Slow, cold start to universe suggested | Science News

Slow, cold start to universe suggested | Science News:

The universe may have emerged not with a hot Big Bang but with a long, cold slog, a physicist proposes in a paper posted online January 21 at arXiv.org.

Over the last half-century, most cosmologists have come to agree that all matter initially exploded from a single point. An instant later, the hot, dense universe ballooned dramatically in an event called inflation. A slower expansion then proceeded for billions of years.

But the Big Bang model requires the universe to start from what physicists call a singularity, a point of infinite density at which physical laws break down. A theory that avoids a singularity without introducing other complications would fit better with quantum mechanics and general relativity, physicists’ best explanations of nature’s fundamental forces.

Christof Wetterich, a theoretical physicist at Heidelberg University in Germany, says he has created such a picture. In Wetterich’s theory, fundamental particles become heavier over time, while gravity weakens. This logic leads to a cosmic history in which the universe still underwent inflation but did not necessarily continue expanding. And instead of starting with a Big Bang, time before inflation could stretch into the infinite past.