Re: why can't we erase information?

From: Russell Standish <r.standish.domain.name.hidden>
Date: Mon, 10 Apr 2006 18:34:42 +1000

On Mon, Apr 10, 2006 at 12:03:47AM -0700, Brent Meeker wrote:
>
> Russell Standish wrote:
> > Unitary evolution preserves information. It is only through
> > measurement by an observer that information can be created or
> > destroyed. Usually, the second law is interpreted as the destruction
> > of information (anyone observing a closed system will over time know
> > less information about the system), so it puzzles me that you have the
> > sign the other way.
>
> What? You're saying that if I observe a system, then I know less about it. You
> must be using some non-standard meaning of "know".
>
> Brent Meeker
>

Yes - in the case of milk being stirred into coffee. Strange as it may
seem, you know more information when the system is initially
structured than after that initial structure has dispersed.

And yes you need to observe it. Entropy is undefined without an
observer.

Cheers

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Received on Mon Apr 10 2006 - 21:58:42 PDT