Understanding How Gravity Bends Light and Relates to General Relativity

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Discussion Overview

The discussion centers around the relationship between gravity and light bending, particularly in the context of the equivalence principle and general relativity. Participants explore the implications of gravitational and inertial acceleration, as well as the concept of spacetime warping.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant questions the meaning of the equivalence of gravitational and inertial acceleration and its implications for light bending and general relativity.
  • Another participant describes a scenario involving a rocket ship to illustrate how light would curve in an accelerating frame, suggesting that gravity should similarly affect light due to spacetime warping.
  • A third participant notes that while experimental observations suggest gravitational mass and inertial mass are equal, this equality is not a required aspect of physics, referencing the equivalence principle.
  • This participant also explains Einstein's intuition regarding the observations of an observer in a gravitational field compared to one in an accelerating frame, highlighting the perceived similarities in experiences.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and interpretation of the equivalence principle and its implications, indicating that multiple competing views remain and the discussion is not resolved.

Contextual Notes

Some assumptions about the nature of gravitational and inertial mass, as well as the interpretation of spacetime warping, are not fully explored. The discussion also relies on the participants' interpretations of experimental observations and theoretical implications.

moatasim23
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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?
 
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moatasim23 said:
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!
 

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