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Modern Physics

Blazing goIITian

Joined:	12 Dec 2007
Post:	1249

14 Jun 2010 18:41:59 IST

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Think about it......Einstein Podolsky Rosenberg Experiment...?

None

Try to think about this question and when all your knowledge has been used, search wiki. for this experiment and read Bohr's remark to this experiment.

Imagine a particle A to be a rest hence the center of mass is at rest and the velocity of center of mass and hence the momentum is 0. The particle A decomposes to two particles B and C which move at 180degree angle.What you do is that you make the uncertainity of position of B as small as possible and let the momentum have a huge uncertainity -who cares.And then you measure the momentum of C very carefully neglecting the position of C.

The uncertainity of position of B is z then minimum uncertainity in momentum is of order h/z. But momentum of B=momentum of C hence as we can measure the momentum of C with an uncertainity smaller than h/z we can in a way defy uncertainity principle but which is true........so where lies the fallacy?

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Comments (1)

edison

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Joined: 19 Oct 2006

Posts: 7537

15 Jun 2010 13:27:25 IST

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Well its a very good question and posed very beautifully.

As far as measuring of position of B and that of momentum of C is concerned the two cannot be done simultaneously the term very important in Uncertainty principle. In the question also we are measuring position of the particle at one instance and then momentum of the particle at other instance and then we say that two are related which is not the case as particle has got wave nature that is it is no more a point particle but a diffused entity that has a spread of wave function according to quantum mechanics. Thus correlating the momentum of B with C is not possible the measurement of momentum and position has to be done for the same particle and that too at the same instant.

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