# I Understanding Schrodinger's cat

1. Jul 28, 2016

### kent davidge

(Sorry for my bad English.) I learned something about Schrodinger's equation and 2 and 3 dimensions, as well particle confined in a box and the behavior of the atoms using Schrodinger's analysis. But I don't understand why a superposition of states is necessary* in the Schrodinger's cat experiment. Also, I would like to know how the wave functions must be added for the cat. Would we add the wave functions for each atom that makes the cat one-by-one?

*Would it be necessary in order to the wave functions become more localized?

Last edited: Jul 28, 2016
2. Jul 28, 2016

### Staff: Mentor

The wave function of the cat is very complex and not the addition of the wave-functions of the atoms because its all entangled.

The cat is never in a superposition of position as a search on this forum will show - it has been discussed many times.

Thanks
Bill

3. Jul 29, 2016

### kq6up

The Schrödinger's cat thought experiment was conceived by Erwin Schrödinger to explain the awkwardness of the Copenhagen interpretation of QM. If a QM system is in a superposition of states, what actually causes the collapse? There is obviously a collapse according to the Copenhagen interpretation because asking what slit the electron traveled through is a meaningless question. For example, in the two slit experiment the QM gives the wave interference of probabilities of finding an electron impacting a screen. The average pattern on the screen is the superimposed states interfering with one another (the wave pattern), and the individual marks on the screen are observation (collapse). The Copenhagen interpretation implies that the observer his/herself may also become entangled and become a part of the superimposed system -- since there is no clear demarcation where the system ends and the observer begins. This can cause some sort of infinite regress. So that also means the cat can be in a superposition of states, and that on its face seems absurd. This is what Schrödinger was trying to point out.

See https://en.wikipedia.org/wiki/Von_Neumann–Wigner_interpretation

Regards,
KQ6UP

4. Jul 29, 2016

### kent davidge

bhobba Thank you.