The dimensionality of space-time

[PB666]

http://nautil.us/issue/29/scaling/the-case-for-fewer-dimensions

So far, the theory that comes closest to explaining these dimensional gymnastics is known as asymptotic safety, a dark-horse candidate for quantum gravity that dates to the late 1970s. It supposes that gravity has a kind of built-in governor, rendering it “safe.†Features of gravity that we never see in daily life kick in near the Planck scale-http://nautil.us/issue/29/scaling/the-case-for-fewer-dimensions

So basically, since we haven't been able to fathom quantum gravity, other ideas pop up, such as how, on the quantum scale does gravity keep from turning the entire universe of matter into infintisimally small black holes. The argument, I think, is that because of quantum gravity, particles on the smallest scales don't hang in one place to long, they continue to shift in the quantum version of space time, and dimensionality (which defines 3D space) gives way to undefinable dimensionality that sort of works as one dimensional (at least for a particle to exist it does so at a point for unquantifyable amount of time).

Its quantum whack a mole (or kerbal).

The way this is explained if we go back into space, say a million miles and look at the coast of Great Britian we can draw a best path of the coastline. If you then take a picture for GSO, that path increases, alot because you have more detail, you still see the silloette of the earth, if you then take a picture for LEO that orientation begins to wane, you might have to look for local landmarks (where is spain, Ireland), but you can see alot more coastline. And finally if you then take a high resolution image from a cessna you get a very much higher detail but you would have to go back to the previous picture or use GPS to know what part of the coast you are on. Then finally you land the cessna on a beach and you see much longer coastline than you expect, the coast is moving with every wave, its not flat but three dimensional. Then if we went to a coastal rock we would see all the nuances of the rock, we might be looking up or sideways or down, the sense of east and west would be gone, and our dimensional space would be governed by the rock itself. So at the quantum scale space is ambiguous relative to macroscopic definitions.

And even if asymptotic gravity is not the ultimate theory, it might still be a useful stepping stone to a putative theory in which space emerges from an underlying spaceless level. “Between ‘no spacetime’ and ‘usual spacetime,’ there may well be ‘weird spacetime,’ †says Daniele Oriti of the Max Planck Institute for Gravitational Physics in Potsdam, Germany.

Ah but how useful is the zone of 'no spacetime', are we likely to be able to fathom anything at that scale. Ok, to keep from being a hypocrite I have talked about this here, where there could be a level of the universe where other 'behaviors' supercede that of known quantum physics. The problem is that its a hypothetical that gets away from the theory of relativity, because its a point beyond which relativistic physics has no say, its behavior a consequence of these behaviors acting on a large scale (mass action). Namely to get rid of complete relativity and argue that position from an event along one dimensional may have meaning, that not all points in the universe are equal as part of a coordinate system that manages things like dark energy or how quantum fluctuations behaves (See other thread on behavior of quantum fluctuations under high accelerations). This is all speculative stuff, certainly possible but not easily proven. So to give an example, it space is one dimensional in a way that connects everything back to the singularity, and everything is on a 1D track, but adjacent stuff can be related to each other. Lets say I could know my velocity to all other particles, then minimally I can see things moving out at the same velocity are all moving away from me, and things on the interior are moving out less quickly, etc. So now we have space-time to explain these relationships, but on the quantum scale everything is stastically in the same comoving 'structure' (plus or minus a few light beams) and so these relationships are less meaningful. What is important is how these entities manage their survival and keep from blasting the ability to interrelate by cavitating. The asymptotic safety is a way of managing this and may be the way quantum gravity transitions from planck's scale to relativistic space-time.

Is this actually quantum gravity, lol, that question is above my paygrade. lol.

The definitions here are highly circular, the universe could devolve into tiny black holes that eventually make all matter and energy disappear, but since it doesn't then we assume there are modulators. So if the force of gravity is prevented from acting to its nth degree on small scales, it might be coerced to acting at the larger scales in a much more diffuse way.

Reuter points out that the early universe did look scale-invariant: Density variations of every size had the same magnitude. This supports the asymptotic-safety theory, and a spacetime that is a fundamental feature of nature. But other theories offer alternative explanations for the scale-invariance.

I should add the density variations of the earliest phases of the universe were purely energetic, and the force particles that permit mass may have been too unstable at those energies. Although the question arises as to why.

The problem is this theoretical early phase of the universe is not visible to us, we do speculate on how things get so uniformly red-shifted at the limit of the visible universe and the answer is inflation, and the question of how inflation was triggered and the answer is that it was triggered by a highly energetic quantum singularity. As we then speculate on its qualities on being that space-time misbehave, in fact relativity may not have existed, and the only force of substance was quantum gravity, given the argument above it was not sitting around, and according to quantum mechanics is would sit in many variant places at once, not limited to space and possibly inflative. So this is an If and If and If argument, answer is we cannot be sure, its too far before the 1st opaque period. So how useful is having a theory that predicts the non-spacetimey misbehavior of the early universe.

The critical issue for us, its not how things work on a truely planck's scale, we will never see this and at best we see indirect effects of indirect effects; nor how it work in the massively dense energetic universe, but how these things affect rank-and-file spacetime, are there secret key points in which we can tweek the universe and make it giggle for us without having to use a Pentaelectronvolt supercollidor.

Edited October 8, 2015 by PB666

[justidutch]

Is it possible that the very edge of the expanding universe is still in a quantum state; the very edge is still in the one dimensional state leading to the runaway expansion?

Be advised I have no background in physics or maths or any sciences whatsoever, beyond high school.

[PB666]

yep..

[problemecium]

Familiar with MOND?

This isn't the only theory I've encountered wherein gravity doesn't perfectly follow the inverse square law as we'd always presumed. At this point I'm starting to have a hunch it really doesn't.

That parable with the satellite scans and the rock also reminds me of String Theory's ideas about tiny rolled-up extra spacial dimensions.