pengvado comments on Open thread for January 1-7, 2014 - Less Wrong

2 Post author: NancyLebovitz 01 January 2014 03:54PM

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Comment author: pragmatist 04 January 2014 07:27:22AM 1 point [-]

A low entropy microstate takes fewer bits to specify once you're given the macrostate to which it belongs, since low entropy macrostates are instantiated by fewer microstates than high entropy ones. But I don't see why that should be the relevant way to determine simplicity. The extra bits are just being smuggled into the macrostate description. If you're trying to simply specify the microstate without any prior information about the macrostate, then it seems to me that any microstate -- low or high entropy -- should take the same number of bits to specify, no?

Comment author: pengvado 04 January 2014 01:42:57PM *  2 points [-]

If you can encode microstate s in n bits, that implies that you have a prior that assigns P(s)=2^-n. The set of all possible microstates is countably infinite. There is no such thing as a uniform distribution over a countably infinite set. Therefore, even the ignorance prior can't assign equal length bitstrings to all microstates.