Are photons energy? What is energy, anyway?

Almost correct. An excitation of a quantum field, is a matter-field; or it's a matter-wave.
Since clearly the quantum field is not material until it "has" an excitation. Ok?

 

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Here you both support the notion that the change in energy IS a photon. Why is there an electromagnetic field (like in electronics), and can there be such a field anywhere if there are no charged particles to generate it?
Or are you going with the idea that photons have their own "independent" quantum field?

 

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I say the argument comes down to this:

On the one hand we have thermodynamics, "thermal" or "thermalised" states of matter, on the other theories that say everything is particles interacting with fields, then generally the particles ARE also fields.
Supporting the latter theories is the partial unification of the weak interaction and the electromagnetic interaction. Both based on the idea that the interactions are symmetries of spacetime, some of them "acting" at much smaller distances, subatomic ones.

So we have SU(2) x U(1). Field symmetries. Thermodynamic states are really distributions of "energy", per particle in a system of particles. You can "choose" that the particles are classical (so they don't act on each other "at a distance", like charged particles do).

 

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To Arf, if you had to answer these questions with either "Yes" or "No", what would you answer?

1. Can all photons be categorized as pure energy, and nothing else?

2. Can all pure energy be categorized as photons, and nothing else?

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To James R and/or exchemist, if you had to answer this question with either "Yes" or "No", what would you answer?

1. Can all pure energy be categorized as pure energy, and nothing else?

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Arf, I have tried my best to make the questions to both parties as fair as I possibly could. You have two questions because you are in the unfortunate position of claiming that photons are pure energy, and pure energy is photons. If you are not claiming both, then you are admitting they are not the same thing as each other. So you must answer "Yes" to both, otherwise your claim is virtually meaningless. (Other than perhaps to say that the closest thing we have to "pure energy" is photons, which is still very much debatable since kinetic energy and gravitational potential energy seem to be just as close to "pure energy".)

The other side is only claiming that pure energy is pure energy, so there is only one question for them, to which they obviously must answer "Yes".

 

I don't recall having anything to say about "pure" energy. I'm more in the group that says energy is a thing you can define, once you have an "interaction" defined.
And that you don't need "pure" energy, energy of a field or of an interaction does the job already.

Consider the modern-day answer to the question, why does light travel at c in a vacuum? Which is, it doesn't interact with the Higgs field.

 

Perhaps you'd be more comfortable answering these less detailed versions of the questions then?

1. Can all photons be categorized as energy?

2. Can all energy be categorized as photons?

Consider your words:

You saying, "Energy of a field," makes energy a property of a field.

You saying, "Energy of an interaction," makes energy a property of an interaction.

This puts you on the same side as James R and exchemist, who are the ones saying that energy is a property.

 

Yeah, but only sort of. See if you can spot the difference between what they keep saying, and what I'm saying.

My version, once again, is that particles have energy because they get it from interactions, but these interactions are also particles.
Or conversely it seems but equivalently, fields have energy if they interact with other fields. Energy, whatever it really is, appears to conform to specifications as a physics tool. Is it real is the same question as does a pair of electrons really exchange a photon.

Consider a universe containing a single electron in a normal spacetime. Then this electron has an electric field around it; if the electron accelerates, the local distortion in this field can propagate as "free" electron-field energy. QED (see also the lepton matter-field eqn of Dirac).

 

Since I've said nothing about "pure energy", I can seriously dispute everything you say here. I can still assume then, that you don't know or understand a word of field or gauge theories? I kinda thought we were talking about photons and electromagnetic energy. About which you've said FA that amounts to a coherent argument.

For instance, whether infrared photons raise or lower temperature; you made the obvious error of replacing the "stuff" that the photons interact with, with some molecules "colliding" like classical particles. I have answered that question he posted, you dick. I don't like repeating myself, but, it seems to be an inevitable conclusion that electromagnetic energy is a form of . . . energy! so is gravitational energy . . .

And we've discussed the Doppler effect, so energy is relative because frequency is relative to a direction of propagation, from a fixed or moving point. So what IS electromagnetic energy relative to? It's relative to two charged particles, which may or may not be in relative motion.

 

Explain why the Schrodinger eqn was developed to explain/predict electron orbitals in hydrogen? In its form as an electron (lepton) orbital or resonant state, it's a field equation, the field is the electron. Remember?

The equation has "energy" eigenvalues for the electron field = matter field . . .

Or, in your version the eigenvalues are "associated with" the electron orbitals, not with the electron "itself".

 

But somehow watching TV when it's off isn't that absorbing. Pun intended.

 

I hope you've seen an electroscope. When there's a charge present you get some separation, it persists or doesn't "leak away" and the separation persists--a force pushes two objects apart because they are "charged".

Ok, where does the energy come from that keeps the objects separated? What does it have to do with your understanding of a field, i.e. an electric field?

 

I'm not wrong.

The reason is, you consider the proton in the atom to be at rest, the electron then is in a potential well. The potential goes into the wave equation as . . . potential energy.
It's what accounts for the boundary of the solution(s). What does it represent? It represents the energy in the matter-field of a proton, as the electron sees it. You say you understand this stuff.

 

You're saying here, the energy keeping the plates apart is in this field of charge . . .?
And you agree that, the charge has to flow into something first? It does this quite passively once you have a "charged" object it can flow out of?

 

For god's sake. You're quite sure electron orbitals are described by a two-particle equation? The equation has to account for the "frequency" of the proton as well as the electron?