Shutterstock/Dr. Norbert Lange
This story is part of our “Cosmic Perspective” series, which confronts the incredible vastness of the universe and our place in it. Read the rest of the series here.
We think of this universe as containing everything that exists, has existed in the past, and will exist in the future, but that may not be the case – there are many ways other universes could exist.
One is that we may be part of a branch of an infinite number of universes collectively known as the multiverse. These universes could have emerged shortly after the Big Bang, could be hiding in extra dimensions, or could suddenly appear whenever quantum properties shift from different states into a single reality.
The idea of a multiverse rose to scientific prominence in the 1980s with the invention of inflation, a period when the early universe suddenly expanded. Inflation explains why the universe is so flat and smooth, but it also predicts the creation of many independent bubble universes.
Cyclic Universe
But inflation is only one path to a multiverse, and it has its critics. In recent years, many cosmologists have turned to alternative theories, such as cyclical universe theory, which claims that the universe is expanding and compressing infinitely. These theories still claim multiple universes, but at different times.
“What I don’t like about inflation is that there is very little true prediction. You never get back more than you put in.” Neil TullochPhysicist at the University of Edinburgh in the UK…