Earth not center of the universe, surrounded by 'dark energy': UBC cosmologistsDecember 19, 2008Earth's location in the Universe is utterly unremarkable, despite recent theories that propose toppling a foundation of modern cosmology, according to a team of University of British Columbia researchers. Polish astronomer Nicolaus Copernicus's 1543 book, On the Revolutions of the Heavenly Spheres, moved Earth from being the centre of the Universe to just another planet orbiting the Sun. Since then, astronomers have extended the idea and formed the Copernican Principle, which says that our place in the Universe as a whole is completely ordinary. Although the Copernican Principle has become a pillar of modern cosmology, finding conclusive evidence that our neighbourhood of the Universe really isn't special has proven difficult. In 1998, studies of distant explosions called "type Ia supernovae" indicated that the expansion of the Universe is accelerating, an observation attributed to the repulsive force of a mysterious "dark energy." However, some scientists put forward an alternate theory: They proposed that the Earth was near the centre of a giant "bubble," or "void," mostly empty of matter, and strongly violating the Copernican Principle. If this were the case, gravity would create the illusion of acceleration, mimicking the effect of dark energy on the supernova observations. Now some advanced analysis and modeling performed by UBC post-doctoral fellows Jim Zibin and Adam Moss and Astronomy Prof. Douglas Scott is showing that this alternate "void theory" just doesn't add up. Their findings are published today in the journal Physical Review Letters. The researchers used data from the Wilkinson Microwave Anisotropy Probe satellite, which includes members from UBC on its international team, as well as data from various ground-based instruments and surveys. "We tested void models against the latest data, including subtle features in the cosmic microwave background radiation - the afterglow of the Big Bang - and ripples in the large-scale distribution of matter," says Zibin. "We found that void models do a very poor job of explaining the combination of these data." The team's calculations instead solidify the conventional view that an enigmatic dark energy fills the cosmos and is responsible for the acceleration of the Universe. "Recent advances in data collection have brought us to the era of precision cosmology," says Zibin. "Void models are terrible at explaining the new data, but the standard dark energy model works very well. "Since we can only observe the Universe from Earth, it's really hard to determine if we're in a 'special place,'" says Zibin. "But we've now learned that our location is much more ordinary than the strange dark energy that fills the Universe." University of British Columbia |
|||||||||||||||||||||
| Related Dark Energy Current Events and Dark Energy News Articles ESA spacecraft may help unravel cosmic mystery When Europe's comet chaser Rosetta swings by Earth tomorrow for a critical gravity assist, tracking data will be collected to precisely measure the satellite's change in orbital energy. The results could help unravel a cosmic mystery that has stumped scientists for two decades. Precise picture of early Universe supports 'dark matter' theory A detailed picture of the seeds of structures in the universe has been unveiled by an international team co-led by a Cardiff University scientist. Science at the Petascale: Roadrunner Results Unveiled The world's fastest supercomputer, Roadrunner, at Los Alamos National Laboratory has completed its initial "shakedown" phase doing accelerated petascale computer modeling and simulations of a variety of unclassified, fundamental science projects. Scientists use world's fastest supercomputer to model origins of the unseen universe Understanding dark energy is the number one issue in explaining the universe, according to Salman Habib, of the Laboratory's Nuclear and Particle Physics, Astrophysics and Cosmology group. Vanderbilt astronomers participate in new search for dark energy The most ambitious attempt yet to trace the history of the universe has seen "first light." The Baryon Oscillation Spectroscopic Survey (BOSS), part of the Sloan Digital Sky Survey III (SDSS-III), took its first astronomical data on the night of Sept. 14-15 at the Sloan Foundation telescope in New Mexico. Rebirth of an icon: Hubble's first images since Servicing Mission 4 Astronomers today declared the NASA/ESA Hubble Space Telescope a fully rejuvenated observatory ready for a new decade of exploration, with the release of observations from four of its six operating science instruments. Dark Energy From the Ground Up: Make Way for BigBOSS Several ways have been proposed to examine dark energy, in hopes of finding out just what it is. One of them, "supernovae" for short, certainly works: it's how dark energy was discovered in the first place. Other independent techniques, such as weak gravitational lensing and baryon acoustic oscillation, also promise great power but are as yet unproven. NASA celebrates Chandra X-Ray Observatory's 10th anniversary Ten years ago, on July 23, 1999, NASA's Chandra X-ray Observatory was launched aboard the space shuttle Columbia and deployed into orbit. Radio telescopes extend astronomy's best 'yardstick' Radio astronomers have directly measured the distance to a faraway galaxy, providing a valuable "yardstick" for calibrating large astronomical distances and demonstrating a vital method that could help determine the elusive nature of the mysterious Dark Energy that pervades the Universe. Cosmology's Best Standard Candles Get Even Better 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, have found a new technique that establishes the intrinsic brightness of Type Ia supernovae more accurately than ever before. More Dark Energy Current Events and Dark Energy News Articles |
|||||||||||||||||||||
|
|||||||||||||||||||||
|
|||||||||||||||||||||