6 ms·

You're in good company. Something similar, minus the hydrogen phase, is proposed by Roger Penrose: https://en.wikipedia.org/wiki/Cycles_of_Time https://en.wikip

by ewzimm 1y ago

You're in good company. Something similar, minus the hydrogen phase, is proposed by Roger Penrose: https://en.wikipedia.org/wiki/Cycles_of_Time https://en.wikipedia.org/wiki/Cycles_of_Time

6gvONxR4sf7o 1y ago
I went to a talk of his on CCC ages ago, and it was such a fascinating combination of geometry, causality, and asymptotics. I have absolutely no clue whether it's reasonable physically, but independent of that, it's just a really elegant fusion of topics in a fun to think about way. Worth a read for anyone who just appreciates elegant new ways of combining mathematical structures.
- sellmesoap 1y ago
  I've also seen this talk, at the behest of some spaced out friends of mine, an amazing experience and I still think about the universe through the lens of that talk!
mensetmanusman 1y ago
Apparently time ceases when absolutely all mass is gone, because mass is required for a clock. This of course requires the decay of protons.
- MattPalmer1086 1y ago
  Why would time cease because all the measuring devices were gone?
  - sourdoughness 1y ago
    My understanding of this idea is that once the universe reaches a state of maximum entropy (this is the “heath death” of the universe, where everything is a uniform, undifferentiated cloud of photons, then time stops being meaningful because there can be no change from moment to moment. In a sense, time _is_ the change from low to high entropy - if you don’t have any entropy gradient, you can’t have any time either.
    - Panzer04 1y ago
      This sounds sort of like the "if a tree falls in a forest and no one hears it, did it make a sound". if time passes and there's no observable difference, did it pass? I guess it makes no meaningful difference, but it's not really answering the underlying question of if some variable is advancing or not.
      - joquarky 1y ago
        I enjoy this thought experiment. If nobody logs in to a multiplayer game, does the game world still exist? Sure there are files sitting on a server somewhere waiting to be read when the first user logs in, there may even be a physics engine polling abstract data structures for updates, but the game world doesn't render without players present with their computers bringing all this data into a coherent structure. Also, for an extra existential kick, realize that it renders /independently/ in the GPU/CPU/RAM of each player's computer.
    - Zorass 1y ago
      [dead]
    - eggn00dles 1y ago
      stuff can still happen after the heat death. the universe will keep expanding, and quantum foam will keep foaming. heat death just implies no work can be done. time still flows
      - MattPalmer1086 1y ago
        And potentially leads to things like Boltzmann Brains, given enough time! Quantum fluctuations can still create wildly improbable things, even if only briefly.
    - MattPalmer1086 1y ago
      I've always rejected the idea that time is entropy change. First, in many local processes entropy moves from high to low (e.g. life). Nobody says that time is moving backwards for living things. It only increases if you consider the system it is embedded in as well. So this idea that entropy is time is something that only applies to the entire universe? It's true that we don't see eggs unbreaking, or broken coffee cups flying off the floor and reassembling. This increase in entropy seems to give an "arrow" of time, but to my mind this view (ironically) confuses cause with effect. If you have any causal system (cause preceding effects) then you will always see this type of entropic increase, by simple statistics. There are just many, many more ways for things to be scrambled and high entropy than ordered and low entropy. So yes, entropy does tend to increase over time, but that's an effect of being in a causal system, not the system itself. At least, that's my view.
  - voxelghost 1y ago
    >Why would time cease because all the measuring devices were gone? Partly, but mostly because there would be no lunch, so there would be no illusion of lunch-time any more.
    - MattPalmer1086 1y ago
      This is clearly the correct answer :)
  - mikhailfranco 1y ago
    If everything is massless, everything travels at the speed of light, and nothing experiences any time (photons travel null geodesics with zero spacetime interval). This is required to make Penrose's end state Conformal i.e. scale invariant, so that it can arbitrarily Cycle to a small scale to make a new Bing Bang Cosmology (CCC).
    - MattPalmer1086 1y ago
      Yes, that's a good point. But does that mean that the quantum field fluctuations in the space time the massless radiation moves through also ceases?
- butlike 1y ago
  Isn't mass filtered into this [environment, reality] by the higgs mechanism?

by ewzimm 1y ago

You're in good company. Something similar, minus the hydrogen phase, is proposed by Roger Penrose: https://en.wikipedia.org/wiki/Cycles_of_Time https://en.wikipedia.org/wiki/Cycles_of_Time

6gvONxR4sf7o 1y ago

I went to a talk of his on CCC ages ago, and it was such a fascinating combination of geometry, causality, and asymptotics. I have absolutely no clue whether it's reasonable physically, but independent of that, it's just a really elegant fusion of topics in a fun to think about way. Worth a read for anyone who just appreciates elegant new ways of combining mathematical structures.

sellmesoap 1y ago
I've also seen this talk, at the behest of some spaced out friends of mine, an amazing experience and I still think about the universe through the lens of that talk!

mensetmanusman 1y ago

Apparently time ceases when absolutely all mass is gone, because mass is required for a clock. This of course requires the decay of protons.

MattPalmer1086 1y ago
Why would time cease because all the measuring devices were gone?
- sourdoughness 1y ago
  My understanding of this idea is that once the universe reaches a state of maximum entropy (this is the “heath death” of the universe, where everything is a uniform, undifferentiated cloud of photons, then time stops being meaningful because there can be no change from moment to moment. In a sense, time _is_ the change from low to high entropy - if you don’t have any entropy gradient, you can’t have any time either.
  - Panzer04 1y ago
    This sounds sort of like the "if a tree falls in a forest and no one hears it, did it make a sound". if time passes and there's no observable difference, did it pass? I guess it makes no meaningful difference, but it's not really answering the underlying question of if some variable is advancing or not.
    - joquarky 1y ago
      I enjoy this thought experiment. If nobody logs in to a multiplayer game, does the game world still exist? Sure there are files sitting on a server somewhere waiting to be read when the first user logs in, there may even be a physics engine polling abstract data structures for updates, but the game world doesn't render without players present with their computers bringing all this data into a coherent structure. Also, for an extra existential kick, realize that it renders /independently/ in the GPU/CPU/RAM of each player's computer.
  - Zorass 1y ago
    [dead]
  - eggn00dles 1y ago
    stuff can still happen after the heat death. the universe will keep expanding, and quantum foam will keep foaming. heat death just implies no work can be done. time still flows
    - MattPalmer1086 1y ago
      And potentially leads to things like Boltzmann Brains, given enough time! Quantum fluctuations can still create wildly improbable things, even if only briefly.
  - MattPalmer1086 1y ago
    I've always rejected the idea that time is entropy change. First, in many local processes entropy moves from high to low (e.g. life). Nobody says that time is moving backwards for living things. It only increases if you consider the system it is embedded in as well. So this idea that entropy is time is something that only applies to the entire universe? It's true that we don't see eggs unbreaking, or broken coffee cups flying off the floor and reassembling. This increase in entropy seems to give an "arrow" of time, but to my mind this view (ironically) confuses cause with effect. If you have any causal system (cause preceding effects) then you will always see this type of entropic increase, by simple statistics. There are just many, many more ways for things to be scrambled and high entropy than ordered and low entropy. So yes, entropy does tend to increase over time, but that's an effect of being in a causal system, not the system itself. At least, that's my view.
- voxelghost 1y ago
  >Why would time cease because all the measuring devices were gone? Partly, but mostly because there would be no lunch, so there would be no illusion of lunch-time any more.
  - MattPalmer1086 1y ago
    This is clearly the correct answer :)
- mikhailfranco 1y ago
  If everything is massless, everything travels at the speed of light, and nothing experiences any time (photons travel null geodesics with zero spacetime interval). This is required to make Penrose's end state Conformal i.e. scale invariant, so that it can arbitrarily Cycle to a small scale to make a new Bing Bang Cosmology (CCC).
  - MattPalmer1086 1y ago
    Yes, that's a good point. But does that mean that the quantum field fluctuations in the space time the massless radiation moves through also ceases?
butlike 1y ago
Isn't mass filtered into this [environment, reality] by the higgs mechanism?