By Anupum Pant
Does quantum entanglement make faster-than-light communication possible?
We know the entangled particles must have undefined spins before we measure them because if they didn’t they would sometimes give the same spin when measured in a direction perpendicular to their well-defined spins (and they never do).
We know the entangled particles can’t have hidden information all along about which spin they will give in different directions because if they did we would measure different results at the two detectors >5/9ths of the time and we don’t – we only get different results 50% of the time.
We can’t use this behaviour to communicate faster than light because we can only pick the direction to measure in, we can’t force the spin to be up or down – and it will be random with 50/50 probability. When the two detectors pick the same direction to measure in the results at one detector will be random but the opposite random of those measured at the other detector, which is a bit spooky. – via Veritasium