Light Deflection & Speed: Gravity's Effect?

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Discussion Overview

The discussion centers around the effects of gravity on the speed and deflection of light, exploring theoretical aspects and seeking equations to quantify these effects. Participants engage with concepts from general relativity and the nature of light's interaction with gravitational fields.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Conceptual clarification

Main Points Raised

  • One participant questions whether gravity can reduce the speed of light and seeks an equation for light deflection due to gravity.
  • Another participant asserts that gravity does not reduce the speed of light but affects its energy, clarifying that light follows geodesics in curved spacetime.
  • A participant expresses gratitude for the information but requests a simple equation to predict the bending of light.
  • Another reply humorously refrains from directly answering the equation question but suggests searching for "gravitational deflection of light" for various references.
  • One participant acknowledges that while a simple equation exists, a general relativity approach would likely be complex and notes the existence of multiple methods to calculate light deflection.

Areas of Agreement / Disagreement

Participants express differing views on the nature of light's interaction with gravity, particularly regarding whether gravity reduces the speed of light or affects its energy. The search for a simple equation to calculate light deflection remains unresolved, with multiple approaches suggested.

Contextual Notes

There is a lack of consensus on the specific equations or methods for calculating light deflection, and the discussion reflects varying levels of complexity in the approaches suggested.

zepp0814
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is it possible that gravity reduce the speed of light, and addtionally does anyone know an equation to calculate the exact deflection of light due to gravity.
 
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It does not reduce the speed but does reduce the energy.

Note that specifically gravity doesn't deflect light. Light follows geodesics, which are "curved" by gravity.

Specifically gravity curves spacetime, light travels geodesic paths through spacetime.
 
thanks a lot but so is there a fairly simple to equation that some what accurately predict the bend in the light
 
zepp0814 said:
thanks a lot but so is there a fairly simple to equation that some what accurately predict the bend in the light?

It is with astounding self-restraint that I resist the temptation to answer exactly the question you asked (The answer is "yes") and instead suggest that if you google for "gravitational deflection of light" you'll get many references at various levels of complexity.

The very last equation at http://www.theory.caltech.edu/people/patricia/lclens.html is probably pretty close to what you're looking for.
 
Last edited by a moderator:
Yes it would be a simple equation, that said I'd imagine a GR approach would be very complicated.

I don't know of a common way to calculate, surely though there are many different ways to.
 

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