suppose two rockets with a passenger are nearing speed of light velocities and are going opposite directions. Relative to eachother one rocket will seem stationary while the other rocket will look like it’s going almost twice the speed of light. What do both passengers see?

Question

I can’t wrap my head around it. But maybe it might be a very silly question with a simple answer.

In: Physics

Answer 1

Addition of velocities doesn’t work like that near the speed of light

In a classical reference frame, u=v+u’

In a relativistic reference frame, u=(v+u’)/(1+vu’/c^(2))

They just see the other rocket go by at very close to the speed of light, much closer than they actually are from a static reference frame.

Let’s say v=.9c and u’=.9c

u=1.8c/(1+.81c^(2)/c^(2)) = .99c (approximately)

And this is what you would see if you were on one rocket observing the other