Exploring Spacetime Curvature and Light

[Isaac0427]

Hi,
So according to GR, energy bends spacetime, right? So that would include both light and mass. If I am understanding this right, light bends spacetime, and is also affected by the spacetime curvature. Could someone explain exactly what the spacetime curvature does to light (I mean like how it affects the movement and dynamics of light, not gravitational lensing). Thanks in advance!

 

[harrylin]

Hi,
So according to GR, energy bends spacetime, right? So that would include both light and mass. If I am understanding this right, light bends spacetime, and is also affected by the spacetime curvature. Could someone explain exactly what the spacetime curvature does to light (I mean like how it affects the movement and dynamics of light, not gravitational lensing). Thanks in advance!

Probably you should clarify better what you would like to hear, for gravitational lensing is an important aspect of how space-time "curvature" affects "the movement and dynamics" of light...

 

[HallsofIvy]

I am not sure what you mean by "I mean like how it affects the movement and dynamics of light, not gravitational lensing". Gravitational lensing is a result of gravity affecting the movement and dynamics of light! Light moves along geodesics in space.

 

[A.T.]

Light moves along geodesics in space.

In spacetime.

 

[HallsofIvy]

Right, thanks.

 

[Isaac0427]

I am not sure what you mean by "I mean like how it affects the movement and dynamics of light, not gravitational lensing". Gravitational lensing is a result of gravity affecting the movement and dynamics of light! Light moves along geodesics in space.

Like how it affects the speed of light, or how light travels from light's perspective. Not just how light looks to us near an object with a lot of mass.

 

[A.T.]

Like how it affects the speed of light

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

or how light travels from light's perspective.

What?

 

[Isaac0427]

What?

From your perspective if you were light. But I understand it now.

 

[Ibix]

An important point in relativity is that there is no such thing as the perspective of light. It is never possible to be moving alongside a light ray, and trying to work out what would happen if you did do that impossible thing always leads to contradiction and confusion.