Random switch setting in bell theorem

In summary, the conversation discusses Bell's theorem and an analogy that explains it. The concept of randomness and how it relates to the experiment is also discussed, as well as the connection to the double slit experiment. The purpose of Bell's theorem is to prove Einstein's idea of entanglement in quantum physics, which states that the properties of entangled particles are determined before measurement. However, quantum mechanics predicts that the results of the experiment will violate certain statistical properties, known as Bell's inequalities. The conversation also mentions a website that provides more information on Bell's theorem.
  • #1
rajeshmarndi
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I was trying to understand Bells theorem and I found this site
http://www.upscale.utoronto.ca/PVB/Harrison/BellsTheorem/Analogy.html
easy to understand.

I found the "The Second Analogy: More Boxes" in it easy to grasp. But one thing I didn't understand in it, where it uses the word random and expect all possible setting occur equally. Like, here it says,

"But the switch settings are made at random, so we expect each of the six possible results in the above table to occur with equal frequency. So both lights flash the same color one-third of the time."

Here when we say the switch setting are random, then how is it, that all possible setting occur equally. When it is random, it is possible, only one switch setting can occur all the time OR how is it that all possible setting occur equally?

Thank you.
 
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  • #2
If the switch settings are random and you repeat the experiment many times, you will expect see to all settings about equally often - google for "law of large numbers". It's not necessary that they all occur exactly the same number of times to see a violation of the inequality.
 
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  • #3
Nugatory said:
If the switch settings are random and you repeat the experiment many times, you will expect see to all settings about equally often - google for "law of large numbers". It's not necessary that they all occur exactly the same number of times to see a violation of the inequality.
Thanks for the reply.
Why do we take switch setting at random and also why are the three different state of particles(here speed, size and shape) are also random?
The device can also record the state of the entangled particles created and the switch setting. So that later it can be checked what was going on.

Also is this experiment similar to double slit experiment?

I understand bell's theorem is all about proving einstein idea and entanglement(quantum physics). For e.g according to quantum physics when pair of object are entangled, say a pair of gloves i.e if one is right hand then the other will be left hand. According to QM the other gloves is not determined before one of the gloves is checked. But according to einstein, they both are determined before the experiment is done.
 
  • #4
Read through the material here: http://www.drchinese.com/Bells_Theorem.htm

The essential point of Bell's theorem is that if the properties of both members of the entangled pair are determined before the measurement (as Einstein and many others expected) then the results of randomly chosen measurements of a large number of pairs will have certain statistical properties: they will obey Bell's inequalities.

Quantum mechanics predicts that under certain circumstances when there are (at least) three possible measurements, the results will violate the inequalities.
 

Related to Random switch setting in bell theorem

1. What is "random switch setting" in the context of Bell's theorem?

"Random switch setting" refers to the experimental setup used in Bell's theorem, also known as the Bell test, to test the principle of locality and the existence of hidden variables in quantum mechanics. In this setup, two entangled particles are sent to distant observers, and the measurement settings of each observer are randomly chosen to test if the particles' behavior is affected by the distance between them.

2. What is Bell's theorem and why is it important?

Bell's theorem is a famous result in quantum mechanics that shows the incompatibility between the principles of locality and realism. It states that no local hidden variable theory can reproduce all the predictions of quantum mechanics, and therefore, quantum mechanics is inherently non-local. This theorem has important implications for our understanding of the fundamental nature of reality.

3. How does random switch setting work in Bell's theorem experiments?

In a Bell test, two observers are given the task of measuring the properties of two entangled particles that were previously in contact but are now separated by a large distance. The observers use random number generators to choose the measurement settings for their particles, and their results are compared to test if the particles' behavior is affected by the distance between them.

4. What are the limitations of random switch setting in Bell's theorem experiments?

One of the main limitations of random switch setting in Bell's theorem experiments is that it assumes that the observers' measurement choices are truly random. However, there is always a possibility of hidden correlations or biases in the choice of measurement settings, which could affect the outcome of the experiment. Additionally, the distance between the observers could also introduce potential biases in the results.

5. Can random switch setting be used to prove or disprove the existence of hidden variables?

No, random switch setting alone cannot prove or disprove the existence of hidden variables. It can only provide evidence for or against the principles of locality and realism. Other factors, such as the accuracy of the measurement devices and the experimental setup, also play a crucial role in determining the validity of any conclusions drawn from a Bell test.

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