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- Thread starter intervoxel
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- #2

bhobba

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A photon's momentum vector points in the direction of its propagation but interacts with particles off its axis.

Why do you say that?

Thanks

Bill

- #3

naima

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Then every direction have the same probability.

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O.k., so this is not the case since the direction is defined at the moment of the interaction with the target (or if the recoiled source hits something) and the consequent simultenous definition of the recoil direction of the source by entaglement, right? My question remains though: how reflection is possible or how hits on one side of the mirror are privileged?Why do you say that?

Thanks

Bill

Hope this reply makes sense :)

- #5

bhobba

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O.k., so this is not the case since the direction is defined at the moment of the interaction with the target (or if the recoiled source hits something)

Why do you think you can extrapolate a direction from where it hits a target - think about the double slit - with both slits open you cant say which slit it went through or what direction it had - indeed even if it had the property of direction.

Why do you think a photon has the classical property of 'propagation'?

In QM its much better not to ascribe properties like propagation etc except when observed.

Thanks

Bill

- #6

bhobba

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See Feynman - QED Strange Theory Of Light And Matter.My question remains though: how reflection is possible or how hits on one side of the mirror are privileged?

Thanks

Bill

- #7

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So you mean that, when observed, the received photon's momentum does not necessarily has to be aligned with the photon's origin position? It could be pointing for example at an angle of 90 degrees?Why do you think you can extrapolate a direction from where it hits a target - think about the double slit - with both slits open you cant say which slit it went through or what direction it had - indeed even if it had the property of direction.

Why do you think a photon has the classical property of 'propagation'?

In QM its much better not to ascribe properties like propagation etc except when observed.

Thanks

Bill

I suppose that for many photons most of received momentum is aligned so light sailing is possible.

- #8

Nugatory

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Did you follow through on Bhobba's suggestion that you find and read Feynman's book? If not, do so.So you mean that, when observed, the received photon's momentum does not necessarily has to be aligned with the photon's origin position? It could be pointing for example at an angle of 90 degrees?

- #9

bhobba

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So you mean that, when observed, the received photon's momentum does not necessarily has to be aligned with the photon's origin position? It could be pointing for example at an angle of 90 degrees?

Momentum aligned with position?

They are independent variables.

Thanks

Bill

- #10

naima

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I think that his question is about the conservation of the momentum.

- #11

bhobba

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I think that his question is about the conservation of the momentum.

The very essence of QM is all you can predict is averages and momentum conservation is preserved on the average.

Why exactly is that an issue?

Thanks

Bill

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