Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: D on 29/08/2015 17:12:35
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Accordion to eternal inflation the space is constantly expanding my question is does that expansion effect the distance between the multiverse since the space outside the universe is fundamentally different from the space inside the universe(based on theory of eternal inflation) could the space outside the multiverse be expanding everywhere simultaneously or is it similar to big bang expansion? or is it something completely different?
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Accordion to eternal inflation the space is constantly expanding my question is does that expansion effect the distance between the multiverse since the space outside the universe is fundamentally different from the space inside the universe(based on theory of eternal inflation) could the space outside the multiverse be expanding everywhere simultaneously or is it similar to big bang expansion? or is it something completely different?
No. It doesn't even make sense to think of multiple universes to have a distance between them. If you're thinking in terms of some sort of analogy then your analogy is flawed.
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There may be a lot of opinions expressed in this thread, but I think the important thing to remember is that the only real answer to your questions is: “don’t know”.
To give any definitive answer we would have to establish the “reality” of eternal inflation, the multiverse and the nature and dynamics of anything that might, or might not, be outside our observable Universe.
Having said that, bring on the opinions!
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Accordion to eternal inflation the space is constantly expanding
Irrelevant Trivia: Accordions have their own, unique way of expanding - but it tends to be a cyclic expansion.
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Understand that there is no evidence of eternal inflation. So it is conjecture and guessing. However, the theory posits that inflation never ended, and that our universe is simply a "bubble" that formed from a much larger multiverse that is under constant inflation, producing an infinite amount of "bubbles". These bubbles are a small part of the multiverse that randomly stopped inflating, perhaps due to a quantum fluctuation, and entered a lower energy state. These bubbles themselves now expand outwardly inside the so called multiverse. Think of steam bubbles rising and expanding in a pot of boiling water.
Now, to answer your question, it would be the case that the space between these bubbles is inflating/expanding. This is itself the "eternal inflation", the expansion of the multiverse, giving rise to more and more bubble universes like our own inside of it. Most bubbles would never interact directly. However, if two bubbles formed close enough to each other, they could collide. This collision should produce a measurable effect on our universe.
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There may be a lot of opinions expressed in this thread, ...
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More to the point a better response would be It's not known.. because saying your way might be taken that the individual doesn't know the answer when in actuality the answer exists whereas It's not known... means that science itself doesn't have a response.
In this case the question is meaningless in that different universes don't exist in a manner in which one can think of them as being spatially separated but distinct.
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More to the point a better response would be It's not known.. because saying your way might be taken that the individual doesn't know the answer when in actuality the answer exists whereas It's not known... means that science itself doesn't have a response.
Point taken, Pete. This links to Mordeth’s quote:
“Now, to answer your question, it would be the case that the space between these bubbles is inflating/expanding.”
Given that these bubbles exist, it is not known that space exists between then.
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This links to Mordeth’s quote:
“Now, to answer your question, it would be the case that the space between these bubbles is inflating/expanding.”
Given that these bubbles exist, it is not known that space exists between then.
Before I respond, I want to be want to be clear that I am not arguing in favor of eternal inflation. There is no empirical evidence of its validity. That said, Bill, the theory itself presumes that there is a background multiverse that creates bubble universes, like ours. It is this multiverse that presumably is eternally inflating. Further, it is posited that the space between each bubble is expanding as part of the overall eternal inflation. So yes, in the context of the theory, the space (multiverse) between bubbles expands. This "space" is an eternally inflating false vacuum. Your statement is simply irrelevant in this context, as "it is not known" if the theory is accurate at all in describing our universe. But again, in the context of the theory there is space between each bubble and it is expanding.
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That said, Bill, the theory itself presumes that there is a background multiverse that creates bubble universes, like ours.
It was interesting to see someone else who had arrived at the point I reached when I was looking at the difference between multiverse and bouncing universe ideas. This is from my notes:
“On the face of it the idea of an evolving sequence seems very different from the concept of a multitude of co-existing universes. Is it, though? If we stick with the majority view; namely, that our Universe had a beginning, and that time was created along with the Universe, then, presumably, in a multiverse, we have to accept that time is created along with every other universe. Each universe, therefore, exists with time as an integral part of its structure, but, outside the universes there is no time. It follows, therefore, that if time does not exist outside the universes, it makes no sense to differentiate between a succession of universes, on the one hand, and a collection of co-existing universes, on the other. If no time exists between, or anywhere outside them, there is no perceivable difference. If there is no space outside a single universe, it makes no sense to talk about where it exists. Similarly, if no time exists outside a single universe, it is nonsense to talk about when it exists. It seems reasonable to argue that what holds good for one universe must hold good for every universe in a multiverse. If we cannot say when each universe exists, we cannot distinguish between a sequence and a contemporaneous collection, because there is no discernable difference. There is, of course a "but" at this point. The eternal inflation theory avoids this problem by having innumerable universes constantly "bubbling" into existence, like a cosmic pan of boiling water. This does imply that time is not confined to each universe. Time must exist between the universes, and so presumably, must space.”
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So basically, nobody knows the answer to these things. Further adding to the confusion is the possibility that space and time, if they exist between the universes, may or may not be extensions of the three of space and one of time we are familiar with, and may in fact involve dimensions of which we are unacquainted. Perhaps such dimensions could be unrollments of the tiny circular dimensions hypothesized in string theory, and the dimensions we know might be rolled up in these other universes or between them. Or perhaps some other arrangements. Who can tell? It is a complete mystery.
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...Each universe, therefore, exists with time as an integral part of its structure, but, outside the universes there is no time.
Why do you think that there is no time in the multiverse? If it is expanding - the whole basis of the inflationary multiverse - and producing bubble universes, it must be taking time to do so. What happens inside each bubble universe is a continuation of that, although the characteristics of spacetime inside a bubble universe probably differs from that of the multiverse itself.