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Originally Posted by OngBonga
So does this mean that my idea that everything interacts with everything is possibly true?
I think I have to agree, but I caution you to understand that my agreement is not very profound.
The amount of interaction happening between, say, free electrons which are more than 1 nm apart, is vanishingly small and truly negligible. I pick electrons for the example because they are stable and exert electro-repulsive forces on each other. I say free electrons to exclude any bound systems, like a molecule, in which the electrons will affect each other in a transitive way, due to the structure of that system.
I mean, the electrons in your fingers are not affecting any theoretically measurable change in the electrons in your brain, except for the neuron cascade which carries that information in a transitive way.
Originally Posted by OngBonga
Is this hard fact? Or an assumption based on current understanding? Can it be that the interaction is so tiny that it's impossible for us to measure?
That's as hard a fact as we come by... so maybe incorrect, but almost definitely not. Neutrinos were predicted by many to exist and have no electric charge before we ever observed them. The presence was hypothesized because there was a problem with our application of conservation laws in quantum interactions. By hypothesizing these neutrinos, we could fill in the blanks of certain intrinsic properties of the particles and balance the books as far as conserved quantities.
They were originally hypothesized to be massless, but experiments and theory have since shown that they are not massless, but have very tiny masses in comparison to all other particles except photons.
Being a particle which has no electric charge, it does not interact with electromagnetic fields. As such, it does not interact* with photons, which are the quanta of the EM fields. *does not interact via electromagnetic interactions
However, as I stated, neutrinos do have mass, and therefore curve spacetime, and that expresses forces (energy/momentum changes) to photons... so they do interact via gravitation.
Note that neutrons are not fundamental particles, and while they have 0 net electric charge, they are composed of u,d,d quarks which have charges of +2/3, -1/3, -1/3, for a total of 0 net charge from the outside, but not the inside.
Originally Posted by OngBonga
Ok, I mean my understanding of fields is really hazy. I kinda compare EM fields to gravity, which I can sort of get my head around. The gravity itself it not a physical thing, it's a consequence of a phsyical thing. That consequence has energy, because it distorts spacetime and effects mass. But the energy source is mass... I guess my point is that anything that is under the influence of gravity (ie everything) is actually being influenced by mass, something physical, not gravity, which is merely how we observe the influence. Like, when we go down a slide, it's not gravity that is causing us to slide down, it's the mass of the earth. Gravity and mass are essentially one and the same... isn't it the case that EM fields are one and the same with whatever causes the field? They are intricately linked, they are the same physical thing.
Ugh. I see what you mean... you mean that you can't hold a field in your hand, and therefore it's not a "thing," so it's not physical.
I meant, fields are measurable and express observable consequences, and are therefore physical.
We agree that fields are real and measurable and can affect changes to non-fields... so let's not get hung up on the def. of physical.
Originally Posted by OngBonga
I'm sure we've talked about this before, but I have something of a problem with the idea of zero-mass particles. I just think it's very close to zero-mass. I get that even with a mass of 0.000000000000000000000000000000000000000000000000 00001, we still need infinite energy to accelerate to c, so the velocity of a photon hints that it is indeed massless. But I feel that what is actually happening is our understanding breaks down, in particular our understanding of infinity.
You're postulating that a photon needs to be accelerated to c. That means you believe there is such a thing as a photon moving at less than c. If you can prove this is the case, I'm thinking nobel prize.
(Don't try to invoke index of refraction, here, though. That's a statistical phenomenon and not actually slowing the photons down, but causing them to spend time interacting with other stuff and not just zipping along.)
If they're not massless, then it requires a finite amount of energy to slow them down, which we have not been able to do, yet, either.
Originally Posted by OngBonga
If a photon is massless, well it's then going to be my assumption that it is the consequence of something that does have mass.
A photon is an excitation of the electromagnetic fields. It's a wave moving through a medium, I don't see why it being massless is an issue, aside from that it's the only particle that seems to be massless.
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