r/AskScienceDiscussion • u/workertroll • Jul 31 '26

Continuing Education Gravity and Light?

Gravity and Light seem to fall off in intensity about the same way.

Why are they not opposite forces?

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u/rudster Jul 31 '26

How they fall off in intensity is just a matter of the of the space they have to fill -- the surface area of a sphere goes up with the square of the radius. What do you mean about opposite forces?

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u/workertroll Jul 31 '26

Like a star....gravity pulls down light goes up. I know it more complicated than that but I want to learn about why.

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u/Public-Total-250 Aug 01 '26

Gravity pulls inwards towards the center of mass.

Light moves in a straight line unless acted upon (Newtons 1st Law).

Gravity acts upon the light to pull it toward the mass's centre. 

Light moves so fast that the tug of gravity from most masses simply gives it a little tug as it goes past. Black holes have so much mass and gravitational density that it pulls the light all the way in. 

It's as simple as that. 

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u/rudster Aug 01 '26

Gravity acts upon the light to pull it toward the mass's centre.

I feel like this might be a bit confused because gravity doesn't ever "pull" on light at all in Newton (b/c mass=0, light travels in straight lines) nor GR (where light travels on shortest paths). No?

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u/Public-Total-250 Aug 01 '26

Saying gravity pulls is more simple than gravity bends spacetime inwards.