Von Neumann measurement scheme

[bluecap]

I've been studying the von Neumann measurement scheme (and understanding the math part) where the system and apparatus are quantum in contrast to the orthodox where the apparatus is classical. I'd like to know the following.

1. Is the von Neumann measurement scheme 100% orthodox and believed by the mainstream? I'm asking this because some full fledged physicists like Vanheez71 doesn't even believe in the Bell's Theorem or think that setting up one of the apparatus has no influence (whether non-local or non-realistic, etc.) on the other (he attributed everything to ensembles). He doesn't even believe in the Kochen-Specker Theorem. See his endless debates with Demystier and others. so I wonder if he or others also doesn't believe in the von Neumann measurement scheme.

2. How do you understand it?

3. Is the von Neumann cut related to the von Neumann measurement scheme? If not, can you give example of the math of the von Neamann cut? The math of the von Neumann measurement scheme is simply entanglement of the system and apparatus.

4. Why is there another Heiserberg cut? How does it differ to the von Neumann cut. If they are the same. Did Heisenberg and von Neumann discover the cut at the same time?

 

[PeterDonis]

I've been studying the von Neumann measurement scheme

You need to give references that you are using. Without something specific it's not going to be possible to have a productive discussion.

Is the von Neumann measurement scheme 100% orthodox and believed by the mainstream?

Physics doesn't work this way. The question you should be asking is, is the scheme testable? Does it make correct predictions?

I'm asking this because some full fledged physicists like Vanheez71 doesn't even believe in the Bell's Theorem or think that setting up one of the apparatus has no influence (whether non-local or non-realistic, etc.) on the other (he attributed everything to ensembles). He doesn't even believe in the Kochen-Specker Theorem. See his endless debates with Demystier and others. so I wonder if he or others also doesn't believe in the von Neumann measurement scheme.

I'm

You should not presume to say what other PF members do or do not "believe". I suspect you have misinterpreted things that you have seen posted, but in any case, statements like this are off topic.

How do you understand it?

This is much too vague. You need to find a specific question about something you are having trouble understanding.

Is the von Neumann cut related to the von Neumann measurement scheme?

This can't be answered unless we have a specific reference you are using, so we know what you think you are referring to by these terms.

Why is there another Heiserberg cut? How does it differ to the von Neumann cut.

Same comment as above.

 

[PeterDonis]

I am closing the thread since the OP is much too broad and no references are given. @bluecap if you can give a specific reference and come up with a specific question about something you don't understand (preferably with a specific concrete example of the issue), you can open a new thread to discuss that specific issue.