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> how can there ever be a shortage of energy I think it's not so much a shortage of energy, but that there thermodynamic equilibrium and thus no available ener

> how can there ever be a shortage of energy I think it's not so much a shortage of energy, but that there thermodynamic equilibrium and thus no available energy to do anything. I don't think this will ever happen tho, it's pretty clear to me that making energy more dense is a universal process.

sghiassy 3y ago
Not really - look up “heat death” of the universe.
- jjaken 3y ago
  Heat death doesn’t mean “no heat” or that energy has depleted. It just means that energy is fully dispersed. All kg the hear exists, it’s just that no one place has any more than anywhere else, and so there is no longer any transfer of energy.
  - A_D_E_P_T 3y ago
    > so there is no longer any transfer of energy. Ah, but there is. The Second Law is a statistical law, not an absolute law. On long enough timescales, low-probability fluctuations in local entropy will allow for energy transfer. These fluctuations will also allow for the formation of structures. (Boltzmann himself was of the opinion that the low-entropy universe emerged from a higher-entropy background state. And indeed there's nothing in physics to rule out the emergence of Boltzmann Brains and even Boltzmann Galaxies from homogeneous and maximally entropic universes in "heat death." This is a philosophical problem of the highest order, because it implies that we're not necessarily going from "less likely to more likely states" as the video implies, but rather from a relatively deterministic state to a probabilistic state.)
    - jjaken 3y ago
      Oh interesting, I didn’t know that
- credit_guy 3y ago
  The "heat death" of the universe is a concept that deserves to die. The second principle of thermodynamics is true only if you ignore gravity. In the presence of gravity, systems tend to go towards lower entropy, just see how a planetary system can form out of a gas cloud.
  - consilient 3y ago
    > In the presence of gravity, systems tend to go towards lower entropy, just see how a planetary system can form out of a gas cloud. This isn't correct: the entropy (and energy) of the gas cloud goes decreases as it collapses, but the entropy of its surroundings increases faster as it radiates.
    - credit_guy 3y ago
      Is that a fact? Or just a hypothetical way that could save the second principle?
      - consilient 3y ago
        It's a fact. See for instance https://arxiv.org/pdf/0907.0659.pdf https://arxiv.org/pdf/0907.0659.pdf
        credit_guy 3y ago
        It's more like an opinion. Of one particular guy who has a Ph.D. in Physics. But there are many, and there is no consensus overall. Here's the relevant quote from wikipedia [1] Recent work has cast some doubt on the heat death hypothesis and the applicability of any simple thermodynamic model to the universe in general. Although entropy does increase in the model of an expanding universe, the maximum possible entropy rises much more rapidly, moving the universe further from the heat death with time, not closer. This results in an "entropy gap" pushing the system further away from the posited heat death equilibrium. Other complicating factors, such as the energy density of the vacuum and macroscopic quantum effects, are difficult to reconcile with thermodynamical models, making any predictions of large-scale thermodynamics extremely difficult. [1] https://en.wikipedia.org/wiki/Entropy#Cosmology https://en.wikipedia.org/wiki/Entropy#Cosmology

sghiassy 3y ago

Not really - look up “heat death” of the universe.

jjaken 3y ago
Heat death doesn’t mean “no heat” or that energy has depleted. It just means that energy is fully dispersed. All kg the hear exists, it’s just that no one place has any more than anywhere else, and so there is no longer any transfer of energy.
- A_D_E_P_T 3y ago
  > so there is no longer any transfer of energy. Ah, but there is. The Second Law is a statistical law, not an absolute law. On long enough timescales, low-probability fluctuations in local entropy will allow for energy transfer. These fluctuations will also allow for the formation of structures. (Boltzmann himself was of the opinion that the low-entropy universe emerged from a higher-entropy background state. And indeed there's nothing in physics to rule out the emergence of Boltzmann Brains and even Boltzmann Galaxies from homogeneous and maximally entropic universes in "heat death." This is a philosophical problem of the highest order, because it implies that we're not necessarily going from "less likely to more likely states" as the video implies, but rather from a relatively deterministic state to a probabilistic state.)
  - jjaken 3y ago
    Oh interesting, I didn’t know that
credit_guy 3y ago
The "heat death" of the universe is a concept that deserves to die. The second principle of thermodynamics is true only if you ignore gravity. In the presence of gravity, systems tend to go towards lower entropy, just see how a planetary system can form out of a gas cloud.
- consilient 3y ago
  > In the presence of gravity, systems tend to go towards lower entropy, just see how a planetary system can form out of a gas cloud. This isn't correct: the entropy (and energy) of the gas cloud goes decreases as it collapses, but the entropy of its surroundings increases faster as it radiates.
  - credit_guy 3y ago
    Is that a fact? Or just a hypothetical way that could save the second principle?
    - consilient 3y ago
      It's a fact. See for instance https://arxiv.org/pdf/0907.0659.pdf https://arxiv.org/pdf/0907.0659.pdf
      - credit_guy 3y ago
        It's more like an opinion. Of one particular guy who has a Ph.D. in Physics. But there are many, and there is no consensus overall. Here's the relevant quote from wikipedia [1] Recent work has cast some doubt on the heat death hypothesis and the applicability of any simple thermodynamic model to the universe in general. Although entropy does increase in the model of an expanding universe, the maximum possible entropy rises much more rapidly, moving the universe further from the heat death with time, not closer. This results in an "entropy gap" pushing the system further away from the posited heat death equilibrium. Other complicating factors, such as the energy density of the vacuum and macroscopic quantum effects, are difficult to reconcile with thermodynamical models, making any predictions of large-scale thermodynamics extremely difficult. [1] https://en.wikipedia.org/wiki/Entropy#Cosmology https://en.wikipedia.org/wiki/Entropy#Cosmology