Quora answer: Spacetime: Can a star which is billions of light years away be actually next to us in a higher dimension?
The exact answer to this question I do not know, but would like to know as well. But what I do know is that hyperspheres get larger and then smaller again as you go up the ladder of dimensions. They peak out between five and seven dimensions in terms of surface area and size. Then they get smaller and smaller the higher you go. Right now M theory is 11 dimensional. F Theory is 12 and 14 dimensional. To my mind we could interpret this fall of in the size of hyperspheres as gathering things in the universe closer together because each higher hypersphere contains the lower hyperspheres. And one speculation is that the nth degree of dimension, i.e. the highest whatever that is or perhaps even infinite degree occurred at the Big Bang. Under that assumption we could see what is happening as the Universe cools as producing lower and lower dimensional asymmetries. It seems to be if that were true then it could be that at the highest dimension that the universe could be at the Big Bang still gathers the entire universe in a very compact space in that dimension, and expansion in some sense comes from the unraveling of dimensionality down to the place where it widens out below the level of M theory. Not sure whether physus take this expansion of the size of hyperspheres as we come from an arbitrarily high dimensions down to a lower dimension into account. I think they are assuming that the universe has a set dimension. But it seems the truth of unification of theory and perhaps the multiverse theory as well might be something like this:
In the Multivese which is a very high dimensional plasma and thus with hyper sphere radii that are very small and thus it is very compact, probably less than Planck length by a lot, some asymmetry occurs which causes the dimensionalities within these high dimensional hyperspheres to start to unravel, and perhaps it is at the barrier of Planck length that the actual big bang occurs, but regardless during the Big Bang this unfurling is still happening until we get down to dimensions at which the size of the hyperspheres get much larger, and this itself could account for the expansion of the universe and dark energy. In other words in this speculation dark energy is really the expansion of hyperspheres that occurs at lower dimensions eventually we hit the F theory and then the M theory levels, and the unraveling continues until the universe hits the fourth dimension, and at that point a phase change occurs because the fourth dimension has no set topology and thus that is where our physics is rooted with its set constants for the universe, but then a further symmetry breaking produces three dimensionality and the asymmetry between spacetime or timespace and that the realm we experience, but the actual universe itself is four dimensional and that is inscribed in relativity and quantum mechanics and their use of imaginary numbers in their formulation.
If this picture were true it would explain a lot. It would explain dark energy as merely the continued unfolding of the higher small dimensions into the larger big dimensions which then produces an expanding universe. In this theory the universe is expanding because it is unraveling into lower dimensions and they are bigger than the containing dimensions. If lower dimensions are bigger than the containing dimensions that is going to produce an inflationary pressure. If that unraveling is continual rather than just something that happens once and then is set, then that is a constant inflationary pressure. But to your question, we are still nested in these very small hypespherical high dimensions at the same time we are in the lower ones that are bigger and so in this sense we are right on top and gathered to everything in the universe all the time at these higher dimensions. But whether as three dimensional creatures we could travel in them is another question, and that is to my mind doubtful. But another consequence of this idea is that it might explain some of the structure of the universe in as much as there is a concentration of mass in the universe. These hyperspheres get larger until they get to around the fifth or seventh dimension in terms of size and volume but then they get smaller until they get to the fourth and third dimensions. In the fourth dimension there is no set topology so that is like reaching a point that is fully freeform and where there is perfect movement which is like an Bose-Einstein condensate. I think that the paradoxes at the Planck scale may be resolved by this topological anomaly. But then the symmetry breaking out of that produces spacetime/timespace out of the matrix of four dimensional time or four dimensional space, which together is eight dimensional. These eight dimensions occur within the fourth dimension as the double covering of that space by the Octonion. So with respect to the Octonion it is as if four dimensional space were folded back on itself and that folding is the difference between four dimensional space and four dimensional time and all possible symmetry breaking between time and space between. The fact that there is perfect motion within the fourth dimension, and the fact that spacetime/timespace is folded in that dimension though the octonion suggests that it might be possible to slip through if we were able to actualize ourselves at that level because there should be no topological constraints and the folding in the Octionin suggests that there is some sort of reflexive superpositioning of the matrix on itself.
If it is true that we are nested in higher dimensional hyperspheres of some arbitrary high dimension then actually everything that is spread out as spacetime or timespace is literally interprenetrated, and we know that effect physically as entanglement under Bells Theorem which has proved to be correct. Since all matter in the universe was together at the big bang that means everything in the universe is entangled with everything else. So this leads to a second argument for interpenetration of everything which is the Mahayana position of Fa Tsang and other nondual philosophies in other traditions as well.