How do radio waves travel through space if they don have a medium to travel through?
How, five circular answers so far (radio waves don’t need a medium because electromagnetic waves don’t need a medium). There actually is a medium, of sorts. It’s called the vacuum. It differs from media made of matter though in being “Lorentz Invariant”. That means, amongst other things, it has no preferred reference frame in which it can be said to be stationary. Most people thing of “vacuum” as being equivalent to “nothing”, but nothing can be farther from the truth. It’s actually a rather busy place full of virtual fields and has many tangible properties such as curvature and a metric. Nothing, on the other hand, has no properties. Modern physics treats radio waves (indeed all forms of particles and waves) as a sort of excitation of the vacuum state.
