PRIDE CHEKERASpecial Theory of Relativity
Einstein was fascinated by light that he spent his time pondering
on gedanken experiments relating to light. He wanted to deduce
the behavior of bodies in relation to space-time at these high
speeds of light.
Train Passengers gedanken experiment
One of his gedanken experiments is that: suppose there are
passengers in a carriage of a relativistically accelerating
(approaching speed of light) train in a railway; there are two
clocks attached at opposite sides of the carriage. Then a flash
bulb in the carriage emits two beams of light which traveled to
both clocks in opposite directions. What will happen?
According to Einstein, passengers in the carriage will see the
two beams illuminating the clocks at the same time, and see the
same time displayed on the clocks.
But to an observer who is outside its totally different. When
beams of light were emitted, from the frame of reference of the
stationary observer outside, the passengers at the back of the
carriage are moving into the beam and those in front of the
carriage are moving away of the beam.