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V_V comments on Steelmaning AI risk critiques - Less Wrong Discussion

26 Post author: Stuart_Armstrong 23 July 2015 10:01AM

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Comment author: Wei_Dai 29 July 2015 08:26:20AM *  0 points [-]

From what I understand, if you chill everything down then you also change resistance in the semiconductor along with all the other properties, so it probably isn't as easy as just replacing the copper wires.

From the sources I've read, there aren't any major issues running CMOS at 77 K, you only run into problems at lower temperatures, less than 40 K. I guess people aren't seriously trying this because it's probably not much harder to go directly to full superconducting computers (i.e., with logic gates made out of superconductors as well) which offers a lot more benefits. Here is an article about a major IARPA project pursuing that. It doesn't seem safe to assume that we'll get AGI before we get superconducting computers. Do you disagree, if so can you explain why?

Comment author: V_V 29 July 2015 10:06:46AM *  -1 points [-]

I guess people aren't seriously trying this because it's probably not much harder to go directly to full superconducting computers (i.e., with logic gates made out of superconductors as well) which offers a lot more benefits

It takes energy to maintain cryogenic temperatures, probably much more than the energy that would be saved by eliminating wire resistance. If I understand correctly, the interest in superconducting circuits is mostly in using them to implement quantum computation.
Barring room temperature superconductors, there are probably no benefits of using superconducting circuits for classical computation.

Comment author: Wei_Dai 29 July 2015 12:26:59PM *  0 points [-]

From the article I linked to:

Studies indicate the technology, which uses low temperatures in the 4-10 kelvin range to enable information to be transmitted with minimal energy loss, could yield one-petaflop systems that use just 25 kW and 100 petaflop systems that operate at 200 kW, including the cryogenic cooler. Compare this to the current greenest system, the L-CSC supercomputer from the GSI Helmholtz Center, which achieved 5.27 gigaflops-per-watt on the most-recent Green500 list. If scaled linearly to an exaflop supercomputing system, it would consume about 190 megawatts (MW), still quite a bit short of DARPA targets, which range from 20MW to 67MW.

ETA: 100 petaflops per 200 kW equals 500 gigaflops per watt, so it's estimated to be about 100 times more energy efficient.

Comment author: V_V 29 July 2015 03:40:41PM *  -1 points [-]

Ok, I guess it depends on how big your computer is, due to the square-cube law. Bigger computers would be at an advantage.

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