Tony650
I thought that "colour" was simply how our eyes interpret a certain range of frequencies within the visible portion of the spectrum; is this what you mean by the photons themselves being coloured? Are you simply referring to the wavelength of the light in question?
Light in the 400 - 700 nanometer range is the visible light we percieve as colors.At the 400 nm end light is violet and at the 700nm range it is red.Our brain interprets the colors based on their unique wavelength or combination thereof.
There is a site that deals with the application of light and vision in normal people and colorblind people that might help explain things in greater depth and clarity.
http://home.pacifier.com/~ppenn/page7sc.html
Something else...I just realized that I'm using the words "frequency" and "wavelength" interchangeably. Are they, in fact, the same thing, in this context?
No they are different but connected.The smaller the wavelength the greater the frequency.Wavelength times frequency equals the speed of light.At the highest frequency/smallest wavelength {most energetic} are the gamma rays at 10*-6 nm while at the lowest frequency/largest wavelength {least energetic} are the radio waves.
Hmm...so an individual atom won't display colour?
The
nucleus is not involved in the propogation of electromagnetism only the eletron as they gain and then release energy as photons when transitioning from one energy level to another
What I'm really having trouble with is how a single atom can show colour when the necessary wavelengths are so much larger. I keep falling back (no doubt due to my layman's understanding of particle physics) on the analogy of the cannonballs and the grain of sand. Is this a mistake on my part? Perhaps it's giving me an inaccurate impression.
Well that because the photons come in discrete packets known as quanta and are measurable individually and at the same time they are elctromagnetic waves propogating through space.The individual photons quanta aspect will confuse you but the wave aspect is what will allow the colour to be mediated as its interacts with the color cones in our eyes.the electrons in the color cones absorb the photons and again release them as the information is transmitted through the nervous system to the brain.Poton to electron to photon on and on in a cascade effect throughout our biological pathways.It does take an accumulation of photons to stimulate the cones though I do not at the moment recall how many.
Welcome to the mysteries of our humanity.Deep wonders indeed.Puzzles within puzzles. Hope you enjoy them because it gets better with the depth you go in studying these phenomena.
Just to clear it up in my mind, how does a photon compare in size, roughly, to an atom. Is the grain of sand/cannonball analogy (representing atom/photon, respectively) anything close to reality?
Feynman descrbed it this way.If you were to take an atom and enlarge it to the size of a room in your house the elctrons would occupy the walls while the nucleus would be just a barely visble speck in the center.The electron would be about 10,000 times smaller and invisible at this scale.As for photons though I am not sure if there is a definite size since the energy is dependent on the frequency multiplied by Planck constant.This is getting into an area that is difficult for me due to the mathematics involved. I will try to see if I can get my head around the concepts involved and bring back a satisfactory answer.
"Calling Atheism a religion is like calling bald a hair color."
--Don Hirschberg