# Will the universe reach thermal equilibrium even though its expanding exponentially?

Empirical evidence supports that the scale factor is proportional to the following.

a(t) = e^(HT)

Where the distance between any two objects are

D(t) = a(t)Δx

Where x does not measure physical distance, but a conventional coordinate distance.

This means that eventually any physical distance (Even quantum wavelengths) will grow exponentially and eventually a big rip will happen. My question is how can the universe truly reach heat death or thermal equilibrium if its going to expand so fast in the far future? My intuition tells me that it will asymptotically approach maximum entropy.

## Answers and Replies

The effect of exponential growth of the scale factor will be negligible at the everyday scale. So I believe even though the distance between objects will keep increasing, the structures in the universe, galaxies and atoms etc would not be greatly affected. Of course the size of the atom would be slightly larger now but it won't break off. At those scales the atomic forces will be dominant.

The effect of exponential growth of the scale factor will be negligible at the everyday scale. So I believe even though the distance between objects will keep increasing, the structures in the universe, galaxies and atoms etc would not be greatly affected. Of course the size of the atom would be slightly larger now but it won't break off. At those scales the atomic forces will be dominant.

At first you may be correct, but the scale factor is exponentially growing. As t approaches infinity, a will become so great, it will eventually overwhelm the atomic forces.

I don't think heat death is the case (or the major concern, for that matter) in a Big Rip scenario. The observable universe of every particle would shrink much, much faster than the speed of light, so, heat cannot flow. You should search for both terms (Heat death and Big Rip) on Wikipedia; the articles are pretty good.