1

Electromagnetic waves are generated by accelerating electric charges.

Photons on the other hand, tend to describe something different, specifically the particle nature of electromagnetic waves as detected experimentally.

Is it something like EM waves are like the ripples in water, but photons are like the individual molecules of water in a wavefront? Or is it like the amplitude of the wavefront?

According to this answer, phonons can be thought of as molecules of the medium, but photons don't move in a medium. If we were talking about current, we would have electrons acting as a waveguide, but EM waves are different.

(Is it too far off to think of the electromagnetic field as a medium? e.g. like a 2d matrix full of 0s, and if I place a +5 value in a corner, it spreads out to the three adjacent cells in the next step, and so on.)

Also, if there is a difference between the two, why are they always mentioned as synonymous? Is it a common mistake?

Blacklight MG
  • 202

4 Answers4

3

There are three main concepts here, not two:

  1. the photon,
  2. the quantum field mode (somewhat like a quantum wavefunction)
  3. the classical electromagnetic wave.

The relationship is as follows.

A quantum field mode is a continuous function of position and time, quite like a wave. It is also quite like a quantum wavefunction though not exactly the same. We are usually interested in quantum field modes having a well-defined frequency.

A photon is a way of talking about how much energy is in some quantum field mode. The more energy, the more photons.

A classical wave is an approximation to what happens when you have a large number of photons in a group of quantum field modes all of similar frequency and spatial shape.

All this can be made precise via the mathematics. Then main thing to note is that the electromagnetic wave, which can be thought of as oscillating electric and magnetic field, corresponds to a stream of a large number of photons, and the quantum field modes that are involved have a shape in space and time similar to the shape of the resulting electromagnetic wave.

Andrew Steane
  • 65,285
2

Photons are quantized excitations in spatial modes of the electromagnetic field.

Jagerber48
  • 16,234
1

I recommend reading about the Glauber State (https://en.wikipedia.org/wiki/Coherent_state). It's a quantum state version of a coherent, monochromatic, EM plane wave--$Ae^{i(\vec k\cdot \vec x - \omega t)}$

The key takeaways are that it is not an eigenstate of the photon number operator, rather it's an eigenstate of the annihilation operator, the variance of the number of photons is equal to the mean number of photons, and as the mean number of photons becomes large, it approaches a classical plane wave.

Also: it is a sum of Fock states (eigenstates of the number operator), and is not the squiggly photon we see in Feynman diagrams.

JEB
  • 42,131
0

I'm telling you here that the relationship between photons and electromagnetic waves is based on a very new electromagnetic and quantum theory: the 'mutual energy flow theory'. According to this theory, there are two types of electromagnetic waves: lagging waves and leading waves. Lag waves are emitted by the source. The advanced wave is emitted from the trap. The radiation source includes the primary coil of the transformer, the transmitting antenna, and the light source that radiates photons. The trap includes the secondary coil of the transformer, the receiving antenna, and the screen for receiving light. The synchronization of lagging and leading electromagnetic waves generates mutual energy flow. The mutual energy flow density is close to the Poynting vector, but it is not a Poynting vector, but a so-called mixed Poynting vector. It is a type of energy flow formed by mixing lagged waves and leading waves. The mutual energy flow is generated at the source and annihilates at the sink, thus possessing the properties of particles. Zhao believed that mutual energy flow is photons.

Furthermore, according to this new theory, many mutual energy flows can combine to form macroscopic electromagnetic waves, which are similar to the electromagnetic waves of Maxwell's equations. Therefore, we can say that many photons combined can form macroscopic electromagnetic waves. This also provides the relationship between electromagnetic waves and photons.

In addition, Zhao discovered that Maxwell's electromagnetic theory was actually flawed The magnetic field in Maxwell's equations is not actually a magnetic field, but an average magnetic field on a small loop. The average magnetic field and magnetic field are consistent under quasi-static conditions. But for electromagnetic waves, there is a 90 degree phase difference between the average magnetic field and the magnetic field. Therefore, according to Maxwell's electromagnetic theory, the electric and magnetic fields of electromagnetic waves are in phase, which is actually incorrect. Actually, the electric field and the average magnetic field remain in phase. The electric and magnetic fields of electromagnetic waves actually have a phase difference of 90 degrees. This way, electromagnetic waves are actually reactive power. Electromagnetic waves do not actually transmit energy. The energy is transmitted through mutual energy flow, which is active power. Mutual energy flow is generated at the source and annihilates at the sink, possessing all the properties of photons. Therefore, mutual energy flow is photons. Zhao discovered that many photons can form macroscopic electromagnetic waves, which are very similar to waves that satisfy Maxwell's equations. Zhao's theory can be found in his recently published book:

https://www.amazon.com/Electromagnetic-wave-theory-photons-electromagnetic/dp/B0D983KC2B/ref=sr_1_3?crid=336EQQ784850K&dib=eyJ2IjoiMSJ9.jLR6SQad_84j2M7QDzomQRfiLEyf7M9qygkMZ0NYuGu5trwDE5A7KHKmS7BAJA8mTtJ1Oq_M67Stcq89Sax9wNB2zWOeUK8xiH_rKLFn84o4f_JKUCryEO-3uLG4uo_rZuZbBU3C9gjQ2Go73j9Gh3OE-YQt9eMI6stQAtIzv01XKq7db3U0bbHO1oTKbmwaQgNCJfT6tUsk_-YersSok0Har2we7QyOYoMZnFV1FO4.FHb4GXPLbbpzPIbhXVk6b7kZnUc0MF1Z41eGhEKp7go&dib_tag=se&keywords=photons+waves&qid=1723510689&s=books&sprefix=photons+waves%2Cstripbooks-intl-ship%2C92&sr=1-3

ShRenZhao
  • 197