No I mean if I throw a permanent magnet into a black hole, is it an antenna? Because it’s radiating radio waves. Does that make it an antenna?

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It isn't a permanent magnet... you can't use it to hang a picture on your fridge. But the antenna is the medium in which the moving electric field/moving magnetic field is created.

All of our understanding of physics comes from making up models of reality and seeing how close to reality they match. The model of reality that treats all particles as excitation in fields is part of the single most accurate model humanity has ever come up with.

Is this model a true analogy of reality? Yes? Maybe?. At some level our 'real' understanding of realty turns into a version of "shut up and calculate" or "we don't know". It 'seems' reality is a bunch of rubber sheets stacked on top of each-other. Waves and ripples move through them and the energy from one sheet can transfer into other sheets like as if they touched eachother. Waves in one can 'bump' and create waves in other fields. "Physical things" are again just excitations in one or more of these rubber sheets.

The best answer to "what is a field?" is the definition of a field because that's what the model of reality assumes it is. True or not.

>In this case, the electromagnetic field

I asked which one?

>Perturbations in that field,

How does this field differ from the fields surrounding charged particles such as electrons and protons? Is this the same field? Are electrons and protons then not also "perturbations?"

If this is an explanation from quantum field theory, how does this description of one single, continuous electromagnetic field differ from the luminiferous aether? And, again, how do we understand the fields surrounding stationary or moving charged particles?

A permanent magnet is a magnetic dipole. It doesn't create "excitations," a magnetic field forms surrounding the two poles, pointing out of the north end and into the south end.

Moving a magnet doesn't typically create light because the motion doesn't typically produce a sufficient amount of energy to excite electrons and cause the excitation-decay process that occurs in, say, LEDs. Said another way, the material physics for free electrons recombining with "holes" simply doesn't exist here. Theoretically it should be possible to move a magnet with the right frequency and in the correct plane near an LED to produce a bit of light, but this would be rather difficult because the direct interaction between this magnet and the electrons in the semiconductor material would be rather weak. Obviously we can use motors to rotate magnets in an electric generator to produce electricity in cables and wires and then create useful circuits that way, but the physics of photon production a bit more complex than just moving a magnet around.

Moving a magnet can induce an electrical current in a conductive material, i.e. a copper wire. This is because the magnet interacts strongly with the free electrons in the conductive material, and the electrons move to produce a current. Photons are released most commonly when an electron "decays" energy states (it loses energy) and changes from a high energy state to a lower energy state. The frequency of light emitted depends on the energy difference between these states, known as the "band gap." Semiconductors have many different medium sized band gaps. Conductors have band gaps with actually "overlap" and cross each other, indicating little to no energy change is necessary for the electrons to change states. This is why they can move so freely in the conducting band to create current. Insulators, meanwhile, have very large band gaps and the amount of energy required for an electron to change states in an insulator often while break down the material, i.e. burn it.

When you move a magent around, you simply cause that magnetic dipole to "wiggle," but this is not a photon. A photon is a continuously oscillating electrical and magnetic field moving through spacetime, with those fields oriented perpindicular to each other. Only if you understand higher-order quantum field theory should you try to make sense of the description of a photon being an "excitation of the electromagnetic field." I don't like that description. It is not good for lay people, and I don't even know if it is agreed upon in the physics community. It is its own electromagnetic fields, and they are oscillating constantly. It's not a ripple of water propagating outwards from some disturbance losing energy as it travels, like you threw a pebble into a pool. It is a much more complicated particle and wave than that.

Edit: I want to add something else here. Some people have stated that moving around a magnet does produce light waves, but that is not necessarily true. A changing magnetic field can induce a current, but only where free electrons are present, and a current does not necessarily produce light, or at least any useful light beyond the imperceptible statistical stray photon. A photon is a "packet" of energy which exhibits the characteristics of both a particle and a wave. It is a fundamental piece or building block of energy in the universe. Moving a magnet around does not inherently induce some quantized amount of energy to be flung about the universe in the form of a photon. A moving magnetic field, in a vacuum, is not itself any form of energy, even though the movement of this magnetic field superficially is similar to the changing magnetic field of a photon. A changing magnetic field can induce a force - the electromagnetic force - on free charges, but no energy exchange takes place until electrons begin moving.

Whether the magnetic field itself uses photons - being the fundamental carrier particle for the EM force - to "communicate" with or "touch without touching" the electrons is something of a much higher level debate, to the best of my knowledge.

So is the magnet here an antenna?

Phisical things consist of atoms, which consist of subatomic particles, which are disturbances in their coresponding fields, so fields interact with other fields.

In this case, the electromagnetic field. As I understand field theory, it states that forces exist as fields everywhere through spacetime. Perturbations in that field, where it rises to a non zero value, are interpreted as force carrying particles or bosons. So we could state that the photon is an excitation in the electromagnetic field just as the W and Z bosons are for the weak field.

I don't know what an "excitation" is. When I try to think about it, the first thing is a la ola wave at a soccer game - excited people.

They have 3 vaginas, but the 3 vaginas are inside the cloaca, so there is only one external opening.

The penis is two-pronged to penetrate both lateral vaginas at the same time, though typically only one is fertile at a time. The penis is also inside the cloaca while not erect.

They also have 2 uteri.

The middle vagina is for the baby to leave any of the uteri, and then the baby leaves the body by the cloaca and then gets into the pouch.

https://trishansoz.com/trishansoz/animals/marsupial-reproduction.html

Is there any difference between marsupials whose pouch opens upward or downward? Are they anatomically the same aside from that switch?

>excitations of a pre-existing field

What "pre-existing field" are you refering to? What sources exist to create such a field?

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The analogy doesn't hold well at this point. The previous comment saying "Electromagnetic radiation always travels as waves" is misleading because neither classical waves or particles can describe all the behaviours of EMR.

If you're asking "Where in the wave is the photon", the answer is that it's in all the places at the same time until you check. You can consider the height of the wave to be the probability that the photon would be in that position if you were to measure it. The position and path a photon travels is literally not concretely defined until it is measured, at which one of the possible positions is randomly selected. When we have a lot of photons we can sweep a lot of the probabilistic stuff under the rug by summing them all together into something that resembles our intuitive understanding of waves, but it does not mean that a single photon is a tiny wave.

The previous comment said "The concept of a photon being a light particle is incorrect", which is true, but the concept that it is a wave is also equally incorrect. They're both interpretations that aim to simplify the probabilistic nature of quantum objects into something intuitive to us, and which interpretation you use will depend on which behaviour you want to describe. Can you model electromagnetic radiation travelling as particles? Yes absolutely, but you'd be describing it in terms of the sum of those infinite probabilistic potential paths the particles could travel.

I have a very basic question. What is a field? I mean I know what the definition is, but what is it really? What makes a field, a field? Do they even exist? How does light, which is an excitation in a field, interact with physical things?

Isn’t a blur filter just a predetermined set of vectors where each pixel is moved according to the corresponding vector? I assume if I blur the same picture twice I’d end up with two pictures that are identical, ie the same blurring effect occurred.

If I know what was moved in which direction, u should be able to inverse that and end up with the original picture no? So unless blurring filters aren’t deterministic or I don’t have the ‘key’ to what happened I should be able to do it right?

A radio broadcast is made by waving around electric charges in a broadcast antenna. It is received by those radio waves themselves waving around electric charges in the receiver antenna.

Why do ferrets die if they don’t breed? Do their wild relatives have the same problem or is it strictly a domestic thing?

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It's what we're here for :) as long as the stuff isn't going to waste it's all good!

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