London, April 16 : A new controversial analysis by an astronomer of Indian origin has suggested that the Big Bang might not have come at the beginning of the Universe, but after a long and slow period of shrinkage.
According to a report in Nature News, the theory has been put forward by Amit Yadav, an astronomer at the University of Illinois at Urbana-Champaign.
If this theory holds any ground, it would show that the early universe did not inflate with the smoothness that many theorists expected.
"The standard, canonical models will be ruled out if this holds," said Yadav. "The simplicity is gone," he added.
Yadav's provocative result suggests that models of inflation - a furious hyperexpansion in the instant after the Big Bang, 13.7 billion years ago - have to be much more complicated than previously thought, or else that inflation never occurred at all and that the Big Bang came after a period of contraction.
"If the result sticks, it would be the first time that one of the predictions of simple inflation failed. And it could also lead to a radical reinterpretation of what the Big Bang was and whether it marked the universe's beginning," said Yadav.
Standard, simple inflation - needed to achieve a flat, smooth universe - holds that, just after the Big Bang, a uniform negative gravitational field drove a brief period of accelerated expansion.
Then the field died out, creating the matter and energy known in the universe today and leaving an afterglow of microwave radiation just a few degrees above absolute zero.
If simple inflation theory is right, this imprint should be almost, but not quite, perfectly gaussian - a pattern with smooth-looking noise.
The Illinois researchers measured the degree of gaussianity in a map built with data from the Wilkinson Microwave Anisotropy Probe (WMAP), a satellite launched in 2001 to measure the afterglow, which is known as the cosmic microwave background (CMB).
The analysis of Yadav and his adviser Benjamin Wandelt, which took months of supercomputer time, showed that the CMB map was not at all gaussian.
According to them, there is a certainty of 99.5% that the CMB is not gaussian.
But, Eiichiro Komatsu, a cosmologist at the University of Texas at Austin and a member of the WMAP science team, recently published a similar analysis with fresher data that did not draw the same conclusion.
"We don't see any compelling evidence yet that non-Gaussianity exists. So, simple inflationary models still fit the data pretty well," he said.
Komatsu, Yadav and others interested in this crucial question will refine their computational models and await the completion of the next stage of WMAP data collection.