Why Does Light Bend Away From the Sun?

[Carnivroar]

I am reading God's Equation by Amir Aczel and he talks a lot about the early observations of eclipses which showed a displacement of the starlight around the sun, because space is curved around massive objects.

But why does light bend away from the sun? If it's being affected by gravity, wouldn't it be pulled towards it?

 

[PAllen]

Why do you say it is bent away? That is not true. See here for a picture and discussion:

http://en.wikipedia.org/wiki/Kepler_problem_in_general_relativity#Bending_of_light_by_gravity

 

[Carnivroar]

Why do you say it is bent away? That is not true. See here for a picture and discussion:

http://en.wikipedia.org/wiki/Kepler_problem_in_general_relativity#Bending_of_light_by_gravity

Really? The picture in the book (which I can't find online) shows a graph with the sun the middle and various stars around it. There are arrows pointing the stars away from the sun showing their displacement.

Page 136 if anyone has the book.

 

[PAllen]

Ok, I see your confusion. The light is bent toward the sun. However, if you are comparing the observed direction of a star with the expected direction, it is away from the sun. If you connect the ends of a chord with a straight line, imagine the straight line is the expected direction. Now, the tangent to an end of the chord points further away from the center of curvature (where the sun is).

 

[Carnivroar]

Ok, I see your confusion. The light is bent toward the sun. However, if you are comparing the observed direction of a star with the expected direction, it is away from the sun. If you connect the ends of a chord with a straight line, imagine the straight line is the expected direction. Now, the tangent to an end of the chord points further away from the center of curvature (where the sun is).

Ah so the arrows are pointing to the expected position, whereas the dots are the actual position under the displacement? Makes sense, but I don't know why they would do it that way. There's no caption in the image, either.

 

[George Jones]

Ah so the arrows are pointing to the expected position, whereas the dots are the actual position under the displacement?

I don't think so.

Ok, I see your confusion. The light is bent toward the sun. However, if you are comparing the observed direction of a star with the expected direction, it is away from the sun. If you connect the ends of a chord with a straight line, imagine the straight line is the expected direction. Now, the tangent to an end of the chord points further away from the center of curvature (where the sun is).

As PAllen has said, bending light towards the Sun produces images that are displaced away from the Sun. See the diagram towards the bottom of

http://www4.ncsu.edu/unity/lockers/users/f/felder/public/kenny/papers/gr1.html.

 

[Carnivroar]

I don't think so.


As PAllen has said, bending light towards the Sun produces images that are displaced away from the Sun. See the diagram towards the bottom of

http://www4.ncsu.edu/unity/lockers/users/f/felder/public/kenny/papers/gr1.html.

Ah, I see. Makes sense. The book fails to explain this. Thank you.