Washington, May 24 : A popular theory that says the universe is finite and relatively small, rather than infinitely large, has gained new ground after re-evaluation of previous data.
The idea that the universe is finite and relatively small, rather than infinitely large, first became popular in 2003, when cosmologists noticed unexpected patterns in the cosmic microwave background (CMB) - the relic radiation left behind by the Big Bang.
The CMB is made up of hot and cold spots that represent ripples in the density of the infant Universe, like waves in the sea.
An infinite Universe should contain waves of all sizes, but cosmologists were surprised to find in 2003 that longer wavelengths were missing from measurements of the CMB made by NASA's Wilkinson Microwave Anisotropy Probe.
One explanation for the missing waves was that the universe is finite.
But the notion soon suffered a setback when astronomers were unable to find an important pattern relating to it.
Cosmologists had predicted that a wrap-around Universe would act like a hall of mirrors, with images from distant objects being repeated multiple times across the sky.
Glenn Starkman at Case Western Reserve University in Cleveland, Ohio, and his colleagues searched for the predicted patterns, but found nothing.
Now, Frank Steiner, a physicist at Ulm University in Germany and his colleagues have re-analyzed the 2003 data from NASA's Wilkinson Microwave Anisotropy Probe, looking for different shapes, including the so-called '3-torus', also dubbed the 'doughnut universe'.
The 3-torus is an extension of the familiar doughnut shape and can be formed from a rectangular piece of paper.
Steiner's team used three separate techniques to compare predictions of how the temperature fluctuations in different areas of the sky should match up in both an infinite Universe and a doughnut one.
In each case, the doughnut gave the best match to the Wilkinson Microwave Anisotropy Probe data.
The team has even been able to pin point the probable size of the Universe, which would take around 56 billion light years to cross.
Steiner believes that new and more precise measurements of the cosmic microwave background to be made by Europe's Planck satellite, which is due to be launched later this year, will help answer the question as to the shape and size of the universe.
"Philosophically, I like the idea that the Universe is finite and one day we could fully explore it and find out everything about it," said Starkman. "But since physics cannot be decided by philosophy, I hope it will be answered by Planck," he added.