# Bending of light

I have read in my Physics book that if gravitational acc and inertial acc are equivalent then gravity must bend light by a precise amount.
What that means?What is inertial acc?
What that equivalency has to do with general theory of relativity i.e with warping of space time?

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I have read in my Physics book that if gravitational acc and inertial acc are equivalent then gravity must bend light by a precise amount.
What that means?What is inertial acc?
What that equivalency has to do with general theory of relativity i.e with warping of space time?
Suppose you are in a rocket ship that is accelerating. Then light must be going from A to B must follow a curve, because the space the light is passing through is accelerating. The light doesn't know anything about that, it follows a straight line relative to the moment it was emitted.

By equivalence light must do the same thing in gravity. YOu can call that warping of space time.

Hi moatasim....

It turns out that based on experimental observation gravitational mass and inertial mass are apparently equal...that is not a required part of physics.

See equivalence principle in wikipedia for more.

http://en.wikipedia.org/wiki/Equivalence_principle

Einstein had great intuition and realized that an observer in a uniform gravitational field would make the same observations as an accelerating observer: so, for example, if you are inside a stationary elevator WITH a gravitational field you feel you feet pressing against the floor...just like you do in an accelerating elevator without any gravitational field (say in outer space).

So he figured gravitational mass and inertial (accelerating) mass would have the same measures...and he could guess about characteristics of gravity by applying what he knew about acceleration.

That was really helping!