The phrase “heat death of the universe” refers to two different, mutually exclusive possibilities:
The universe gets so hot, that it’s practically impossible for any organism to maintain enough organization to be able to sustain itself and create copies of itself
Or:
The universe gets so cold, that everything freezes to death, and no organism can put make work happen to create more copies of itself
Originally, the heat death hypothesis referred to #1, we thought that the universe would get extremely hot. After all, heat death is a natural consequence of the second law of thermodynamics, which states that entropy can only increase, never decrease, and ceteris paribus (all else equal) when entropy increases, temperature also increases.
But ceteris is never actually paribus, and in this case, physicists found out that the universe is constantly getting bigger, things are always getting further apart. When volume is increasing, things can get colder even as entropy increases, and physicists now expect that, given our current understanding of how the universe works, possibility #2 is more likely, the universe will eventually freeze to death.
But our current understanding is only ever the best guess we can make of what the laws of the universe actually are, not the actual laws themselves. We currently expect the universe will freeze, but we could very well find evidence in the future that the universe will burn instead. Maybe (quite unlikely) things will just happen to balance out, so that the increase in temperature due to entropy equals the decrease in temperature due to the expansion of the universe.
Perhaps we will discover a loophole in a set of laws that would otherwise suggest a heat death of one kind or the other, but where a sufficiently intelligent process can influence the evolution of temperature so as to counteract the otherwise prevailing temperature trend—in the vein of (I’d like to note that I do not intend to imply that any of these are likely to happen) creating a large enough amount of entropy to create a permanent warm zone in a universe that is otherwise doomed to freeze (this would probably require a violation of the conservation of energy that we currently have no reason to believe exists), or using an as-yet undiscovered mechanism to accelerate the expansion of the universe that can create a long-lasting cool zone in a universe that is otherwise doomed to burn.
Hrm. I though it referred to distribution of energy, not temperature. “heat death of the universe” is when entropy can increase no more, and there are no differentials across space by which to define anything at conscious scale. No activity is possible when everything is uniform.
The phrase “heat death of the universe” refers to two different, mutually exclusive possibilities:
The universe gets so hot, that it’s practically impossible for any organism to maintain enough organization to be able to sustain itself and create copies of itself Or:
The universe gets so cold, that everything freezes to death, and no organism can put make work happen to create more copies of itself
Originally, the heat death hypothesis referred to #1, we thought that the universe would get extremely hot. After all, heat death is a natural consequence of the second law of thermodynamics, which states that entropy can only increase, never decrease, and ceteris paribus (all else equal) when entropy increases, temperature also increases.
But ceteris is never actually paribus, and in this case, physicists found out that the universe is constantly getting bigger, things are always getting further apart. When volume is increasing, things can get colder even as entropy increases, and physicists now expect that, given our current understanding of how the universe works, possibility #2 is more likely, the universe will eventually freeze to death.
But our current understanding is only ever the best guess we can make of what the laws of the universe actually are, not the actual laws themselves. We currently expect the universe will freeze, but we could very well find evidence in the future that the universe will burn instead. Maybe (quite unlikely) things will just happen to balance out, so that the increase in temperature due to entropy equals the decrease in temperature due to the expansion of the universe.
Perhaps we will discover a loophole in a set of laws that would otherwise suggest a heat death of one kind or the other, but where a sufficiently intelligent process can influence the evolution of temperature so as to counteract the otherwise prevailing temperature trend—in the vein of (I’d like to note that I do not intend to imply that any of these are likely to happen) creating a large enough amount of entropy to create a permanent warm zone in a universe that is otherwise doomed to freeze (this would probably require a violation of the conservation of energy that we currently have no reason to believe exists), or using an as-yet undiscovered mechanism to accelerate the expansion of the universe that can create a long-lasting cool zone in a universe that is otherwise doomed to burn.
Hrm. I though it referred to distribution of energy, not temperature. “heat death of the universe” is when entropy can increase no more, and there are no differentials across space by which to define anything at conscious scale. No activity is possible when everything is uniform.
At least, that’s my simplistic summary - https://en.wikipedia.org/wiki/Heat_death_of_the_universe gives a lot more details, including the fact that my summary was probably not all that good even in the 19th century.