What is the mathematical expression of the process of the wave functions collapsing?

[george1962]

TL;DR Summary

What is the mathematical expression of the process of the wave functions collapsing?

People very often say the collapse of the wave functions in the discussion of quantum mechanics, then how to write this process in math form?

 

[anuttarasammyak]

Non- diagonal components of density matrix disappear. No process but a sudden change.

 

[george1962]

Non- diagonal components of density matrix disappear. No process but a sudden change.

It does not make sense, but still thanks ！

 

[Vanadium 50]

What doesn't make sense? If you mean "I don't know what a density matrix is", that's fine, but then this thread should be B-level.

 

[berkeman]

What doesn't make sense? If you mean "I don't know what a density matrix is", that's fine, but then this thread should be B-level.

Agreed.

@george1962 -- Should I change this thread prefix from "I" (undergraduate physics level) to "B" (basic high school math level)?

 

[george1962]

I mean the “ sudden change”

 

[Vanadium 50]

I mean the “ sudden change”

What doesn't make sense? That a number used to be non-zero and now it's zero? That's perfectly sensible. It happens all the time in physics. ("A ball is dropped from rest at a height h")

 

[PeterDonis]

TL;DR Summary: What is the mathematical expression of the process of the wave functions collapsing?

People very often say the collapse of the wave functions in the discussion of quantum mechanics, then how to write this process in math form?

See here for the basics:

https://www.physicsforums.com/threads/the-7-basic-rules-of-quantum-mechanics.971724/

For more details, consult any QM textbook.

Thread closed as the OP is now taking an unscheduled vacation.