Eliezer_Yudkowsky comments on Thoughts on the Singularity Institute (SI) - Less Wrong

256 Post author: HoldenKarnofsky 11 May 2012 04:31AM

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Comment author: Eliezer_Yudkowsky 22 March 2013 10:22:26PM 6 points [-]

Kawoomba, there is no known case of any NP-hard or NP-complete solution which physics finds.

In the case of proteins, if finding the lowest energy minimum of an arbitrary protein is NP-hard, then what this means in practice is that some proteins will fold up into non-lowest-energy configurations. There is no known case of a quantum process which finds an NP-hard solution to anything, including an energy minimum; on our present understanding of complexity theory and quantum mechanics 'quantum solvable' is still looking like a smaller class than 'NP solvable'. Read Scott Aaronson for more.

Comment author: Qiaochu_Yuan 22 March 2013 10:37:38PM 8 points [-]

One example here is the Steiner tree problem, which is NP-complete and can sort of be solved using soap films. Bringsjord and Taylor claimed this implies that P = NP. Scott Aaronson did some experimentation and found that soap films 1) can get stuck at local minima and 2) might take a long time to settle into a good configuration.

Comment author: Eliezer_Yudkowsky 22 March 2013 11:29:22PM 3 points [-]

Heh. I remember that one, and thinking, "No... no, you can't possibly do that using a soap bubble, that's not even quantum and you can't do that in classical, how would the soap molecules know where to move?"

Comment author: Manfred 23 March 2013 12:15:02AM 1 point [-]

Well. I mean, it's quantum. But the ground state is a lump of iron, or maybe a black hole, not a low-energy soap film, so I don't think waiting for quantum annealing will help.

Comment author: Eliezer_Yudkowsky 23 March 2013 01:41:40AM 1 point [-]

waves soap-covered wire so it settles into low-energy minimum

dies as it turns into iron

Comment author: [deleted] 23 March 2013 06:51:09PM 0 points [-]

I also seem to recall Penrose hypothesizing something about quasicrystals, though he does have an axe to grind so I'm quite sceptical.

Comment author: CCC 23 March 2013 07:28:47AM 0 points [-]

I saw someone do the experiment once (school science project). Soap bubbles are pretty good at solving three- and four-element cases, as long as you make sure that all the points are actually connected.

I don't think that three- and four-element cases have local minima, do they? That avoids (1) and a bit of gentle shaking can help speed up (2).

Comment author: Cyan 23 March 2013 01:32:12AM *  3 points [-]

In the case of proteins, if finding the lowest energy minimum of an arbitrary protein is NP-hard, then what this means in practice is that some proteins will fold up into non-lowest-energy configurations.

Yup.