[extropy-chat] FWD (SK) Heisenberg's Uncertainty Principle

[Alfio Puglisi]

On Tue, 16 Mar 2004, Mike Lorrey wrote:

>It is essentially that there are more than one characteristic of a
>quantum particle. The uncertainty principle states that if you observe
>the value of one characteristic, the act of observation disturbs the
>particle, such that you can never know what the original values of the
>other characteristics were.
>
>For example, if you observe the position of a particle, you cannot know
>what its spin was before you observed the position (and vice versa).
>
>It is not physically possible to observe a particle without receiving
>some amount of information from it. That information requires some type
>of broadcast via energy or other particles. This causes the change in
>characteristics.
>
>Nor is 'observation' dependent upon human beings to observe.
>Chlorophyll observes the wavelength of photons all day long without a
>human around, else trees would not live.

This last paragraph is the important one. If one takes the "observation
disturbs the particle" view, it's not just human observation
with lamps and particle accelerators. Each and every interaction with
other particles is an "observation", with the other particle observing
the first to judge how it should react, etc. The net result is that, if
the particle has any interaction whatsoever with the rest of the world,
its characteristics are subject to uncertainty. And, if it doesn't
interact, there's no way to know its characteristic, so they are totally
indeterminate :) you can't win.

Alfio