# fields and photons?

#### interested

Just for my own clarity I'm not quite sure what you mean by "Einstein's photon" and QED's photon. Yes, Einstein had derived E = pc (v = c since we have a photon) and only used the energy and momentum properties, but what specifically do you mean by a QED photon?

-Dan
Hi Dan
Qouting from https://www.britannica.com/science/quantum-electrodynamics-physics#
"
QED rests on the idea that charged particles (e.g., electrons and positrons) interact by emitting and absorbing photons, the particles that transmit electromagnetic forces. These photons are “virtual”; that is, they cannot be seen or detected in any way because their existence violates the conservation of energy and momentum. The photon exchange is merely the “force” of the interaction, because interacting particles change their speed and direction of travel as they release or absorb the energy of a photon. Photons also can be emitted in a free state, in which case they may be observed as light or other forms of electromagnetic radiation.
"

My understanding at the moment is the Photons in the free state are the same as Einsteins photons. These are not the propagators of radio waves, they carry inertia and spin and have momentum they are particles in their own right. Radio waves are propagated by virtual photons which represent a wave, of electromagnetic energy.

#### benit13

Hi Dan
Qouting from https://www.britannica.com/science/quantum-electrodynamics-physics#
"
QED rests on the idea that charged particles (e.g., electrons and positrons) interact by emitting and absorbing photons,

...

My understanding at the moment is the Photons in the free state are the same as Einsteins photons. These are not the propagators of radio waves, they carry inertia and spin and have momentum they are particles in their own right. Radio waves are propagated by virtual photons which represent a wave, of electromagnetic energy.
The second statement above is incorrect because radio waves are not charged particles.

Radio waves are a specific form of EM radiation treated as a wave. They are waves.

If you want to treat radiation as particles, then they will be real photons. Real photons do not interact with virtual photons. Nothing is required for propagation (EM radiation can transmit in a vacuum).

QED, afaik, ignores all of the above and treats everything as a quantum field.

Last edited:
1 person

#### Woody

ElectroMagnetic waves are the mechanism by which charged particles interact.

A single charged particle can only accept or emit certain fixed amounts of energy (during a single interaction)
This fixed quantity of energy is the amount of energy in one photon at a specific wavelength (frequency).

However when you have lots of particles together (all individually emitting single photons) as you would for the electrons racing up and down the antenna of a radio station, then you clearly get a wave.

Don't get too hung up on virtual particles and virtual photons,
These are (essentially) mathematically theoretical entities that arise from the uncertainty principle.
Because it is fundamentally impossible to know the exact energy at any particular location at any precise time,
It is impossible to define an absolute zero energy.
As a result virtual particles and virtual photons can arise, literally from nothing, and exist for very short periods of time, before reverting to nothing.

2 people

#### Woody

Further thoughts

Actually the mechanisms for generating radio waves and the shorter wavelengths are rather different.
The absorption and emission of a photon by an electron is a very different mechanism from the motion of electrons in an aerial.

However the EM disturbances generated by these two mechanisms
are very much the same phenomena, just on different scales.

One could perhaps take the resonant frequency of the radio receiver as an (imperfect) analogue for the fixed frequency requirements of the electron.

2 people

#### interested

ElectroMagnetic waves are the mechanism by which charged particles interact.

A single charged particle can only accept or emit certain fixed amounts of energy (during a single interaction)
This fixed quantity of energy is the amount of energy in one photon at a specific wavelength (frequency).

However when you have lots of particles together (all individually emitting single photons) as you would for the electrons racing up and down the antenna of a radio station, then you clearly get a wave.

Don't get too hung up on virtual particles and virtual photons,
These are (essentially) mathematically theoretical entities that arise from the uncertainty principle.
Because it is fundamentally impossible to know the exact energy at any particular location at any precise time,
It is impossible to define an absolute zero energy.
As a result virtual particles and virtual photons can arise, literally from nothing, and exist for very short periods of time, before reverting to nothing.
I fully recognize that virtual photons are just a mathematical tool in QED to explain the interactions between charged particles. I do not think I have any problems there.

The problem in my understanding is a photon has no electrical charge, yet a radio wave is transmitted by an electric field. https://en.wikipedia.org/wiki/Radio_wave

How can a radio wave be transmitted by photons with no electrical charge? The only way I see a radio wave could be transmitted by photons is if the photon was to have electrical properties, like which virtual photons are allowed to have in their exchanges. Is there more than one type of photon. Is a gauge boson different to a photon of light with no electrical properties.

#### topsquark

Forum Staff
I fully recognize that virtual photons are just a mathematical tool in QED to explain the interactions between charged particles. I do not think I have any problems there.
Actually it's a lot more than that, but that's a topic for another thread if you want to talk about it.

The problem in my understanding is a photon has no electrical charge, yet a radio wave is transmitted by an electric field. https://en.wikipedia.org/wiki/Radio_wave

How can a radio wave be transmitted by photons with no electrical charge? The only way I see a radio wave could be transmitted by photons is if the photon was to have electrical properties, like which virtual photons are allowed to have in their exchanges. Is there more than one type of photon. Is a gauge boson different to a photon of light with no electrical properties.

There are a couple of equations which describe electric fields and magnetic fields. One of them says that a non-constant magnetic field creates an electric field and that a non-constant electric field creates a magnetic field. It's always amazed me that if you have an electric field and magnetic field with the right phase difference you get a (self-reinforcing) wave which travels with a speed of $$\displaystyle \dfrac{1}{\sqrt{\epsilon _0 \mu _0}}$$ which we now call c. It's a light wave.

So there is no need for light to have an electric charge to propagate. I should also mention that radio waves are simply light waves at a given frequency.

More details upon request.

-Dan

Addendum: Oops! I missed the last question. If I'm reading this correctly it seems you are wondering if there is such a thing as a virtual photon with a charge? No. Virtual particles occur when we have at least a two point Feynman diagram. In the case we seem to be talking about we have two incoming electrons and a photon is exchanged between them. This photon is a virtual particle in this case and is never observed in an experiment. Virtual particles do not have well defined momenta and we have to Mathematically integrate over to keep everything nice and free of anomalies. It's only the momenta that isn't well defined. If it's a photon, virtual or not, then it has no charge.

You can also have an electron as a virtual particle in some reactions. In that case the electron's momentum is not well defined, but it does have a charge of -1.

More details upon request here, too.

Last edited:
1 person

#### interested

Actually it's a lot more than that, but that's a topic for another thread if you want to talk about it.

There are a couple of equations which describe electric fields and magnetic fields. One of them says that a non-constant magnetic field creates an electric field and that a non-constant electric field creates a magnetic field. It's always amazed me that if you have an electric field and magnetic field with the right phase difference you get a (self-reinforcing) wave which travels with a speed of $$\displaystyle \dfrac{1}{\sqrt{\epsilon _0 \mu _0}}$$ which we now call c. It's a light wave.

So there is no need for light to have an electric charge to propagate. I should also mention that radio waves are simply light waves at a given frequency.

More details upon request.

-Dan
Soliton waves are often used to represent individual photons, as self reinforcing distortions in the vacuum of space. The equation giving c $$\displaystyle \dfrac{1}{\sqrt{\epsilon _0 \mu _0}}$$ is dependent on the permittivity of space, if the capacitance of space was to change then c would be different.

The near field effect around an antennae has various phase differences between the magnetic field and electric fields. How is this explained by photons, with no electrical or magnetic field.? https://www.everythingrf.com/community/what-are-near-field-and-far-field-regions-of-an-antenna

Addendum: Oops! I missed the last question. If I'm reading this correctly it seems you are wondering if there is such a thing as a virtual photon with a charge? No. Virtual particles occur when we have at least a two point Feynman diagram. In the case we seem to be talking about we have two incoming electrons and a photon is exchanged between them. This photon is a virtual particle in this case and is never observed in an experiment. Virtual particles do not have well defined momenta and we have to Mathematically integrate over to keep everything nice and free of anomalies. It's only the momenta that isn't well defined. If it's a photon, virtual or not, then it has no charge.

You can also have an electron as a virtual particle in some reactions. In that case the electron's momentum is not well defined, but it does have a charge of -1.

More details upon request here, too.
Might photons passing through virtual particle pairs in the vacuum of space polarize them in some way causing a momentary polarized electrical field as they pass through space and thus induce a voltage in a receiving antennae. Alternatively how can a or multiple particles carrying just inertia induce a voltage in a receiving antennae.

#### topsquark

Forum Staff
Okay. I am able to talk more about the generalities rather than specific topics. I don't believe I've said anything that can't be applied but I really don't know much about antennas so I'm going to have to bow out before I steer you wrong somewhere.

-Dan

#### muon

How can a radio wave be transmitted by photons with no electrical charge? The only way I see a radio wave could be transmitted by photons is if the photon was to have electrical properties, like which virtual photons are allowed to have in their exchanges.
Gauge bosons are like the go-betweens, between interacting particles. It's the particles that have the charge, not the bosons. For example, if gravitons transmit gravity, do the gravitons themselves need mass? No, because they're likewise just the quantum unit of the field. The photons don't "take the charge from particle A to particle B". They just sort of communicate so the particles can see each other and interact.

When an electron repels another electron, because they're both negative, it's because electron A emits a photon, which is absorbed by electron B, which then moves away slightly. If the photon "carried the charge", then the charge wouldn't have been conserved. Electron A only has a electric charge -1, so if it emitted a particle such as the photon that had non-zero electric charge, it would have had to create additional electric charge out of nowhere for that new particle, which it can't do. That's why photons have zero charge. In other forces such as the weak force, whose bosons (the W+ and W-, at least) do have electric charge, that is mediated by virtual bosons, but still even then the charge is conserved, because when e.g. an electron emits a virtual W- boson as part of some interaction (see for instance a feynman diagram of electron capture), that electron then immediately *turns into* a neutrino, because it LOST its charge; that W-, which has a -1 electric charge, took it it from the electron.

As a disclaimer I don't really know what I'm talking about, but I think this is mostly correct

Last edited:

#### interested

They just sort of communicate so the particles can see each other and interact.
I understand

Virtual particles/photons are exchanged in feynman diagrams, these virtual particles might not exist in reality but it works mathematically and electrons repel because of these interactions representing fields. The fields do exist and are part and parcel of the electron, ie if the electron lost its field, it is no longer an electron. A muon that loses its mass becomes an electron and neutrino or something else https://en.wikipedia.org/wiki/Muon#Muon_decay

----------
Could a photon interact with the zero point field which does exist, and cause the ZPF to become polarized momentarily by the photon as it crashes through it or is perhaps absorbed and emitted as passes through. Could this be a mechanism behind how a radio wave induces a voltage in a receiving antennae.?

My reasoning is a photon can knock an electron off an atom and give it a polarity momentarily until the electron is reabsorbed. A photon is slowed down by absorption in the atmosphere or in a liquid. See Cherenkov radiation

Could the ZPF > virtual particle pairs > Heisenberg uncertainty cause the capacitance of space and affect the speed of light not unlike Cherenkov radiation?

Edit In my defence I might be an idiot and might be asking the wrong questions. Maybe some other persons put an idea into my head ref the zero point field https://en.wikipedia.org/wiki/Zero-point_energy QED ! How does a electrically neutral photon pass through the ZPF ? and result in a electrically polarized radio wave ?

Last edited: