LCD screens use pixels composed of red, green, and blue. The screen produces a wide range - millions - of distinct colours by brightening or dimming the three colours above. So in a physical sense, one could argue that red green and blue are the "basic" colours, at least as far as human eyes are...
Best answer: LCD screens use pixels composed of red, green, and blue. The screen produces a wide range - millions - of distinct colours by brightening or dimming the three colours above. So in a physical sense, one could argue that red green and blue are the "basic" colours, at least as far as human eyes are concerned.
Outside of that, "colour" falls into the portion of the electromagnetic spectrum known as "visible light". The EM spectrum is a variety of EM waves of different wavelengths. At one end you have long wavelengths such as radio waves, and at the other end you have very short wavelengths such as gamma rays. Visible light is somewhere in the middle. X-rays and microwaves are in there somewhere as well.
Concerning visible light, the longer wavelengths result in what we see as red light and the shorter wavelengths result in blue. Some animals can see outside of our visual range. Bees, for example, can detect shorter wavelengths than we can. They can see into the part of the EM spectrum we call ultraviolet.
I'm going to move on to something else and at first it might seem like a digression, but it isn't.
The shortest possible measurement in the universe is called a "Planck length", named for the physicist Max Planck. It's more-or-less equivalent to:
000,000,000,000,000,001 metres, (and I had to break this over two lines because Yahoo wouldn't represent it properly),
although practically speaking if you actually were that small, the physical laws as you know them become irrelevant. But the point is, you cannot get a smaller distance than a Planck length. You can't be half-a-Planck length away from something. It's the shortest distance there is.
So when it comes to wavelengths, we've already established that some wavelengths are longer than others, and the difference in the length of the respective waves is responsible for different effects. We've also established that red light is a longer wavelength that blue light, meaning that if you start with red light and shorten its wavelength, you will go through all the colours until eventually you reach blue light.
But you can't have a wavelength shorter or longer than another by less than a Planck length. Suppose you have red light, and you increase its wavelength by a Planck length. This difference will be indistinguishable to your eyes, but the wavelength will yet be longer.
So now we're talking about two wavelengths:
Original wavelength + 1 Planck length
But you couldn't now decide that your new wavelength is too long, and decide to make a wavelength that is
Original wavelength + 1/2 Planck length
because we've already established that the Planck length is the shortest possible distance.
In effect, this puts an upper limit on the number of possible colours. That limit is probably meaningless as it means there are about a septillion different possible wavelengths within the visible light portion of the EM spectrum.
Forgive me but I'm not about to try to list a septillion different colours.
1 week ago