Traveling to alternate universes

[diezir]

We have a three-dimensional universe, and if we include space-time - four. So, in Stranger Things, the characters do not travel to another dimension, but rather to another version of Earth in a parallel universe. This is hypothetically true. If space-time goes on forever, it only makes sense that it should repeat itself.

 

[sophiecentaur]

This is hypothetically true. If space-time goes on forever, it only makes sense that it should repeat itself.

Any sort of 'hypothesis' can be discussed but that doesn't imply it will "make sense". Just don't try to bring Physics into this it won't run.

 

[phinds]

We have a three-dimensional universe, and if we include space-time - four. So, in Stranger Things, the characters do not travel to another dimension, but rather to another version of Earth in a parallel universe. This is hypothetically true.

You don't seem to understand the concept of other "parallel" universes being the same thing as the multiverse and if they exist (which is doubtful) they are causally disconnected from ours. Stranger Things is FICTION. Don't try to make science out of it.

If space-time goes on forever, it only makes sense that it should repeat itself.

That seems to make sense to you but it makes no sense to me. The integers go on forever. Do they repeat themselves?

 

[phinds]

Although this thread started off as a question in cosmology (sort of), it has morphed into something that should be in the science fiction forum, not cosmology.

 

[ergospherical]

It's definitely possible! For example Dr Strange traveled to the dark dimension to engage Dormammu, and Scott Lang used Pym particles to enter the quantum realm.

 

[elcaro]

Summary:: How can we travel to another universe?

How can we travel from one alternate universe to another?, how could we prove that it has happened?

What "our universe" is is pretty well defined by the fact that it at least contains the part we can visit, which is part of the causally connected part of the universe. So any place we can in principle visit is already part of our universe. Other universes are causally disconnected from our universe, which we therefore can't visit.

 

[fresh_42]

Although this thread started off as a question in cosmology (sort of), it has morphed into something that should be in the science fiction forum, not cosmology.

Agreed. And moved.

 

[Hornbein]

Alternative Universe? You can't get there from here.

 

[sophiecentaur]

Stranger Things is FICTION.

It is also very derivative, repetitive and boring. I watched about three of the first episodes. Yawn; not enough car chases or bar fights.

 

[Rive]

We have a three-dimensional universe, and if we include space-time - four. So, in Stranger Things, the characters do not travel to another dimension, but rather to another version of Earth in a parallel universe. This is hypothetically true. If space-time goes on forever, it only makes sense that it should repeat itself.

That's called 'technobabble'. You are doin' it right.

Regarding the 'repeat' thing: if you make a random series of variables: like decimals of a number there will be sequences which repeat themselves with some statistical chance. That's true.
As far as we understand now the problem with the universe - any universe - is that the possible number of values (states) its 'decimals' can take is pretty big (practically infinite). You need some infinite-on-infinite-on-infinite kind of number of repeats to have significant pieces (not the whole - just pieces) to repeat themselves.

Just keep on with the technobabble. That's more reliable. Sort of.

 

[Jarvis323]

This is hypothetically true. If space-time goes on forever, it only makes sense that it should repeat itself.

Max Tegmark seems to think so, with some assumptions.

There is the many worlds hypothesis which says that everything that can happen (has non-zero probability according to Quantum mechanics) does happen, but reality branches off into different causally separate realms (different realms, rather than spatially separated universes or worlds). In that scenario there is a reality with every possible version of you.

Tegmark, however, argues that, given some randomness properties, and an infinite number of finitely describable universes, you get the same thing, where everything that can happen does happen in some universe.

The Multiverse Hierarchy
https://arxiv.org/pdf/0905.1283.pdf

There was a discussion on PF related to this.

https://www.physicsforums.com/threads/quantum-immortality-without-mwi.997952/

 

[Hornbein]

Max Tegmark seems to think so, with some assumptions.

There is the many worlds hypothesis which says that everything that can happen (has non-zero probability according to Quantum mechanics) does happen, but reality branches off into different causally separate realms (different realms, rather than spatially separated universes or worlds). In that scenario there is a reality with every possible version of you.

Tegmark, however, argues that, given some randomness properties, and an infinite number of finitely describable universes, you get the same thing, where everything that can happen does happen in some universe.

The Multiverse Hierarchy
https://arxiv.org/pdf/0905.1283.pdf

There was a discussion on PF related to this.

https://www.physicsforums.com/threads/quantum-immortality-without-mwi.997952/

If there is an infinity of worlds then each one has zero probability. Lebesque integration was invented to deal with this.

I remain to be convinced that an infinite Universe is finitely describable.

 

[Jarvis323]

Alternative Universe? You can't get there from here.

Tegmark estimates that the nearest identical copy of you is probably only about ##10^{10^{29}}## m away in a level ##\text{I}## multiverse. But there would be many near perfect copies as well, and I'm not sure how close they would be.