[ExI] The subjectivity of entropy, the role of the observer...==> Rational metaethics
kanzure at gmail.com
Thu Feb 28 16:06:02 UTC 2008
On Thursday 28 February 2008, Jef Allbright wrote:
A good post, it's making me wonder where he's getting his material.
> The connection in the other direction is less obvious. Suppose there
> was a glass of water, about which, initially, you knew only that its
> temperature was 72 degrees. Then, suddenly, Saint Laplace reveals to
> you the exact locations and velocities of all the atoms in the water.
> You now know perfectly the state of the water, so, by the
> information-theoretic definition of entropy, its entropy is zero.
> Does that make its thermodynamic entropy zero? Is the water colder,
> because we know more about it? Ignoring quantumness for the moment,
> the answer is: Yes! Yes it is!
Saint Laplace, supposedly being a mystical being able to reveal this
information to you, would have to directly measure all of these pieces
of information -- otherwise I would have to argue that it is _not_
colder. In other words, whether it is St. Laplace or yourself that does
the measurements: the measurements must be within this universe, else I
would have to debate the point that it is colder. But this is just
nit-picking, since the basic point that anything that you know more
about gets colder. (That's why programmers hate documentation: it's
> Which is to say: To form accurate beliefs about something, you really
> do have to observe it. It's a very physical, very real process: any
> rational mind does "work" in the thermodynamic sense, not just the
> sense of mental effort.
I wonder what the correlation is between thermodynamic 'work' (heat
cycles?) and mental effort. I know that it's not one-to-one, but still.
More information about the extropy-chat