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User: seamus1981

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  1. think this is still consistent with causality on Physicist Trying To Send a Signal Back In Time · · Score: 1
    My understanding with these "action at a distance" experiments (quantum cryptography is an example I am more familiar with) is that no information is actually transmitted faster than the speed of light.

    In quantum cryptography, for example, Alice and Bob want make sure that no Eve is eavesdropping. They can do this because they exchange information with entangled particles: Alice keeps one and sends one to Bob. If Eve has been tampering ("measuring") the Bob's particle, the measurement which Alice performs on her own particle will be affected. However in order for Alice to know if her measurement has been affected, she must also know the result of Bob's experiment: they must pick the phone up and tell each other the results of their experiment. Therefore - regardless of whether Eve's tampering has affected Alice;s measurement "instantanously", information cannot be exchanged faster than the telephone call, which is classical and must be slower than the speed of light.

    In this experiment it seems to me the situation must be similar. The fact that one of the particles is delayed by 50 microseconds over 10 miles seems like no coincidence: in special relativity temrs an event 10 miles awayand 50 microseconds away is actually simulataneous (on the surface of the same light cone). Therefore this seems not to breach causality.