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The quantum/classical limit is a function of temperature and not size, though it's generally harder to bring a large system sufficiently close to ground state t
by marginalia_nu 3y ago
The quantum/classical limit is a function of temperature and not size, though it's generally harder to bring a large system sufficiently close to ground state to avoid decoherence.
- tsimionescu 3y agoIt is not yet known what the limit actually is. Theoretically, a very hot mass of atoms that doesn't interact with its surrounding environment could still be in a superposition and display quantum effects - though it's very hard to perform such an experiment. Decoherence happens because of interactions with the environment, it doesn't happen for an isolated system as far as the theory goes. In fact, proponents of MWI believe that the whole universe, which is an isolated system, is itself a quantum system.
- marginalia_nu 3y agoThe separation of experiment and environment is an artificial distinction. Decoherence is caused by random phase shifts, which may appear due to interaction with the environment, but by the entropic definition of temperature, a sufficiently large and warm object will be disorderly enough to have this effect as well. You can not be hot and coherent at the same time, as the first implies a large degree of disorder and the other implies a large degree of order. > In fact, proponents of MWI believe that the whole universe, which is an isolated system, is itself a quantum system. MWI doesn't make any experimentally verifiable predictions as far as I'm aware, so is not particularly in this discussion.