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Name: Ross
Status: other
Grade: 12+
Location: PA
Country: USA
Date: Summer 2012


Question:
The uncertainty principle ( http://en.wikipedia.org/wiki/Uncertainty_principle ) says that as a person knows more about a particle's position, then less is known about the particle's momentum, and vice-versa. Quantum entanglement ( http://en.wikipedia.org/wiki/Quantum_entanglement ) makes two previously independent particles identical to each other. If two particles were quantum entangled, and then one was precisely measured for its position, while the other was precisely measured for its momentum, then the particle's position and momentum are known at the same time. Would that nullify the Uncertainty Principle by Dr. Heisenberg? Or am I misunderstanding one of the two theories?

Replies:
Ross, When the particles are entangled, measuring one particle affects the other particle. If you find the position state of the first particle, then the position state of the second is set. At this time, the entanglement ends. If you measure the momentum of the second particle, you make that particle’s position less known. Because the entanglement has ended, this no longer affects the first particle.

Dr. Ken Mellendorf Physics Instructor Illinois Central College


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