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-   -   what constitutes a QM observation? (http://www.physicsforums.com/showthread.php?t=7666)

Glenn Oct23-03 12:20 PM

what constitutes a QM observation?
 
When discussing quantum mechanics, what constitutes an observation?

-Glenn

jcsd Oct23-03 12:29 PM

Re: observation?
 
Quote:

Originally posted by Glenn
When discussing quantum mechanics, what constitutes an observation?

-Glenn

'Measurment' is the temr usually used, unfortunately there is no precise defintion for what constitutes a measurement apparatus and thus a measurment(this is known as the quantum mechanical measurement). The best definiton is probably: "an irrevesrible change to the measurmewnt apparatus".

Glenn Oct23-03 12:40 PM

I guess I am still not clear on the "observation" part of all this. In a book I am reading, the author is repeatedly referring to them as "conscious" observations, or "intelligent" observations.

Is there a clearer explanation?

Thanks,
Glenn

jcsd Oct23-03 01:17 PM

An observer is the person who makes the measurment. It's a sticky subject as there are many theories on how to resolve the quantum mechanical measurment problem, but no defintive answer.

chroot Oct23-03 01:48 PM

Generally, you consider closed systems. Anything inside that closed system that is made to affect something outside the system (therefore making it no longer "closed") is a measurement.

- Warren

Glenn Oct23-03 01:55 PM

Can a subatomic particle, atom, molecule, or larger cause the collapse of its own wave function?

-Glenn

selfAdjoint Oct23-03 04:14 PM

No, but its interaction with things around it can. Look up decoherence.

jby Oct24-03 11:01 PM

Quote:

Generally, you consider closed systems. Anything inside that closed system that is made to affect something outside the system (therefore making it no longer "closed") is a measurement.
I don't quite understand this. How does something inside a closed system affect something outside the system? After all, this seems contradictory to the word closed. Seems like a tongue twister to me. :P

jcsd Oct25-03 11:24 AM

Quote:

Originally posted by Glenn
Can a subatomic particle, atom, molecule, or larger cause the collapse of its own wave function?

-Glenn

In convential quantum mechanics no, but there is a theory of spontaneous collapse where in a manner simlair to radioactive decay wavefunctions of particles spopntaously collapse, howvere attempts to detect any spontaneous collapse have failed.


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