Does Electromagnetic radiation travel faster than the speed of light?

Main Question or Discussion Point

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After doing some reading, I've found that Electromagnetic radiation travels at the speed of light in a vacuum. EMR also travels in the path of a wave. Whereas, light and/or light photons travel in the path of a straight line.

Having said that, the path of the wave will have a greater distance of travel from point A to point B than would a straight line. Therefore, I have to conclude that Electromagnetic radiation actually travels faster than the speed of light, at least in a vacuum.

Would this be true..?

Answers and Replies

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Matterwave
Science Advisor
Gold Member
Light IS electromagnetic radiation...how can the two travel at different speeds?

Matterwave is correct, however I believe your misunderstanding comes from a deeper problem with the way you are looking at this.

Light as a wave is not a wave like the circular waves on a pond, it is a condensed area which exhibits wave behavior (my terminology here is sloppy, wikipedia 'wave packet' for a better understanding), waves (and wave packets) would not travel a greater distance than a straight line, why would they?

DrGreg
Science Advisor
Gold Member
After doing some reading, I've found that Electromagnetic radiation travels at the speed of light in a vacuum. EMR also travels in the path of a wave. Whereas, light and/or light photons travel in the path of a straight line.

Having said that, the path of the wave will have a greater distance of travel from point A to point B than would a straight line. Therefore, I have to conclude that Electromagnetic radiation actually travels faster than the speed of light, at least in a vacuum.
You seem to think radiation follows a "wavy path" rather than a "straight path". It doesn't. The wave is the radiation, and the wave moves in a straight line in empty space.

You do know, don't you, that "light" is just the name we give to electromagnetic radiation within a particular range of frequencies and that all forms of electromagnetic radiation are composed of photons?

Is it correct to say that the "wave" part is not moving in the direction of flight at all? They are fields at right angles to one another which alternately express the energy of the photon in its electric field and magnetic field perpendicular to the direction of flight (alternating at a frequency proportional to the energy).

Or is that too much of a classical view?

mfb
Mentor
They are fields at right angles to one another
And they (or, alternatively, their positions) move with the speed of light.

Bill_K
Science Advisor
They are fields at right angles to one another which alternately express the energy of the photon in its electric field and magnetic field
This is not correct. The energy does not alternate back and forth between the electric and magnetic fields. The electric and magnetic fields in a light wave are in phase, reaching their peak value at the same time, and simultaneously falling to zero at a later time.