Astronomers from the Sloan Digital Sky Survey (SDSS-III) have made the first measurement of the cosmic expansion rate just three billion years after the Big Bang.
|Last Updated: Nov 14, 2012, 11:15 AM IST|Source: Bureau
London: Using a new technique for measuring the three-dimensional structure of the distant Universe, astronomers from the Sloan Digital Sky Survey (SDSS-III) have made the first measurement of the cosmic expansion rate just three billion years after the Big Bang.
For the past five billion years, the expansion of the Universe has been speeding up, powered by the mysterious repulsive force known as “dark energy.”
But the new measurements showed that the expansion of the Universe was slowing down 11 billion years ago.
“If we think of the Universe as a roller coaster, then today we are rushing downhill, gaining speed as we go,” said Nicolas Busca of the Laboratoire Astroparticule et Cosmologie of the French Centre National de la Recherche Scientifique (CNRS), one of the lead authors of the study.
“Our new measurement tells us about the time when the Universe was climbing the hill -- still being slowed by gravity,” he stated.
The new measurement is based on data from the Baryon Oscillation Spectroscopic Survey (BOSS), one of the four surveys that make up SDSS-III. It utilizes a technique pioneered by the SDSS in 2005 called “baryon acoustic oscillations (BAO).”
The new measurement does not look at galaxies at all. Instead, it makes use of the clustering of intergalactic hydrogen gas in the distant Universe.
SDSS-III researchers’ new measurement of the BAO peak, combined with measurements of the same peak at other points in the Universe’s history, paints a picture of how the Universe has evolved over its history.
The BOSS measurements show that the expansion of the Universe was slowing down 11 billion years ago due to the mutual gravitational attraction of all of the galaxies in the Universe -- but that as the Universe expanded, the constant repulsive force of dark energy began to dominate as matter was diluted by the expansion of space.
“No technique has ever been able to probe this ancient era before,” said BOSS principal investigator David Schlegel of the Lawrence Berkeley National Laboratory.
“Back then, the expansion of the Universe was slowing down; today, it’s speeding up. How dark energy caused the transition from deceleration to acceleration is one of the most challenging questions in cosmology,” he added.
Nicolas Busca summarizes: “It looks like the roller coaster crested the hill just about seven billion years ago, and we’re still going.”
The results were presented in a paper submitted to the journal _Astronomy and Astrophysics.
ANI
By clicking “Accept All Cookies”, you agree to the storing of cookies on your device to enhance site navigation, analyze site usage, and assist in our marketing efforts.
Cookies Setting
By clicking “Accept All Cookies”, you agree to the storing of cookies on your device and the processing of information obtained via those cookies (including about your preferences, device and online activity) by us and our commercial partners to enhance site navigation, personalise ads, analyze site usage, and assist in our marketing efforts. More information can be found in our Cookies and Privacy Policy. You can amend your cookie settings to reject non-essential cookies by clicking Cookie Settings below.
Manage Consent Preferences
Strictly Necessary Cookies
These cookies are necessary for the website to function and cannot be switched off in our systems. They are usually only set in response to actions made by you which amount to a request for services, such as setting your privacy preferences, logging in or filling in forms. You can set your browser to block or alert you about these cookies, but some parts of the site will not then work or you may not be able to login.
Functional Cookies
These cookies enable the website to provide enhanced functionality and personalisation. They may be set by us or by third party providers whose services we have added to our pages. If you do not allow these cookies then some or all of these services may not function properly.
Targeting Cookies
These cookies may be set through our site by our advertising partners. They may be used by those companies to build a profile of your interests and show you relevant adverts on other sites. They are also used to limit the number of times you see an advert as well as help measure the effectiveness of an advertising campaign. They do not store directly personal information, but are based on uniquely identifying your browser and internet device. If you do not allow these cookies, you will experience less targeted advertising.
Performance Cookies
These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. They help us to know which pages are the most and least popular and see how visitors move around the site. All information these cookies collect is aggregated and therefore anonymous. If you do not allow these cookies we may not know when you have visited our site, and may not be able to monitor its performance.