Where does light "go"?

[Bullgrit]

My question is prompted by this article:
http://www.foxnews.com/science/2013/07/31/photons-faster-than-light-particles/?intcmp=features

What happens to light over distance? Why is it dark over there 10 meters from the lamp?

Bullgrit

 

[Dioltach]

It gets eaten. There are things in the dark. They're hungry.

 

[tomBitonti]

My question is prompted by this article:
http://www.foxnews.com/science/2013/07/31/photons-faster-than-light-particles/?intcmp=features

What happens to light over distance? Why is it dark over there 10 meters from the lamp?

Bullgrit

It spreads out. There is the same amount of it, but it has to fill a larger area.

A 2D analogy would be a ripple of water in a pond: As the ripple moves away from the source, the ring expands.

This works both for an analysis based on wave mechanics and for particle mechanics: Wave mechanics have an expanding sphere shaped wavefront. Particle mechanics replace the wavefront with a probability distribution. Both lead to a inverse square reduction of the light intensity.

A curious thing: The wavelength of the light doesn't change. When the light finally interacts with something, it does so with the same wavelength as when it is emitted. With particle mechanics, that means the interaction over a large possible area occurs at a single point.

There have been theories of "tired light" proposed as a mechanism for the red-shift of distant bodies, but these have been shown to fail to match the available evidence, so have been discounted.

I'd be very cautious of the idea presented by the linked article. Seems somewhat fringe. (Or perhaps mis-interpreted: Would the new particles be slightly faster or a lot faster than light?)

Thx!

TomB

 

[Olgar Shiverstone]

It's pitch dark. You are likely to be eaten by a grue.

It's not that it's dark, it's just less light, because the light has been more diffuse. Get the light diffuse enough, and you'll perceive it as no light, rather than shadowy light 20' radius.

 

[jonesy]

It gets eaten. There are things in the dark. They're hungry.

The grue fear light, though.

 

[Morrus]

Isn't there some inverse square law stuff also going on? In addition the the same amount of light having to cover a larger and larger area (spherically, that presumably increases very rapidly - pi r squared).

 

[Janx]

tom's answer sounds about right.

I imagine that technically, there is a blinky light somewhere on the ISS that just happens to be pointing at some alien's house on Blito-P3 and if he just happens to have a photonic register setup, he can just happen to capture that one photon that just happens to be travelling that way from the ISS.

But he won't see the blinky light on the ISS because it's too far away. And most of the other photons from the blinky light where shot off in other directions. And the likelyhood of ANOTHER photon from that blinky light happening to line up with his device is pretty slim.

So in effect, they probably travel forever, until they hit something. But like a shotgun blast in space, while it may be pretty obvious that you shot at me from 3 feet away, the pellets from that shot are pretty widely dispersed by the time they travel a light year, even though the pellets themselves haven't changed.

that about sums up my layman's understanding of photons.

 

[darjr]

The inverse square law.
The intensity of illumination is proportional to the inverse square of the distance from the light source.

http://www.portraitlighting.net/inversesquare_law.htm

From the above article. It's like said above, the light is spread out over more area the further it is from the source.

 

[tomBitonti]

So in effect, they probably travel forever, until they hit something. But like a shotgun blast in space, while it may be pretty obvious that you shot at me from 3 feet away, the pellets from that shot are pretty widely dispersed by the time they travel a light year, even though the pellets themselves haven't changed.

That shotgun analogy is a good one.

(Also, besides darkness, grues tend to twisty passages, all alike. Beware!)

Thx!

TomB

 

[Grumpy RPG Reviews]

It gets eaten. There are things in the dark. They're hungry.

I like this theory the best as it is backed up by the most evidence.