Seems like there’s a difference between viability of AI, and ability of AI to shape a randomized environment. To have AI, you just need stable circuits, but to have an AI that can shape, you need a physics that allows observation and manipulation… It’s remarkable that googling “thermodynamics of the game of life” turns up zero results.
It’s remarkable that googling “thermodynamics of the game of life” turns up zero results.
It’s not obvious that thermodynamics generalizes to the game of life, or what the equivalents of energy or order would be: at first glance it has perpetual motion machines (“gliders”).
Yup, Life does not have time-reversibility, so it does not preserve the phase space volume under time evolution, so it does not obey the laws of thermodynamics that exist under our physics.
But one could still investigate whether there is some analog of thermodynamics in Life.
There also is a cellular automata called Critters that does have time reversibility.
If by ‘time reversibility’ you mean ‘a cellular automaton in which every configuration has a unique predecessor’, then is that important to thermodynamics? And does our world/universe have this property?
Yeah, so if every configuration has a unique predecessor that we have conservation of information, because you can you can take some future state and evolve it backwards in time to find any past state, so any information present in the state of the universe at time T can be recovered from any later state, so in that sense information is never lost from the universe as a whole.
This means that if I know only that the universe is one of N possible states at some time T, then if I evolve the universe forwards, there are still exactly N possible states that world could be in, since by time-reversibility I could rewind each of those states and expect to get back to the N original states from time T. This is what Eliezer refers to as “phase space volume is preserved under time evolution”.
This in turn implies the second thermodynamics, because among all possible configurations of the whole universe, there are only a small number of configurations with short descriptions, but many configurations with long descriptions (since there are fewer short descriptions than long descriptions), so it can never be that a randomly-selected long-description configuration is likely to evolve over time to a short-description configuration, since two configurations can never evolve to the same future configuration, so there are too few short-description configurations to be shared among the astronomically more numerous long-description configurations.
Our universe, remarkably, does have time-reversibility. It is called unitarity in quantum physics, but even in ordinary Newtonian mechanics you can imagine a bunch of billiard balls bouncing around on a frictionless table and see that if you knew the exact velocity of each ball then you could reverse all the velocities and play the whole thing backwards in time.
The black hole information paradox is called a paradox because general relativity says that information is lost in a black hole, but quantum mechanics says that information is never lost under any circumstances.
Yeah it could be that Life has some property that makes it impossible to do observation or impossible to do manipulation. I was imagining that observation would happen by shooting out some fairly large structure that interacts with the environment and shoots back gliders in a way that depends on what the structure of the environment was. It would of course be impossible to measure the environment at the level of individual cells, just as it is impossible to read off individual values from the wavefunction in our universe, and also observing the environment would change the environment, just as it does in our universe.
Seems like there’s a difference between viability of AI, and ability of AI to shape a randomized environment. To have AI, you just need stable circuits, but to have an AI that can shape, you need a physics that allows observation and manipulation… It’s remarkable that googling “thermodynamics of the game of life” turns up zero results.
It’s not obvious that thermodynamics generalizes to the game of life, or what the equivalents of energy or order would be: at first glance it has perpetual motion machines (“gliders”).
Yup, Life does not have time-reversibility, so it does not preserve the phase space volume under time evolution, so it does not obey the laws of thermodynamics that exist under our physics.
But one could still investigate whether there is some analog of thermodynamics in Life.
There also is a cellular automata called Critters that does have time reversibility.
If by ‘time reversibility’ you mean ‘a cellular automaton in which every configuration has a unique predecessor’, then is that important to thermodynamics? And does our world/universe have this property?
Yeah, so if every configuration has a unique predecessor that we have conservation of information, because you can you can take some future state and evolve it backwards in time to find any past state, so any information present in the state of the universe at time T can be recovered from any later state, so in that sense information is never lost from the universe as a whole.
This means that if I know only that the universe is one of N possible states at some time T, then if I evolve the universe forwards, there are still exactly N possible states that world could be in, since by time-reversibility I could rewind each of those states and expect to get back to the N original states from time T. This is what Eliezer refers to as “phase space volume is preserved under time evolution”.
This in turn implies the second thermodynamics, because among all possible configurations of the whole universe, there are only a small number of configurations with short descriptions, but many configurations with long descriptions (since there are fewer short descriptions than long descriptions), so it can never be that a randomly-selected long-description configuration is likely to evolve over time to a short-description configuration, since two configurations can never evolve to the same future configuration, so there are too few short-description configurations to be shared among the astronomically more numerous long-description configurations.
Our universe, remarkably, does have time-reversibility. It is called unitarity in quantum physics, but even in ordinary Newtonian mechanics you can imagine a bunch of billiard balls bouncing around on a frictionless table and see that if you knew the exact velocity of each ball then you could reverse all the velocities and play the whole thing backwards in time.
The black hole information paradox is called a paradox because general relativity says that information is lost in a black hole, but quantum mechanics says that information is never lost under any circumstances.
Yeah it could be that Life has some property that makes it impossible to do observation or impossible to do manipulation. I was imagining that observation would happen by shooting out some fairly large structure that interacts with the environment and shoots back gliders in a way that depends on what the structure of the environment was. It would of course be impossible to measure the environment at the level of individual cells, just as it is impossible to read off individual values from the wavefunction in our universe, and also observing the environment would change the environment, just as it does in our universe.