Multiverse Theory

Multiverse theory suggests that our universe, with all its hundreds of billions of galaxies and almost countless stars, spanning tens of billions of light-years, may not be the only one. Instead, there may be an entirely different universe, distantly separated from ours — and another, and another. 

Indeed, there may be an infinity of universes, all with their own laws of physics, their own collections of stars and galaxies (if stars and galaxies can exist in those universes), and maybe even their own intelligent civilizations.

It could be that our universe is just one member of a much grander, much larger multitude of universes: a multiverse.  The concept of the multiverse arises in a few areas of physics (and philosophy), but the most prominent example comes from something called inflation theory. 

Inflation theory describes a hypothetical event that occurred when our universe was very young — less than a second old. In an incredibly brief amount of time, the universe underwent a period of rapid expansion, "inflating" to become many orders of magnitude larger than its previous size, according to NASA.

Inflation of our universe is thought to have ended about 14 billion years ago, said Heling Deng, a cosmologist at Arizona State University and an expert in multiverse theory. "However, inflation does not end everywhere at the same time," Deng told Live Science in an email. "It is possible that as inflation ends in some region, it continues in others."

Thus, while inflation ended in our universe, there may have been other, much more distant regions where inflation continued — and continues even today. Individual universes can "pinch off" of larger inflating, expanding universes, creating an infinite sea of eternal inflation, filled with numerous individual universes.

In this eternal inflation scenario, each universe would emerge with its own laws of physics, its own collection of particles, its own arrangement of forces and its own values of fundamental constants. This might explain why our universe has the properties it does — particularly the properties that are hard to explain with fundamental physics, such as dark matter or the cosmological constant, Deng said.

"If there is a multiverse, then we would have random cosmological constants in different universes, and it is simply a coincidence that the one we have in our universe takes the value that we observed," he said.   READ MORE...