Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: katieHaylor on 29/09/2017 11:08:54

Title: How do electromagnetic waves propagate through a vacuum?
Post by: katieHaylor on 29/09/2017 11:08:54
Sharath says:

I understand the force carriers of an EM wave are photons, but since they also travel through a vacuum,  I am at a loss of understanding even after searching through many sources as to how they are able to travel without any medium, unlike other waves like sound waves.

Could you please explain the mechanism of the propagation of EM waves through vacuum?


Can you help?
Title: Re: How do electromagnetic waves propagate through a vacuum?
Post by: Kryptid on 29/09/2017 22:50:11
As best as I understand it, the electromagnetic field itself is what propagates electromagnetic radiation (including light). You can visualize a wave of light as being a disturbance or change in an electromagnetic field that moves through the field at the speed of light.
Title: Re: How do electromagnetic waves propagate through a vacuum?
Post by: geordief on 30/09/2017 01:33:00
As best as I understand it, the electromagnetic field itself is what propagates electromagnetic radiation (including light). You can visualize a wave of light as being a disturbance or change in an electromagnetic field that moves through the field at the speed of light.
A bit like pulling yourself up by your own bootstraps? The electric field propagates and the magnetic field comes along for the ride?Am I close?
Title: Re: How do electromagnetic waves propagate through a vacuum?
Post by: Kryptid on 30/09/2017 05:41:42
A bit like pulling yourself up by your own bootstraps? The electric field propagates and the magnetic field comes along for the ride?Am I close?

I've seen it described in different ways. Another way I've seen it described is that the electric component of the photon gives rise to a magnetic component and that in turn gives rise to another electric component and the process repeats. : https://upload.wikimedia.org/wikipedia/commons/c/cd/The_Photon.png (https://upload.wikimedia.org/wikipedia/commons/c/cd/The_Photon.png)
Title: Re: How do electromagnetic waves propagate through a vacuum?
Post by: evan_au on 30/09/2017 07:15:51
Quote from: Sharath
I understand the force carriers of an EM wave are photons
Light is carried as particles
- bullets and micrometeorites also are particles, and propagate quite well through a vacuum
- so it should be no surprise that photons can also propagate through a vacuum.

Bullets can also be viewed as waves, and they manage to propagate through a vacuum, too...
- That might need a bit more explanation (one day...)
Title: Re: How do electromagnetic waves propagate through a vacuum?
Post by: jeffreyH on 30/09/2017 08:50:44
There is energy in the vacuum. There is an energy, mass equivalence. However, the Higgs field does not seem to give mass to these quantum fluctuations. They are not particles. If a photon interacts with a disturbance in the vacuum this could be said to be similar to a medium.
Title: Re: How do electromagnetic waves propagate through a vacuum?
Post by: geordief on 30/09/2017 10:47:27
I've seen it described in different ways. Another way I've seen it described is that the electric component of the photon gives rise to a magnetic component and that in turn gives rise to another electric component and the process repeats. : https://upload.wikimedia.org/wikipedia/commons/c/cd/The_Photon.png
I thought fields extended indefinitely in space.That image seems to show the two fields  extending a finite distance .Do they actually extend indefinitely in the direction at right angles to the direction of propagation? (the image being for illustrative purposes)
Title: Re: How do electromagnetic waves propagate through a vacuum?
Post by: Kryptid on 30/09/2017 19:11:07
I thought fields extended indefinitely in space.That image seems to show the two fields  extending a finite distance .Do they actually extend indefinitely in the direction at right angles to the direction of propagation? (the image being for illustrative purposes)

Electromagnetic fields do extend indefinitely into space. What you are seeing in the image is the amplitude of the photon, which is different from the range of the field that makes up the photon. Amplitudes are finite. Even for a hypothetical, infinite ocean, the waves in the ocean will have a limited amplitude.