Once, I read that Einstein founded the special relativity theory by imagining how an observer moves at the speed of light. How does this thought experiment work? How to reach from this imagination to ...
Let's say we have two photons, whose momentum vectors point to opposite directions. Also spin angular momentum vectors of the photons point to opposite directions. (Sum of spins is zero) Now we ...
Case 1: two people wake up in spaceships accelerating at 1g. They can measure or observe anything inside the room but not outside. They couldn't determine if they were on a spaceship or on earth. ...