(Once again I wrote this on Sunday, but forgot to post it on Monday)
When we are considering the Universe we are considering something that we are part of, and of which we share the characteristics, such as, for example, existence. We can exist only because the Universe exists and the Universe exists, at least in part, because we exist. It is conceivable that in some way a universe could exist with nothing in it, much like a mathematical empty set but it would be pretty boring.
Or would it? Maybe I’m applying some anthropocentric reasoning to that statement. After all, the concept of a mathematical empty set is very useful in mathematics, and but then again, “useful” is a human concept.
A universe may be non-empty, but have no life in it. We, from another universe can conceive of such a universe, but there can be no perceiving of that universe if we rule out the possibility of visiting it from our Universe. We can’t even tell if such a universe exists, so some would argue that the question of its existence is meaningless.
That’s a valid argument, but then again, out Universe was not perceived by any entity in the billions of years prior to the evolution of life. Of course the question of the early existence of our Universe before the coming of life, is not meaningless to us – we know that it must have existed for us to exist.
Of course, we can conceive of other universes other than our own, but do other universes exist in any real sense, apart from our own. A universe is self contained in the sense that there is no logical reason to conceive of anything outside of it. It is all of physics, all of existence.
One definition of universe is:
a distinct field or province of thought or reality that forms a closed system or self-inclusive and independent organization
This is a pretty good description of what I am writing about I’d say. The key word for me is “closed”. If something is closed it contains whatever it contains and the outside is irrelevant so far the contents are concerned.
Though now I come to think of it, maybe that is not true. If we have a can of beans, we know what is inside it by the label, and we can open the can with a can opener. Maybe the contents of our Universe are visible on the outside, on the label as it were.
Our Universe has laws, or appears to have laws. The laws appear to be universal – that is, they apply everywhere in our Universe without exception. An atom here behaves the same as a similar atom here would and conceptually swapping them would make zero difference.
We do not know all the laws but we humans believe that we can know all the laws and I believe this to be true, even if it might take longer than the life of the Universe for use to discover and understand them all. By laws, I mean “how stuff works” and even if the ultimate answer is “because that’s the way the Universe works” and there is no deeper meaning than that, I’d still consider them laws.
One bizarre possibility though, is that there is no order and the Universe is totally random, and only appears to have order. When we look at an expansion of the number Π we mostly find what seems to be random digits. Occasionally however we find runs of digits which look like they are non random, such as a lengthy series of the digit “3”, but eventually the random appearance returns.
This feature of the number Π can be used for amusement, such finding one’s own name “encoded” in Π, or any other string. Maybe our Universe is like a very long encoded string in the number Π, which seems to be ordered but actually isn’t. Maybe at some future instant things will revert to the real random state that the Universe is its real state.
Some physicists and cosmologists postulate alternate universes to account for some of the weirder facets of Quantum Physics, but in the broader sense we can consider universes which are similar but different and unrelated to ours. Would we want to visit such universes? Could we conceivably do so?
It seems to me to be unlikely that we could visit other universes, as the only methods that we could use are physical ones and our Universe encapsulates its physicality. That is, the physical laws pretty much define it. A frog can leap from a pond, since frog, pond, the air and the surroundings of the pond are physical, but simple leaping cannot take the frog to another universe, no matter how hard he jumps. A human can use physics to travel the Universe, but using physical means it doesn’t appear possible for us to jump out of our pond.
Would we really want to visit other physics-based universes? The other universes would have to be pretty much the same physically, our physical bodies would suffer – imagine for an example a universe where protons decay in minutes instead of in aeons. We would die in seconds.
Our best prospects for universe-hopping would be those universe which are probability neighbours. That is, they share the same physics as our Universe, but some events happened differently. For example, one can contemplate a universe where slaving never happened or where France’s hegemony dominated the early USA and French language and culture dominate in the North Americas.
Of course, we are used to a physical Universe, but it is conceivable that other universes may be not physically based. It’s extremely difficult to even talk about such universes, should they (in some sense) exist, and my mind keeps trying to populate such conceptual universes with things, and things are presumably physical entities, and would not be able to exist in a non physical universe. Probably!
Perhaps our physical nature hampers us in understanding the real nature of things. Perhaps we can only conceptualise things based on our nature. After all our thoughts are the end result of physical processes evolving over billions of years and are implicit in the history of our Universe and encoded in a way in the Big Bang.