Einstein's Happiest Thought: Gravity inside accelerating lift

Albert Einstein completely changed our understanding of the universe which he figured out from a simple phenomenon - a lift going up. Einstein described it as the happiest thought of his life.

You would feel that your weight is increased while going up in a lift with acceleration. But according to Newton's law of gravitation, Earth is not pulling you more. So, why do we feel the extra force? The usual answer to this is that it's a pseudo force caused by the acceleration. A static observer will deduce that the extra force is required to balance the force equation.
However, nobody ever tried to look at it from the point of view of the accelerating observer inside the lift. Einstein argued that an accelerating observer would be unable to differentiate between gravity(ignoring tidal force) and acceleration of the lift. This realization led him to the path of General relativity, perhaps the greatest discovery of human history.

[audrijachoudhury]

As usual it was so very nicely presented!!

[ManualCs-wkxj]

Oh, we can vanish gravity in small regions of space by freefall