Dragon Ball's Hyperbolic Time Chamber

gwern

A time dilation tool from an anime is discussed for its practical use on Earth; there seem surprisingly few uses and none that will change the world, due to the severe penalties humans would incur while using it, and basic constraints like Amdahl's law limit the scientific uses. A comparison with the position of an Artificial Intelligence such as an emulated human brain seems fair, except most of the time dilation disadvantages do not apply or can be ameliorated and hence any speedups could be quite effectively exploited. I suggest that skeptics of the idea that speedups give advantages are implicitly working off the crippled time dilation tool and not making allowance for the disanalogies.

Master version on gwern.net

A time dilation tool from an anime is discussed for its practical use on Earth; there seem surprisingly few uses and none that will change the world, due to the severe penalties humans would incur while using it, and basic constraints like Amdahl's law limit the scientific uses. A comparison with the position of an Artificial Intelligence such as an emulated human brain seems fair, except most of the time dilation disadvantages do not apply or can be ameliorated and hence any speedups could be quite effectively exploited. I suggest that skeptics of the idea that speedups give advantages are implicitly working off the crippled time dilation tool and not making allowance for the disanalogies.

Master version on gwern.net

Even the so-called Embarrassingly parallel problems, those whose theoretical performance scales almost linearly with the number of cpus, in practice scale sublinearly in the amount of work done per dollar: massive parallelization comes with all kinds of overheads, from synchronization to cache contention to network communication costs to distributed storage issues. More trivially, large data centers have significant heat dissipation issues: they all need active cooling and many are also housed in high-tech buildings specifically designed to address this issue. Many companies even place data centers in northern countries to take advantage of the colder climate, instead of putting them in, say, China, India or Brazil where labor costs much less.

Problems that are not embarrassingly parallel are limited by Amdahl's law: as you increase the number of cpus, the performance quickly reach an asymptote where the sequential parts of the algorithms dominate.

I can't help but think that there being no obvious candidates means the candidates wouldn't be fantastically useful.

Take P-complete problems, for instance. These are problems which are efficient (polynomial time) on a sequential computer, but are conjectured to be inherently difficult to parallelize (the NC != P conjecture). This class contains problems of practical interest, notably linear programming and various problems for model checking. Being able to run these tasks overnight instead of in one year would a significant advantage.

A HTC would come with serious overhead costs too; the cooling is just the flip side of the electricity - a HTC isn't in Iceland and the obvious interpretation of a HTC as a very small pocket universe means that you have serious cooling issues as well (a years' worth of heat production to eject each opening).

Take P-complete problems, for instance. These are problems which are efficient (polynomial time) on a sequential computer, but are conjectured to be inherently difficult to parallelize (the NC != P conjecture). This class contains problems of practica

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Dragon Ball's Hyperbolic Time Chamber

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Dragon Ball's Hyperbolic Time Chamber

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