist for the mission, "and by making accurate mass measurements of galaxies, we should be able to measure dark matter, as well."

Listen to the January 20, 2009 "365 Days of Astronomy" Podcast and my interview with Steve Edberg, and/or read more about the SIM Lite mission below!
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Profiling Potential Supernovae

Nancy Atkinson — Mon, 12 Jan 2009 21:19:05 +0000

Just as psychologists and detectives try to "profile" serial killers and other criminals, astronomers are trying to determine what type of star system will explode as a supernova. While criminals can sometimes be caught or rehabilitated before they do the crime, supernovae, well, there's no stopping them. But there's the potential of learning a great deal in both astronomy and cosmology by theorizing about potential stellar explosions. At the American Astronomical Society meeting last week, Professor Bradley E. Schaefer of Louisiana State University, Baton Rouge, discussed how searching through old astronomical archives can produce unique and front-line science about supernovae – as well as providing information about dark energy — in ways that no combination of modern telescopes can provide. Additionally, Schaefer said amateur astronomers can help in the search, too.
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Did Dark Matter Power Early Stars?

Nancy Atkinson — Fri, 02 Jan 2009 23:41:48 +0000

The first stars to light the early universe may have been powered by dark matter, according to a new study. Researchers from the University of Michigan, Ann Arbor call these very first stars "Dark Stars," and propose that dark matter heating provided the energy for these stars instead of fusion. The researchers propose that with a high concentration of dark matter in the early Universe, the theoretical particles called Weakly Interacting Massive Particles(WIMPs), collected inside the first stars and annihilated themselves to produce a heat source to power the stars. "We studied the behavior of WIMPs in the first stars," said Katherine Freese and her team in their paper, "and found that they can radically alter the stellar evolution. The annihilation products of the dark matter inside the star can be trapped and deposit enough energy to heat the star and prevent it from further collapse."
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More Evidence Earth is Not Center of Universe

Nancy Atkinson — Wed, 31 Dec 2008 22:58:52 +0000

If you're certain the Universe revolves around you, I have some bad news for you. Researchers from the University of British Columbia say Earth's location in the Universe is utterly unremarkable, despite recent theories that propose Earth is at the center of a giant void in space. A decade ago, it was discovered the Universe's expansion was accelerating. This continually expanding Universe was attributed to dark energy, the highly repulsive and mysterious stuff that has yet to be detected. But some scientists came up with an alternate theory where Earth was near the centre of a giant void or bubble, mostly empty of matter. But new calculations solidify the case that dark energy permeates the cosmos.
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More Thoughts (and now math!) On What Came Before the Big Bang

Nancy Atkinson — Wed, 17 Dec 2008 01:05:30 +0000

CMB Timeline. Credit: NASA

Physicist Sean Carroll gave a wonderful talk at the June 2008 American Astronomical Society meeting about his "speculative research" on what possibly could have existed before The Big Bang. (Here's an article about Carroll's talk.) But now Carroll and some colleagues have done a bit more than just speculate about what might have come before the beginning of our Universe. Carroll, along with Caltech professor Marc Kamionkowski and graduate student Adrienne Erickcek have created a mathematical model to explain an anomaly in the early universe, and it also may shed light on what existed before the Big Bang. "It's no longer completely crazy to ask what happened before the Big Bang," said Kamionkowski.
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Chandra Telescope Searches for Antimatter

Nancy Atkinson — Fri, 31 Oct 2008 23:34:14 +0000

The Bullet Cluster. Credit: X-ray: NASA/CXC/CfA/M.Markevitch et al.; Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al.

Say the word "antimatter" and immediately people think of science fiction – anti-universes, fuel for the Enterprise's warp-speed engines and so forth. But Captain, we can't change the laws of physics; antimatter is the real deal. Antimatter is made up of elementary particles, each of which has the same mass as their corresponding matter counterparts –protons, neutrons and electrons — but the opposite charges and magnetic properties. When matter and antimatter particles collide, they annihilate each other and produce energy according to Einstein's famous equation, E=mc2. But antimatter isn't something that's available on every corner drugstore (and neither is plutonium, to continue with the movie theme) and there's not very much of it around, so it seems. But, according to theory, it wasn't always that way, and scientists are using the Chandra X-ray Observatory to hunt for evidence of antimatter that was present in the very early universe. And it's not an easy job…
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Hawking to Retire, But Not Quit

Nancy Atkinson — Tue, 28 Oct 2008 01:58:59 +0000

Cosmologist Stephen Hawking will retire from his post at Cambridge University next year, but he still intends to continue his exploration of time and space. University policy is that officeholders must retire at the end of the academic year in which they become 67. Hawking will reach that age on Jan. 8, 2009. Hawking is the Lucasian Professor of Mathematics at the university, a title once held Isaac Newton. The university said on Friday that he would step down at the end of the academic year in September, but would continue working as Emeritus Lucasian Professor of Mathematics. Hawking became a scientific celebrity through his theories on black holes and the nature of time, work that he carried on despite becoming severely disabled by amyotrophic lateral sclerosis, or ALS.
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Scientists Detect "Dark Flow:" Matter From Beyond the Visible Universe

Nancy Atkinson — Tue, 23 Sep 2008 16:08:03 +0000

Just as unseen dark energy is increasing the rate of expansion of the universe, there's something else out there causing an unexpected motion in distant galaxy clusters. Scientists believe the cause is the gravitational attraction of matter that lies beyond the observable universe, and they are calling it "Dark Flow," in the vein of two other cosmological mysteries, dark matter and dark energy. "The clusters show a small but measurable velocity that is independent of the universe's expansion and does not change as distances increase," said lead researcher Alexander Kashlinsky at NASA's Goddard Space Flight Center in Greenbelt, Md. "The distribution of matter in the observed universe cannot account for this motion."

"We never expected to find anything like this," he said.
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Ten Mysteries of the Solar System

Ian O'Neill — Mon, 18 Aug 2008 23:42:14 +0000

We've all wondered at some point or another what mysteries our Solar System holds. After all, the eight planets (plus Pluto and all those other dwarf planets) orbit within a very small volume of the heliosphere (the volume of space dominated by the influence of the Sun), what's going on in the rest of the volume we call our home? As we push more robots into space, improve our observational capabilities and begin to experience space for ourselves, we learn more and more about the nature of where we come from and how the planets have evolved. But even with our advancing knowledge, we would be naive to think we have all the answers, so much still needs to be uncovered. So, from a personal point of view, what would I consider to be the greatest mysteries within our Solar System? Well, I'm going to tell you my top ten favourites of some more perplexing conundrums our Solar System has thrown at us. So, to get the ball rolling, I'll start in the middle, with the Sun. (None of the following can be explained by dark matter, in case you were wondering… actually it might, but only a little…)
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