Question: Are there other universes?

Robert Hampson answered on 17 Nov 2014:

The answer is that we don’t really know. Some mathematical models of the way our universe works suggest other universes may also exist. Most of physicists’ suppositions in this area are guess work based on mathematics. However, general and special relativity were essentially Einstein’s mathematical guesswork too and they turned out to be right so who knows…?

Some physicists have suggested the idea of parallel universes as a response to what is known as the Anthropic Principle. The Anthropic Principle is the observation that the fundamental constants of the universe fall within the extremely narrow parameters required for the emergence of conscious and sapient life in the universe. Religious people often use this as an argument for god (The universe is required to be very fine tuned to support life, the universe cannot fine tune itself, therefore something else must have fine tuned it indicating a being who created the universe). The response goes that many different universes were created, and we just happen to be in one with the right constants allowing us to come into existence to eventually observe it. As I say, this also fits with some mathematical models of the universe. However, it also seems to make it more complicated and fine tuned than in the first place because some kind of alternative universe production mechanism would now be required.

There are also some arguments that alternative dimensions have kind of been folded up inside this one, so there may actually be alternative realities inside this universe.

The problem with these ideas is that unless these alternative realities or universes interact in some way with our universe, there is no way of testing for them. If you cannot test for them, you cannot scientifically prove their existence.