Since light doesn't have mass, how do massive things like black holes and galaxies have warping effects on it?

Answer 1

Einstein's General Theory of Relativity states that every object that has mass warps space to a varying degree, based on its mass (the amount of matter, not necessarily its weight). Since photons have no mass (they have no mass at rest, which is impossible for them, and they have no mass when in motion. That is why they travel at the speed of light), they SHOULDN'T be affected by something's mass, but...

This is where the question asked above goes to. Space is warped by an object's mass. The more mass it possesses, the more it warps space around it, and the further away from that mass the warping is felt. Photons move through space, so they are affected directly by this warping. The photon is affected indirectly by the mass of the object, but not directly, as any object with mass would be.

This was most clearly demonstrated by measuring the angular change in the position of stars behind the sun during a total solar eclipse in the late 1910's. It was this set of measurements that proved Einstein's General Theory of Gravity as far as the rest of the scientific community was concerned. So far, this theory has not been disproved by anything else we've been able to come up with.

So the warping effect that the question mentions is actually the effect on space-time, NOT an effect on the photons. The photons pass through space in a straight line, from thier source, but space, itself, is neither flat nor straight. Therefore, the photons can have thier courses changed by an object with enough mass to warp space noticeably in its path, even if that path is light years away from a super-massive object.

Answer 2

Light does not have REST mass, meaning that when it is not moving it has no mass. But light when moving does have mass.

However, the current scientific thought is that it is not gravitational attraction that warps light, but an effect on the space-time continuum which warps space, as described in the General Principle of Relativity. Actually, I think that theory is slightly ridiculous.

Answer 3

Gravity effects light by warping space. This was what Einstein was all about. His theory of relativity explains how that happens. See NASA's answer to your question in the link below.

Answer 4

Who says light dosent have mass? Man may not be able to measure the mass of light, but the efect of the "black holes" on light may prove it really has mass.
There is always another view point in science, few if any facts that don't change....

Answer 5

Light is comprised of photons, which (don't quote me) should have some tiny mass, since they are affected by gravity. I might be wrong, but I was always told that even light has weight, so I assume it has mass also. Weight is the effect of gravity on mass.

Answer 6

Check out this website for the answer - kind of long-winded, but addresses your question perfectly:

http://math.ucr.edu/home/baez/physics/Relativity/SR/light_mass.html

Answer 7

don't ask questions like this because obviously from most of the answers that are posted people just don't know what they are talking about.