Do emitted photons accelerate?

[Leo_Bloom]

The speedoflight-stop-speedoflight (whomever said that upthread–thanks!) makes me think of the (a) conceptual problem for me and partly OP, I believe, in the question and answer byplay:

The word “light” is taken two ways, in the absence of further elucidation (heh). We’re told, and answered here, “light” slows down, because the “speedoflight-stop” nexus arrives as a bunch like that.

A complicating pre image has two components that “a” photon–is “that” photon and that perhaps more importantly, any thing that merits being “a” thing, if it undergoes the stop-"backup"up and we buy into that, just like we’ve bought into a reality of speed-of-light is a “real” time, we expect each “stop” to be a real time.

Which it is, but not at the energy-interaction moment within that traveling nexus which is accountable (i.e. countable) as such only in retrospect when we get hit by it). “That” photon that got “stopped” had no time to ramp-up, unstop instantaneously, whatever image floats your boat.

That photon is history and to the next in line in creation/energyform there was no “stop.”

ETA: so the image of “it took x years” for that photon to travel through the sun’s layers to reach us" is -fundamentally different (except for the statistical inferences) than the image that, say, “a molecule of Napoleon’s fart travelled x miles in the atmosphere to reach someon’e nose.” Which has been OP’d, BTW.

[Pasta]

@Hari_Seldon

The reason light travels slower in a medium like glass or water (or hydrogen clouds in the galaxy) than in a vacuum is that it is constantly being absorbed and re-emitted by the atoms of the medium. More precisely, it hits an atom, an electron is raised to a higher energy level, then, after a small, but non-zero time, the electron falls back to its ground level and emits a photon of the same wavelength since that depends only on the change in energy level.

Here’s a post from a previous thread on this question discussing why this picture is wrong.

[Hari_Seldon]

Well thanks, I guess, Pasta. Clearly what I said was, unsurprisingly, wrong, but I certainly wasn’t happy with your last comment that no classical analogy works. Guess I never will understand QM. What about my comment on neutrino mass?

[rat_avatar]

@Hari_Seldon

Well thanks, I guess, Pasta. Clearly what I said was, unsurprisingly, wrong, but I certainly wasn’t happy with your last comment that no classical analogy works. Guess I never will understand QM. What about my comment on neutrino mass?

Most likely none of us will have an intuitive understanding of QM but keep trying.

The analogy you used is a common explanation particularly when trying to conduct thought experiments in more classical forms. We all have a tendency to either not notice the disclaimers or to forget that they were called out. There is also a segment of science education that teaches thought experiments as being descriptive of the fundamental actions.

This is typically not a malicious effort but even this video uses the broken analogy and has 1.2M views.

But don't let the fact that an intuitive understanding will most likely be elusive, these theories have been experimentally verified and it is actually enjoyable to learn why you are wrong and move on to the next misconception.

The photon’s wave and quanta qualities are two observable aspects of a single phenomenon but a “photon” also really a just thought experiment. It is used to describe properties that are difficult to visualize.

I like the idea of thinking of a lens as a resonator, but even that analogy doesn’t work very far but at least it does reduce my cognitive dissonance that something that acts like a particle when it hits a photoreceptor also goes through all portions of the lens.

Note that as GR and QFT are not unified and so both are incomplete there is also a challenges when talking about concepts that cross disciplines. Lots of quantum physicists only have undergrad SR and lots of GR experts are confounded by QFT.

If my obsession with physics has done anything it has freed me from being concerned about being correct, or being hurt when proven wrong. I do need to work on actively trying to call out when I am talking in absolutes but I am getting better.

Anyway, don’t give up, keep digging and learning. Not intuitively understanding these subjects is normal and it sounds like you are on the cusp of being OK with that.

It becomes far less frustrating and more rewarding to study when you get past that point.

It sounds like you are close to that stage. You don’t have to understand QFT in an analogy form to make transistors, computers, lasers, cell phone etc… you just need to be open to knowing it is testable and that so far is works.

[Pasta]

@Hari_Seldon

I certainly wasn’t happy with your last comment that no classical analogy works.

To be clear, no classical analogy works at these wavelengths if you want to think in terms of photons (particles). Classical waves are okay, up to a point.

What about my comment on neutrino mass?

Spot on.