What is conveying the information that a charrge or magnet is nearby, so that a compass, electron, etc. know there’s something there? Information is being communicated. then that field has a greater potential compared to closer. But what is the field made of? Photons? What is being sensed by the objects?
I asked that same question of to everyone of my electrical engineering professors in college; no one knew the answer.
Virtual photons are the most succinct answer I can give. I’m sure other folks here will give more detail shortly. But they are exchanged between electrons. Think of the uncertainty principle as to why the fields die out with distance…
The electric field is made of… itself. It is very much a ‘thing’ in and of itself. We have different ways of describing it mathematically; static electric/magnetic fields can be thought of as ‘virtual’ photons that can ‘mediate force’ when they are exchanged, and oscillating electromagnetic fields can be thought of as made up of photons. Our modern understanding is that photons are ‘excitations’ of the electromagnetic field, and the field itself is real.
It’s a fundamental force in our universe. Just like gravity, it is a fundamental aspect of the very fabric of space-time and matter.
I’ll leave it to the resident physicists to take it deeper.
If you insist on describing the field as “made up of something”, then what it’s made up of is virtual photons. But then, you could just as easily describe photons as being a manifestation of electromagnetic fields.
Actually, no. What you’re describing there is relevant for forces carried by massive particles, such as the weak force or (approximately) the strong force, and which therefore have Yukawa-like potentials which fall off exponentially. But photons are massless, so the only falloff you get with distance is the inverse square falloff, which is simply due to the fact that space is three-dimensional.
You are correct. My thinking was overlapping the generation of EM radiation per the virtual photon/uncertainty principle. The aging process has not been kind to my memory and I’m relying on my “gut” feelings on long ago readings.
Years ago, I was skimming through Larry Gonick’s Cartoon Guide to Physics that finally provided the answer for what made up an electric field.
So, then, since we’re on this subject: what makes up the components of a magnetic field?
What is a “virtual” photon? How are these generated? How are they received? How does this not violate conservation of energy, if they’re produced at all times? Do we have any explanation of how/why charged/magnetic things get moving, like we do with gravity bending space? It makes more intuitive sense that things bounce off each other, but this attraction-only force I don’t understand.
Aren’t they the same thing, essentially? (Really asking here…all I have is my high school physics to fall back on, and that was 22 years ago)
Yes, they’re the same thing. You can treat them as separate things, the way most descriptions of Maxwell’s equations do, but it’s arguably more elegant to just treat them as parts of a single tensor (2d matrix) field. Or you can pretend that magnetism is just the relativistic correction of the electric field, though that doesn’t always work as well.
Electric fields are made of potential.
Per the second description, that’s what I suspected, but did not have the intellectual abilities to pursue this (re: too lazy to slake my general thirst for knowledge).
Though many experts in the field of electricity claim they don’t know the answer, it’s obviously made up of experts.
It is a mathematical artifact. You can’t observe virtual photons – they are a way of mathematically describing force exchange. One of the best tools we have to make quantum field theory tractable is perturbation series expansion. The terms in the perturbation expansion can be thought of as contributions from things that look like photons, except can violate conservation of energy for short periods of time. One must be careful not to be too seduced by these terms in the perturbation expansion.
With that said, it’s like this: in the path-integral formulation of quantum mechanics, mathematically, if you want to find the path a particle is going to take, you can imagine that it takes “all paths”, even “virtual” paths where the particle is going faster than light or violating energy conservation. But if you sum them all up, the particle is found to follow a path that obeys the known laws of physics. Similarly for electrons and photons. If you have a charge (say an electron), you have to sum up all possibilities, including, for example, the electron emitting a photon and then reabsorbing it later, even if energy is not conserved during that time. Similarly, an electron can emit a photon of negative energy, and it can be absorbed by another electron, causing it to attract. Or it can emit a photon of positive energy, and it can be absorbed by another electron, causing it to repel. You sum up all of these possibilities, even if they violate energy conservation, in order to calculate the probabilities of various things happenings. But this is just a mathematical formalism for calculating things; it doesn’t necessarily mean that these things are actually happening or that these virtual photons are ‘real’ (that’s why they are called ‘virtual’ after all – because they are NOT real).
Well, it doesn’t work if magnetic monopoles exist–which they might. I did find this, which goes through the math. The derivation is for a straight, infinite wire, and I suspect that the math would get too hairy for anything else.
Or what makes up the components of a gravitational field?
Rats. Way to ruin my evening, Dr. Strangelove. Now it’s a scotch ale with Hans de Vries, rather than South Park/Family Guy.
[Homer Simpson] Stupid thirst for knowledge and beer! [/Homer Simpson]…
Somebody famous, someone like Murray Gell-Mann, has a quip about this. It’s something like “Fields are the fundamental object. If we had any sense, it would be the notion of the single, free-floating electron which should really strike us as abhorrent, not the field.”
It’s best to learn how to treat them in as many different (equivalent) ways as possible - that way when you have a problem to solve, you can attack in from a choice of several different approaches, one of which might very well be more convenient to use than any of the others.
The graviton is to gravitation what the photon is to electromagnetism. So if we’re going to say that the electromagnetic field is made up of virtual photons, then by the same token, the gravitational field is made up of gravitons. But we can’t describe the gravitational field in terms of gravitons nearly as easily as the analogous description for electromagnetism (in fact, it’s so hard that nobody’s managed to do it yet), so for actually working with gravitational fields, we generally use other descriptions that don’t involve force-carrying particles at all.
But I thought we were talking about electric fields, not EM fields which are a completely different animal.