[chongli]

I don't think you realize how large of a number 2^155 is. The number of atoms comprising the entire planet earth is on the order of 10^49 or 2^162 [0]. Thus, to store all possible chess positions using only the material available on planet earth you'd have only 2^7 or 128 atoms available to store each one. All of this is ignoring the amount of energy you'd need to operate such a device, which is even more staggering.

[0] http://www.fnal.gov/pub/science/inquiring/questions/atoms.ht...

[ybird]

A petabyte of storage would have been unthinkable 20 years ago. Think of the not too distant future.

[ybird]

Using the following dataset of year to max drive size in bytes per year [1a][1b]: {1956,5.00E+06},{1979,5.71E+08},{1980,1.00E+09},{1991,1.00E+09},{1992,2.10E+09},{1997,1.68E+10},{2003,3.70E+10},{2005,4.00E+10},{2006,1.60E+11},{2006,7.50E+11},{2016,5.00E+12}

Linear regression provides the equation: year = 4.222874399 ln(numBytes) + 1896.534826

Assuming the average bits required to represent a board state is 160 [2], then: 2^155 positions x 160 bits = 9.13e47 bytes

4.222874399 ln(9.13e47) + 1896.534826 = 2362.87979

So, a projection shows that by year 2362, we could have a single storage drive holding every permutation of a board state, so it would be less than 2 drives to store the states along with the move to make for that board. Add more drives and you pull that date in.

References:

1a. http://www.pcworld.com/article/127105/article.html 1b. http://www.computerworld.com/article/2473980/data-storage-so... 2. http://codegolf.stackexchange.com/questions/19397/smallest-c...