What constitutes a QM observation?

In summary, the concept of observation in quantum mechanics is closely tied to the idea of measurement and the measurement apparatus. There is no definitive definition of what constitutes an observation, but generally it is considered to be an irreversible change to the measurement apparatus. The observer is the person who makes the measurement, but there are different theories on how to resolve the quantum measurement problem. A closed system is one in which there is no interaction with the outside world, but in quantum mechanics, interactions with the outside world can cause a collapse of the wave function.
  • #1
Glenn
When discussing quantum mechanics, what constitutes an observation?

-Glenn
 
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  • #2


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".
 
  • #3
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
 
  • #4
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.
 
  • #5
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
 
  • #6
Can a subatomic particle, atom, molecule, or larger cause the collapse of its own wave function?

-Glenn
 
  • #7
No, but its interaction with things around it can. Look up decoherence.
 
  • #8
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
 
  • #9
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.
 

What constitutes a QM observation?

A quantum mechanics (QM) observation is when a system is measured or observed, causing it to collapse from a state of superposition to a definite state. This can also be referred to as the wave function collapse. The following are five frequently asked questions about what constitutes a QM observation.

1. What is the role of the observer in a QM observation?

The observer plays a crucial role in a QM observation as they are the one who measures or observes the system. This measurement causes the wave function to collapse and the system to be in a definite state. Without an observer, the system would remain in a state of superposition.

2. Does a QM observation have to involve conscious observation?

No, a QM observation does not necessarily have to involve conscious observation. Any interaction or measurement with the system can cause the wave function collapse. This means that even inanimate objects can act as observers in a QM observation.

3. Can a QM observation be reversed?

No, a QM observation is irreversible. Once the wave function collapses and the system is in a definite state, it cannot be reversed back to a state of superposition. This is known as the collapse postulate in quantum mechanics.

4. How is a QM observation different from classical observation?

In classical observation, the act of measuring does not affect the system being measured. However, in QM observation, the very act of measuring or observing causes the system to change. This is due to the probabilistic nature of quantum mechanics and the collapse of the wave function.

5. Are there any limitations to what can be observed in QM?

Yes, there are limitations to what can be observed in QM. The Heisenberg uncertainty principle states that certain properties of a system, such as position and momentum, cannot be simultaneously known with certainty. This means that there will always be a degree of uncertainty in our observations of quantum systems.

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