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HolyPommeDeTerre t1_j9q4m9k wrote

Reply to comment by NZGumboot in Physicists Use Quantum Mechanics to Pull Energy out of Nothing by Vailhem

Yes my intuition was "input 1 in one of the particle" (change it's state in a expected way) to observe the behaviour of the other entangled particle. But as you state that, influencing the state of the particle will break entanglement.

But, from there, how are we sure the particles are entangled if we can't act on any of them and reflect a resulting change in the other particle.

I guess we can observe both particles surrounding environment and see that there are similitudes ?

Anyway thank you for your time helping me understand :)

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NZGumboot t1_j9q7l51 wrote

Basically what they do is create a huge number of entangled particles, separate each pair into locations A and B, then measure each the state of all of the particles at both locations (this breaks the entanglement, but that's okay.)

The measurements at A and B appear perfectly random according to all the tests of randomness that we have. But when you bring the measurements from A and B together, you find that they are correlated -- each pair might be e.g. in the same state, or the opposite state, depending on how the entanglement was created. A and B can be arbitrarily far apart.

You might think, well that's easy to explain, when you created the entanglement it set the state of each at that point. But no, you can prove that isn't the case, and that it must be the case that the entangled particles both have an indefinite state until they're measured, and the measurement of one affects the state of the other across any distance. (The proof is called Bell's inequality, see this video for more: https://youtu.be/ZuvK-od647c)

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HolyPommeDeTerre t1_j9q94lp wrote

Thank you very much. You are gluing multiple things I have in my head together. It's a very clear explanation.

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