Most everybody is familiar with the Big Bang — the notion that an impossibly hot, dense universe exploded into the one we know today. But what do we know about what came before?
In the quest to resolve several puzzles discovered in the initial condition of the Big Bang, scientists have developed a number of theories to describe the primordial universe, the most successful of which — known as cosmic inflation — describes how the universe dramatically expanded in size in a fleeting fraction of a second right before the Big Bang.
But as successful as the inflationary theory has been, controversies have led to active debates over the years.
Some researchers have developed very different theories to explain the same experimental results that have supported the inflationary theory so far. In some of these theories, the primordial universe was contracting instead of expanding, and the Big Bang was thus a part of a Big Bounce.
Some researchers — including Avi Loeb, the Frank B. Baird, Jr. Professor of Science and chair of the Astronomy Department — have raised concerns about the theory, suggesting that its seemingly endless adaptability makes it all but impossible to test.