A question about light speed.

[TrulySorry]

I even understand the content of the passage i copied...or the original equation lol. I just know it dealt with slowing down light

[Bree Fletcher]

So what would be the result of this?

Well, as a little thought experiment...

Say you were, (doen't matter how, just go with it) just barely outside the event horizon, and were shining a beam of light directly away from the black hole. I think the gravity should be enough to reduce the light's speed, though it's still capable of moving away from the black hole. On the other hand, it's nagging at me that there's something ese that comes into play, some sort of strange relativistic thing, that would mess with time and force it to keep that speed, I'm not sure...

Anyone want to help there?

(By the way, I'm pretty sure that as far as bending light around gravity goes, you'd only reduce the average velocity, and not the actual speed.)

[Rota]

It goes slower through those materials because the photons hit particles on the way through, I think this question is asking about whether it still travels at the same speed as in a vacuum when it is bouncing around.

That is really what I was thinking. Can light travel slower in a vacuum? Can a beam of light energy just travel at a casual speed, rather than the constant sprint of the speed of light.

But, it's nice to know that something as simple as friction can slow down light.



What about wavelengths?


Recall the post I made about the "road" on the first page of this thread. Does a beam of light with greater amplitude, and shorter wavelength travel slower than a beam with short amplitude, and long wavelength? I would think it should work that way, since the light-energy of that beam has to travel a longer route over a given distance.

[Bree Fletcher]

Recall the post I made about the "road" on the first page of this thread. Does a beam of light with greater amplitude, and shorter wavelength travel slower than a beam with short amplitude, and long wavelength? I would think it should work that way, since the light-energy of that beam has to travel a longer route over a given distance.

If I remember right, the amplitude changes nothing at all, and the frequency should change inversely to accomodate shorter or longer wavelengths, effectively making the speed come out to the same.

[ninno20]

Iv heard the same as TC they can slow down the speed that light travels.
But then there is also the theory that the laws of physic's are a local thing and are not the same in other parts of the universe, so anything is still possible when we don't fully know everything about it.

[TrulySorry]

More copied material here but....

Danish physicists performed an experiment where they slowed light down to only 38 miles per hour or about 57 kilometers per hour. They did this by sending a beam through a material made of sodium atoms cooled to near absolute zero (-273?C or -460?F). They achieved this low temperature by using lasers to slow down the atoms, through a special method used in quantum mechanics called the Bose-Einstein condensate. (Explanation of this goes away beyond the scope of this course).

[Bree Fletcher]

Iv heard the same as TC they can slow down the speed that light travels.
But then there is also the theory that the laws of physic's are a local thing and are not the same in other parts of the universe, so anything is still possible when we don't fully know everything about it.

It varies depending on your frame of reference, yes (not exactly different location, but different speed and such), meaning that you can take many frames of reference that are different than ours and say that (c) is slower. But... that seems like a cop-out. I think it might be more meaningful to figure out if the speed of light can be lower within our own frame of reference.

EDIT: That was in your earlier post already, Trulysorry. It's still just using refraction, like in glass, which we already agreed works.

[Rodri]

Event Horizon.

Theoretically, the gravity well of a large black hole is so great that once you cross the event horizon, nothing (including light) can escape. Meanwhile it is said that if you ever found a real black hole that the event horizon would show every star, planet, alien spaceship (or whatever) that had ever crossed that event horizon and got sucked into the black hole, for all time. The reason is related to the gravity pull at the event horizon slowing light to a standstill so that the visible image remains frozen long after (well, forever theoretically) the actual object has been destroyed. So gravity can slow the speed of light I guess. It would be interesting to measure the speed of light in relation to some big gravity objects such as a dense star and then measure the speed of light coming from that object at further distances to see if there is some variation as the light escapes from that gravity well. If these theories are right, then there should be some measurable difference as the gravity reduces.

It gets kind of messy because there is a gradual red-shift of any light caught at the event horizon, which would eventually become unobservable to the human eye and because massive gravity can bend light, so the actual position of the event horizon is different from the observed position. My measurements would be difficult to quantify because of this bending of light.

[Bree Fletcher]

Event Horizon.

Theoretically, the gravity well of a large black hole is so great that once you cross the event horizon, nothing (including light) can escape. Meanwhile it is said that if you ever found a real black hole that the event horizon would show every star, planet, alien spaceship (or whatever) that had ever crossed that event horizon and got sucked into the black hole, for all time. The reason is related to the gravity pull at the event horizon slowing light to a standstill so that the visible image remains frozen long after (well, forever theoretically) the actual object has been destroyed. So gravity can slow the speed of light I guess. It would be interesting to measure the speed of light in relation to some big gravity objects such as a dense star and then measure the speed of light coming from that object at further distances to see if there is some variation as the light escapes from that gravity well. If these theories are right, then there should be some measurable difference as the gravity reduces.

It gets kind of messy because there is a gradual red-shift of any light caught at the event horizon, which would eventually become unobservable to the human eye and because massive gravity can bend light, so the actual position of the event horizon is different from the observed position. My measurements would be difficult to quantify because of this bending of light.

So you're finally expanding on what I asked yesterday... but I think I finally figured out why it was nagging me that this might not slow down light: What if it slows down time as well? I mwan, what if, say, you succeed at making light go at 0.5c, from an "objective" (using that term in an abstract sense, as everything's always relative ) point of view. What if time then goes at 0.5 times normal speed as well, from that same "objective" view? Then, light's essentially still going at speec c.

[Rota]

So you're finally expanding on what I asked yesterday... but I think I finally figured out why it was nagging me that this might not slow down light: What if it slows down time as well? I mwan, what if, say, you succeed at making light go at 0.5c, from an "objective" (using that term in an abstract sense, as everything's always relative ) point of view. What if time then goes at 0.5 times normal speed as well, from that same "objective" view? Then, light's essentially still going at speec c.

I actually had a question about time that was very similar to my question here about light speed. I might make another thread someday for that one.