Why Does Light Bend Away From the Sun?

In summary, the conversation is about light bending around massive objects and the confusion about whether it is bent towards or away from the object. It is clarified that the light is bent towards the object, but when comparing the observed and expected positions, it appears to be displaced away from the object. A diagram is referenced to better understand this concept.
  • #1
Carnivroar
128
1
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?
 
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  • #3
PAllen said:
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.
 
  • #4
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).
 
  • #5
PAllen said:
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.
 
  • #6
Carnivroar said:
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.
PAllen said:
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.
 
  • #7

Related to Why Does Light Bend Away From the Sun?

1. Why does light bend away from the sun?

Light bends away from the sun due to the phenomenon of refraction. This is caused by the change in speed of light as it passes through different mediums, such as the Earth's atmosphere. The sun's intense heat causes the air to have varying densities, which causes the light to bend as it passes through.

2. How does refraction cause light to bend away from the sun?

Refraction occurs when light travels through a medium with a different refractive index, causing it to change direction. The change in density of the Earth's atmosphere near the sun causes the light to slow down and bend away from its original path.

3. Is it only the sun that causes light to bend?

No, light can bend when it travels through any medium with varying densities. This can include water, glass, or even air. The sun's intense heat and the Earth's atmosphere just happen to be a common example of this phenomenon.

4. Does light always bend away from the sun?

No, the direction of light bending depends on the angle at which it enters the medium. In some cases, light may actually bend towards the sun if it enters the medium at a certain angle. This is known as negative refraction.

5. What other factors can affect the bending of light from the sun?

The bending of light can also be influenced by other factors such as the Earth's curvature and the presence of other objects in the path of the light. These can cause the light to bend in different directions, making it appear as though it is coming from a different source.

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