Author: Jesper Antonsson
Date: 15:00:55 01/14/05
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On January 13, 2005 at 11:12:09, Dieter Buerssner wrote: >One other number. The mass of the earth is 6*10^24 kg. It is mainly made of iron >(the core). But say it was out of oxygen (which is lighter, so we overestimate >the number of atoms). The atomic mass of oxygen is 16 g/mol. Avogadro's constant >is 6.022e23 mol^-1. The number of atoms in the earth is: > > 6e24 kg / 0.016 kg/mol * 6e23 mol^-1 = 5.76 * 10^46 The calculation is incorrect. (e24*e23 = e47 > e46). The real answer should be Xe50, I guess. No matter. Some estimate that chess is only 1e40 positions, and if we are really optimistic about the alpha-beta gain and use some tricks, perhaps sqrt(1e40) = 1e20 positions would suffice. 1e20 oxygen atoms weighs: (1e20 / 6.022e23 mol-1) * 16 g/mol = 0.0027 g 1e20 bits is also "only" 12,500,000 Tbyte (of course, a bit per position won't suffice, but anyway...). I would guess that the installed world hard disk base is somewhere close to this number, and that these sizes will actually be in reach of very-high-end database systems within 20 years. Furthermore, if we calculate one billion nodes a second, we may build such a solution hash table in 1e11 seconds, or 1.7e9 minutes, or 2.7e7 hours, or 1157407 days or 3170 years. Too much, but only by a few orders of magnitude. Perhaps we can speed it up by parallelism. Solving chess may very well be forever unfeasible, but I think the jury is still out there regarding how much work that has to be done to find a solution, and while this is the case, we really don't know much about this.
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