# Dark energy and oscillating universe?

1. Jul 6, 2004

### kurious

If I take two spherical regions of space about one metre in radius,
they would contain about 10 ^ - 27 kg of dark energy each.
If I now say that the centres of these regions are one metre apart,
and assume that there is rest mass associated with dark energy (this rest mass being uniformly distributed in each of the spherical regions),
then using Force = G m1 m2 / r^ 2 I would get a force of attraction
for the spheres of 10^ -11 x 10^ -27 x 10^ - 27 / 1 x1 = 10^ -65 Newtons.

If these two spherical regions obeyed Hooke's law F = - constant x extension
then 10^ - 65 = k x 1 (I am assuming that earlier in the universe when it was smaller the centres of the spheres converged and at equilibrium there was no distance between them)
k = 10^ -65
Let's postulate that the universe oscillates regularly between a big bang and a big crunch.

The frequency of a harmonic oscillator is given by:

w = ( k/m)^1/2

w = ( 10^ -65 / 10^ -27) ^ 1/2

w = 10^ -19 s^-1.

So the universe would oscillate once every 10^ 19 seconds.
Is my calculation a valid calculation?

2. Jul 6, 2004

### Antonio Lao

Experimentally, it will take over 300 billions years to verify your calculation.

3. Jul 10, 2004

### geistkiesel

I don't kow about your calculations but your Big Crunch physics has a problem. Using Hubble logic the stellar matter is supposed to reverse direction and head back to the center of it all, compress as pre-Big Bang and let 'er rip once more, right?

It can't happen anything like that. Even if there was a total reversal of expanding stellar matter in straight lines back to the center point, there will come a time when gravity effects start pulling the stellar matter together at huge velocities that would impart large deviations from the straight line trajectories. Slingshots like you've never seen! Nothing would crunch, it would just redistribute in the universe.
I'd rather watch Mayberry reruns.

4. Jul 10, 2004

### force5

geistkiesel is right!

I agree with everything you said. At the end of cosmic expansion, there will be no stellar mass around to reverse direction. At that stage, there will only be dark matter and dark energy. The dark matter will contract and eventually begin sucking up all of that dark energy like a big sponge until DM and DE are reunited as one. Then and only then will the cycle be complete and ripe for the next BB.

I think I'll go watch Andy now.