What constitutes a QM observation?

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Glenn

When discussing quantum mechanics, what constitutes an observation?

-Glenn
 

jcsd

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Re: observation?

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

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

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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

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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

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

-Glenn
 

selfAdjoint

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

jby

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

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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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