Could Dark Energy lead to a big bang?

[newjerseyrunner]

I had a thought a while ago, but it was removed because I cited a youtube video of physicists talking rather than papers, so I'll have another go.

My thought was that the universe could be cyclical and infinite even if heat death is the eventual end of the universe as we know it. During the big bang, inflation could have caused virtual particles to not be able to annihilate each other because space expanded faster than light (Hawking radiation.)

The universe is known to be expanding and accelerating because of dark energy. When calculating all of the known forces out (fully aware that our understanding of the universe is incomplete,) we determine that the universe should die of heat death with entropy increasing to the maximum and space expanding forever.

So that brings me to my question: if dark energy causes the universe to expand faster and faster, eventually, shouldn't it get to such a degree that it's expanding faster than light again? It this point, wouldn't the virtual particles that are constantly created and destroy be unable to destroy each other and suddenly fill the universe with gamma rays and basically start the whole of cosmic evolution again?

 

[Chalnoth]

As far as we know, dark energy doesn't cause the universe to expand faster and faster. The rate of expansion is still slowing down, and the simplest models have the rate of expansion gradually slowing to a constant value (given by the cosmological constant).

This is called an accelerated expansion because if the expansion rate is constant, then things get faster as they get further away from one another, so that objects within the universe are accelerating away from one another.

 

[newjerseyrunner]

Oh ok, so the universe is accelerating because of scale, but the expansion at the scale of virtual particles, it's actually slowing? I didn't know that, thanks.

 

[Chalnoth]

Oh ok, so the universe is accelerating because of scale, but the expansion at the scale of virtual particles, it's actually slowing? I didn't know that, thanks.

The rate of expansion is defined as velocity over distance. That is, at a given rate of expansion, a galaxy that is twice as far away is receding twice as fast. If that rate is a constant, then as things get further, they recede faster.

Virtual particles don't come into it.