# Space Elasticy

1. Apr 16, 2008

### L3v3L

Ok first off I would like to state that I don't know much about physics and am very grateful to anyone who had the kindness to help me out.

The first and only time some one ever explained to me how gravity worked, they got a rubber surface and put a heavy ball on it, making the sheet of rubber bend. So because i have no idea what units or scientific words ill try and use what i can :D

First off i would like to know if the elasticy of space is constant, if earth would cause the same warp effect on space here and in any other part of the universe.

If so has this constant always been the same, was the elasticy what it is today what it was at the early stages of the universe?

I thought about all the answers that my ignorant mind could come up with, and what i understand is that if it has always been constant, even at the early stages of the universe, where there was larger density wouldn't more black holes pop up at that stage? and if it isn't constant and gradually getting weaker as the universe expands and stretches the fabric of space would that make blackholes occur more at that stage?

I don't know what reply i might get, but id like to ask all my questions in just one post, and take the beating all at the same time, so taking everything I put into account, what implications would this have on time, as space and time are seen as one, constant elasticy or a variable elasticy would have an effect on time right?

Thank you again, oh and sorry for my drastic attempt at english writing.

2. Apr 18, 2008

### Staff: Mentor

Hi L3v3L, welcome to PF.

The rubber-sheet analogy is a very imprecise analogy. It is not really best to think about it in terms of elasticity. I wouldn't recommend taking it too seriously.

That said if you look at the Einstein field equation:
$$G_{ab} = {8\pi G\over c^4} T_{ab}$$

you will see that $$T_{ab}$$ is the stress-energy tensor, so I guess in some sense you could consider $$G_{ab}$$ a strain with an elasticity of $${8\pi G\over c^4}$$. However, don't take that very literally.

Regarding the constancy of $${8\pi G\over c^4}$$ between the beginning of the universe and now: I have no idea.

Last edited: Apr 18, 2008