Einstein's Theory of Relativity

Relativity is full of paradoxes, but arguably the most paradoxical one is the law of addition of velocities. According to Newtonian physics, if an object moves with velocity v_1 in one reference frame, then in a different reference frame moving with velocity -v_2 with respect to the original, the object should move with velocity v_1+v_2 . However, this turns out to be incorrect, especially for objects moving at very high speeds. The correct velocity addition formula according to the special theory of relativity is v = \frac{v_1+v_2}{1+v_1v_2/c^2} where c is the speed of light. In particular, if v_1 = c , we get \frac{v_2+c}{1+v_2/c} = c independently of what v_2 is! So, the light has the same speed in every reference frame.

Puzzle