- #1
Buzz Bloom
Gold Member
- 2,519
- 467
- TL;DR Summary
- I recall reading somewhere (I cannot remember where) that there are situations in which the consequences of a measurement change if the result of the measurement is destroyed.
I would much appreciate it if someone can help me find a source discussing this topic. I tried a search on the Internet with several alternative ways to express the question, but nothing worked.
I have in mind a particular example, but I do not know if it is applicable to this question as a demonstration of a change.
Two particles are created with entangled spin. Each particle has a detector to measure it's spin. There is an angle between the orientations of the two detectors. The fraction of experiments in which the two detectors assign the same spin value to the two particles depends on this angle. What happens if two detectors are at different distances from the creation of the particle pair, and the closer detector destroys its measurement a very short time after the measurement was made if the value is "up"?
I have in mind a particular example, but I do not know if it is applicable to this question as a demonstration of a change.
Two particles are created with entangled spin. Each particle has a detector to measure it's spin. There is an angle between the orientations of the two detectors. The fraction of experiments in which the two detectors assign the same spin value to the two particles depends on this angle. What happens if two detectors are at different distances from the creation of the particle pair, and the closer detector destroys its measurement a very short time after the measurement was made if the value is "up"?