Huygens' principle and the absence of back propagation

[DaTario]

Hi All,

In wave theory, we learn that Huygens' principle apply and that every point in a wave front acts like it was a source. According to this, it seems that from a given wave front we would see, after some small time interval, not only the the propagated wave front but another one corresponding to the back propagation of the primary wave front. It is a fact that we do not observe this back propagating wave front (at least it seems not to exist).

Does anyone know how to explain this absence ?

OBS: I have once heard that obliquity is a key concept in this context, but it is not clear how it works in the explanation.

Thank you all

Best wishes

DaTario

 

[jtbell]

See Doc Al's post in this thread:

https://www.physicsforums.com/showthread.php?t=236864

 

[DaTario]

Thank you,

Best wishes

DaTario

 

[DaTario]

by usisng the obliquity factor in integrals to evaluate the amplitude at a certain position and at a certain time one, in fact, obtains the expected results? Or is this concept (obliquity factor) just a way to get outo from the discussion? Is this used in calcutating amplitudes and wave front shapes?

Best wishes

DaTario