Huygens' principle and the absence of back propagation

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Discussion Overview

The discussion revolves around Huygens' principle in wave theory, specifically addressing the absence of back propagation of wave fronts. Participants explore the implications of this principle and seek explanations for why back propagating wave fronts are not observed, with a mention of the concept of obliquity as potentially relevant.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • Some participants note that according to Huygens' principle, every point in a wave front acts as a source, which raises the question of why back propagating wave fronts are not observed.
  • One participant mentions having heard that obliquity is a key concept in understanding the absence of back propagation, though its application remains unclear.
  • Another participant questions whether the obliquity factor is a legitimate method for evaluating amplitudes and wave front shapes or if it serves merely as a way to sidestep the discussion.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the explanation for the absence of back propagating wave fronts, and multiple viewpoints regarding the role of obliquity remain contested.

Contextual Notes

The discussion includes unresolved questions about the application of the obliquity factor in calculations and its relevance to the observed phenomena.

DaTario
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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
 
Science news on Phys.org
Thank you,

Best wishes

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
 

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