[SEQ RERUN] Reductionism

MinibearRex

[SEQ RERUN] Reductionism — LessWrong

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Shmi14y00

Saying "you cannot" is awfully gutsy.

True, let's say that I'd bet my house on it not being done in my lifetime.

Are you familiar with renormalization groups?

Yes, in the HEP context.

They're a mathematical tool for getting high-level laws out of low-level laws.

Not quite. You can use renormalization to help explain some of what you observe at lower energies from a HE model point of view. I am yet to see an RNG prediction of a new low-energy effect, though I suppose it might happen for one-level-up problems, but not for any kind of multi-level jumps (do you seriously think that one can potentially renormalize quarks to cognitive biases?)

The only theoretically unsolved problem I know of between QFT and predicting planes is the prediction of a periodic solid as the ground state of your structural metal, though there are probably a few more.

You are confusing predicting with explaining.

Mitchell_Porter14y10

I can't figure out what you're trying to say. Are you saying:

(1) QFT is inherently incapable of explaining the aerodynamics of rigid macroscopic bodies, ever

(2) QFT can do that in principle, but in practice we can't yet justify some of the intermediate steps

(3) QFT can do that in principle, but in practice it's pointless because the higher-level theories already tell you everything about the higher levels

(4) something else?

0Maelin14y

To quote the article, "The map is not the territory, but you can't fold up the territory and put it in your glove compartment." Eliezer's point is not that we should discard all our higher level models. Of course you can't feasibly build a working 747 using a subatomic particle model. Of course you need to use higher level models if you want to get any useful work done. His point is that we need to recognise that they are models; that the universe does not really work with different rule sets for different levels. A street directory of your town isn't actually your town. It is important to understand this, so you don't end up trying to go to your friend's house by jumping up and down on the appropriate page. But that doesn't mean you should throw the street directory away.

0MinibearRex14y

Are you saying that such a task would be prohibitively difficult, and presumably not something that is worth the effort, or are you saying that doing this is impossible in principle?

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