Many Universes and the "Real" one.
Some physicists talk about the potential for a multiverse of universes similar to our own and others less so. Assuming there are universes to accommodate every possible position and spin of every subatomic object so literally all possible events and chains of events do occur in one of these universes. What makes our universe more real than the others, or what makes us sure ours is the real one? And if all equally really, what makes our free will actions significant if we are merely balancing an equation and our choices are just the leftovers that weren't played out elsewhere?
Comments (12)
If each moment is a (separate) temporal cross-sectional slice of "the universe" (in effect, like multiple universes of arbitrary, discrete, intervals), what makes today more real than other days?
:100: :up:
That's a whopper of a hypothesis! I can't get beyond it. :roll:
Well that is a theory some have. Not Sean Carrol as much who seems to think that new universes may only come about to accommodate paradoxes we create. But assuming all possible universes mathematically exist, what gives our reality a nod? Do we have free will or just the outcomes that are leftover?
Arghhhh people are confusing multiverse with many-worlds again. Multiverse is actually sensible, based on the fact that the age of the universe is finite, and light can only have gone a finite distance in the age of the universe. So there are regions of the universe that are causally inaccessible to us and always will be. We can't see them or measure them or experience them in any way. And for all we know there are a lot of them, and their fundamental physical constants may be different than ours. That's multiverse theory.
Many-worlds is an interpretation of quantum mechanics. In QM, an object exists in a state of superposition, meaning that it exists every way it can possibly exist. When we measure it, the "wave function collapses," as they say, and we only observe one specific thing to happen. This is the Copenhagen interpretation and it's the standard way of thinking about QM. It has problems, one of which is, what exactly is a measurement, and how does it cause one outcome to be chosen out of all the other possible ones.
In many-worlds, there is no wave function collapse. At every moment, every possible outcome of an experiment or observation splits off into a different world. The car turns right in one world and left in another. The electron is spin up and spin down. The cat is awake or sleeping. That's Sean Carroll's sweet take on the famous Schrödinger's cat experiment in which a cat is both alive and dead. Carroll says there's no need to kill a cat. And in one of his videos he relates the story that Schrödinger's daughter said, "I think my father just didn't like cats."
In many-worlds, which had very little mind share or support in the 20th century but is now making a resurgence, the cat is awake in one world and asleep in another, and the same is true about everything that could possibly happen. Sean Carroll is one of the contemporary proponents of the idea, and he has a lot of compelling arguments for it.
That said, of course "our" universe is ours, but the people (if there are any) in the other universes feel that theirs is equally real. That's true in both multiverse and many-worlds theory, which I repeat are two completely different ideas.
One point that should be made about the multiverse is that it is extremely sensible. We know for a fact that the observable universe is only a small part of the overall universe. We have no way of knowing what else lies outside our light cone.
I'll add that I'm no physics expert, I have a degree from the university of Youtube so double check what I say. And if you have any legal questions, I have a law degree from years of watching reruns of Law and Order. It's amazing how much you can know these days without knowing anything.
Is this for me? Yes, as I understand it. Although of course we're talking about 4D spacetime or 10D string theory or whatever. There's more than that to it in the details of course. It's based on inflation. But essentially there's a lot of the universe that we'll never know about due to how far light could have traveled in the age of the universe; and the theory of inflation says that the unobservable universe is filled with other universes.
https://www.space.com/25100-multiverse-cosmic-inflation-gravitational-waves.html
That's the problem with describing reality in terms of possible worlds, we lose the premise whereby we distinguish what is actually the case, the real, from what is possible. There is no such thing as the real world in that description, because giving one world a special status would negate the premise which gives all possible worlds equal status as possible worlds.
This is similar to the is/ought gap. One might propose principles whereby we could designate what "is", but the two ways of mapping would remain fundamentally incompatible such that the two ways would not be on the same map.
It is and it isn't. To the extent it is, everything, something, and/or nothing makes it more real.
Quoting TiredThinker
We are and we are not sure. To the extent we are sure, everything and/or something makes us sure. Ours is and is not the real one, and to the extent it is, everything and/or something makes it the real one.
Quoting TiredThinker
Our actions are and are not significant. To the extent they are significant, everything and/or something makes them so.
As to the question what "something" might be, why it might be anything. Anything at all. In fact, something is everything you can think of, and nothing at all.
Where "All" exists, it must and must not, and sometimes, only sometimes, necessarily account for the absence of itself. That is uncomfortable for some, but not really, not always.
What a wonderful idea to spend millions researching multi-universes when we're all drinking polluted water breathing toxic air.