In the case of black holes, lights are pulled into by great gravitational force exerted by the dying stars (which forms into a black hole). If light has no mass, how is light affected by gravity?
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Under Newtonian gravity, where masses attract each other, light would indeed not be affected by gravity, and would always travel in a straight line.
But as it turns out, the Newtonian description of gravity wasn’t entirely correct, and gravity doesn’t actually work as an attractive force between masses.
Rather, the presence of mass changes the shape of space itself, such that “straight” lines aren’t actually straight, but are bent in the presence of heavy masses. Light still travels in a “straight” line, but space itself is not Euclidean in the presence of mass, such that even parallel straight lines can intersect for instance (such as what happens with gravitational lensing).
According to Newtonian gravity, it can’t. Light has no mass, therefore it isn’t affected by gravity. Newtonian gravity is, however, just an approximation. It turns out that things with no mass *can* be affected by gravity, and that’s what Einstein described in 1915.
Light is unaffected, at least that’s what Einstein postulated and we still do today. Light travels in a straight path, but what light sees as a straight line isn’t a straight line from a distance and this is how you derive in principle the Einstein relativity relations.
The energy mass equivalence. What we cassualy refer to as mass is actually the restmass of an object. Light doesn’t have any. But what light has is energy. Thats why sunrays are hot for exmaple.
This energy “converts” to relativistic mass according to the mass energy equivalenze. That relativistic mass is what is influenced by gravity
My understanding is that light (photons) do have mass, but it’s very, very miniscule which is why gravity sources bend light. I could be wrong however so might want an answer from an astrophysics.
According to general relativity, gravity is the result of mass causing a curvature of space-time.
Photons always travel in what they think is a straight line. The thing is, if you travel a locally straight line in a curved space, your path ends up curving over a long distance. It’s kind of like how if you walk in a straight line on Earth you’ll eventually end up back where you started.
Photons are basically the universe’s flat earthers
Einstein, not Newton. Gravity is well described in classical mechanics as interactions between masses. But once outside of that realm, it turns out, gravity changes the space-time, hence Einsteins explanation; it doesn’t affect photons, it changes the path in space that those photons travel through.
Since E=mc^2, although light has no mass, its energy is mass-equivalent and is affected by gravity due to an object’s mass in the same proportion, as if it’s mass was m=E/c^2
Another way to view this is that light travels in a “straight line” through local space, but if that space itself is curved, then that “straight line” is a curve.
It’s like a Dragon Ball Z spirit bomb. It has no physical form but it sure does have a lot of energy in it. You can still interact with it, move it around, and if you drop it will fall to the earth. Because the force of the earth will still attract the force of that energy.
Even shorter they are different forms of the same thing.
Objects with mass warp spacetime. Light follows straight paths. A straight path through warped spacetime is curved to an outside observer.
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