I'm very curious about how light is created.
I'm trying to get back to some type of real understanding about why everything on the sub-atomic level vibrates and the implications for the preservation of both the conservation of energy and conservation of momentum.
How is light created at the atomic level?
How is light created at the atomic level?
Atoms are composed of nuclei, agglomerates of protons and neutrons, which have electrons in orbitals around them; as many electrons as protons so that normally atoms are neutral.
What keeps atoms stable is that the orbitals exist at specific energy levels given by the solution of the potential problem in quantum mechanics , of a charge in the potential well of another charge, for example the hydrogen atom. At the micro level, the charges do not orbit around their center of mass system but are described as probability distributions that tell us the probability to be found in a specific (x,y,z) space point.
The carrier of the electromagnetic interaction is the photon, an elementary particle which obeys the quantum mechanical form of the Maxwell equations. It has spin 1 and zero mass and it carries the electromagnetic energy as h*nu where h is the Planck constant and nu the frequency of the wave that can be built up from an ensemble of such photons.
The electrons of the atoms are usually at the lowest orbital. Above the filled energy levels there exist orbitals that the potential predicts but are unfilled. A disturbance of the electron in its orbital, by thermal interactions of atoms for example, can kick an electron to such a higher orbital When it falls back in the ground state it was before the disturbance, electromagnetic energy is radiated, in the form of a single frequency photon that has the energy of the difference between these two orbital energy levels.
This is the black body radiation that mass of atoms at a certain temperature emit, called black body radiation when in an ensemble, as from the radiation of the sun.
An ensemble of photons, zillions of them, build up the classical electromagnetic wave which statement can be shown mathematically, but is not a simple formula. If you are interested read up this blog entry by Motl.
Quite simply moving charges create dynamical electromagnetic fields. Charges moving in the appropriate spatial pattern create dynamical patterns of the electromagnetic field which radiate outwards. We call such radiating patterns of the electromagnetic field "light".
Thus atoms create light because the charged electron moves in the appropriate pattern to emit electromagnetic radiation.
If I understand your question correctly, you're asking about how energy is conserved in the process by which an atom emits light. That's easy: if an atom has excess energy (i.e., if it is in an excited state), it can get rid of that energy by emitting a photon and changing to a less excited state. The photon will carry an amount of energy essentially equal to the difference in energy between the excited state and the less excited state (minus whatever energy goes into recoil).
If you're asking about the mechanism by which the light wave (photon) is generated, you may get answers that range from "Don't ask" to "it just happens". My favorite answer gets thumbs-down from people I respect so I won't give that answer. However, it is fair to say that in the brief interval between when the atom in is its excited state and its less excited state, there is a fluctuation of charge distribution that occurs at a frequency corresponding to the energy difference divided by Planck's constant. A fluctuation of charge distribution results in a fluctuation in the electromagnetic field. The EM field fluctuation propagates as an electromagnetic wave: as a photon, which oscillates at the fluctuation frequency and carries an amount of energy equal to the frequency times Planck's constant.
Any fundamental particle with an electric charge has a probability of emitting a photon in any given time period. This has nothing to do with vibrations within the Standard Model of Particle Physics. Visible light is simply made up photons with a particular wavelength.
Emission of a photon does reduce the energy of the fundamental particle, although the amount is so small, and is often counterbalanced by the energy gained from absorbing photons from nearby fundamental particles, so the impact of a single photon emission is minimal. Of course, at an overall systems level, it can add up, which is why shooting a laser or pointing a light bulb at something makes it hot, and why a laser or light bulb requires energy to operate.
