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

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Discussion Overview

The discussion revolves around the concept of the heat death of the universe, exploring its implications, time scales, and the processes involved. Participants engage in a conceptual examination of the conditions leading to heat death, including temperature equalization and the fate of stars.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants define heat death as a state where all stars are dead and the universe reaches a uniform temperature.
  • There is a suggestion that the universe's temperature tends towards zero due to its expansion.
  • One participant questions whether the temperature of the universe can equalize in a finite time period if all stars are dead.
  • Another participant argues that the process of temperature equalization is asymptotic, indicating it does not occur in a finite time frame.
  • It is proposed that the universe may reach a state where energy concentrations are insufficient to sustain entropy-reversing processes long before achieving thermal equilibrium.
  • A participant estimates that it could take at least 100 billion years or more for current young stars to die out, suggesting that the timeline for heat death may extend significantly beyond this period.

Areas of Agreement / Disagreement

Participants express differing views on whether the temperature equalization process can occur in a finite time frame, with some arguing for an asymptotic process while others suggest a finite timeline may be possible. The discussion remains unresolved regarding the exact time scale for heat death.

Contextual Notes

There are limitations in the assumptions made about stellar evolution and the implications of cosmic expansion on temperature equalization. The discussion reflects varying interpretations of these processes without reaching a consensus.

sadhu
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what is heat death of universe?
 
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All stars are dead and the universe is the same temperature everywhere, so nothing more can happen.
 
mathman said:
and the universe is the same temperature everywhere
and because of expansion of the universe, this temperature tends to ZERO. :(
 
well suppose all stars are dead then will the temperature of the universe equalise in a finite time period....
 
sadhu said:
well suppose all stars are dead then will the temperature of the universe equalise in a finite time period....
Correct.
 
what does it mean
 
sadhu said:
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'.
 
Wallace said:
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.
 
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.
 

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