Date: Thu, 1 Nov 2001 21:47:20 -0800 From: "Crist J. Clark" <cristjc@earthlink.net> To: Lamont Granquist <lamont@scriptkiddie.org> Cc: Stephen Montgomery-Smith <stephen@math.missouri.edu>, "Nicpon, John" <John.Nicpon@SouthTrust.com>, freebsd-chat@FreeBSD.ORG Subject: Re: Unix Philosophers Please! Message-ID: <20011101214720.G4360@blossom.cjclark.org> In-Reply-To: <20011031170629.C865-100000@coredump.scriptkiddie.org>; from lamont@scriptkiddie.org on Wed, Oct 31, 2001 at 05:20:33PM -0800 References: <3BE08283.EC81A8ED@math.missouri.edu> <20011031170629.C865-100000@coredump.scriptkiddie.org>
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On Wed, Oct 31, 2001 at 05:20:33PM -0800, Lamont Granquist wrote:
>
>
> On Wed, 31 Oct 2001, Stephen Montgomery-Smith wrote:
> > > "Nicpon, John" wrote:
> > >
> > > Please specifically define where data goes that is sent to /dev/null
> >
> > Answer 1. Data is not like energy. There is no "conservation of data"
> > law. So the data simply "disappears".
>
> Doesn't thermodynamics second law actually imply that data has to
> disappear and that with the heat death of the universe data will be at a
> minimum? For meaningful data to exist there needs to be order, while the
> 2nd law requires that systems evolve to less ordered states.
The 2nd law does not require that systems must evolve to less ordered
states. The 2nd law says that the entropy of an isolated system can
never decrease. A fine distinction, but important.
> The only uncertainty about this that I've got is that random systems can
> actually be very dense with data. Think about a compressed and encrypted
> file, which should be indistinguishable from /dev/random output.
>
> I guess the difference between those two is that there is only a single
> state which validly represents the comprssed and encrypted file.
The distinction is that the compressed and encrypted file is _not_
a random string of bits. Yes, it may appear random and pass
statistical tests for "randomness," but that does not mean it is
random. Another frequent example is the digits of pi (or any other
transcendental number),
3
1
4
1
...
If you were to run all of your statistical tests on that set of
numbers, it would appear to be random. But it is not. If you tell me
any arbitrary position in the bit stream, I can tell you what the next
value will be. Not random.
> Contribute to the Heat Death of the Universe! pipe everything to /dev/null!
Actually, though it may be counter-intuituve, the best way to add to
hasten the Heat Death is to _save_ data. It takes work (in the
thermodynamic sense) to save data (to disk, to memory, or to even to
your brain). The efficiency of getting the work done is where the
entropy is seriously increased.
--
Crist J. Clark | cjclark@alum.mit.edu
| cjclark@jhu.edu
http://people.freebsd.org/~cjc/ | cjc@freebsd.org
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