Recent content by Cl4r4

Sometimes this topic sounds similar to those situations in college where we cut (or limit) the parabolic trajectory because the launched particle could not go bellow the solid ground. It is an external intervention based on reasonable properties or limitations of the system.

Thank you, vanhees71. Nice animations. But you are then saying that the reason we cut the "right-moving wave-component in this region" is not causality, is it?

In the context of quantum mechanics, more specifically when solving the problem of the particle in the step potential we introduce "by hand" the cancelation of a term which propagates, say, from the infinity (at right) to the left (suposing that the particle is incident from minus infinity). And...

I am aware that this barrier shaped profile in the existence of the electron tends to introduce Fourier components which are richer than I have initially thought and are in some sense undesirable in this argument...

It seems then that causallity may be the theoretical agent that keeps the wave in its direction of movement. Suppose we can turn off-on-off the existence of an electron in a certain position of empty space. After this initial stage (non existing eletron - existing electron (for a short time...

But (sorry for this question) in solving these equations for a wave in free space do we naturally scape from having a back propagating wave component appearing out of nothing (or better, out of the body of the ongoing initial direct wave) ?

Thank you, vanhees71. Ok, I agree with you, but the situations you are describing are in some sense "helping" Huygens principle. I would like to consider a wave in the middle of its media, far from obstacles. Let's think of a sea wave in the middle of the ocean. At a given instant t0 we look at...

Thank you all (vanhees71, hutchphd and tech99), but regarding this last post by vanhees71 I would like to know if the approach via more envolved integrals like Fresnel-Kirchhoff formula, for instance, produces the due suppression of the backward component. I am referring to integrals that does...

Ok, tech99, I think you are correct in this point. So let me suggest that we concentrate on waves that take place on the surface of water. Some times I think that Huygens principle is more an enemy than a friend. I think the two proposals made to adjust it are too much "ad hoc". I still miss the...

But when we speak of absortion we are adding matter, atoms, to this context of a beam of light propagating in space. I think it would be better to try to discuss the application of Huygens principle to light in a scenario with vacuum.

Thank you, tech99. But this is basically what the work of Miller proposes, isn't it? My question has more to do with the "why". Why every wave front must have another behind it?

Hi All, Huygens principle has been extended with two independent efforts in order to reform its original feature that gives rise to a back propagating wave. 1) Fresnel proposed the obliquity factor ##(1/2)(1 + \cos\theta)##. 2) Miller proposed two kinds of emissions (dephased). D. Miller...

Is it correct to say that part of the light this lamp produces comes from the sequence: 1) atom gets ionized 2) electron accelerates (its ion too, of course) 3) collision between accelerated electrons and atoms (or ions) 4) atom (or ion) gets excited with this collision 5) atom (or ion)...