Unsolved Mysteries: How do Accelerated Charges Radiate?

Surprisingly, there is no general formula for this! This failure of theoretical physics is linked to the infinite energy problem of the electric field of an electron...
See, e.g. Feynman lectures II, chap. 28 about electromagnetic mass or Landau Lifshitz II, § 75.

[Greg_Chase]

We had to tackle this issue to uncover the exact physical nature of EM waves being created and propagated. We started with the Abraham-Lorentz force, aka "Radiation Resistance", which creates a recoil effect on the accelerated particles that create the EM waves.

The underlying reason to the question "Why is an EM wave created and then radiate" is because Nature finds ways to dissipate away concentrations of energy.

If you drop a rock in a pond, Nature dissipates the impact energy and does not let it remain at the point of impact. The energy is carried away in circular waves, ripples of water on the pond. The concentration of energy at the impact point is distributed into larger and larger volumes of matter and space.

In the case of the 'rock dropped in pond' the medium that aids Nature in dissipating the concentration of energy - is water.

For EM waves, we took the atmosphere out of our reasoning by observing "a radio antenna creates and propagates electromagnetic waves in open space" as all our satellites and space vehicles.have demonstrated.

It came down to this: there is a polarizable medium, there are constituents of the Vacuum, able to continue the polarization of an electric field, and a magnetic field, through space. Since the electric field and the magnetic field have both polarities (electric field of an EM wave takes on both negative and positive polarity, magnetic field of an EM wave takes on both North and South poles) the constituents of the Vacuum are dipole in nature.

We know the Vacuum has an impedance of 377 ohms and a Vacuum Permittivity and a Vacuum Permeability. There must be constituents of the Vacuum to manifest the impedance, permittivity, and permeability. You cannot get 377 ohms, permittivity, and permeability from "absolutely nothing"

1) oscillating electrons in a radio antenna create local polarization of the Vacuum constituents immediately adjacent the antenna
2) just outside the layer of immediately adjacent Vacuum constituents, similar polarization of the Vacuum constituents occurs, and continues on, in a radiative dissipation, carrying the concentrated energy away from the antenna, at the speed of light

The problem in modern physics is "space is empty". Challenge someone with conventional thinking to explain where the 377 ohms comes from and their claim that there is utter 'emptiness'.

We work at artificial gravity devices and our work forced us to think beyond conventional physics to motivate the creation of in situ, non-translatory accelerations of the charged particles in our devices to mimic conventional accelerations of matter objects.

Conventional physics has chronic, stubborn 'blind spots' that are clung to with blind obedience.
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[richardchandler]

Thank you for this frank and illuminating snippet of information. I like Richard Feynman's lectures on physics books too, because he too is upfront about problems in basic electromagnetism.

[douglasstrother]

Matt Sands wrote an article on the Quantum Effects of radiation in Storage Rings while he was working at SLAC. The punchline was that the electron trajectories have little kinks in them when a photon is radiated. He said, "That was the most creative thing I've done."
I got to work with him a few decades back at UC Santa Cruz.

[johnsmith-frsx]

That's a show stopper question. So Maxwell's EM equations and their quantum mechanical variants (QED) don't handle such a basic phenomenon. We may be amused by how idiotically arrogant were authorities on "science" in ancient times, but in the future people will be amused at our time period as well. Lots of ego-driven posturing by "authorities" who engage in less than honest theorizing today. For example the "solutions" of Einstein's GR equations which involve ridiculous information non-conserving coordinate transforms and the sneaky redefinition of "coordinate singularity" to fake removal of the real event horizon singularity.

[emanueledistefano]

0:47 Such a formula actually exists, and is not approximated nor valid just in a particular case, and it's usually referred to as "angular distribution of radiation"; it defines the power radiated per unit of solid angle, it is deduced from Lienard-Wiechert fields (exact solutions to Maxwell's equations) and you may integrate the formula in the whole 4π solid angle to obtain the Larmor formula.

For reference, see the notorious Jackson's book "Classical Electrodynamics", §14.3 "Angular distribution of radiation emitted by an accelerated charge"


Would you please let me know if you were aware of this approach? And if so, why then you instist that there is no exact formula? Maybe I'm missing something.

P.S. In my opinion, in classical electrodynamics there are indeed some problems unsolved and phenomena not well understood to this day, such as the problem of self-force, mass renormalization and the radiation emitted by a free falling charge.

[philipoakley]

One big issue is the teaching of waves in 1d (x-t) as a starter to plane (plain?) waves which leads to the (strong) expectation that a radiated 'particle' (quanta) of energy can ever be a plane wave in 3d+t. Maxwell's equations, with their Curl E and Curl H components does not support plane waves with Curl=0, nor that they are sine (simple exponential) waves.

It is worth looking at Wavelet theory (e.g. G. Kaiser, A friendly guide to wavelets. Boston, Mass.: Birkhäuser, 1994.) to see that the EM field photon transmission can occur properly (see Part 2, Chapter 9: Introduction to Wavelet Electromagnetics).

As to why there is photon transmission in 'all' directions.... (never explained by Mott)

[wesbaumguardner]

What I would like to know is how two charged particles interact. If there are two charged particles that are the same charge, they are supposed to repel, and if they are oppositely charged, they are supposed to attract. What is going on between them that causes them to either repel or attract?

[martinsoos]

I went the other direction and started studying radio transmitters and receivers. And if I am getting the problem of polarization right, then you left out the spin orientation of the photon. I am looking at coherency of the transmissions signal and finding that all the numbers of transmission energy Vs receiving energy, well, lets say the numbers aren't available. Been combing over U-Tube video and Google terms for at least a year now. The worst part is that it leads me to believe that the capture, pass through, or reflection also is affected by the orientation of the electron requiring at least two parts to make up the electron.

[vincemorgan]

Near-field magnetic fields are fully coupled to the source charges. A very well made electromagnet with say a toroidal core can be, ideally, entirely near-field. In fact so near-field that the magnetic field cannot be discerned externally. Such an electromagnet makes a very poor radio transmitter. A superconductor displays only near-field electromagnetic fields.
I have wondered if thermal loss from conductors, and electromagnetic cores, is in fact also far-field phenomenon. Becoming photons as it breaks away from the source.
The fact that arrangements that are entirely near-field are, essentially, free of energy losses and far-field radiates accountable energy leads to an interesting possibility.
Perhaps thermal losses in a conductor is simply some of the, otherwise, entrained magnetic field associated with an accelerating, or simply moving, charge breaking off so to speak, into thermal photons.
I have wondered if this might simplify what seems to be an area that has not been thoroughly explored.
These are only my thoughts and I know they may not be of much value to anyone but myself. But I too have wondered and was thrilled to see you bring up the subject Dr. Unzicker.

[BurevestnikM]

At the surface of the wire, we have Poynting vector, the directional energy flux (the energy transfer per unit area per unit time) of an electromagnetic field.
E x H is derived from Poynting theorem, which physically means the energy transfer due to time-varying electric and magnetic fields is perpendicular to the fields.

[johnnyq]

Not true. Given charge and current density distributions, general formulas exist for calculating the scalar and the vector potentials, and they can be found in every college EM textbook (e.g. Griffiths). Not being able to derive a pretty-looking closed-form expression for the potentials is one thing, but we do have the formulas. Dipoles, quadrupoles, and such are mere approximations to the sources meant to characterize the dominant form of the radiation fields.

[chrimony]

"This failure of theoretical physics is linked to the infinite energy problem of the electric field of an electron..."

More, please.

[richardgreen]

Maxwell's Laws pertain to electricity - which means it is a macro-theory because electricity is a macro-phenomena. Maxwell's Laws work quite nicely when controlling streams of electrons (or other charged particles) - at macro-scales. As a macro-theory, it does not attempt to describe the micro-constituents (atoms/electrons) and may or may not apply at the atomic scale. According to Maxwell's Laws, electrons in atoms should radiate energy and fall into the nucleus. Since atoms are stable, a better *model* was needed. Quantum Models were created to provide a better description of atoms (and eventually scaled-up to molecules and solids). The quantum algorithms produce very good results and satisfy the "empirical" - but provide no geometry or structure that would "explain" the atomic-scale phenomena. The models use billiard-ball and planetary metaphors ... and those metaphors work to some extent, but provide too little detail to actually explain the "spin" and "magnetic moment" phenomena while remaining internally consistent.

[fbeat]

Dear Mr Unzicker, I was under the impression that radiation from a charged particle was understood in terms of the Lienard-Wiechert Potencials within the classical electrodynamics framework of Maxwell’s equations. How does this fit with the idea that the radiation of a charged particle is not understood? Is it a matter of limitations of classical electrodynamics more generally, or is it that even within that theoretical framework the issue is not really understood? If so, how? I would really like to get your thoughts. By the way, thank you so much for your videos, they are refreshing.

[michaelperrone]

At high energies it would be unsolved because particle production can happen in many ways and you're operating well beyond the uncertainty limit. What's the issue here?

[baraskparas]

Only fools answer rhetorical questions that nobody knows the answer to. I am one of those so here goes. The charge is derived from elementary particles that have a quantised imbalance between emanating and entering fundamental particles ( call them virtual photons if you like). Any quantised energy that can accelerate these charged elementary particles is vectored inwards through their core and is comprised of photons (decelerated groups of fundamental particles) itself. This creates an oscillation in the imbalance ( the charge ) that is always emanated as photons perpendicular to the instantaneous vector of the oscillation . The frequency and therefore energy of the em waves emitted is the frequency of the oscillating charge and requires a higher energy photon to cause those oscillations. The core of long lived elementary particles is a portal to another dimension, the 4th, ( space-time is 3 dimensional) that is the source of matter, antimatter, dark matter and dark energy all of which are comprised of fundamental particles.

[Shukla_]

Is there any real particle exist in nature that has no spin ? What are the relation between spin and charges ?

[alexandrinago]

Dear professor Unzicker. Thank you for your video. We do not know how they radiate, but do we know how much radiation is emitted? Or do we only have approximations? Also, do accelerated charges radiate as seen by co-accelerated charges? Do we know the answer to the latter question? Thanks.

[aubreydebliquy]

I think the solar wind may occur as a result of processes in the atmosphere producing ions of like charge to the sun which means they repel more up than down or horizontal

[JerryMlinarevic]

Clue: two kinds of charges are involved not just one.