colours we can't comprehend.

[mollykins]

is it possible that colour we can't comprehend exist.

Isn' t there someone who aparantly can se infra-red, but would the other parts of the electro-magnet spectrum, have their own colours, that we can't imagine?

[Milvus]

In general humans can't see Infrared at one end or ultraviolet at the other. It might be possible for some humans to see Near Infrared (NIR) but Medium and Long wavelength (MWIR and LWIR) are way outside of human capabilities. Many predators see infrared (cats etc) and insects and some birds see into the ultraviolet range especially where they rely on plants who put out ultraviolet colours we do not see

[Buenchico]

'Colours' are simply labels which humans assign to the varying responses, by the optic nerve and brain, of different wavelengths of electromagnetic energy impacting upon on the eye's retina. If no such response occurs then, by definition, no colour can exist.

Defining infra-red and ultra-violet wavelengths as 'colours' is simply a convenient cheat which enables us to refer to the light from the sun as made up of different colours (even when no such true colours actually exist for part of the spectrum).

Chris

PS: If you're going to ask question like that one, I'll start wondering if you're related to the school girl who asked me a science question that I still can't properly answer after nearly 40 years of seeking an answer. It was that question which led to my very first post on AB ;-)
http://www.theanswerb...e/Question140971.html

[jake-the-peg]

There's a really good reason you can't answer that Chris - It's a really difficult question!

As I recall I bowed out of the hard answer then but basically it's down to the interaction between light and the sea of electrons in the metal

The metals in a mirror are a) very smoth and b stop light from penetrating into them even a little bit

If either of these happen the reflected light will get all jumbled up and you'll get white light.
http://en.wikipedia.o...lection_%28physics%29

Now the hard question - why is that?

The interaction between light and matter is governed by Quantum Electro Dynamics and Richard Feynmann (and others) won a Nobel prize for the work.

The Wikipedia page goes into some detail here:
http://en.wikipedia.o...antum_electrodynamics

And it's a good jumping off place if you fancy finding out about it check out Perturbation theory and QED as well

[beso]

Humans usually have types of three colour receptors which are sensitive to different ranges of wavelengths. The combination of the three responses is interpreted as colour.

Small differences in the response range in different individuals of these receptors can leads to differences in perception of colour.

Some (almost invariably female) have four types of receptors and can distinguish different shades in what look the same colour to the rest of us.

Incidentally, the popular concept that we have Red, Green and Blue receptors is a myth.

[mollykins]

With light, aren't cyan red and yellow the 'primary' colours?

[beso]

Light sources such as televisions use a three colour system with red, green and blue which combine in different proportions to make all shades of colour. They are known as additive primaries.

However it is often erroneously claimed that these are THE primary colours. Generally speaking if the third colour cannot be produced by combining the first two, the three together can be used as primary colours.

In reality a red and shade of blue are essential as they lie at the extremes of the visible spectrum. Green or yellow can be the third colour with the range depending on the shades of red and blue used.

Objects have colours because some of the light falling on them is absorbed and we see what is reflected. Printers use magenta (white-green), cyan(white-red) and yellow (white-blue) to produce a range of shades covering the spectrum. They are sometimes knows as subractive primaries.

[mollykins]

aahhh thanks for that.