Electromagnetic waves travel WITHIN space-time. Space-time is your media.
The interferometer was used to disprove the ether. It will be used again to show propagations of space-time in detecting gravity waves. (Google LIGO and LISA projects).
If needing a media bugs you, consider the media...
yeah, ok, I'm going to have to eat crow. it's still early. what i meant to say was forces, not work. net FORCE is zero, so as with displacement its zero.
my bad.
any displacement due to rotation is tangential to the force so the dot product is zero.
sorry!
Yeah, Young's double slit is the answer. Interference and diffraction.
You can also take Maxwell's equations and show that E and B must satisfy the linear wave equation, implying they are waves.
Have your son hold a 5 lb weight straight out at arms length for 5 minutes, then ask him if he felt like he did any work.
Yes, it's a frame of reference difference. As your son holds the mass, have him imagine he is on the moon. The displacement is obvious.
The NET work is zero if you are...