Shannon's number

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Ted Black
Posts: 17
Joined: Fri Feb 15, 2019 4:46 pm

Shannon's number

Post by Ted Black » Wed Feb 27, 2019 5:15 pm

Any thoughts out there on the total number of possible chess games being larger than the number of atoms in the known universe?

NickFaulks
Posts: 8472
Joined: Sat Jan 02, 2010 1:28 pm

Re: Shannon's number

Post by NickFaulks » Wed Feb 27, 2019 5:43 pm

Ted Black wrote:
Wed Feb 27, 2019 5:15 pm
Any thoughts out there on the total number of possible chess games being larger than the number of atoms in the known universe?
Obviously true.
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Roland Kensdale
Posts: 183
Joined: Sat Mar 01, 2014 1:15 pm

Re: Shannon's number

Post by Roland Kensdale » Wed Feb 27, 2019 5:51 pm

A very accessible video on this by Numberphile is at: https://m.youtube.com/watch?v=Km024eldY1A

It explains how Shannon estimated the figure based on a rough average of 30 legal plies (half moves) in a typical middlegame position. Another mathematician Hardy had a larger estimate but didn't give his working. These are legal games, not sensible games.

Probably the universe which we can study is larger than when the statement was made, though the speed of light may put a finite limit on how much we can observe. It is also expanding.