What is beyond our universe?

Question

Hazel Asher · Accepted Answer

Hmmm...

I see two issues with this question, in my opinion: 1. The definition of universe. The term "universe" refers to all matter and space that exist. This eliminates all other known matter and space, since any other known matter and/or space would be included in this universe by definition. 2. The term is. There are enough problems with the idea of simultaneity within our universe, let alone in relation to something beyond our universe, so what does the word "is" mean? If something "beyond our universe" does not interact with our universe, then in what way is its time related at all? If its time is not related, then there is no meaning to "is." If speaking of something beyond our universe is meaningful, then what is its relation to our universe in terms of time? #color(white)()# Having said all of this, note that historically when we discovered the existence of galaxies outside our own Milky Way galaxy, the term "island universe" was used for galaxies. There is some practical value in this usage since the distances between our own galaxy and some of its more significant "local" neighbours (i.e. discounting the smaller satellite galaxies) are of the order of #2# million light years. So the effect of other galaxies and our practical interactions with them are somewhat limited in human terms. As for the word "is" in this context, what we see is how these local galaxies were #2# million years ago, not as they are "now".

Luke Allen · Answer

undefined There are a number of theories regarding the nature of what exists outside of our universe, such as parallel dimensions, multiple universes, or other forms of existence, but these theories are still speculative and lack empirical support.