<p>Light (in general relativity) follows paths in spacetime dictated by the curvature of spacetime.  That curvature is a result of gravitational distortion of spacetime by energy (and this includes mass as a form of energy).</p>

<p>So light follows curved paths through curved spacetime.</p>

<p>You should not, however, think of light as feeling a gravitational force in a Newtonian sense.  This is <em>not</em> what happens.  You need to forget Newtonian ideas like that in general relativity.   For example, it's tempting to say that light is attracted to a gravitational source, but this is not really the case and can lead to incorrect thinking (e.g. like imagining light was being accelerated, which it is not).</p>

<p>The technical term for paths that light follows in spacetime is <a href="https://physics.stackexchange.com/questions/188859/what-is-a-null-geodesic">null geodesic</a> (the link is to a Q&amp;A on the Physics SE site).  I suspect that's possibly more that the OP wants to knows, but the link is there to investigate if they want to.</p>

CC BY-SA 4.0
2019-02-05T17:28:43.927Z
2019-02-05T17:28:43.927Z
StephenG - Help Ukraine
<p>Lets suppose there is a huge planet having large amount of gravitational pull, then will the light passing through the planet get attracted towards it.</p>

CC BY-SA 4.0
2019-02-05T05:56:34.807Z
Your question is a bit confusing. How can light pass through a planet? FWIW, gravity is the bending of spacetime, so it affects everything, including light. The bending caused by a planet is very small, but the bending of light caused by a star is noticeable.
PM 2Ring
CC BY-SA 4.0
2019-02-05T06:06:38.900Z
A "huge" planet is pretty insignificant in terms of stellar mass and "large-scale" gravity. For example, Kepler-39b is 18x the mass of Jupiter but that's still only about 1.8% of the mass of our Sun.
Chappo Hasn't Forgotten
CC BY-SA 4.0
2019-02-05T06:23:37.273Z
Do you mean "passing by the planet"? In that case, yes, look up gravitational lensing.
Phiteros
CC BY-SA 4.0
2019-02-05T10:08:53.983Z
By "through" do you mean the planet's atmosphere?
George
CC BY-SA 4.0
2019-02-05T14:59:31.303Z
Light passing **any** gravitational field will be curved.  That's part of General Relativity.
Carl Witthoft
CC BY-SA 4.0
2019-02-07T21:14:23.957Z
@PM 2Ring : light doesn't _"follow the curvature of spacetime"_. That's a myth. Light curves wherever there's a gradient in gravitational potential. Spacetime curvature relates to the _change_ in the gradient. The [rubber sheet analogy](https://commons.wikimedia.org/wiki/File:Spacetime_curvature.png) isn't perfect, but it's not totally wrong. Imagine you were very small, and somehow standing on the rubber sheet. When you flick a marble, it takes a curved path wherever the sheet is sloping. The curvature of the light beam is different to the curvature of the sheet.
John Duffield
CC BY-SA 4.0
2019-02-07T21:37:13.647Z
@John Please don't put words in my mouth. Clearly, light doesn't follow the trajectory of a body with mass in the same location, travelling in the same direction. Massive bodies follow timelike geodesics, light follows null geodesics.
PM 2Ring
CC BY-SA 4.0
2019-02-07T22:33:09.003Z
@PM 2Ring : sorry for putting words into your mouth, and thanks for distinguishing light and massive bodies. But do note that light doesn't curve because it follows a null geodesic. A geodesic is an abstract thing that doesn't actually exist. See the second paragraph [here](https://einsteinpapers.press.princeton.edu/vol7-trans/156?highlightText=%22spatially%20variable%22) for the reason Einstein gave.
John Duffield
<planet><gravity><light>
Can light be curved due to heavy gravitational force?
ranjith 
# Can light be curved due to heavy gravitational force?

(Asked by: username_0 on 2019-02-05)

Lets suppose there is a huge planet having large amount of gravitational pull, then will the light passing through the planet get attracted towards it.

**Tags:** planet, gravity, light

> **Comments:**
> **username_1**: Your question is a bit confusing. How can light pass through a planet? FWIW, gravity is the bending of spacetime, so it affects everything, including light. The bending caused by a planet is very small, but the bending of light caused by a star is noticeable.  
> **username_2**: A "huge" planet is pretty insignificant in terms of stellar mass and "large-scale" gravity. For example, Kepler-39b is 18x the mass of Jupiter but that's still only about 1.8% of the mass of our Sun.  
> **username_3**: Do you mean "passing by the planet"? In that case, yes, look up gravitational lensing.  
> **username_4**: By "through" do you mean the planet's atmosphere?  
> **username_5**: Light passing **any** gravitational field will be curved.  That's part of General Relativity.  
> **username_6**: @username_1 : light doesn't _"follow the curvature of spacetime"_. That's a myth. Light curves wherever there's a gradient in gravitational potential. Spacetime curvature relates to the _change_ in the gradient. The [rubber sheet analogy](https://commons.wikimedia.org/wiki/File:Spacetime_curvature.png) isn't perfect, but it's not totally wrong. Imagine you were very small, and somehow standing on the rubber sheet. When you flick a marble, it takes a curved path wherever the sheet is sloping. The curvature of the light beam is different to the curvature of the sheet.  
> **username_1**: @John Please don't put words in my mouth. Clearly, light doesn't follow the trajectory of a body with mass in the same location, travelling in the same direction. Massive bodies follow timelike geodesics, light follows null geodesics.  
> **username_6**: @username_1 : sorry for putting words into your mouth, and thanks for distinguishing light and massive bodies. But do note that light doesn't curve because it follows a null geodesic. A geodesic is an abstract thing that doesn't actually exist. See the second paragraph [here](https://einsteinpapers.press.princeton.edu/vol7-trans/156?highlightText=%22spatially%20variable%22) for the reason Einstein gave.  

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## 1 answers

### Answer by username_7 on 2019-02-05. Score: 3

Light (in general relativity) follows paths in spacetime dictated by the curvature of spacetime. That curvature is a result of gravitational distortion of spacetime by energy (and this includes mass as a form of energy).

So light follows curved paths through curved spacetime.

You should not, however, think of light as feeling a gravitational force in a Newtonian sense. This is *not* what happens. You need to forget Newtonian ideas like that in general relativity. For example, it's tempting to say that light is attracted to a gravitational source, but this is not really the case and can lead to incorrect thinking (e.g. like imagining light was being accelerated, which it is not).

The technical term for paths that light follows in spacetime is [null geodesic](https://physics.stackexchange.com/questions/188859/what-is-a-null-geodesic) (the link is to a Q&A on the Physics SE site). I suspect that's possibly more that the OP wants to knows, but the link is there to investigate if they want to.


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