While at the mall today, listening to all the chatting and other sounds, a thought crossed my mind. When you yell, or create any sort of sound, the sound wave continues to travel until you can't hear it anymore, right? So can you apply this principle to light? Does light have a finite distance it can travel, where it then dissipates into nothing(Or maybe into something else, I'm not quite shure.)? Or does it just travel forever, assuming it isn't stopped by anything? Stuff like this crosses my mind on a daily basis, and this is the first time I've decided to share. Thoughts?
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RE: Dissipation of light?
Contrarly to sound, light is an energy. Sound is only a vibration in air (this means that there can't be sound in space, since there is no air). Light, being a form of energy can and will continue to "shine" until a solid non-translucent object will block it. A good example: Stars. Stars are thousands of millions of kilometers away, and yet you can see them.Truth lies in loneliness, When hope is long gone by -Blind Guardian, The Soulforged
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RE: Dissipation of light?
I can't believe I didn't think about that. Maybe I didn't ponder this enough. Your first sentence cleared up almost everything.Comment
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RE: Dissipation of light?
Light isn't just simply 'energy'. It has properties of both of waves and particles.
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RE: Dissipation of light?
So even if it is made of waves and particles, the aforementioned properties still apply, right?Comment
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Semantics can really be killer in a discussion of light.
fusi0n, light actually IS just simply energy, though, as you said, it does still retain properties of both waves and particles. A photon is just a packet of energy of a specific wavelength.
And yes, magister, everything Verruckter said is true. Actually, check that, he's not 100% correct. While the principle remains true (about light propagation being only vaguely related to that of sound), light doesn't have to strike anything physical to stop. It can simply be cancelled out by another like wave that's just shifted a half a phase.
--Guido
Originally posted by GrandiagodComment
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Yes guido, I forgot about that.And yes, magister, everything Verruckter said is true. Actually, check that, he's not 100% correct. While the principle remains true (about light propagation being only vaguely related to that of sound), light doesn't have to strike anything physical to stop. It can simply be cancelled out by another like wave that's just shifted a half a phase.
As an example, gravity can actually alter light's course. If you look at a sunset, the sun is actually further down than you see it, but because of the gravity, light bends and you see it higher.Truth lies in loneliness, When hope is long gone by -Blind Guardian, The Soulforged
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Gravity doesn't alter light's path.
Gravity warps spacetime, through which light follows the shortest distance (a geodesic, which is the equivalent of a straight line, just in spacetime).
--Guido
Originally posted by GrandiagodComment
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Well from what I've heard, the gravity force created by a black hole is so strong that it actually splits the light rays in a way that you can see multiple times one object on the other side of a black hole.Truth lies in loneliness, When hope is long gone by -Blind Guardian, The Soulforged
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This is because the supermassive black hole warps spacetime in such a way that light rays which would ordinarily go off in a direction (a straight line, in this case without the black hole) that wouldn't reach our eyes will actually follow a geodesic that points them at us.Originally posted by Verruckter
If you ever have the chance to observe a solar eclipse you can see this firsthand. While the moon is big enough to cover the entire sun you can still see a nice ring of sunlight around the moon. The light from the sun that we would normally be seeing all dead-ends into the moon. It's the light that's meant to never hit the Earth that you see.
As for the seeing something multiple times, well, focus on something and cross your eyes. Voilá, two of the same image. It's pretty much the same thing there.
--Guido
Originally posted by GrandiagodComment
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No no, that's not what I meant. What you are talking about here is that each eye sees an image, and the brain associates those two images into one. What I wanted to say is that the light coming from once source will actualy be divided in multiple rays, creating "copies" of the objet.Originally posted by GuidoHunter
As for the thing about gravity, my brother keeps on insisting that it does affect light. Normally, with the focus of your eyes, you can tell that something is close or far (something that you can't do while watching television, since the image has no depth). If you look at the horizon, let's say the see, you will have the impression that the land is flat, while it is not. That's because gravity curves the path of light.
Everything I'm saying is taken from my own knowledge and I do not have any sources to prove this, so don't necessarely beleive what I say, even if I beleive it is true myself.Truth lies in loneliness, When hope is long gone by -Blind Guardian, The Soulforged
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Remember when I said that semantics can be killer in a discussion about light? Well, this is why.Originally posted by Verruckter
I'm not saying you (or your brother) are necessarily wrong when you say gravity affects light. What I am saying is that technicalities play a part in this. Gravity does not directly affect light. It directly affects spacetime. This curvature of spacetime determines the light's path.
Okay, let's look at a single photon racing through empty space. It goes in a straight line. Now, let's add a massive object to the system near the photon's path. The photon's path is now altered. To then say "the presence of gravity changed the light's path" (which is what you're saying) is a logical fallacy (post hoc, ergo propter hoc) because it is ignoring any intermediary which, in this case, is the fabric of spacetime.
So, for all intents and purposes, you're right. I just wanted to clarify a technicality.
And I'm saying you're wrong. Photons (read: individual light rays) are, by definition and observation, indivisible. Light rays do not split. What happens is a beam of light (many photons in a concentrated area) will have part of it go one way around a massive object and the other part will go the other way.Originally posted by Verruckter
Remember my example about the eclipse? Well, it looks like there's a light source on the left side of the moon and another light source on the right. Of course, I know it appears in a ring, but that's due to planetary geometry; for the sake of argument, let's just deal with two apparitions. So, since light is bending around the left side, you can look over there and see an image. Since it's also bending around the right side, you can see an image there. But they're the same thing (as per your example). You'll see the image on either side depending on your preferred line of vision. Now, what happens when you cross your eyes? You use two lines of vision to see the same object which will appear twice. That's how my example relates.
--Guido
Originally posted by GrandiagodComment
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Yes, Chardish, I have tried looking on Wikipedia even before you posted that link but I have found nothing.Truth lies in loneliness, When hope is long gone by -Blind Guardian, The Soulforged
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I think we can sum it up with:
Light is weird.
Sound is not.Remember when the platform was sliding into the fire pit and I said 'goodbye' and you were like 'NO WAY!' and then I was all, "we pretended we were going to murder you"? That was great.Comment
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