Cherenkov radiation

[hairykrishna]

R300will said:

isn't wave/particle duality more to do with electrons?

All matter. wavelength=h/momentum.

Getting a deep understanding of why the phase velocity (and the group velocity in the case of some weird stuff) of light changes in materials is not easy. Any short and snappy explanation will probably be wrong.

[Tim330]

http://www.youtube.com/watch?v=2G422z8pDn4

The criticality accident mentioned above was shown in the film Fat Man and Little Boy.

[Ali G]

carmonk said:

Because they do. I think you're confusing group velocity with another velocity, the name of which I can't think of right now (edit: phase, just looked it up), but which describes the speed of the wave peak which is not an actual photon and carries no information.

Quite interesting though that some particles can negotiate their way through certain media more quickly than photons can!

Agree particles not travelling > C and infer from your argument that photons are therefore required to 'bounce around' the medium in question in order to take more time than particle in question.

Therefore, Cherenkov can only take place where the interaction between photon and medium is greater than between particle and medium!

[carmonk]

Ali G said:

carmonk said:

Because they do. I think you're confusing group velocity with another velocity, the name of which I can't think of right now (edit: phase, just looked it up), but which describes the speed of the wave peak which is not an actual photon and carries no information.

Quite interesting though that some particles can negotiate their way through certain media more quickly than photons can!

Agree particles not travelling > C and infer from your argument that photons are therefore required to 'bounce around' the medium in question in order to take more time than particle in question.

Therefore, Cherenkov can only take place where the interaction between photon and medium is greater than between particle and medium!

That's how I read it, yep. Does sound weird but that's physics for you. And I suppose I should have said 'absorbed and emitted' rather than 'bounce around' but still, it all amounts to the same thing.