Universe expansion 'is speeding up'
Last updated: 26 March, 2010
London, Mar 26 (PTI) 13:02 IST
Astronomers have claimed that the expansion of the universe is accelerating, after studying thousands of galaxies using the Hubble Space Telescope.
In its research, an international team has analysed nearly 446,000 galaxies to map the matter distribution and the expansion history of the universe, proving again that Albert Einstein's theory of relativity is indeed correct.
And the astronomers clearly found that the universe was indeed growing faster and faster with time, as predicted by Einstein."Our results confirmed that there is an unknown source of energy in universe which is causing the cosmic expansion to speed up, stretching the dark matter further apart exactly as predicted by Einstein's theory," lead astronomer Ludovic Van Waerbeke of Leiden University in the Netherlands said.
Einstein's theory of general relativity predicts that space and time is a soft geometrical structure of which the shape and evolution are entirely determined by the matter within it.
According to the astronomers, the universe is composed of dark matter and normal matter with third constituent called "dark energy", which over the past two billion years has been the force behind the accelerated expansion of the universe.
"The data from our study are consistent with these predictions and show no deviation from Einstein's theories," Van Waerbeke said.Van Waerbeke pioneered a technique to measure the invisible web of dark matter which was used in the study.
In a method similar to taking an X-ray of the body to reveal the underlying skeleton, the technique, known as weak gravitational lensing, allowed the astronomers to see how the light from distant galaxies is bent and distorted by the dark matter as it travels towards earth.
They then mapped the dark matter structures, which make up 80 per cent of the universe, the media reported.Team member Tim Schrabback said: "What we tested is how the structure of universe grows with time. If the universe expands then the gravitational lensing changes as the distance between the objects has changed.
"I think from that perspective this is quite exciting because this is the first time this measurement has been done with weak gravitational lensing alone. Before it's always been done with other measurements as the lensing was not effective.
"The other thing that is really exciting is that in the next years there will be much larger surveys which will have more accurate measurement for dark energy and expansions, and we will see some very interesting results."
For the survey, a camera aboard the Hubble telescope photographed 575 slightly overlapping views of the same part of the universe, which took nearly 1,000 hours of observation, during which the Hubble circled the earth 600 times.The findings will appear in a forthcoming issue of the 'Astronomy & Astrophysics' journal.