EM radiation

[jeheron]

What is the fundamental origin of electromagnetic radiation?

[Klaynos]

Maxwell's equations applied to accelerating charges.

[jeheron]

I am a high school student in Australia, we briefly discussed Maxwell’s equations in class however what you have said here does not helpfully answer my question (from me at least).

 

It seems to me as unhelpful as saying that the fundamental quality of the universe that causes gravity is an equation Newton published in 1679. I would like to believe Maxwell’s equations, rather than being the fundamental origin of electromagnetic radiation, merely (although amazingly elegantly) describe this radiation.

 

The words "accelerating charges" however begin spark thought in my mind. An accelerating charge induces a magnetic field, which in turn induces an electric field, ad infinitum.

 

Is this perhaps the origin of EM radiation (although not the fundamental origin of course)?

 

Thank you very much Klaynos, for your reply,

Jack

[YT2095]

the Photon would be my guess.

 

or at least that`s the "particle/wave" responsible for it.

[Klaynos]

I am a high school student in Australia, we briefly discussed Maxwell’s equations in class however what you have said here does not helpfully answer my question (from me at least).

 

It seems to me as unhelpful as saying that the fundamental quality of the universe that causes gravity is an equation Newton published in 1679. I would like to believe Maxwell’s equations, rather than being the fundamental origin of electromagnetic radiation, merely (although amazingly elegantly) describe this radiation.

I was mainly just being annoying with my post, as it does answer the question but does not really give the full story... My apologies, it's not been a good morning.

The words "accelerating charges" however begin spark thought in my mind. An accelerating charge induces a magnetic field, which in turn induces an electric field, ad infinitum.

 

That's pretty much it yes. If you apply Maxwell's equations then that's what they tell you happens.

 

Is this perhaps the origin of EM radiation (although not the fundamental origin of course)?

 

Thank you very much Klaynos, for your reply,

Jack

 

Another reason for my first post was to get some more info (which worked to a certain extent). But what do you mean by EM radiation? And what do you mean as a fundemental origin? In my explenation (of sorts) above I've interpreted it to mean radiative fields, but you might also be talking about electrostatic fields?

[swansont]

What is the fundamental origin of electromagnetic radiation?

 

There are basically four ways to get EM radiation

 

accelerate a charge, and Maxwell's equations give you this result. This is responsible for things like bremsstrahlung, like in an x-ray machine (slamming high energy charges into things) or antennas for radios

 

annihilate a particle and an antiparticle

 

have an atomic reaction, e.g. de-excitation (E-M force)

 

have a nuclear reaction, e.g. a decay or de-excitation (nuclear forces)

 

So the question is a bit ill-formed, at this level. There really isn't a fundamental origin. Photons have energy, so basically any interaction can give you photons.

[Severian]

What is the fundamental origin of electromagnetic radiation?

 

Its fundamental origin is the desire to have a local U(1) symmetry for the universe.

 

This U(1) is the symmetry you see in quantum mechanics, where you have a wavefunction [math]\psi(x)[/math] and the probability of finding the particle at a point [math]x[/math] is [math]|\psi(x)|^2[/math]. If I multiply the wavefuntion by a complex phase, i.e. [math]\psi \to e^{i \theta} \psi[/math], no observations change because [math]|e^{i \theta} \psi(x)|^2 = |\psi(x)|^2[/math].

 

In other words, there is a symmetry in the theory. It is the desire to make [math]\theta[/math] in the above vary with [math]x[/math] while still keeping the symmetry which directly insists that you introduce a new particle. And low and behold, it has exactly the properties of the photon.

 

So the photon (and electromagnetism) are a direct consequence of a local U(1) symmetry.