I must be missing something....

I posted this question in the hubble video thread, but I didn't really get an answer, so I'm posting it here.. (Not sure this is even the right spot). Anyway, here it is:

I need to understand something, and maybe someone here can explain this to me. The universe is 15-20 Billion years old according to our scientists. The universe is also 78 Billion lightyears across. Everything supposedly started from the Big Bang. If nothing, except light, can go as fast as light, why is the universe spread out so large?

Basically what I'm saying is, when the big bang happened, poof.. there was everything, which would have traveled in all directions. Given that we buy into Einsteins theory, and that any object that approaches the speed of light, its mass approaches infinity, how is it then that the universe spans 78 billion light years? Given the two fastest objects, let's even say they went the speed of light and had continued at that speed from the time of the explosion in exact opposite directions, to now, shouldn't those two objects should only be a MAXIMUM of 30-40 billion lightyears away from eachother?

I HAVE to be thinking about this incorrectly... It's either that or they all admitted they were wrong without even knowing it...

I'm sure the answer is very simple, but I can't find the flaw in my logic. Maybe someone can give me some insight

Your logic is indeed flawed because you ignore that it is the fabric of space itself that has [expanded]. At the moment of the Big Bang, matter did not actually move relative to the space it resides in.

[edit on 1-10-2006 by apc]

True, the fabric of space-time itself is expanding, carrying everything along for the ride. This isn't to say matter doesn't move freely though space as well though. I think of the expansion of space more like the expansion of our special dimensions.

Here's an example: Say you had a bowl of dough. In that dough matter is represented by raisins. The raisins can move within the dough but very slowly because of the viscosity of the dough. The raisins have a maximum speed they can achieve limited by the medium itself. Now we put that dough into an oven and it expands rapidly. The raisins move away from each other faster than they can move by themselves. The dough is expanding faster than the limits of speed within itself carrying the raisins with it.

Matter itself cannot exceed the speed of light without obtaining an infinite amount of mass. However space-time itself is not bound buy this rule, so the universe can expand as fast as it likes for space itself is the medium that governs the speed of light.

The expansion of the universe shouldn't be limited to the rules that it enforces within itself.

However here's a question that stumps me. If matter is made up of mainly empty space, and the universe is expanding in all directions around us, does this mean that we too are expanding, but cannot observer it because we have nothing to compare it to?

If everything is made up of mostly space and space is expanding equally in all directions, then matter itself must also be growing for atoms themselves are mostly made up of space.

Using the earlier example, its like saying the raisins are also made up of dough and therefore should be expanding too.


[edit on 2-10-2006 by Toasty]

Ah ha! Makes perfect sense, thanks Toasty My problem was I was thinking of space as just .... well, space, not consisting of anything.

We have only guesstamates on how the universe even functioned in the early times much less how time, distance and spacial volume interacted.

Originally posted by Toasty
However here's a question that stumps me. If matter is made up of mainly empty space, and the universe is expanding in all directions around us, does this mean that we too are expanding, but cannot observer it because we have nothing to compare it to?

If everything is made up of mostly space and space is expanding equally in all directions, then matter itself must also be growing for atoms themselves are mostly made up of space.

Using the earlier example, its like saying the raisins are also made up of dough and therefore should be expanding too.

That depends on if there is a "unit" of space. I suspect there is, and that this unit in one form is the fabric of space. In another form it is gravity. When the unit is reverted from gravity back into space, we observe gravitational attraction, as the fabric units increase in number.

Therefore, no. The distance between objects held in a fixed position or orbit retains a static number of units between them. Any units added would just cause movement of the center of mass relative to the source of the added units.

This would also be a mechanical explanation for expansion.