WHAT happened before our universe began? According to two theoretical physicists, if there was a universe before ours then it should have been remarkably similar to this one, with the same basic ingredients and properties. It may even be possible to see a faint picture of our parent universe imprinted on the sky.
Questions about a time before the big bang were once thought to be meaningless, because according to Einstein's general theory of relativity, the universe began at a singularity - a mathematical point with infinite density at which all calculations break down.
However, physicists now believe that the theory of relativity is limited and the effects of quantum mechanics would have blurred out the singularity just a little, so at a crucial moment the density of matter and radiation was not infinite. If this was the case, it becomes possible to try to work out what led up to that moment.
CONTINUED AT: http://space.newscientist.com/article/mg19826514.300-did-prebig-bang-universe-leave-its-mark-on-the-sky.html?DCMP=ILC-hmts