What is Heat death: Definition and 34 Discussions

The heat death of the universe (also known as the Big Chill or Big Freeze) is a theory on the ultimate fate of the universe, which suggests the universe would evolve to a state of no thermodynamic free energy and would therefore be unable to sustain processes that increase entropy. Heat death does not imply any particular absolute temperature; it only requires that temperature differences or other processes may no longer be exploited to perform work. In the language of physics, this is when the universe reaches thermodynamic equilibrium (maximum entropy).
If the topology of the universe is open or flat, or if dark energy is a positive cosmological constant (both of which are consistent with current data), the universe will continue expanding forever, and a heat death is expected to occur, with the universe cooling to approach equilibrium at a very low temperature after a very long time period.
The hypothesis of heat death stems from the ideas of Lord Kelvin, who in the 1850s took the theory of heat as mechanical energy loss in nature (as embodied in the first two laws of thermodynamics) and extrapolated it to larger processes on a universal scale.

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  1. H

    I Entropy Real? End of Time? - Veritasium Video

    Is entropy real? It seems like it's not real because it depends on how you group microstates together into a macrostate, and the way you group them can be arbitrary. For example (at 13:04 of the video below), there are 91,520 microstates in the macrostate “9 in left; 1 in right” but 627,264...
  2. S

    I Avoiding heat death in an accelerated expanding universe?

    https://en.m.wikipedia.org/wiki/Heat_death_of_the_universe Is the heat death of the universe completely unavoidable in an universe with an accelerated expansion dominated by dark energy like ours? Or can there be any way to avoid it according to current knowledge, observations and experiments...
  3. M

    B Low entropy early Universe and the heat death musings

    I came upon a realization recently. The early universe is always described to have begun in a state of extremely low entropy and it's been increasing ever since. But the same amount of stuff exists now as it did back then. Only thing that's changed is how big the universe is now vs then. So...
  4. R

    I Heat death of the universe and the 3rd law of thermodynamics

    If the universe keeps expanding and eventually ends in a "big freeze" or heat death, does this contradict the third law of thermodynamics? The third law of thermodynamics states that a crystal at absolute zero has zero entropy. Since the entropy of the universe can never decrease, as the age...
  5. durant35

    I Can a finite universe end in heat death?

    Hello guys, I was reading some models about the topology and size of the universe (always a controversial topic), then a question came to my mind. It is predicted that our universe will expand until it reaches heat death. Can a closed, finite universe also reach heat death and be described by...
  6. D

    Electromagnetic Radiation temperature

    Is there a meaningful way to convert the energy of an electromagnetic wave to a temperature? I mean this more along the lines of how the universe has a temperature of 2.7 kelvin due to electromagnetic radiation. I'm honestly just curious to determine the temperature of the universe after nearly...
  7. G

    I Would Heat Death overcome Strong Nuclear Force?

    Hi, layman here. As I understand, the theoretical Heat Death of the universe would imply that the accelerating space expansion reaches an expansion rate so big that it takes bodies and eventually even fundamental particles apart, leaving them alone up to an ultimate point in which no particle...
  8. wolram

    B Final Temperature of the Universe: Effects of Dark Energy and Spatial Curvature

    I know there are a few ways the universe can end, if it ever does, but at what temperature would the universe be in after heat death?
  9. G

    I Heat Death of the Universe, Total or Not?

    Let's assume that the universe will evolve over time to resemble the one predicted by heat death theorists. We're also assuming that the Big Bounce, Crunch, Rip etc. don't occur. Is it possible that while it resembles a heat death scenario, the heat death will never be total? That means: is it...
  10. E

    Can We Engineer Our Own Stars to Prevent the Heat Death of the Universe?

    Assuming the law of thermodynamics holds true throughout the entirety of the universe, is it theoretically possible to engineer our own stars and solar systems, and would doing so prevent the proposed eventual "Dark Age" of the universe? We understand how stars are formed, so what's stopping us...
  11. goat-on-a-stick

    How can quantum tunneling create Big Bang after heat death?

    Wikipedia states that, after he heat death of the universe: "Random quantum fluctuations or quantum tunneling can produce another Big Bang in years." How would this work?
  12. Stephanus

    The End of the Universe: Heat Death and the Fate of Matter

    Dear PF Forum Can I ask something quoted from a closed thread? In a closed thread: https://www.physicsforums.com/threads/predicted-heat-death-of-the-universe.824652/ This quote was presented by a Brian Cox. A scientist? And if he is, I'd like to ask this question. Is it technically possible...
  13. J

    Predicted Heat Death of the Universe

    Predicted Heat Death of the Universe In his thought provoking documentary “Wonder of the universe” ( ) Professor Brian Cox explains the thinking behind current predictions for the “Heat death of the universe”. He explains the predictions through the effect of the second law of thermodynamics...
  14. G

    Does anyone NOT believe heat death is the final destination?

    And if not, what do you believe?
  15. S

    Difference between Heat Death and the Big Freeze ?

    Difference between Heat Death and the "Big Freeze"? I'm a little confused. My understanding of the two is that once energy has been distributed evenly all through the universe from reactions and processes occurring, then there will be no more space for more energy to be distributed, and no more...
  16. K

    Quantum heat death already occured?

    To experts in Bell's Theorem and Non-locality.. like DrChinese... what do you think of this. is there a way to refute it? http://blogs.scientificamerican.com/critical-opalescence/2013/11/18/cosmological-data-hint-at-a-level-of-physics-underlying-quantum-mechanics-guest-post/ Someone said...
  17. Nugso

    Heat Death of the Universe: Is It Inevitable?

    Hello. I a few hours ago opened a new thread called "Big Crunch". But now that I've learn that it's not really possible for Big Crunch to happen, I also look for another possibilities. It looks like the best theory is Heat Death. It says that all stars will be dead the temperature will be the...
  18. M

    Entropy of a vacuum and heat death of the universe

    According to the third law of thermodynamics, one could argue that a vacuum has zero entropy, since it has only one ground state and a temperature at absolute zero. However, assuming the accelerated expansion of the universe to result in a 'heat death', i.e. a state of absolute thermal...
  19. A

    Temperature of the Heat Death of the Universe?

    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...
  20. Z

    Heat death, quantum uncertainty and Feynman's Path Integral

    Hi all, as a complete noob, I must first ask that people understand that I have only a layman's understanding of cosmology. However, after watching a few of Brian Cox's lectures on entropy and the heat death of the universe, I had a rather interesting thought (although as I am not a...
  21. narrator

    Entropy, heat death and black holes

    Talking about the big bounce and black holes in another thread made me wonder about the life span of black holes, especially in the heat death scenario. If the U went through heat death, does that mean that black holes would also exhaust their energy? Do black holes die, and if so, what...
  22. E

    How does Heat Death work in a universe with negative curvature?

    I'm assuming that the observer witnesses all other particles enter a horizon, be it an event horizon or the particle horizon. Thus the observer's observable universe would contain himself only. Is this understanding correct and can it happen in finite time? Also does such a universe have time...
  23. T

    Heat death the ultimate endgame?

    I recently caught Brian Cox in BBC's Wonders of the Universe. I got caught on the heat death theory of the end of the universe. I understand the concept of entropy and that the universe is heading toward a state of maximum entropy. Cox used the example of desert sand to illustrate high...
  24. Z

    The Scale Factor & Universe Entropy: Examining Heat Death

    Empirical evidence supports that the scale factor is proportional to the following. a(t) = e^(HT) Where the distance between any two objects are D(t) = a(t)Δx Where x does not measure physical distance, but a conventional coordinate distance. This means that eventually any physical distance...
  25. wolram

    Exploring the Debate: Heat Death vs. Bounce as the Ultimate Fate of the Universe

    How many will argue that heat death is a better end to our universe rather than a bounce into a new universe
  26. D

    Exploring the Inevitable Heat Death of the Universe

    I heard that eventually the universe will end in heat death where everything becomes cold and lifeless and immotile. Is this true and is it inescapable? What can we perhaps do about it?
  27. C

    Cosmological Models Predicting Heat Death of the Universe

    I have read that some cosmological models predict a heat death of the universe. Eventually all matter (beggining with superclusters, clusters, then galaxies, then stars) will lose all energy and separate (due to expansion which will eventually occur even on a galactically local level) so that...
  28. V

    Can the Heat Death of the Universe Be Prevented?

    Is there a way that the hypothetical heat death of the universe can be prevented, if the danger exists? The heat death is a possible final state of the universe, in which it has "run down" to a state of no thermodynamic free energy to sustain motion or life. In other words, It has reached...
  29. Loren Booda

    Fate of matter with universal heat death

    Assuming the eventual heat death of the universe, would there be a time when all matter becomes superconducting, or manifests as quantum condensates?
  30. S

    Heat Death of the Universe: Exploring an End

    what is heat death of universe?
  31. S

    Exploring the Expansion of the Universe and Heat Death

    I have been reading the archives of Physics Forums, some threads about the expansion of the universe and also the upcoming Heat Death that people keep talking about. However, there are a few things that keep bugging me: First of all, atoms have not so far shown any tendency not to cluster...
  32. Lrdmora

    Exploring the Heat Death Theory: What is It and How Does it Work?

    I read about this once and then forgot where I read it, very simplified the theory goes like this: Intelligent beings create heat. Most items in a civilized culture create heat ie light bulbs, computers, etc. At some point a civilization will create more heat than can be dissipated and...
  33. wolram

    Exploring Possibilities of the Universe's Survival Beyond Heat Death

    i have been thinking how our universe could continue if it suffers heat death, i can think of one possibility , that is that a bose einstein condensate could form, is that a possibility? if it is then interactions between BECs could rekindle our universe
  34. K

    Conceiving a Net Decrease in Entropy: Is Heat Death Avoidable?

    Yo, d00ds, my Physics book mentions the concept of Heat Death (All the energy in the universe going to an unusable form) but says that it might not be valid if the universe is bounded in certain ways Does that just mean that if the universe hits a Big Crunch, it won't experience Heat Death...