stretching space

[lemur]

What if instead of thinking of the early universe of the big bang as expanding spacetime in some abstract sense, you just thought of it as a small, dense ball of matter? Then, think of the expansion of that ball as a process of stretching the contents out despite a limited amount of space between them. So instead of the contents "expanding into" space, they are actually stretching space between them like trying to expand a vacuum within the atmosphere. Another way to describe this would be to say that gravity originated as perfectly contracted spacetime and henceforth began expanding to allow more distance between particles/objects, yes some areas remain(ed) less expanded (e.g. galaxies, stars, planets, interstellar clouds, etc.) In this way, would it be necessary to view gravity as a force, or could it be viewed as simply varying degrees of expansion of spacetime? Also, could it be that the expansion was caused not by a "bang," i.e. pushing force from the center, but rather a "pull" as its surroundings were drawn outward for some reason?

Edited May 20, 2011 by lemur

[md65536]

What if instead of thinking of the early universe of the big bang as expanding spacetime in some abstract sense, you just thought of it as a small, dense ball of matter? Then, think of the expansion of that ball as a process of stretching the contents out despite a limited amount of space between them. So instead of the contents "expanding into" space, they are actually stretching space between them like trying to expand a vacuum within the atmosphere. Another way to describe this would be to say that gravity originated as perfectly contracted spacetime and henceforth began expanding to allow more distance between particles/objects, yes some areas remain(ed) less expanded (e.g. galaxies, stars, planets, interstellar clouds, etc.) In this way, would it be necessary to view gravity as a force, or could it be viewed as simply varying degrees of expansion of spacetime? Also, could it be that the expansion was caused not by a "bang," i.e. pushing force from the center, but rather a "pull" as its surroundings were drawn outward for some reason?

If the universe were thought of as an expanding (inflating) ball... (it might not be valid to do this)...

 

Yes, I think you could define a changing measure of distance, such as "one unit = radius of the universe". Then using that measurement, the universe remains a ball with radius of one unit, and everything inside it shrinks and contracts into "patches" of greater density.

 

You might be able to reconcile gravitational acceleration with the equivalence principle, in that a frame under the influence of gravity is equivalent to an accelerating frame.

Perhaps something like... the strength of a gravitational field is related to the rate at which it contracts.

 

Everything shrinks relative to the size of the universe, so it always seems like there is more room in the universe... it appears to be expanding relative to everything.

 

 

Upon re-reading your post, I don't think this is what you're talking about.

When you say "expand a vacuum within the atmosphere", do you imagine pushing everything else out of the way, so that the atmosphere (analogous to the universe) remains the same size, and everything outside of the vacuum gets pushed together (analogous to gravity)?

Or do you imagine that the atmosphere is being pulled larger, and everything in stays where it is, so that the distance between things remains the same but those distances diminish relative to the increasing size of the atmosphere? If you mean the latter, then no I don't think that the expansion of the universe explains the effect of gravity.

 

 

 

One interesting side-effect of imagining the size of the universe being fixed and the size of everything else changing relative to that is this: If the universe started out as a singularity, couldn't it be considered to still be a singularity?

[Light Storm]

I'm all about alternate theories to 'infinite amount of matter appeared and exploded' but I'm not sure about this one. What is the outside force pulling it apart?

[lemur]

Upon re-reading your post, I don't think this is what you're talking about.

When you say "expand a vacuum within the atmosphere", do you imagine pushing everything else out of the way, so that the atmosphere (analogous to the universe) remains the same size, and everything outside of the vacuum gets pushed together (analogous to gravity)?

Or do you imagine that the atmosphere is being pulled larger, and everything in stays where it is, so that the distance between things remains the same but those distances diminish relative to the increasing size of the atmosphere? If you mean the latter, then no I don't think that the expansion of the universe explains the effect of gravity.

I find the insights in your post interesting, but I was not so much talking about relativizing the units as you seem to be saying. When I used the "expanding a vacuum with the atmosphere," I was just referring to the atmosphere as a source of vacuum-force for the expanding empty volume. In other words, expanding a vacuum-volume in outer space doesn't create more vacuum force because there's no external pressure acting on the walls of the vacuum. So what I'm really saying is that a ball of matter could have internal cohesion among the particles in such a way that they could be "stretched away from each other." So, if you look at the large distances between galaxies, for example, you would think that these distances are just stretched surfaces of contact between the galaxies, which used to be contiguous. It would be sort of like looking at the continents as drifting away from each other except the space between them would be viewed as contracting-force that is slowing losing its cohesion as it gets stretched.

 

One interesting side-effect of imagining the size of the universe being fixed and the size of everything else changing relative to that is this: If the universe started out as a singularity, couldn't it be considered to still be a singularity?

Yes, I find it interesting to imagine that the big bang is actually the experience of a black-hole singularity from the inside, but that doesn't really relate to the issue of this thread. I'm more focussed on the issue of space between galaxies as streched-out cohesion between previously contiguous matter. E.g. like if you had a ball of matter alone and pulled it apart despite its internal cohesion, it could grow more voluminous though the gaps between the surfaces of the fragments would just be expanded versions of the microscopic gaps that were there when the fragments were still connected.