Since all electromagnetic waves travel at the speed of light … shouldn't its name be Speed of Electromagnetic wave?
[Physics] Shouldn’t “speed of light” really be “speed of electromagnetic waves”
electromagnetic-radiationspeed-of-lightterminologyvisible-light
Best Answer
The speed of light is a geometrical property of the flat spacetime. See What is so special about speed of light in vacuum? and also Special Relativity Second Postulate for more on this. Any massless object necessarily travels at this speed, so it applies not only to electromagnetic radiation but also to gravitational waves.
Describing $c$ as the speed of light is largely historical since light was only understood to be electromagnetic radiation after Maxwell's work, and of course the theory of gravitational waves had to wait for Einstein. Nevertheless the description is perfectly accurate since the speed of light is indeed $c$, and the description is both more succinct and elegant that the propagation speed of any massless object.