[tsimionescu]

That is not the current understanding of quantum mechanics, as far as I know. Wave/particle dualism says that different experiments can either view light as a wave or a particle (never both) and that speaking about the nature of light when an experiment is not being performed is non-scientific by definition.

Importantly, light very much behaves like a conventional wave in many real experiments - the interferometer experiment being one of the oldest and most well known. It is not a probability wave in that case, but an actual physical wave (now known to be an oscillation in the electro magnetic field, but long assumed to be a mechanical wave in the luminiferous aether).

[_0w8t]

Experimentally one never observes waves. Light is detected based on its interaction with electrons and that is always by an electron absorbing a quanta of energy, not via some continuous process as would be the case with waves.

Classically one can imagine that as if electron was hit by a particle. But then we have light diffraction and interference, which classically is described as a wave. So from a classical point of view light travels as a wave but interact as a particle.

As of nature of the light, then consider that there is a reformulation of a classical electrodynamics that eliminates electromagnetic waves all together. There are only electrons that interacts with each other directly with no waves in between. Feynman spent quite some time trying to develop quantum electrodynamic based on that. He failed. Still the point stands that we never observe light directly but only through its effects on electrons and other charged particles. So it could be that what we call light is a theoretical artifact and there is no light in reality.

[consilient]

> So from a classical point of view light travels as a wave but interact as a particle.

And the classical point of view is wrong. Photons resemble classical particles in a few respects, and classical waves in a few others, but at the end of the day they're neither.

> Still the point stands that we never observe light directly but only through its effects on electrons and other charged particles.

This is true of literally everything. "Direct" observation does not exist. Every atom, every cell, every person, every planet, every star - you know them by their effect on your sense-data, or else not at all.

[blueprint]

photons dont exist, dude, except in connection with and at the site of the detector. study some qft and then you can go talk about it on the internet with authority.

and yes direct observation exists. that's what measurement is. and that's all you can ever "observe" unless you incorporate the wavefunction, which also doesn't "exist".

[consilient]

> study some qft

I have. Srednicki and Weinberg are sitting on my bookshelf right now.

> photons dont exist, dude, except in connection with and at the site of the detector.

Exactly backwards.

Photons fall out of mode-expanding asymptotic EM field states just like any other particle. It's the interaction picture that can't be rigorously built up out of particle states.

[blueprint]

good to know you're informed, but it doesn't mean we're communicating effectively.

what i said is not backwards unless you use the inverse understanding of "exist". and how can photons exist without interaction? they don't. they're localizations by detectors. until then, they only "exist" as the probability wave. that's due to nothing localizing them. that's how i mean "exist". so it's not really meaningful to use that word.

btw "any other particle" doesn't fall out of EM fields.

[consilient]

> btw "any other particle" doesn't fall out of EM fields.

I very obviously meant that XYZ-particle states fall out of mode expansions of the XYZ-field, not that all particles are EM quanta.

> what i said is not backwards unless you use the inverse understanding of "exist". and how can photons exist without interaction?

Exactly the same way any other field configuration can? The state space of the free EM field simply is the photon Fock space.

The state space of an interacting 4D EM field is unknown and may well not exist, hence the need for perturbative approaches and renormalization - in which particle states again emerge as terms in the perturbation series.

[jpk]

This comment is needlessly hostile. It's ok to correct someone if you think they're wrong, but this tone isn't conducive to curious conversation.

[blueprint]

so it's the tone of my textual words? i think you're mistaking my laughter at their blatant and willful ignorance for hostility, and quite honestly it sounds like you're projecting that hostility. from the start I've been incorrectly downvoted and critiqued while being the primary commenter in this child thread providing a semblance of correct view. to be quite frank i deserve an apology, not some nitpick that comes from your personal assumption about my tone. but i know i won't get one because it's not hostility you care about at all. a lot of you commenters here are pretty hilarious. but not in a good way.

[d1sxeyes]

At this point anyone who is as certain about the nature of light as you seem to be may well be right, but is demonstrating a level of confidence the literature does not yet seem to support.

Although there are those who believe that photons only exist at source and at the detector, there is some experimental evidence which contradicts that (for example, this 2013 paper in which researchers 'read' information from a photon without destroying it, which implies its continued existence between creation and observation: https://doi.org/10.1126/science.1246164).

For what it's worth, I am also of the opinion that your tone was hostile, and yes, 'textual words' can and do have a (metaphorical) tone. Regarding downvoting and critiquing, there's an old adage about if you walk into a room and it smells of dog shit, maybe someone in the room stepped in something on the way in, but if every room you walk into all day stinks, well maybe you should check your own shoes.

[blueprint]

you are wrong, and you don't "know". the waves interfere with themselves unless they are measured. then the plate measures interfered waves in the form of singular photons, not waves. look it up.

silly downvoters.