In quantum mechanics, a single particle is also a wave and vice versa. Light is in fact the thing where this observation was first discovered - it had been proven to be a wave for at least a few decades when Einstein discovered the quantum nature of the photovoltaic effect, proving it is also a particle. This discovery was the very start of quantum mechanics, in fact.
"in fact", that was not the very start of quantum mechanics. Einstein's work was preceded by 5-10 years by investigation into the cause of quantized black body radiation. that's why we have Planck's constant and the notion of quantized oscillators. why are you going around talking with such authority? QM and nature is more amazing than you realize. particles are not waves "and vice versa". particles don't exist nor do any classical waves of energy in the way you keep saying as if they're facts. only the wavefunction travels. please be more careful about posting so authoritatively. comments such as yours are why it takes people so long to stumble onto the reality of nature, if they ever are so lucky.
Your comment is a bit strange. Light doesn't travel as photons. Photons exclusively exist at the site and instant of detection of the wave of probability of detection that light really travels as.
When light is redshifted, it loses energy, therefore the wavelength becomes longer.
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).
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.
> 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.
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".
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.
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.
https://preposterousuniverse.com/wp-content/uploads/grnotes-...