How do we know that the measurement affects the result?

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SUMMARY

This discussion centers on the impact of measurement on quantum particles, particularly in the context of quantum entanglement. Participants highlight that measuring entangled particles does not confirm their entanglement independently; it requires joint measurements and statistical analysis. The conversation also emphasizes that the nature of measurements influences results, with the first measurement affecting subsequent measurements due to the collapse of the quantum state. Furthermore, the discussion touches on the limitations of using terms like "measure" and "observer," which can lead to misconceptions in quantum mechanics.

PREREQUISITES
  • Understanding of quantum mechanics principles, particularly quantum entanglement.
  • Familiarity with measurement theory in quantum physics.
  • Knowledge of Bell test experiments and their implications.
  • Basic grasp of statistical analysis in experimental physics.
NEXT STEPS
  • Research the implications of Bell test experiments on quantum communication.
  • Explore the Relational interpretation of quantum mechanics for alternative perspectives.
  • Study the concept of quantum state collapse and its effects on measurement outcomes.
  • Investigate advanced textbooks like Ballentine for precise terminology in quantum mechanics.
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Physicists, quantum mechanics students, researchers in quantum information science, and anyone interested in the foundational aspects of measurement in quantum theory.

danHa
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how do we know that measuring effect the result . how can we know weather quant would behave differentially if we wouldn't measure it .
and if we do know the difference between quant that had been measured for example one quant can interference with it self if it haven't been measured in some lactation in space . so why two entanglement quant are consider as not capable of transfer data. if we can tell weather one practical has been measured for example suppose that we have a lot of entanglement particles and two location and we would shot them trough two slices and the same time . and we would put measure the device in one location would we see interference in the other? example of experience
 

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atyy said:
Bell test experiments are consistent with the quantum formalism that measurement affects the result, yet cannot be used for communication.
https://en.wikipedia.org/wiki/Bell_test_experiments
but if the measuring device is not interacting with the world would it change the the result as well if not maybe it just matter of point of view ,because for knowing that the statistic has change we need to send the other side if the measuring was happened or not .so we can say that in the point of view of the thins that interacting with the measure device are difference so they see difference result. because the location of something is relative to other thins but it can be relative only to things that are interacting with that
 
danHa said:
but if the measuring device is not interacting with the world
It's unclear to me what you mean by this. Do you possibly mean that there is no recording of the outcome of the measurement?
 
danHa said:
how do we know that measuring effect the result . how can we know weather quant would behave differentially if we wouldn't measure it .
and if we do know the difference between quant that had been measured for example one quant can interference with it self if it haven't been measured in some lactation in space . so why two entanglement quant are consider as not capable of transfer data. if we can tell weather one practical has been measured for example suppose that we have a lot of entanglement particles and two location and we would shot them trough two slices and the same time . and we would put measure the device in one location would we see interference in the other? example of experience

1. There is no test that will independently confirm or refute whether a particle is entangled. That can only be done by measuring both (all) entangled particles, and usually it requires a statistical sample to be sure.

2. Measuring is not the determining factor in and of itself. It is the nature of the joint measurements that controls.

3. As a general rule, entangled particles do NOT exhibit interference as you suggest.
 
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DennisN said:
It's unclear to me what you mean by this. Do you possibly mean that there is no recording of the outcome of the measurement?
I mean that there is some thing that the quant is interact with but this thing is not interact with nothing outside world so we can say that the quant location is relative to this thin would also effect on the location of the quant
 
danHa said:
how do we know that measuring effect the result . how can we know weather quant would behave differentially if we wouldn't measure it .

To me this seems like a strange way to say this, because without a measurement there's no result in the first place. If you do two measurements with a very short time interval between them, then the result of the 2nd measurement is likely to be close to that of the first one. This is a result of the system "collapsing" to an eigenstate that corresponds to the measured result, and can be described as the first measurement affecting the result of the second.
 
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hilbert2 said:
To me this seems like a strange way to say this, because without a measurement there's no result in the first place. If you do two measurements with a very short time interval between them, then the result of the 2nd measurement is likely to be close to that of the first one. This is a result of the system "collapsing" to an eigenstate that corresponds to the measured result, and can be described as the first measurement affecting the result of the second.
but would it be third measured because it has to be on the same quant
 
danHa said:
but if the measuring device is not interacting with the world would it change the the result as well if not maybe it just matter of point of view ,because for knowing that the statistic has change we need to send the other side if the measuring was happened or not .so we can say that in the point of view of the thins that interacting with the measure device are difference so they see difference result. because the location of something is relative to other thins but it can be relative only to things that are interacting with that

The measuring device is always conceived of as being in the real world and interacting with it, ie. it produces a result that you can observe.
 
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  • #10
Everything measured in physics is in the real world!
 
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  • #11
Personally, I think these kinds of questions would have died out decades ago if better terminology than "measure" and "observer" had been chosen. Those two words were just asking to anthropomorified and misused.
 
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  • #12
bobob said:
Personally, I think these kinds of questions would have died out decades ago if better terminology than "measure" and "observer" had been chosen. Those two words were just asking to anthropomorified and misused.
my way of seeing it is that the quant function are relative to the things it interact with so when you measure it you can find difference point of views so in case of quantum entanglement the two quant properties are relative to each other so when you know about the measure in one place it like you interact with the measure device in one place
 
  • #13
bobob said:
Personally, I think these kinds of questions would have died out decades ago if better terminology than "measure" and "observer" had been chosen. Those two words were just asking to anthropomorified and misused.
Along with "particle"... The vocabulary is the way it is for historical reasons. Advanced textbooks (I'm thinking of Ballentine right now, but there are plenty of other meritorious examples) are precise in their use of the language, but that precision does not trickle down.
 
  • #14
danielhaish said:
my way of seeing it is that the quant function are relative to the things it interact with so when you measure it you can find difference point of views so in case of quantum entanglement the two quant properties are relative to each other so when you know about the measure in one place it like you interact with the measure device in one place
I'm not sure I understand what you mean, but there is an interpretation called Relational interpretation of quantum mechanics.
 
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  • #15
DennisN said:
I'm not sure I understand what you mean, but there is an interpretation called Relational interpretation of quantum mechanics.
thanks that what I meant because if time is relative the location of practical may be relative to how many test you do
 
  • #16
danielhaish said:
thanks that what I meant because if time is relative the location of practical may be relative to how many test you do

The time order of measurements on entangled particles is not a factor in the observed results. That means it is not important. Relativity is not important either.
 
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