Everybody heard about light traveling at 186,000 miles per second and, this for thousand , and million of years.Where does it get it's fuel from?

motzart, light gets its fuel from energy from chemical reactions,
such as the nuclear reactions in the sun,
but this light does not travel for ever like it is worded in your question.

light does not lose speed as it travels(as something on wheels or some mechanical thing would, as it lost energy) , neither does sound, their speed is determined by their medium.

They do however lose INTENSITY.
so, they lose energy over time, but in space there is little to obstruct the light, so it can travel for long distances before it loses too much intensity,
but for example under water, after a couple hundred feet, light has lost most of its intensity,

hope that this has helped you answer your question,
if not, email me or post here and i will try to clarify stuff for you,

in the meantime, check out this linkhttp://www.howstuffworks.com/light.htm

-chris

Bibc14, I think the reason why light would lose intensity is because of the area of dispersal. If a certain amount of light intensity disperses over an area twice the original area, the intensity would be half, right? And if a light source radiates in every direction equally (in a circle or sphere), then the farther the light gets from the source, the larger the dispersal area.

To answer the question, isn't light just a chain reaction? It's not really traveling, but it's energy is being passed from one atom to the next adjacent and only appears to be traveling.

Intensity changes with the inverted square of the distance from the source.

Example: Light has a certain intensity after it has travelled 1 kilometer. When it has travelled 2 kilometers, it's intensity has changed by the inverted square of the distance:
1 divided by 2-squared = 1/4

So the light travelled twice as far, but it's 1/4 as intense.

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And light is not a chain reaction: there are not enough atoms in the "vacuum" of space for light to travel in that fashion.

Light behaves like both matter and energy: it acts as if it travels in little packets ("photons"), but it also has characteristics of waves. It's weird stuff.

Light is produced (simply put) by electrons shifting from one place to another within an atom: the change is in the the electrons' orbit about the atom's nucleus. There are several different distances from the nucleus at which electrons will orbit the nucleus. When an electron shifts from one level to another, it releases light energy: it creates a photon.

I hope this helps.

light does not actually lose any intensity as it travels. say you have a ball emittign light. if you have some kind of a detector that is also ball shaped and surrounds the ball emitting light, then you can collect all the light and measure the intensity. now expand the sphere to a larger size so that it is further away from the light, but still completely surrounds the light. you will measure the same intensity. intensity is the amount of power per unit solid angle (which is basically like an normal angel except in 3 dimensions instead of two). The only reason you will generally measure less light as you move further away from a light source is that you generally use the same sized detector so at further distances you are covering less of the total area the light is.
one of newton's laws of motion states that an object in motion will stay in motion unless acted upon by an outside force. this is how light is able to travel without losing energy... it simply keeps going at the same speed without running into anything so it never slows down (if it does run into something you have to consider other factors, but in the case of just travelling through open space). normal objects on earth are large enough that they undergo frequent collisions with other objects (the air, the ground), and lose energy because of those collisions, but in space even normal objects will maintain whatever speed they're given for a long time becasue there are so few objects to slow them down (no air).

so basically the answer is light doesn't lose energy because it doesn't get slowed down by things like air resistance.

If light does not lose intensity, then why does it only reach certain depths underwater,
and why do certain wavelengths reach deeper depths than other wavelengths.
Even a laser beam can not reach the distances under water that it can reach in space.
In an ideal world, light may not loose intensity, but in the actual world, nothing is perfect, so i think that in addition to intensity loss through increased area of the dispersal, light may lose energy through its travels through the medium.
-Chris

The very specific speed of light is its speed in a vacuum. The ratio of its speed through a vacuum to its speed through a different medium is called the refractive index of that medium. Some refractive indices are:

1.00 vacuum
1.0003 air
1.33 water

fuse,
im aware of the refractive index of light, and the different speeds of light in different media, but that only explains how much the light bends when it comes to an interface and how fast the light travels in the media, right?
So where do we stand on the loss of energy observed through loss of intensity in the light.
-Chris

My knowledge on the subject of electromagnetic radiation (light) is so far very hazy, but I'll do my best.

•First, I should mention what we already know about the energy of a single light ray / photon (don't know the proper terms and units yet). Each photon's energy is very, very small (e.g. red light: 3 x 10^-19 J per photon.

•Each photon has 0 mass (or very small, I don't know which). This means that, fast as they travel, it requires very little energy to stop them or deflect them. E.g. a mirror.

•Almost every object that is not emitting light, is absorbing it and/or reflecting it and/or refracting it. Absorption or emission occurs when, as anguilla said, an electron moves from one "shell" to another in an atom.

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So, when light travels through a vacuum, every photon is free to move and none are blocked in any way; - e.g. by absorption, refraction. This means that no fuel is required to keep them moving.

In air or water, light is not quite as free to move (forced to slow down for some reason) but still not much is being absorbed (we can still see through air and water for long distances). This means that some of the photons are being absorbed by the water molecules to heat them up, and some are possibly reflected.

Think of there being a cube of water in a vacuum. The majority of light entering the cube will emerge at the other side at the same speed that it entered (186 000 m.p.h.), but some will have been absorbed. Most photons did not hit any water molecules at all, hence still no fuel is required.

Hope that helps, though I think my reasoning is wrong.

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Squirrel

i didn't see bibc's comment on my post until this topis was brought to the top of the list again....
bibc:
i see where we were miscommunicating. light is made up of individual particles called photons. it is true that light does lose energy if individual photons are absorbed by something, but this has nothing to do with 'fueling' light as all the other photons contiunue completely unaffected. oyu can tell this because photon energy is proportional to frequency (color) and the light does not change color.
so yes, in the sense that individual photons may be absorbed, light loses energy as it travels through a dense medium, but this has noithing to do with the question about fueling because the individual photons do not lose energy.