I’m am trying to figure out where light came from. Any hypothesis are appreciated.
Posted: May 4th 2009
Eric_PK
I think the simplest answer is “light is an inherent property of the universe”. Once of the fundamental particles is the photon, and a bunch of photons is what we see as light.
(that’s a simplification – the reality (because of quantum mechanics) is far, far stranger. Do a search on “double slit” experiment…)
Posted: May 6th 2009
SmartLX www
It probably wasn’t somebody saying, “Let there be light.”
Really, REALLY simple version: certain chemicals, in certain states (reacting, exploding, fusing, etc.) give off radiation of all sorts. Almost anything which does not give off this radiation is at least able to reflect it, so it gets everywhere.
Animals’ eyes, including ours, are able to detect and interpret a small subset of that radiation – a particular range of wavelengths. That’s how we “see”. We therefore gave this subset of the spectrum a name: light.
As for light’s origin as a whole, it has been around for as long as the chemicals which produce it. The Big Bang was a hotbed for close contact and rapid reactions, so the universe would have been extremely bright to any observer right from the get-go.
Posted: May 5th 2009
logicel
Light is a form of electromagnetic radiation or EMR whose physical properties can be explained by a particle (photon) or wave model. EMR is emitted to carry away excess energy when atoms interact in chemical or nuclear reactions. This author is not aware of any explanation of the exact quantum electrodynamics or QED causing the creation of EMR.
During chemical and nuclear reactions, electrons often change energy states. When an electron changes to a lower energy state, a photon is emitted to carry away the difference in energy, in conformance with the law of the conservation of energy. Conversely a photon can interact with an electron raising its energy state (e.g. as happens in solar panels and photosynthesis).
Sunlight is created when two hydrogen atoms fuse into one helium atom resulting in surplus energy much of which is emitted as EMR part of which is light. Starlight is exactly the same, but emitted by very distant suns/stars. Moonlight, on the other hand, is light generated by the sun and reflected by the moon.
On earth, light may be generated by chemical reactions, for example, in fires, candles, phosphorescence (insects, algae, etc.). Another major source of light on earth is electrical in which electric current excites atoms provoking them to emit photons.
Posted: May 5th 2009