# Does Light Bend?

So, I was talking with my friends about light for some arbitrary reason, when one of them said that light could bend. We debated this for several minutes, but neither side came out correct. So I went on Wikipedia to further educate myself in the matter, and I found one side note about light bending, which did little to shed light on the matter (pun intended).

So, does light bend, and if so, why?

I think it doesn’t simply because I’ve always viewed light as a straight line, much like I view the timeline.

If someone could sort out this matter for me, I would be grateful.

Yes, light bends, for example if gravity is acting upon it. There are probably other ways to bend light (I dunno if reflection/refraction count for you), but that’s the most common one, and it happens to all light everywhere, constantly.

No, I wasn’t including refraction/reflection, but thanks for the insight into gravity bending light. But my only question now is how far does light bend? I mean, it can’t be more than a few minuscule amounts, otherwise, a good chunk of the Earth would be kept in twilight for a while.

Twilight currently is caused by refraction in the atmosphere. The bending of light wouldn’t cause twilight, it’d just mean that more of the earth is lit than dark.

But to answer your question, you’re right, light doesn’t bend much at all. It takes a very VERY large mass to bend light significantly. The most famous of such masses is a black hole. Black holes are called “black” holes because they are so massive that light cannot escape their gravitational pull. You should also look up gravitational lenses, because those are a very interesting light bending effect as well.

Thanks for the info. You have definitely explained this to me thoroughly.

I guess I was wrong… Lol.

Black Holes bend light, I wonder why there’s so many fantasy about Black Holes?

I told him that already <_<

Oh lets see now, oh you did. My bad are there some Black Holes that will not pull in the light. I remember hearing something about a star that its core collapse and the star resist the gravity of the Black Hole and continue shining.

Gravity can’t generate light, once a star has collapsed, all fusion in it has ceased, so no more light is produced. It’s either dark and cold, or a black hole.
Or it could have exploded, too.

just so you know, gravity does generate light, indirectly.

Every star has a constant struggle between it’s radiation force, that tends to make the star expand, and its gravitatory force, that tends to make it collapse.

Whenever a star runs out of fusable fuel, radiation stops, and gravity makes it collapse. But guess what? Stars are made of gas. What happens if you reduce the volume of a gas, while keeping the same amount of gas?

Bingo, pressure and temperature increase. More temperature = reaching enough kinetical energy to beat the nuclear repulsive forces = fusion starts again = radiation is restored = star stabilizes again = produces light.

Let’s collapse all of this together.

Gravity = Light, oh yeah.

and yes, Gravity can bend light. Light is made of photons. Photons are waves, and particles at the same time. In wave form, they travel so fast and have such minimal mass that they are virtually unaffected by gravity, however, really intense gravitatory fields, as Tim pointed, black holes, CAN exert enough force over the photons to trap them.

And stars have 3 possible deaths, just so you know, and don’t go around saying bullshit.

Any star with less than 3 times the mass of our Sun, will burn Hydrogen, then collapse, reactivate and burn Helium (red giant), collapse again, inflate into a supergiant, cool down, and burn Carbon, collapse again, burn Oxygen, at which point, it’ll become a molten Iron core that is unfusable, and will slowly radiate away whatever little energy it has left (White dwarf).

Stars with between 3 and 10 times the mass of our sun will collapse to a point where the nuclear repulsive forces are defeated, and matter is collapsed into a state where there are no empty space between atoms, read, a neutron star, a superdense entity that often spins sending ‘pulses’ of energy like a lighthouse, called ‘Pulsar’.

Stars with more than 10 times the mass of the Sun will pull a cataclysmic explosion, a supernova, expelling its outer layers, while the core collapses past a neutron star into a black hole.

And, Black holes do emit energy. Hawking’s radiation and such. Of course, this is all purely theoretical, but so far it complies with actual observation.

Also, what WotW said is part true. Many galaxies, as well as outer-universe ancient structures known as Quasars, have int heir cores some kind of super-powerplant, powered by a super blackhole.

Also, as for light bending, refraction does that, as Tim said, as well (although the sky being blue thing and such is not caused by refraction, but by Rayleigh Scattering)

If the light goes through any media that has a refraction index gradient, such as, air at different temperatures (air in contact with a hot road, hot near the road, colder above), will cause the light’s trajectory to bend as it goes through the media. That’s what causes really hot roads to look like they have melted when you drive on them.

So yeah, I suggest having a look at a Physics book before saying random shit again.

whoa X.x
too much to take in at once!
brain implodes

uhm… light is bright?

xD

Wow…Thanks for the info, CFX.

A new question erupted when I presented the information gathered from this topic. Does light bend, if at all, due to planetary gravity. We concluded that it must bend a very minuscule amount, but we’re still not sure, and thus, I wanted to check it out with you guys. So, does light bend to a point of being visible when affected by a planet?

Any particle’s trajectory changes when acted upon by gravity, as far as I understand. For instance, the Moon bends light enough that we can always see a ring of light around it during a solar eclipse, even though it’s covering the Sun completely.

Augh, sorry. I was thinking in the back of my head “wait, that can’t be quite right” as I typed it, but typed it anyway to look smart >_>
Apologies to anyone I misled.

Also, I’m not quite sure what CFX meant when he said that Black Holes generate light, but what I think he meant (since this is what I understand to be true) is that the black hole’s gravity gives off light, by pulling in matter from space (such as the hydrogen present everywhere). This forms so called Accretion Disks, which emit light in the way CFX described.
The actual black hole object itself can’t give off light, since light can’t get out past the event horizon (the point of no return for light).

I might be wrong, though, and there might be some quantum effect or something that lets light escape.

That was the answer I was seeking. Thanks.

Hm, I can’t find anything about the Moon, but the Sun definitely bends light enough for us to see it (well, the Sun is too bright for us to see it, but during an eclipse, you can).
http://www.esa.int/esaSC/SEM7I9R1VED_index_1.html

I didn’t say that black holes emit light, I said they emit energy signatures.
Or at least, that’s what the (AGAIN: PURELY THEORETICAL) quantic analysis of them says. It’s Hawking radiation that they emit, not light.

Ah, I see.