Essay:Everything exists

Ideas exist with or without someone to think of them; put into mathematical terms, this is like stating that a system of equations existed before they were written down. Time in a system of equations doesn't pass as much as it all exists simultaneously - you can assign any value to the time variable to see what that "universe" looks like at that time. In this way, so too can our universe be expressed as a system of equations which contain every possible configuration across time, and every other universe for that matter. Combine these three facts (ideas exist without an ideator, all of time exists "simultaneously", and all universes can be expressed entirely as an idea), it's trivial to see that all possible universes and all possibilities within those universes must exist by definition.

Unfortunately, while these universes all exist, that doesn't mean we can necessarily go to them. In addition, this conception ensures that most universes can't be visited, as they do not contain you and thus cannot by definition. There will always be a version of any given universe which contains you, but you can never visit one you are not already in.

If physics were all there was to this universe, this would be a mere philosophical curiosity. However, because of other conclusions which can be made from first principles, this has powerful implications.