What constitutes a QM observation?

[Glenn]

When discussing quantum mechanics, what constitutes an observation?

-Glenn

 

[jcsd]

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]

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]

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]

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]

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.