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Temperature of the Heat Death of the Universe?

  1. Aug 22, 2012 #1
    Is there a way to calculate the temperature of the heat death of the universe based on the total amount of energy currently in the universe. And if the total amount of energy in the universe is zero (compose dof equal and opposite parts) is it possible for the parts to cancel each other out and return to a state of non-existence? Furthermore, I have heard that when the heat death of the universe happens everything will be at the exact same temperature, that is the velocity of all particles will be the same. But do we have a clue as to what type of particles will be around? Also, if everything is at the exact same temperature would that mean the universe could all be in a super fluid state?
  2. jcsd
  3. Aug 22, 2012 #2
    In an expanding universe, which we think we live in, the temperature of heat death, if it ever occurs, will be zero.

    Energies, not velocities.
  4. Aug 22, 2012 #3
    Thank you, can you tell me where you know this from or a good direction to search in to get the finer details of the idea?

    What I was saying was that the energy, and temperature (meaning the velocity) of all particles will be the same at the point when entropy is at a maximum. But that's even wishy-washey since they shouldn't have any velocity or energy available to do work. An interesting question now is will there still be energy present in the form of mass? My instinct says there would not be.
  5. Aug 22, 2012 #4
    Energy is constant, so its density is ever thinner as the expansion continues.

    Massless particles, such as photons, always move at the speed of light, no matter what their energy. Energy of massive particles depends on their mass and their velocity, so particles with different masses in thermal equilibrium must have different velocities. Except, of course, the equilibrium at 0 K, where all massive particles must freeze into cosmic microwave background - which will become a misnomer, because it will not be microwave, but infinite-length-wave.
  6. Aug 22, 2012 #5
    Yes but what I'm also wondering or thinking is that all matter should be in the same form at the heat death of the universe (photons), do you know anything about this?
  7. Aug 22, 2012 #6
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