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QA is non-linear when discretised, so no, no one is "replacing" anything. There is no "digital physics", it's a PR term of a hype industry, not the title of any

QA is non-linear when discretised, so no, no one is "replacing" anything. There is no "digital physics", it's a PR term of a hype industry, not the title of any, eg., textbook on area of physics. Physics is not computable to arbitrary precision, both chaos and qm require physics to use non-computable numbers.

naasking 4y ago
> QA is non-linear when discretised, so no, no one is "replacing" anything. I don't know what any of this is referring to as I never mentioned "replacing" anything. > There is no "digital physics", it's a PR term of a hype industry, not the title of any, eg., textbook on area of physics. Incorrect: A Computable Universe, https://www.worldscientific.com/worldscibooks/10.1142/8306#t=aboutBook https://www.worldscientific.com/worldscibooks/10.1142/8306#t... > Physics is not computable to arbitrary precision, both chaos and qm require physics to use non-computable numbers. Also incorrect, and put most succinctly by Peter Shor [1]: Because of quantum mechanics and the uncertainty principle, the value of a physical constant can't be defined to more than 60 or 70 digits. And any finite-precision number by definition is computable. See also [2] for alternative conceptions. [1] https://physics.stackexchange.com/questions/16889/non-computable-numbers-in-physics#comment40236_16893 https://physics.stackexchange.com/questions/16889/non-comput... [2] https://arxiv.org/abs/1003.5831 https://arxiv.org/abs/1003.5831
- mjburgess 4y ago
  That's a textbook on the idea, not a text book on an area of physics using that idea. Of course there are many books professing the idea, there are none, eg., providing a computable formalism for classical mechanics. The value of a physical constant can be defined to abitarily many digits, that's a misunderstanding of QM which limits the measurement precision in conjugate variables. But even were our measurement limited to finite precision, the world certainly isnt.
  - naasking 4y ago
    > That's a textbook on the idea, not a text book on an area of physics using that idea. A textbook on the various ways that idea can be and has been used. The notion that physics is computation is still new, and that arguably started with Wheeler first casting physics as information in "It from bit". I predict the next century will see further application of some forms of finitism to physics to resolve various difficulties. Edit: I also want to note that at least two big names I know of are exploring cellular automata-based theories for QM, so there is direct work on computation-based models of physics. > providing a computable formalism for classical mechanics. Of course there is, the usual way works fine. Any computation with 70 digits of precision is far beyond our abilities to measure experimentally. Certainly such computations aren't tractable at this time, but that's a different matter. > But even were our measurement limited to finite precision, the world certainly isnt. Why is that "certain"? Don't you see how this is an unscientific assertion? Science is about what can be measured, so you have no basis to claim that a continuous theory must be true and a discrete theory false if you can perform no experiment to distinguish them.

naasking 4y ago

> QA is non-linear when discretised, so no, no one is "replacing" anything. I don't know what any of this is referring to as I never mentioned "replacing" anything. > There is no "digital physics", it's a PR term of a hype industry, not the title of any, eg., textbook on area of physics. Incorrect: A Computable Universe, https://www.worldscientific.com/worldscibooks/10.1142/8306#t=aboutBook https://www.worldscientific.com/worldscibooks/10.1142/8306#t... > Physics is not computable to arbitrary precision, both chaos and qm require physics to use non-computable numbers. Also incorrect, and put most succinctly by Peter Shor [1]: Because of quantum mechanics and the uncertainty principle, the value of a physical constant can't be defined to more than 60 or 70 digits. And any finite-precision number by definition is computable. See also [2] for alternative conceptions. [1] https://physics.stackexchange.com/questions/16889/non-computable-numbers-in-physics#comment40236_16893 https://physics.stackexchange.com/questions/16889/non-comput... [2] https://arxiv.org/abs/1003.5831 https://arxiv.org/abs/1003.5831

mjburgess 4y ago
That's a textbook on the idea, not a text book on an area of physics using that idea. Of course there are many books professing the idea, there are none, eg., providing a computable formalism for classical mechanics. The value of a physical constant can be defined to abitarily many digits, that's a misunderstanding of QM which limits the measurement precision in conjugate variables. But even were our measurement limited to finite precision, the world certainly isnt.
- naasking 4y ago
  > That's a textbook on the idea, not a text book on an area of physics using that idea. A textbook on the various ways that idea can be and has been used. The notion that physics is computation is still new, and that arguably started with Wheeler first casting physics as information in "It from bit". I predict the next century will see further application of some forms of finitism to physics to resolve various difficulties. Edit: I also want to note that at least two big names I know of are exploring cellular automata-based theories for QM, so there is direct work on computation-based models of physics. > providing a computable formalism for classical mechanics. Of course there is, the usual way works fine. Any computation with 70 digits of precision is far beyond our abilities to measure experimentally. Certainly such computations aren't tractable at this time, but that's a different matter. > But even were our measurement limited to finite precision, the world certainly isnt. Why is that "certain"? Don't you see how this is an unscientific assertion? Science is about what can be measured, so you have no basis to claim that a continuous theory must be true and a discrete theory false if you can perform no experiment to distinguish them.