Talk:Matter wave

Standing matter waves

Thinking of standing matter waves as a separate class seems to me to be erroneous. That would be saying that the standing modes of an electromagnetic wave form a separate class, whereas it is simply an emergent phenomenon given boundary conditions imposed on a travelling wave: it is just a superposition of travelling waves. In this context, multi-particle waves do not appear to behave as a superposition: the wavevector is determined by the total mass (or perhaps a more complex description). —Quondum 12:53, 8 June 2023 (UTC)

Also, the connection between the effective mass for standing and travelling matter waves is the same in all cases -- via the second derivative, it does not matter whether they are quasiparticles or not. Ldm1954 (talk) 02:33, 9 June 2023 (UTC)

May I suggest that standing matter waves are not analogous to electromagnetic standing modes? AFAIK the latter are purely different boundary conditions. But standing matter waves are idealized models for bound quantum systems where forces alter the waves rather than boundary conditions. We talk about "particle in a box" not in comparison to blackbody radiation but in comparison to hydrogen.

In fact half of de Broglie's original punch was his application of waves to Bohr atoms. Turns out that his treatment did not make the cut, but it was a thing and lit a fire under Schrodinger.

To further this section we need to make contact with matter wave concepts in chemistry. Johnjbarton (talk) 16:54, 9 June 2023 (UTC)

Agreed, what I added was just a stub on that. Ldm1954 (talk) 16:57, 9 June 2023 (UTC)

Sorry, no, standing waves have zero probability flux (group velocity is a less accurate term), and as such are fundamentally different from travelling waves which have a probability flux. Indeed, de Broglie connected hydrogenic states to standing waves in a ring, without doing the detailed math.A case can be made that most eigensolutions such as hydrogenic are standing waves.

Ldm1954 (talk) 02:20, 9 June 2023 (UTC)

I'm sorry that I opened this discussion. I cannot work with this style of argument. —Quondum 10:44, 9 June 2023 (UTC)

My apologies if I came across too strongly, but there are deep differences and this matters. Probably overkill, oversimple:

A travelling matter waves is going from A to B; a standing wave such as a particle in a box is not moving. Both have energy, effective mass and wavelength. Both are eigensolutions for different classes of problems, one free and the other with extra conditions.

For a free travelling matter waves, exponential, one can superimpose different wavevectors of the same modulus -- this is what one has in matter wave elastic diffraction. One can consider the small probe formed in scanning systems as an emergent phenomenon, as it comes from combining many waves. For a matter waves in a box you have to use cos/sin terms, you cannot separate the exponentials -- it is not emergent. Ldm1954 (talk) 12:39, 9 June 2023 (UTC)

My purpose with this thread was not to trigger a debate. Reconciling our perspectives would be nontrivial. —Quondum 13:19, 9 June 2023 (UTC)

"Part of a series of articles about Quantum mechanics"

A box on the right side of the page says: "Part of a series of articles about Quantum mechanics". And yet expanding each of the sub headings inside of the box never shows a link to matter wave. Is that intended? Johnjbarton (talk) 22:55, 11 June 2023 (UTC)

Good thought. I posted on the relevant page, so let's wait for responses. If no or favorable response, consider editing the template. Ldm1954 (talk) 04:26, 12 June 2023 (UTC)

New section ready for review: Matter waves vs. electromagnetic waves (light)

A new section in my sandbox is ready for review: Matter waves vs. electromagnetic waves (light). More can be done but I think the content is useful as is. As throughout this is summary material for other pages (which themselves need work, some of which I have invested).

Please edit there or comment here and let me know what you think. Johnjbarton (talk) 02:02, 17 June 2023 (UTC)

I put in some comments. While parts may be OK for atom optics, I know they are not for electron. I am not the best person to ask for those, but I could ask some of the real experts for some writing. Ldm1954 (talk) 03:07, 17 June 2023 (UTC)

Great comments, I'll work on them. Thanks! Johnjbarton (talk) 14:45, 17 June 2023 (UTC)

I finally got back and fixed up the draft. I made changes for each comment except the one on dispersion. The text already says 'vacuum' a couple of times so I left it as is, with a "?" for the response.

The change I made for coherence may not satisfy, but all I want to get across in this summary is 1) coherence is thing that applies to waves and thus to matter waves 2) it overlaps but does not equal optical coherence. And do this with references.

Please take another look and thanks again for the great review. Johnjbarton (talk) 16:50, 24 June 2023 (UTC)

Just back from travel, please give me a few days. Coherence with electron waves is a well researched topic, as it is critical to $N million electron microscopes. I will write something, plus get some input from friends who build microscopes. Ldm1954 (talk) 14:00, 25 June 2023 (UTC)

I published this section with some small additions. I found an online P. Hawkes book with two pages on coherence and boiled it down two one sentence ;-) I've been looking for P. Hawkes Principles v3 but I guess I will need to visit a UC library to read it, but I think that level would go in an electron optics article anyway.

Resolved

Johnjbarton (talk) 00:13, 7 July 2023 (UTC)

I never got around to looking (I was buried with making Triboelectric effect sensible). It looks good, I am not going to tweak and make H. G. Wells roll over in his grave. Ldm1954 (talk) 18:23, 14 July 2023 (UTC)

de Broglie states his result

We had

• This is a fundamental relation of the theory.

  — Louis de Broglie, 1929 Nobel Lecture

with a ref to his Nobel lecture but it was deleted by @Moriarty49 with an edit summary

• This was vague, and had little to no context. If more could be provided, I think it would reinforce the article

What kind of context is missing? The section is de Broglie's hypothesis and here he announces, in his own words, the key result. How can it be vague? Johnjbarton (talk) 19:43, 6 May 2024 (UTC)