Energy and the end of the universe.

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SUMMARY

The discussion centers on the concept of energy conservation and the implications of entropy in the context of the universe's fate, specifically addressing the "heat death" scenario. Participants clarify that energy can be categorized as "free" or "not free," with the latter leading to a state of thermal equilibrium where no physical changes can occur. The conversation highlights that while energy is not destroyed, its capacity to induce change diminishes, leading to a statistical understanding of entropy. Additionally, the notion of quantum fluctuations suggests that the heat death may not be the definitive end state envisioned by 19th-century physicists.

PREREQUISITES
  • Understanding of thermodynamics, particularly the laws of energy conservation.
  • Familiarity with the concept of entropy and its role in energy transformation.
  • Knowledge of quantum mechanics, especially regarding fluctuations and particle decay.
  • Basic grasp of astrophysics, including stellar processes and the lifecycle of matter in the universe.
NEXT STEPS
  • Research the implications of entropy in thermodynamic systems.
  • Explore the concept of quantum fluctuations and their effects on energy states.
  • Study the current theories surrounding proton decay and its significance in particle physics.
  • Investigate modern interpretations of the heat death of the universe and alternative end-state scenarios.
USEFUL FOR

Astrophysicists, theoretical physicists, and anyone interested in the long-term fate of the universe and the principles of energy dynamics.

mee
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If energy can neither be created or destroyed, why is there supposedly a "heat death" or any sort of death to the universe.
 
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Energy can be free or not. If it's free it can do things, if it's not the only thing it can do is make heat. If the heat is the same temperature everywhere, nothing physical can happen on the larger scale. Entropy is the conversion of free energy into heat energy. The energy is not destroyed but its ability to effect change is no more.

This is now seen as a statistical effect, of the more probable states succeeding the less probable ones. And there could always be a quantum fluctuation, so the heat death is not the ultimate last thing the nineteenth century physicists envisioned.
 
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heat and energy

selfAdjoint said:
Energy can be free or not. If it's free it can do things, if it's not the only thing it can do is make heat. If the heat is the same temperature everywhere, nothing physical can happen on the larger scale. Entropy is the conversion of free energy into heat energy. The energy is not destroyed but its ability to effect change is no more.

This is now seen as a statistical effect, of the more probable states succeeding the less probable ones. And there could always be a quantum fluctuation, so the heat death is not the ultimate last thing the nineteenth century physicists envisioned.

I assume by non free energy you mean matter and by heat you mean fusion or like in the Earth's core perhaps. Does heat not mean like in the cores of stars? Would this heat not effect change like fusion? Will there perhaps be a universe which is full of higher elements with new types of structures we currently don't understand coming into being? Are you basically telling me that "heat death" of the universe is an outdated concept?
 
No, by not free I mean energy confined to jiggling, with no temperature differential anywhere. Matter is unstable on the longest scale (protons eventually decay even in the standard model), so that eventually we are talking about a bath of photons at equilibrium.
 
Thank you.

selfAdjoint said:
No, by not free I mean energy confined to jiggling, with no temperature differential anywhere. Matter is unstable on the longest scale (protons eventually decay even in the standard model), so that eventually we are talking about a bath of photons at equilibrium.

But we have never actually detected a proton decay right?
 

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