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Could there be a greater universe outside the known universe?


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This is speculation and I thought if I posted it here someone might let me know that it has been examined and rejected, or why it can’t be true because …


I have read some of the forums and there are quite a few posters who are knowledgeable in the areas that I am speculating about, and I am hoping to find someone who is willing to be helpful.


You can refer to me as a fringe character because I have no credentials, no formal training in science, and only internet exposure about physics and cosmology gained over the past two or three years. My imagination often gets me thinking about why can’t things be “such and such” a way, and if they were, wouldn’t “something that I can imagine” follow from that.


Clearly we are in an expanding known universe, and recent evidence shows that the rate of expansion seems to be accelerating. The expansion is consistently the same no matter where we look, and everything is receding in such a way that there appears to be no center or leading surface or edge to the known universe.


I have read about why this is the case and the standard cosmology seems to represent this effect as being the result of the idea that as the known universe expands, it is making its own spacetime as it goes (the raisin bread rising in the oven analogy). Therefore, and in accord with general relativity and the cosmological principle, the curvature of the known universe, whether open or closed (probably open), curves the light traveling to us from all directions so there is really no “straight” line of sight.


I am thinking that the exact same thing would happen if, instead of the universe creating spacetime as it expands, it was expanding into a much less dense space surrounding the known universe. Spacetime would be just about as curved as if it was creating spacetime as it goes, and there would still be no detectible center or edge or surface of expansion due to the relativistic curvature of spacetime.


The expansion into a less dense space, meaning substantially empty space, would still provide an environment where the curvature of the known universe would not be interfered with from the surrounding outside area, and light coming to us from within the known universe would be curved just the same.


If this is the case, I can imagine a greater universe out there that our known universe is expanding within. Other thoughts come to mind that I would like to speculate about here if this idea is not already proven to be wrong or calculated to be impossible.


Can someone help me understand if my idea is acceptable or not even though it can’t be proven, or even tested, i.e. is anyone likely to be interested in talking about it?


I wouldn't mind vetting my ideas by PM with anyone who would be willing to give them a "once" over before I post them in a forum.

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You can get "less dense" space? (im not sure, isnt density a property of matter?)


it seems acceptable as any other theory out there, like you said, with current technology it cant be tested and thus cant be proven. Its not an old idea though, i think i have come across it somewhere before.

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You can get "less dense" space? (im not sure' date=' isnt density a property of matter?)


Density is associated with matter, in fact D = M/V (density equals matter divided by volume).




As I understand it, in space, there is a vacuum density and there is matter/energy density. The cosmological principle says that spacetime can be defined by the relationship between vacuum energy and matter/energy density. The cosmological constant is referred to as the vacuum energy density of the universe. That constant defines the "shape" of the universe, i.e. open, flat, or closed.


My OP acknowledges that our known finite universe is expanding and the expansion seems to be accelerating. The acceleration could be due to the difference in the density of the matter/energy of the known universe, and the vacuum energy or negative pressure surrounding the known universe.


My point was it seems that from within our know universe we cannot determine whether the big bang universe is creating spacetime as it expands, or if it is expanding into less dense space (negative pressure of vacuum energy). Either way the curvature of spacetime in the known universe would make it impossible to detect a center or an edge and everything would appear to be receding from us no matter which way we looked.


And if we are expanding into an area of negative pressure, then there might be a greater universe in which our known universe exists and expands.


I was hoping someone could confirm that the fact that we can't detect a center or an edge to the known universe does not exclude the possibility that we are expanding within a greater universe.


I'm wondering if the Big Bang could be an event preceded by a big crunch that formed in the greater universe?

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I'm wondering if the Big Bang could be an event preceded by a big crunch that formed in the greater universe?

I guess the answer to the question posed in the OP (Could there be a greater universe outside our known universe) is, it depends.


If you believe in the view that spacetime is being created as the universe expands, then there was and is no spacetime before or beyond the Big Bang, and the answer to the question is no.


If you believe that the curvature of spacetime that makes it impossible to determine if there is an outside universe, then the answer to the question is you don't know.


That is where I am. I don't know. I don’t think we can know until new evidence is uncovered.


The test of any theory that posits a greater universe as opposed to an endlessly expanding known universe lies in the eventual outcome. Do we expand and create spacetime until the universe suffers complete entropy where all useful energy has been spent, or do we expand until the known universe encounters the matter/energy of the posited outside universe.


Such an encounter would be cataclysmic as our galaxies merged and mingled with the older colder objects that would likely occupy a greater universe capable of generating our known universe from its constituents; maybe an outside universe spatially infinite and infinite in matter/energy.


Such cataclysms would create bursts of gamma rays and cosmic rays which would be clues to the encounter. The signature of those bursts, their frequency, and their widely dispersed direction may eventually give scientists the clues they need to confirm the existence of an outside universe.


So if there is an outside universe the proof would be in the encounter between our known universe and the fringes of that greater universe. We just have to wait and see I guess.


Could "wait and see" be considered enough to make a theory that posits a greater universe testable?

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Could "wait and see" be considered enough to make a theory that posits a greater universe testable?

Wait and see is pretty weak as a test for a greater universe I guess' date=' but let me run another thought by you.


It has to do with the density of the known universe and the balance between the density of matter in the universe with the density of vacuum energy. If there is no such thing as vacuum energy, then the matter energy of the universe equals one. If there is vacuum energy then the sum of the matter energy and vacuum energy equals one and each of the two components make up a percentage of the total.


"The recent matter density ΩM and vacuum energy density ΩL for current data from supernovae (Knop et al. 2003), cluster measurements (based on Allen et al. 2003), and CMB data with H_0 priors (outer contours: Lange et al. 2001, inner: Spergel et al. 2003). These results rule out a simple flat ΩM=1, ΩL=0 cosmology, and indeed the supernovae data rule out cosmologies without vacuum energy. Their consistent overlap is a strong indicator for dark energy dominating the universe with some 70% of the energy density. Also shown is the expected confidence region from just the SNAP supernova program, for ΩM=0.28, ΩL=0.72."


Now science is thinking that this "dark" energy exists within the known universe and is offsetting, in fact more that offsetting the force of gravity in the known universe, resulting in the acceleration of the expansion.


The SNAP project, if it gets funded, will be able to more accurately measure the rate of expansion of the universe and will provide a wealth of new information about "dark" energy.


Now correct me if I'm wrong, but the "dark" energy is now being suggested as 1) the reason why galaxies aren't collapsing faster, and 2) at the same time it is the reason why the known universe is expanding faster (accelerating).


[Edit] Actually the question with galaxies might be why they aren't flying apart faster due to their rotational energy. The answer to that question would be the negative pressure caused by the outward rotation as matter is displaced away from the center of the galaixes. This negative pressure or "dark energy" would slow the outward movement.


They think that "dark" energy within the known universe causes the expansion of the known universe to accelerate and a "dark matter" effect slows the outward expansion of galaxies. Makes sense doesn't it? I think that the dark matter and dark energy are one in the same. Dark energy outside the expansion, or inside the expansion would have the same effect as dark matter. It is just that the operative force of dark energy is negative pressure, and the operative force of dark matter is gravity.


My thinking is that the cause of both the slowing the expansion or the collapse of galaxies and the acceleration of the expansion of the known universe is in fact due to this "dark" energy (the negative pressure of vacuum energy is the same as dark energy), but the cause of the "dark" energy is the displacement of matter energy, not some fixed mix of the two. I suggest that displacement of matter energy due to the relativistic curvature of space and the resulting attraction of bodies in space leaves "dark" energy or call it vacuum energy or negative pressure in the area from which the body was displaced.


If my thinking is correct, the slowing of the collapse of galaxies is due to vacuum energy (negative pressure) caused by the inward displacement of the in-swirling (or just accumulation toward the center) matter energy in the galaxy. If so, the resulting negative pressure due to displacement would slow the collapse.


Also, if my thinking is correct, the acceleration of the expansion of the known universe is caused by this same kind of negative pressure that was caused by the accumulation (inward displacement of matter energy) of a big crunch that might have preceded the Big Bang.


If my thinking is correct, then there is a greater universe within which there was a big crunch that lead to our big bang, and the formation of that big crunch left negative pressure (vacuum energy) as it accumulated. Our known universe is now expanding back into the area (call it an arena) from which it was accumulated, and the vacuum energy that was caused by the earlier inward crunch (inward displacement) is now the cause of the acceleration in the expansion that has recently been noticed.


Do you see the subtle difference between "dark" energy existing within the known universe, and "dark" energy existing outside the known universe? Do you at the same time see the subtle difference between "dark" energy existing within a collapsing galaxy, and "dark" energy existing outside of a collapsing galaxy?


Now to add to the confusion :), as the known universe expands, matter energy is being displaced outward, and that displacement is causing "dark" energy within the expansion. The only difference is that "dark" energy within the expansion is growing and will eventually offset the negative pressure of the "dark" energy outside, and the expansion will begin to slow.


Thus, another test of a greater universe would be the acceleration of the expansion while the outside "dark" energy was greater than the inside "dark" energy (like now), and then the gradual slowing of the expansion as the inside "dark" energy grows and the outside dark energy gets "used up" (the prediction).


Unfortunately again it is a "wait and see" test, though it should occur before the predicted merging and mingling predicted earlier.

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Let's revisit the earlier premise about whether space exists outside the big bang or not.


On another board, Rog posted:


As I understand it the universe behaves like a plum pudding so that the dough (space) of the pudding expands whilst the plums just move with the dough. So in this scenario the galaxies in the universe move with space rather than through space. If' date=' however, the universe is expanding into already existing space then the galaxies would be moving through space with respect to each other. This relative motion would have the effect of breaking time symmetry so that the time would be desynchronized in different galaxies and it would be meaningless to talk about the age of the universe since no two galaxies would agree from their own perspectives. Also galaxies would increase in speed through space the further they were away from us so that galaxies a certain distance from us would recede at speeds greater than the speed of light which is ruled out by special relativity.


R[/quote']I agree with all that. From within the big bang there is no detectable center or edge. Galaxies are moving apart consistently in all directions.


The reason it appears that way is due to the curvature of space. Galaxies are moving away from each other in curved paths due to the mass/energy/motion of the rest of the finite universe. Light coming to us from those galaxies is curved as well.


Because the universe is expanding, it is increasing in volume, and any volume has dimensions. We just can’t see the surface (edge) or detect a center because of the curvature of spacetime. There is an edge or surface leading the expansion. The curvature of space at the “edge” is so great that light coming from there covers an arc and is red-shifted so it appears further from us than it really is.


It wouldn’t matter if we were expanding into existing empty space or if space was being “created” by the expansion. It would look the same from inside.


If anybody can refute this with a link from an accredited source or even a brief explanation of why it is not plausible, I would appreciate it.

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  • 4 weeks later...

There is a difference between the Universe and the Observable Universe. The Observable Universe is limited by the distance light could have traveled since the Big Bang (space can move faster than light, don't ask me why, but plenty of people who say they're experts say so).


If, and this seems very unlikely to me, the space just beyond the Observable Universe is less dense than normal, it would appear that the Universe's accelaration is expanding.

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