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- Thread starter autonomous
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autonomous said:

Search and read up on the EPR paradox, you might be enlightened to know that you weren't the first one to propose the collapse of the uncertainty principle.

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CarlB

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autonomous said:i was wondering, what if you shined two parallel rays of light directly next to each other and shot the particle through them, one being a short wavelength and the other a long wavelength and measured each one. the first ray of light would find the momentum, so when u found the position you could already know its momentum. would this be accurate, considering the speed of the particle is constant?

For your plan to work, you're going to have to measure momentum first, then position. Clearly if you reversed the order, you'd end up screwing up the momentum and get the Heisenberg limit.

So your question really comes down to this. When you make a measurement of momentum, does it also screw up later measurements of position?

The answer is that it does. In QM, to make an accurate measurement of momentum requires that the particle be placed in an approximate eigenstate of the momentum operator. The math then shows that its position cannot be accurately determined.

By the way, the EPR experiment involves correlated particles being measured, one for momentum, the other for position. In your case, you only have one particle, so the Heisenberg uncertainty principle does, in fact, apply.

Carl

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https://www.physicsforums.com/showthread.php?t=78949

In QM, to make an accurate measurement of momentum requires that the particle be placed in an approximate eigenstate of the momentum operator. The math then shows that its position cannot be accurately determined.

To be even clearer, it won't

which is subject to discovery. But it will acquire one if and when a position

measurement is made.

I use the funny verbiage "subject to discovery" because in english the

word "determine" has two meanings and is the source of much confusion

on this topic.

- #6

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The HUP enters the discussion when you try to associate these values of position and momentum to a certain time, a certain initial state and a certain set of physical influences (Hamiltonian). By doing a set of identical experiments you will find statistical dispersion on these results, and it is exactly at this point that HUP appears, if I understood it well.

Best Regards

DaTario

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