What Is the Time Scale for the Heat Death of the Universe?

[sadhu]

what is heat death of universe?

 

[mathman]

All stars are dead and the universe is the same temperature everywhere, so nothing more can happen.

 

[Bright]

and the universe is the same temperature everywhere

and because of expansion of the universe, this temperature tends to ZERO. :(

 

[sadhu]

well suppose all stars are dead then will the temperature of the universe equalise in a finite time period....

 

[DaveC426913]

well suppose all stars are dead then will the temperature of the universe equalise in a finite time period....

Correct.

 

[sadhu]

what does it mean

 

[Wallace]

well suppose all stars are dead then will the temperature of the universe equalise in a finite time period....

I think it is more of an asymptotic process, rather than something that happens in a finite time. You couldn't say 'heat death will occur in X billions years from now'.

 

[DaveC426913]

I think it is more of an asymptotic process, rather than something that happens in a finite time. You couldn't say 'heat death will occur in X billions years from now'.

It's certainly an asymptotic rate of cooling. But it doesn't have to reach equilibrium to be dead. At some point long before that, the universe will reach a point where there is no concentration of energy high enough to be able to sustain even modestly local entropy-reversing processes. Say, when all stars are no warmer than brown dwarfs.

 

[Wallace]

It would be interesting the know roughly what time scale this occurs on. From my vague memories of stellar evolution, I think it would take at least 100 Billions years or more for the current young small stars (which last the longest) to die out. Considering that there is still plenty of star formation in our own galaxy as well as others, and plenty of galaxy mergers still to occur it's probably well over 100 Billion years. That's quite a while considering the Universe is (only!) 13-14 Billion years old at present.