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If light travels at x speed and it's introduced to a gravitational force will it increase in speed or remain the same?

2007-12-28 13:12:56 · 6 answers · asked by Gary88 1 in Science & Mathematics Physics

6 answers

The speed of light in a vacuum is 299,792,458 meters per second or 670,615,343 miles per hour. This is represented by the variable c, which stands for the Latin celeritas, which means speed. There is a consensus among physicists that accepting the general theory of relativity, Einstein's prevailing physics theory, entails accepting the speed of light in a vacuum as a constant. Therefore, any experiment proposing that the speed of light in a vacuum changes over time is viewed in the physics community with great suspicion.
It is widely known, however, that the speed of light is variable when the light is not moving through a vacuum. The ratio of the speed of light through a given medium and through a vacuum is called the medium's refractive index or optical density. Some media have such a high refractive index that they can slow light to the speed of a person walking, or even bring it to a temporary standstill.
For example, the speed of light through air is very close to the speed of light in a vacuum. Depending on how dense the transparent media is, it can slow light to a greater or lesser degree. Water and glass can slow light to 3/4 and 2/3 of c, respectively. Different wavelengths of light also travel at different speeds through different media. For example, blue light travels a different speed than red light when passing through a prism, causing the two to separate in a process called dispersion.
In reality, the speed of light never actually slows down. It is just delayed as the photons are absorbed and re-emitted by atoms in the intervening space. When a light beam exits a transparent medium into a vacuum, it continues traveling at the same rate as when it originally entered, without any added energy. This shows that slowdown is merely illusory.
At least two media are capable of slowing down light tremendously -- Einstein-Bose condensates, and hot rubidium gas. These have both been used to halt light entirely. This was first achieved on a temporary basis in experiments conducted in 2001.

'Of course there is one big anomaly in all this; which also gives rise to lot of hypothesis and imagination for science-fiction is a "black hole"; which is also proves the correctness of this question of yours. Nobody of the answerers here mentioned it and it actually proves wrong all who said gravity can't affect speed of light. Of course there is no known energy source as powerful as a black-hole also proving gravity the strongest known energy in universe. No wonder the science-fiction writers write about time-travel and other dimensional (anti-universe) travel through black-holes because of its property to even change and trap light itself...'

Cheers

Add:
I disagree no known Nuclear reaction is even considered as close to gravitational pull of a black-hole yet; and it is accepted by all scientist and when I talk about gravity I am not talking of gravity of a Pebble but the black-hole.
Cheers

2007-12-28 14:47:47 · answer #1 · answered by DandyCool 3 · 1 0

Actually in the presence of gravity light DOES slow. Example:
For light to not get sucked into a black hole, it has to forever accelerate itself vertically, and remains in a constant position.
Any medium will slow the speed of light down.
The Sun has a huge gravitational influence.
Light will never increase.
At least in general relativity.
In quantum mechanics, there is an effect (I forgot the name, I think it's the Casimir effect) that can make light a little bit faster (about a Planck Length ever light-year or so), but it has no general practicality. So for all intensive purposes, light will be slower than the constant c. Why? Because even in interstellar space there are many atoms (not as much as in the Solar System) and so light will be slower than c.
C = Light in a total vacuum.

Add:
Actually, gravity is considered the weakest force in the universe for some reason. The strongest is the strong nuclear force, then the electromagnetic, then the weak nuclear force, and finally gravity.
Gravity is many, many, many magnitudes lower than even the weak one, but it and the electromagnetic force are the most powerful on the universal scale. However, the universe would be nothing if the strong and weak nuclear forces wouldn't exist, because there would be no atoms, no protons, neutrons, nothing but leptons and quarks.

2007-12-29 01:03:41 · answer #2 · answered by Anonymous · 0 0

Einstein's theory of relitivity says that time and distance may stretch and warp, but the speed of light remains immutable.

The speed of light is the speed of light—always. It is the maximum speed it can go. It does not matter what inertial reference frame you are in. Before the speed of light would change, time and space would stretch and warp. (Light can't go faster than the speed of light. Traveling through a different medium can slow it, however; it would return to its prevoius speed when it exited the different medium though.)

That is what accounts for things like time dilation and length contraction.

P.S. While the speed of light won't change, the velocity of the light can. This is because velocity is speed and direction. A strong gravitational source, like a star (the sun) or a blackhole can change the path (the direction) of light. This would mean the velocity of the light would change. Its speed, however, would remain the same.

2007-12-28 21:30:33 · answer #3 · answered by Kev 3 · 2 0

The light doesn't accelerate, but it does gain energy in the form of shifting its frequency. If you shine a laser towards a gravitational source, it will shift towards blue (or w/e higher frequency). Does not change velocity though.

2007-12-28 21:36:04 · answer #4 · answered by smilam 5 · 0 0

It follows the geodesic path along the spacetime that's warped by the presence of matter. Its speed does not change, as long as its medium (i.e. vacuum) doesn't change.

2007-12-28 21:24:55 · answer #5 · answered by Frank N 7 · 1 0

No, no matter what they say on "Star Trek", sorry.

2007-12-29 18:02:09 · answer #6 · answered by htide 4 · 0 0

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