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Quantum mechanics has no bearing on the macro scale that classical physics inhabit in our current models. We currently have not synthesized the two models into
by kakarot 9y ago
Quantum mechanics has no bearing on the macro scale that classical physics inhabit in our current models. We currently have not synthesized the two models into a singular theory.
Classical physics is deterministic. I thought this was common knowledge...
- TheCoelacanth 9y agoThe whole point of quantum mechanics is that classical physics doesn't fully describe the world. Obviously phenomena that require quantum mechanics to describe them are rarely observable at the macro level, but it's clearly not the case that they are never observable because otherwise we wouldn't have been able to make the observations that led to the idea of quantum mechanics. It seems readily apparent that the future is not predictable solely using classical physics, because the development of the theory of quantum mechanics is something that happened and it could not have been predicted solely based on classical physics.
- kakarot 9y agoThe whole point of quantum mechanics is that classical physics doesn't fully describe the world. Quantum mechanics doesn't have a point, it's a theory based on observation of quantum phenomena. It is currently irreconcilable with classical physics, which we still use to model the universe on useful scales. Quantum mechanics therefore are irrelevant here. The current standard model, which is the best we've got right now, is deterministic on classical scales. Which brings me back to my original comment: Unless our current understanding of physics is completely wrong It's at least a little wrong, but to say that our theory of classical physics isn't deterministic is just wrong. Until we have a better theory, that's just what we have to go with.
- TheCoelacanth 9y agoI'm not saying that classical physics isn't deterministic. I'm saying that classical physics is provably not a fully accurate model even at macro scales. For most problems at the macro scale, our best model is deterministic, but it is also easy to construct scenarios where macro scale events are not deterministic unless quantum phenomena are also deterministic, so clearly our best model is one that acknowledges that macro scale events might not be fully deterministic.
- kakarot 9y agoShow me such a case in the macro scale where the arrow of time reverses or disappears, instead of just postulating.
- TheCoelacanth 9y agoI don't understand what you are asking. Clearly quantum phenomena are observable at the macro scale. Every quantum mechanics experiment is an example of this, e.g. the double slit experiment.
- kakarot 9y agoHow is the double slit experiment an example of non-determinism?
- TheCoelacanth 9y agoLet's say that I set up the double slit and then decide that I will make a macro level decision based on the observation of which slit a particle passes through. The observation of which slit the particle passes through is non-deterministic according to most interpretations of quantum mechanics, so my macro-level actions are now also non-deterministic. Alternatively, take the example of Clinton Davisson and Lester Germer in 1923 and then attempt to predict what papers they will publish in the future using classical physics. Clearly it can't be done because it is dependent on quantum effects.
- kakarot 9y ago> The observation of which slit the particle passes through is non-deterministic according to most interpretations of quantum mechanics, so my macro-level actions are now also non-deterministic That's not true. The double slit experiment shows that as the arrow of time moves, wave patterns predictably emerge. Again, until a better unified theory of everything emerges, we currently have no synthesis between quantum and classical physics and thus measured quantum phenomena are currently irrelevant to physics measured in the classical scale. > Alternatively, take the example of Clinton Davisson and Lester Germer in 1923 and then attempt to predict what papers they will publish in the future using classical physics This is simply a matter of not having enough information. The amount of information required to "predict the future" in the sense you're talking about is ginormous. Your concept of determinism is flawed. Further reading: https://www.lesswrong.com/posts/JrhoMTgMrMRJJiS48/decoherence https://www.lesswrong.com/posts/JrhoMTgMrMRJJiS48/decoherenc... https://www.lesswrong.com/posts/eWuuznxeebcjWpdnH/the-so-called-heisenberg-uncertainty-principle https://www.lesswrong.com/posts/eWuuznxeebcjWpdnH/the-so-cal...