Scale invariance and bubble universes

[PhizzicsPhan]

Max Tegmark has provided a four part taxonomy of multiverse theories (http://arxiv.org/abs/astro-ph/0302131). The first type can be labeled the "bubble universe" multiverse, in which universes like ours are scattered throughout an infinite space in every direction.

Going the other direction, we have in the last century developed a good idea about the nature of the lowest level of reality - the realm of the quantum. There is of course much more to be learned, and much controversy exists over string theory and other theories that attempt to provide a reconciliation of quantum mechanics and GR, but we do seem to have reached in our theorizing and our experimentation the realm where the continuity we see all around us dissolves into discontinuity at the level of the very very small.

A related and very interesting outstanding problem in physics concerns the discrepancy in strength between gravity and the other forces - a difference of about 25-38 orders of magnitude. As of now, it seems no one has a clue why there is such a huge discrepancy.

If we live in a bubble universe, however, it seems we may speculate fruitfully about some of these problems. For example, might not our universe constitute a single quantum for a much larger universe? If this is the case, the strong and weak forces would be invisible from this level, as would EM, and only gravity would play a role. What would a universe look like if only gravity was operative? Further, could it be the case that other forces are hidden from our detection because we can't access the appropriate scale - whether above or below us in the grand chain of being?

 

[FlexGunship]

What would a universe look like if only gravity was operative?

Like the period at the end of this response.

 

[baywax]

"Universe' (universe |ˈyoōnəˌvərs|
noun ( the universe)
all existing matter and space considered as a whole; the cosmos". Can we use this term to describe separate "bubbles" of matter, anti matter etc...? or does the term apply to single and separate units of space, time, matter etc...?

Gravity, as I have been told here on the Physics Forum, is a form of "potential energy" it is not energy in itself but requires actual matter (energy) to "display" its "force".

Scale: here we sit at what we'd consider the middle of all the scales, micro and macro. Yet, that's only because we are here at our size and not giants eating galaxies or mini-humans dancing around on hadrons and sigmas. There are forces and axioms we have never dreamed of just beyond Pluto and just behind that neutrino that passed through my arm today. Whether we are able to observe them and study them doesn't stop the fact that those forces act on us every second of every day. Perhaps tracing the effect and results of these unseen forces back to their source is the only way to find them.