why does light radiate?

[yusufcam (Colin)]

(forgive my curiosity and there is probably a simple answer of which i am unaware)

while i understand with heat how it radiates through thermal exchange.

But why does light radiate? What is its propellant, to give such curiousities as the consistency of its speed.

[Steffen]

Heat radiation (infrared) and visible light are essentially the same, just different wavelengths. The respective photons come into being as elementary particles (electrons) drop to lower energetic levels after having been raised to higher ones previously by way of some excitement (for example thermal motion, being hit by other photons, etc). The photons pick up the difference in energy, the higher the energy conferred onto them the shorter their wavelength. Photons aren't propelled, they come into being at the speed of light.

That's what I remember from my school physics anyway

[rustigsmed (Russell)]

read this the other day and thought of it again after reading Steffen's post

http://www.abc.net.au/science/articl...23/4259590.htm

[yusufcam (Colin)]

Originally Posted by Steffen

Heat radiation (infrared) and visible light areessentiallyhttp://cdncache-a.akamaihd.net/items...rrow-10x10.png the same, just different wavelengths. The respective photons come into being as elementary particles electronshttp://cdncache-a.akamaihd.net/items...rrow-10x10.png) drop to lower energetic levels after having been raised to higher ones previously by way of some excitement (for example thermal motion, being hit by other photons, etc). The photons pick up the difference in energy, the higher the energy conferred onto them the shorter their wavelength. Photons aren't propelled, they come into being at the speed of light.

That's what I remember from myschoolhttp://cdncache-a.akamaihd.net/items...rrow-10x10.png physics anyway

Thanks Steffen

maybe the question should be why does a photon come into being at the speed of light? (which I am led to believe is a universal constant)


trying to get a laymens mental picture