LET THERE BE LIGHT
aeterna luceat eis
understanding of LIGHT (it has so many properties)
We see with it.
is self-perpetuating and propagates through empty space.
its presence, it fills space so it is not really empty.
is itself the stuff that causes electric and magnetic fields, and is the
fundamental cause of forces among charged particles.
is made up of particles (photons) that have a specific position, velocity,
direction, spin, energy, momentum, angular momentum (but no mass).
particles possess an intrinsic periodicity with a frequency and a wavelength.
also possess coherent group properties, and all tend to do the same thing at
the same time (in contrast to electrons, where none do the same thing at the
fact that photons move with a finite speed distorts our perceptions.
perceptions (& electromagnetic forces) depend on our relative distances
from, and our motion relative to, the objects that we see with this light.
we tend to underestimate distances and overestimate times and masses.
electric fields are a game-of-catch between charged particles, moving charges
cause photons to emanate from a place where the charge now isn't, which give
rise to the magnetic field.
LIGHT FROM SOLIDS vs LIGHT FROM GASES
from a heated solid comes in a continuous distribution of colors indicating
only the temperature and not the composition.
from a heated gas contains only certain colors, indicative of the elemental