I'm sure this has been asked before, but: Universes colliding with each other

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The discussion centers on the concept of universes potentially colliding or interacting, with participants clarifying that universes, if they exist, are not like physical objects in space that can collide. Instead, they argue that universes are not embedded in any external space and that the Hubble volume is a mathematical construct within our universe. The idea of dark energy's influence on other universes is debated, with the consensus leaning towards the notion that any interaction is speculative and lacks evidence. Participants emphasize the importance of grounding discussions in established physics rather than speculative concepts. Overall, the conversation highlights the complexities of cosmology and the need for clarity in terminology when discussing the universe and its properties.
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Forgive me for not being a professional cosmologist, but can't the universe collide with another universe? If similar instances of the universe's Hubble volume occur every so often, won't they eventually run up against each other and push each other around like giant jelly balls?

And can't our universe even get sandwiched between two other such universes, compressing ours down to a singularity?

I know I make no sense, but thanks for your patience.
 
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mustang19 said:
Forgive me for not being a professional cosmologist, but can't the universe collide with another universe? If similar instances of the universe's Hubble volume occur every so often, won't they eventually run up against each other and push each other around like giant jelly balls?

And can't our universe even get sandwiched between two other such universes, compressing ours down to a singularity?

I know I make no sense, but thanks for your patience.

Today anything outside our Universe is completely unknown, so who knows?
 
Universes (if there is more than 1) are not like balls in a 3- or 4-dimensional environment which could collide. They are not embedded in some space. They are space (with objects inside).
 
Today anything outside our Universe is completely unknown, so who knows?

As good an answer as any.

Universes (if there is more than 1) are not like balls in a 3- or 4-dimensional environment which could collide. They are not embedded in some space. They are space (with objects inside).

I see. But they can still exert force against each others' volumes, I think. Doesn't the dark energy in one Hubble volume compress or act against the dark energy in the ones it collides with, or do both volumes keep on inflating regardless?
 
How do you define "force" without space(time)?

The Hubble volume is a part of our universe, and its "boundary" is not different from anything else in the universe (its position is just the result of a mathematical calculation). That is a completely different thing.
 
mfb said:
How do you define "force" without space(time)?

The Hubble volume is a part of our universe, and its "boundary" is not different from anything else in the universe (its position is just the result of a mathematical calculation). That is a completely different thing.

Alright, alright, I get it now.

Say you have three universes sitting in a row, with Universe A on the left and Universe C on the right, with universe B in the middle. As A and C expand and "sandwich" B, pressing against it on both sides, will the dark energy in A and C exert any force against the dark energy in B? Will this slow B's inflation at all?
 
mustang19 said:
Alright, alright, I get it now.

Say you have three universes sitting in a row, with Universe A on the left and Universe C on the right, with universe B in the middle. As A and C expand and "sandwich" B, pressing against it on both sides, will the dark energy in A and C exert any force against the dark energy in B? Will this slow B's inflation at all?

No, clearly you DON'T get it. Reread post #3
 
phinds said:
No, clearly you DON'T get it. Reread post #3

Well, going by that post, I'm left with the impression that the universes would more or less merge, with negligible compression between them. I appreciate the answers to my rather crude questions.
 
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First, "universe" === "all there is" and it is unlikely that there is more than one.

There ARE "multiverse" theories that postulate more than one "all there is", but first, they have ZERO evidence and are highly speculative, and second, even they do not say there is any connection of any kind among the different ones.

You should read the forum rules that prohibit personal theories (that is, ones that have no apparent basis in fact). This is a forum for mainstream science and you are just making up speculative concepts.

There are lots of forums on the internet where you can let your imagination run wild, but this is not one of them.
 
  • #10
phinds said:
First, "universe" === "all there is" and it is unlikely that there is more than one.

There ARE "multiverse" theories that postulate more than one "all there is", but first, they have ZERO evidence and are highly speculative, and second, even they do not say there is any connection of any kind among the different ones.

You should read the forum rules that prohibit personal theories (that is, ones that have no apparent basis in fact). This is a forum for mainstream science and you are just making up speculative concepts.

There are lots of forums on the internet where you can let your imagination run wild, but this is not one of them.

You seem like you're speaking from experience. Well, again, thanks for the response. I'll try to stick to solid evidence from now on while I'm here.
 
  • #11
mustang19 said:
You seem like you're speaking from experience. Well, again, thanks for the response. I'll try to stick to solid evidence from now on while I'm here.

I should add that multiverse theories are not banned at all on this forum. Despite evidence, they are a valid topic for mainstream (well, sort of) science. My point on your speculation was about your concept that "universes" somehow occupy the same space-time continuum without being part of the same universe. Actually, that isn't really speculative so much as just nonsensical.

It IS good to let your imagination run, and to "think outside the box". BUT ... on this forum, you are required to first know what's in the box, or to ask questions about what's in the box, not speculate about what's outside the box without any basis in actual physics.

It's a great forum, really.
 
  • #12
phinds said:
I should add that multiverse theories are not banned at all on this forum. Despite evidence, they are a valid topic for mainstream (well, sort of) science. My point on your speculation was about your concept that "universes" somehow occupy the same space-time continuum without being part of the same universe. Actually, that isn't really speculative so much as just nonsensical.

It IS good to let your imagination run, and to "think outside the box". BUT ... on this forum, you are required to first know what's in the box, or to ask questions about what's in the box, not speculate about what's outside the box without any basis in actual physics.

It's a great forum, really.

By "universes" I meant something along the lines of "identical Hubble volumes within the same universe", but I guess the answer is the same.

Apologies if there are stacks of threads on this, but one thing I never understood is what dark energy was. I assume it's something like light, which transfers energy through space. Light is made up of photons, so I'm not sure if dark energy has a similar hypothetical particle which transmits and mediates it, or if it is even supposed to have a particle nature.

It's just a question. If this isn't a place for asking questions about Physics 101 (or would it be 103?), I understand completely.
 
  • #13
By "universes" I meant something along the lines of "identical Hubble volumes within the same universe", but I guess the answer is the same.
Do not use "universes" then, please, if you refer to parts of our universe.
The Hubble volume is a mathematical result of some calculation about our (here: earth) current state in the universe. They "merge" or do not merge in the same way as "a sphere around Earth with radius 100km/s*t" and "a sphere around sun with radius 100km" would "merge". Just a mathematical thing.
 
  • #14
mustang19 said:
Apologies if there are stacks of threads on this, but one thing I never understood is what dark energy was.

There are, so do a forum search. Doing that is something you should get in the habbit of doing before asking basic quesions.
 
  • #15
mfb said:
Do not use "universes" then, please, if you refer to parts of our universe.
The Hubble volume is a mathematical result of some calculation about our (here: earth) current state in the universe. They "merge" or do not merge in the same way as "a sphere around Earth with radius 100km/s*t" and "a sphere around sun with radius 100km" would "merge". Just a mathematical thing.

Thanks for the clarification.

There are, so do a forum search. Doing that is something you should get in the habbit of doing before asking basic quesions.

Got it.
 
  • #16
mustang19 said:
Thanks for the clarification.



Got it.

Also, FIY, you would likely find it VERY informative to read the FAQ in the cosmology section
 
  • #17
Good stuff. Thanks again, phinds.
 
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