Post by Chicago Astronomer - Astro Joe on May 14, 2006 23:15:08 GMT -6
Another universe may have preceded ours, study finds
Three physicists say they have done calculations showing that before the birth of our universe, which is expanding, there was an earlier universe that was shrinking.
The results stem from a theory that claims the fabric of space and time is made up of minuscule, indivisible bits, much as matter is.
The diagram represents our expanding universe as the right branch of the arc. The present time is at the right edge. According to Ashtekar's calculations, when looking backward throughout the history of the universe, 'time' does not go to the point of the Big Bang but bounces to the left branch of the drawing, which describes a contracting universe. High resolution version here.
Scientists believe our cosmos began in a sort of explosion called the Big Bang, when everything that exists—which just previously had been packed into one infinitely dense point—burst outward.
The universe is still expanding, according to this view, because it was born expanding.
According to some proposals, the Big Bang is a repeating cycle. Universes might expand, then shrink back to a point, then expand again. Thus the “bang” would be really more like a bounce.
The idea is appealing in some ways, but scientists have found it far from easy to test. Einstein’s General Theory of Relativity, a key basis for the Big Bang theory, is silent on what happened before that event.
“General relativity can be used to describe the universe back to a point at which matter becomes so dense that its equations don’t hold up,” said Abhay Ashtekar, director of the Institute for Gravitational Physics and Geometry at Penn State University in University Park, Penn.
To go further, physicists must use tools Einstein didn’t have, he added. Ashtekar and two post-doctoral researchers developed such tools through a combination of quantum physics—the science of subatomic particles—and general relativity, which describes the large-scale structure of space and time.
They found that before the Big Bang, there was a contracting universe. Other than the fact that it was shrinking, they added, it was similar to ours in terms of the geometry of its space and time, or spacetime, as cosmologists call it since Einstein found the two are interwoven.
“In place of a classical Big Bang there is in fact a quantum bounce,” said Ashtekar. “We were so surprised by the finding,” he added, that the team repeated the calculations for months to account for different different possible values of various numbers; but the results kept pointing to a bounce.
The findings appear in the current issue of the research journal Physical Review Letters.
More here: www.world-science.net/othernews/060514_bouncefrm.htm
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I'm sure there were previous universes and future one...as well as present multi-universes as well.