London, June 10 : Cosmologists have suggested that colossal structures that stretch beyond the edge of the visible universe, may be responsible for a strange pattern seen in the big bang's afterglow, and could provide precious information about the universe's earliest moments.
According to a report in New Scientist, these massive structures were forged during the period of cosmic inflation nearly 14 billion years ago.
In the first instant after its birth, the universe is thought to have experienced a rapid growth spurt called inflation. During this period, space itself expanded faster than the speed of light.
Inflation solves some cosmological puzzles, such as why relic radiation from the big bang, released when the universe was less than 400,000 years old, is relatively uniform.
Called the cosmic microwave background (CMB), the radiation can be observed in all directions in the sky. It has a slightly mottled appearance due to small differences in temperature from place to place in the early universe.
The temperature differences are thought to be caused by variations in the density of matter, with denser regions being warmer than emptier regions.
But the theory of inflation predicts that the mottling should be equally prominent in all directions.
Curiously, it is 10% more pronounced on one side of the sky than the other, an asymmetry that was reported in 2004.
Now, cosmologists led by Adrienne Erickcek of Caltech in Pasadena, US, think they may have found the reason for this pattern. They suggest the universe has been skewed by the imprint of primordial structures that date back to the period of inflation.
In the inflation scenario, an energy field of still-mysterious origin drives the expansion.
Erickcek and her colleagues argue that the asymmetry could be the remnant of fluctuations in an additional energy field, which started out very tiny, but were blown up by inflation until they were larger than the observable universe.
As a result, the value of this energy field varied from one side of the universe to the other at early times, enhancing the variations in temperature - and matter density - on one side of the sky relative to the other.
The conclusion, if correct, would shatter a cherished assumption about the universe.
"One of the basic tenets of cosmology is that the universe is the same in all directions, and the standard model of inflation is built on that foundation," Erickcek told New Scientist.
"If the asymmetry is real, then it tells us that one side of our universe is somehow different than the other side," she added.