Why does colour exist?

[Kameron]

Sensing light on one wavelength would be inefficient. You'd be ignoring huge amounts of data (light). As such it only makes sense for optical receptors to fire over a wide frequency range. For example the rods in your eyes.

Except that is isn't that wide, it is incredibly narrow compared to the electromagnetic spectrum and a argument for colour perception that starts from the its useful basis is instant flawed because it would also be useful for me to see through wall and I can do that.

And I've discovered something else about myself today with the help of Urban. I am in a remarkably silly mood. Will someone love me please?

 

[Stanley Edwards]

...Go back to your cave.

The question was 'Why Does Colour Exist?' not 'Why Do We Perceive Colour?'. You're only answering the second question.

Most animals have a far better sense of smell than we do. They use that sense to detect poisons. We have developed better colour perception and use that in combination with other senses to recognise poisons or, other threats.

 

[Bob_the_lost]

Except that is isn't that wide, it is incredibly narrow compared to the electromagnetic spectrum and a argument for colour perception that starts from the its useful basis is instant flawed because it would also be useful for me to see through wall and I can do that.

And I've discovered something else about myself today with the help of Urban. I am in a remarkably silly mood. Will someone love me please?

By all means.

I don't agree that it's incredibly narrow. There are physical limits to what organic systems can manage, i doubt there are any ways to be able to see Xrays or Gamma radiation for example. You can't complain that you can't see the IR range if no organic sensor exists or can exist. The electronics to do that are expensive, finiky and last i heard needed LN2 coolant. Admittedly electronics vs organic systems are very different but in this case it's because of the difficulties in getting something that reacts to the correct frequencies of light, if there was such a biological solution it would involve some material that we could have scrounged for our own gear. Could be wrong but that's the implication.

It is slightly wrong apparently, some fish can see in the IR spectrum it seems. Ah well, worth a try.

 

[Bob_the_lost]

The question was 'Why Does Colour Exist?' not 'Why Do We Perceive Colour?'. You're only answering the second question.

Most animals have a far better sense of smell than we do. They use that sense to detect poisons. We have developed better colour perception and use that in combination with other senses to recognise poisons or, other threats.

No you ignorant fop. Colour is how we perceive the frequency of photons.

I've told you why they have different frequencies, did you not even read the posts?

 

[Stanley Edwards]

No you ignorant fop. Colour is how we perceive the frequency of photons.

I've told you why they have different frequencies, did you not even read the posts?

So, why does colour exist? Is it totally for our benefit? I doubt it. And, as someone else has pointed out the known frequency range of colour goes way beyond our perceptions - so, why do those colours exist?

The question is 'Why Does Colour Exist?'. Not 'How Do We Perceive Colour?'.

 

[Crispy]

Why does anything exist? in that case.

 

[Bob_the_lost]

It exists because different atoms/particles have different energy levels and they can only move between them, never occupy a state inbetween. As such they emit photons of certain energy levels and because of the way physics works this means that the photon frequency is determined by this energy.

If you want more than that then go to the library and take out a physics text book.

There. Colour exists because atoms have energy levels.

 

[cybertect]

You can't complain that you can't see the IR range if no organic sensor exists or can exist.

Some snakes can see Infra-red

Of course, what's useful to a snake isn't necessarily *that* useful to a human. Much like trichromatic ultra-violet vision in bees (UV, blue and green) and birds' quadrochromatic vision (red, green and blue and UV) not being relevant enough to humans for it to be selected in evolutionary development.

Most other mammals get away with dichromatic vision (two colours, such as blue-yellow in dogs, but their noses are far more developed than in humans).

 

[Stanley Edwards]

Why does anything exist? in that case.

Anything could, in theory, exist without colour. The why do we perceive colour? is the more interesting question admittedly. Many animals live in a world without colour.

 

[Stanley Edwards]

It exists because different atoms/particles have different energy levels and they can only move between them, never occupy a state inbetween. As such they emit photons of certain energy levels and because of the way physics works this means that the photon frequency is determined by this energy...

So a mirror emits the exact photons with the exact same energy levels as the trees we see in the mirror?

Surely it's the reflected light we perceive and not the emitted light. Unless there is an emitted light to be seen like the sun or, a fire.

 

[Bob_the_lost]

Anything could, in theory, exist without colour. The why do we perceive colour? is the more interesting question admittedly. Many animals live in a world without colour.

No they don't, they just fail to percieve it as colour. They still see light or gain or lose heat through radiation. Even subterrainian cave dwellers radiate.

 

[Bob_the_lost]

So a mirror emits the exact photons with the exact same energy levels as the trees we see in the mirror?

Surely it's the reflected light we perceive and not the emitted light. Unless there is an emitted light to be seen like the sun or, a fire.

Yes it's reflected but what's your point? The mirror as you quite rightly said reflects the light that's already been emitted. Just because you bounce a pool ball off the side of a table it doesn't become something else.

There is no such thing as reflected or emitted light, just photons. All have been emitted, most have been reflected several million times before we see them.

 

[Crispy]

Actually, the cornea is sensitive to some UV (in the 300 - 400 nm range) but the lens of the eye filters these frequencies out. People who have had their lenses replaced with artificial ones in eg. cataract operations can see these frequencies of light.

 

[Stanley Edwards]

Yes it's reflected but what's your point? The mirror as you quite rightly said reflects the light that's already been emitted. Just because you bounce a pool ball off the side of a table it doesn't become something else.

There is no such thing as reflected or emitted light, just photons. All have been emitted, most have been reflected several million times before we see them.

The sun emits light. Trees don't emit light. They reflect light and absorb light. A burning ember glowing red is emitting more light than it is reflecting. I thought you had already explained this earlier.

In a light proof darkroom, can you perceive all the colours that all the surfaces and objects 'emit'?

When I said some animals live in a world without colour I was trying to make the point that many colours exist that we can't perceive. Those colours still exist. So, why do they exist? Not really interested in the answer to that question. The question about colour perceptions is far more interesting.

 

[Stanley Edwards]

Actually, the cornea is sensitive to some UV (in the 300 - 400 nm range) but the lens of the eye filters these frequencies out. People who have had their lenses replaced with artificial ones in eg. cataract operations can see these frequencies of light.

 

[Bob_the_lost]

The sun emits light. Trees don't emit light. They reflect light and absorb light. A burning ember glowing red is emitting more light than it is reflecting. I thought you had already explained this earlier.

In a light proof darkroom, can you perceive all the colours that all the surfaces and objects 'emit'?

When I said some animals live in a world without colour I was trying to make the point that many colours exist that we can't perceive. Those colours still exist. So, why do they exist? Not really interested in the answer to that question. The question about colour perceptions is far more interesting.

Yes they do. They emit photons. The photons you can't see are just as real as the ones you do.

Sorry Stanley but you're just not up to this one mentally. The world does not function on rules made for our benifit. They are, we are and the two interact on a regular basis. Your continual assumption that photons exist to be seen is utter bollocks.

 

[Stanley Edwards]

...
Sorry Stanley but you're just not up to this one mentally...

They reflect photons you dumbfuck. Go on then, explain to me why you can't see the 'emitted' photons in a darkroom.

 

[Bob_the_lost]

They reflect photons you dumbfuck. Go on then, explain to me why you can't see the 'emitted' photons in a darkroom.

Because they don't emit on the visible spectrum.

Christ on a cross, go onto wikipedia and read about IR before you make youself look any more stupid. Hell since you're having so much trouble i'll give you a link to read : http://en.wikipedia.org/wiki/Thermal_imaging

Since infrared radiation is emitted by all objects based on their temperatures, according to the black body radiation law, thermography makes it possible to "see" one's environment with or without visible illumination.

 

[Stanley Edwards]

Because they don't emit on the visible spectrum.

...

So, the light we see is the reflected light and not the emitted light? So, we live in a world of far more colour than we can perceive? Not everything emits infrared energy. Trees do. It's produced during photosynthesis. But, we don't see it. We only see the reflected light.

 

[Bob_the_lost]

So, the light we see is the reflected light and not the emitted light? So, we live in a world of far more colour than we can perceive? Not everything emits infrared energy. Trees do. It's produced during photosynthesis. But, we don't see it. We only see the reflected light.

All the light we see is emitted somewhere but it's probably bounced off things a few times. Unless you're staring straight at an LED/ bulb/ sun / star /computer screen etc. so trying to divide light into reflected and emitted is rather useless. You can't tell the difference between a yellow light source and reflected yellow light from a white light source. It's not possible as the photons would be no different.

We live in a world where energy in the form of photons is flying all over the place. Most of it we cannot see.

EVERYTHING emits photons, google the black body law. Nearly everything emits photons on the IR scale, including pretty much everything that you or i can see or touch.

 

[Stanley Edwards]

That wiki article is well misleading.

Thermal radiation is very different to the reflected light that makes up the vast majority of the colours we perceive in the world.

Possibly colour doesn't exist at all.

 

[Crispy]

There appears to be some weird 'arguments' going on here

Ther is light - or EM radiation - of many frequencies being emitted and reflected all around us nonstop. Our eyes are sensitiveto a small portion of those. The reason are that those wavelengths are particularly strong on the earth's surface (the atmosphere filters out much of the radiation from the sun), and they are able to be focussed by biological equipment. (eg. radio waves would require 'eyes' many meters across)

 

[Crispy]

That wiki article is well misleading.

Thermal radiation is very different to the reflected light that makes up the vast majority of the colours we perceive in the world.

Not at all. A photon is a photon is a photon. If our eyes were sensitive to infrared (aka thermal radiation) we could see heat. Not very well, though - longer wavelengths are harder to focus with optics.

 

[Stanley Edwards]

All the light we see is emitted somewhere but it's probably bounced off things a few times. Unless you're staring straight at an LED/ bulb/ sun / star /computer screen etc. so trying to divide light into reflected and emitted is rather useless.

We live in a world where energy in the form of photons is flying all over the place. Most of it we cannot see.

EVERYTHING emits photons, google the black body law. Nearly everything emits photons on the IR scale, including pretty much everything that you or i can see or touch.

FFS. We can't see them. They are not colours. The vast majority of light we see is reflected. The sun emits the light initially of course, but the colours we see are down to the way objects reflect and absorb light frequencies. Fuck all to do with emitted frequencies we can't perceive.

 

[Stanley Edwards]

Not at all. A photon is a photon is a photon. If our eyes were sensitive to infrared (aka thermal radiation) we could see heat.

Yes, but we fucking well can't see it. Don't you start.

So, you're saying colours exist, but we can't see them. The colours we perceive don't actually exist.

Thermal imaging uses colour representation to reproduce stuff we can't see. It uses colours we can see to show us colours we can't see. Maybe that's why colour exists! To show us the colours we can't see on a spectrum we can see.


The vast majority of colours we see are reflected light. A red cricket ball is not emitting photons from the leather casing. It is reflecting and absorbing the emitted sunlight. The properties of the varnish and pigment control what colour we perceive.

Or, am I wrong again?

 

[Crispy]

No you're not wrong. But your question 'why' does colour exist is a weird one - the answer is that those are the frequencies of light most suited to biological focussing and detection on the surface of the earth. And that's that. The rest of it appears to be an argument about something else entirely, and you're both getting wound up for no reason I can see

 

[Paulie Tandoori]

Colours exist cos without them, sports couldn't happen. Think about it, no snooker, no footie, no rugby, no nothing

 

[Bob_the_lost]

No you're not wrong. But your question 'why' does colour exist is a weird one - the answer is that those are the frequencies of light most suited to biological focussing and detection on the surface of the earth. And that's that. The rest of it appears to be an argument about something else entirely, and you're both getting wound up for no reason I can see

Stanley is getting hippified in a science thread = irritating as fuck.

 

[weltweit]

Colour exists because it is something we can see as colour.

Colour is just something we can see, there are colours we cannot see.

Don't eat that red berry, it is red as a warning!

But the deer cannot see the red berry as red because he is colour blind.

How does the deer know not to eat the red berry? or does he just eat it?

 

[WouldBe]

The vast majority of colours we see are reflected light. A red cricket ball is not emitting photons from the leather casing. It is reflecting and absorbing the emitted sunlight. The properties of the varnish and pigment control what colour we perceive.

Yes but for the cricket ball to reflect red light it has to be illuminated with red light to start with. If you put a cricket ball in a dark room and illuminate it with yellow, green or blue light it won't appear to be red as there is no red light to reflect.

Colours do exist as you can detect them with instruments using either prisms or graticules.

As bob said earlier it's due to the energy levels of the atoms. These energy levels occur naturally but to get an atom you need to exite it to make an electron move to a higher energy level this is normally done by heating the atom. The electrons don't stay at this higher energy level even if you continue to heat the atoms and the electrons fall back to lower energy levels releasing a photon in the process. The energy and hence the colour of the photon depends on the energy difference between the 2 energy levels that the electron moves between.