Re: Quantum theory of measurement

From: Jesse Mazer <lasermazer.domain.name.hidden>
Date: Wed, 12 Oct 2005 17:34:08 -0400

scerir wrote:

>
>From: "Ben Goertzel"
> > [...] but still the records
> > could be kept somewhere,
> > and one can ask what would happen
> > if the records were kept somewhere else [...]
>
>Not sure, but the quote below - about the information
>'in principle' - might be helpful.
>
>"The superposition of amplitudes is only valid if there
>is no way to know, even in principle, which path the particle
>took. It is important to realize that this does not imply
>that an observer actually takes note of what happens.
>It is sufficient to destroy the interference pattern,
>if the path information is accessible in principle from
>the experiment or even if it is dispersed in the environment
>and beyond any technical possibility to be recovered, but
>in principle 'still out there'".
>- Anton Zeilinger, (Rev.Mod.Phys.,1999, p.S-288)
>

An example of this principle is that if you try to do the electron version
of the double-slit experiment in open air rather than in a vacuum, the
electron's interactions with the air molecules will destroy the
interference, even though in practice it would probably be impossible for
human experimenters to reconstruct which slit the electron went through by
measuring all the air molecules.

Jesse
Received on Wed Oct 12 2005 - 17:38:16 PDT