Is the world really colourless?

[Prearius]

I have a question that's bothering me,thought some of you on this forum might have an answer: We see things because (a) they either emit light or (b) they reflect light. Now, visible light is part of the electromagnetic spectrum which put simply is an orderly classification of electromagnetic waves with respect to their frequencies/wavelengths. Now, as I understand it, our eyes can 'see' visible light because they detect electromagnectic waves with a particular frequency (that of visible light) and generate an electrical signal, which is sent to the brain. The brain then interpretes this signal and voila, we get an image. Is colour then a creation of the brain? Is the world in reality colourless?

 

[Danger]

Welcome to PF, Prearius.
Essentially, you are correct. The concept of colour is a human construct, based upon the way that we perceive EM radiation. That is not to say that the world is colourless (all wavelengths are abundant), but the word has no meaning outside of human perception.

 

[russ_watters]

I would adjust that last part to say 'the perception of color is different for different animals'. Google for animal color vision and you'll find links that simulate what colors look like to animals: http://www.colormatters.com/kids/animals.html

 

[Danger]

I would adjust that last part to say 'the perception of color is different for different animals'.

I agree completely about the perception, but the concept of colour is human.

 

[vanesch]

I agree completely about the perception, but the concept of colour is human.

As far as we know, every "concept" is human

 

[GoliathX]

I would adjust that last part to say 'the perception of color is different for different animals'. Google for animal color vision and you'll find links that simulate what colors look like to animals: http://www.colormatters.com/kids/animals.html

I have always found this fascinating.

I understand how it is we are able to determine somewhat what colors some animals can see, but how are we able to determine eyesight for animals that see outside of the visible spectrum? Dolphins-Ultrasound, Bees-Ultraviolet.

Is this also determined by cones?

 

[Danger]

As far as we know, every "concept" is human

Touche...
Goliath... ultrasound is not technically part of the EM spectrum.

 

[Bob S]

About 6% to 8% of males, and about 1% of females, are color blind due to either brain or nerve damage. Military like to have color blind people in their ranks, because color blind peole are better able to spot camouflage.

 

[AUMathTutor]

If you had a mass of neutrons, like, enough neutrons to occupy 1 liter of space (say in a sphere), what color would it be (just neutrons).

Would it be white (reflect all light), black (reflect no light, possible due to its incredibly large mass) or transparent (no electrons jumping around to produce photons, so it just goes right through)?

 

[lightarrow]

If you had a mass of neutrons, like, enough neutrons to occupy 1 liter of space (say in a sphere), what color would it be (just neutrons).

Would it be white (reflect all light), black (reflect no light, possible due to its incredibly large mass) or transparent (no electrons jumping around to produce photons, so it just goes right through)?

I'd propose this as "the question of the year"

 

[vanesch]

I'd propose this as "the question of the year"

see https://www.physicsforums.com/showthread.php?p=2143855

 

[Danger]

Since it would essentially be a very small neutron star, I suspect that the reflected light would be gravitationally red-shifted to a large degree.

edit: Nice link, Vanesch. I just spotted it after posting.

 

[AUMathTutor]

Awesome!

 

[Gear300]

Almost everything (but not necessarily everything) is relative to human perception. Ultimately, the only camera angle we have of the universe is the human mind. Thus, you could probably assume that there are features of nature out there beyond our detection; for example, if we did not evolve to perceive light, how long would it take us to realize the existence of electromagnetic waves? Concepts like this (those involving the level of limitations of our perception) could extend to dark matter and so forth.

 

[Stratosphere]

Sound is the same way as color, you could say that there is no such thing as sound, it is just vibrations picked up by little bones in our ear.

 

[Phrak]

About 6% to 8% of males, and about 1% of females, are color blind due to either brain or nerve damage. Military like to have color blind people in their ranks, because color blind peole are better able to spot camouflage.

Now, that's interesting. A group survival trait. Do you have a link?

 

[russ_watters]

Sound is the same way as color, you could say that there is no such thing as sound, it is just vibrations picked up by little bones in our ear.

No, not really. Sound and light are both continuous spectrums, but sound is not divided into discrete groupings of frequencies by our ears, unlike our eyes.

Regarding the simulations of the differing color vision, the separation of frequencies into colors is accurately depicted by the simulations - what is not (as suggested) is how those colors actually appear to us. Consider this:

We have red, green, and blue photoreceptors in our eyes. What would happen to our perception of color if our brains were re-wired to make the red ones appear green and vice versa?

 

[DaveC426913]

You want to wow your mind, look up tetrachromats.

 

[GoliathX]

No, not really. Sound and light are both continuous spectrums, but sound is not divided into discrete groupings of frequencies by our ears, unlike our eyes.

Regarding the simulations of the differing color vision, the separation of frequencies into colors is accurately depicted by the simulations - what is not (as suggested) is how those colors actually appear to us. Consider this:

We have red, green, and blue photoreceptors in our eyes. What would happen to our perception of color if our brains were re-wired to make the red ones appear green and vice versa?

I am not all that familiar with Synesthesia, having read just a few things. The colors that these individuals associate with sounds, would these colors be only produced by the mind, or could it be possible they are somehow optically viewing these sound waves?

Do they see still the sounds if their ears are covered? How about their eyes? I haven't found anything that specifically touches on this aspect.

 

[Prearius]

Almost everything (but not necessarily everything) is relative to human perception. Ultimately, the only camera angle we have of the universe is the human mind. Thus, you could probably assume that there are features of nature out there beyond our detection; for example, if we did not evolve to perceive light, how long would it take us to realize the existence of electromagnetic waves? Concepts like this (those involving the level of limitations of our perception) could extend to dark matter and so forth.

That ultimately everything is relative to human perception is a brilliant concept. Correct me if I'm wrong, but I think that's somehow related to the observer problem in quantum mechanics (in essence, a state changes merely by looking at it). That's quite puzzling.

 

[DaveC426913]

I am not all that familiar with Synesthesia, having read just a few things. The colors that these individuals associate with sounds, would these colors be only produced by the mind, or could it be possible they are somehow optically viewing these sound waves?

Do they see still the sounds if their ears are covered? How about their eyes? I haven't found anything that specifically touches on this aspect.

It's is a brain-wiring thing. i.e. it's internal. Pathways from eye nerves affecting auditory processing parts of the brain and vice versa.

 

[Danger]

Sound is the same way as color, you could say that there is no such thing as sound, it is just vibrations picked up by little bones in our ear.

True, and perception of it varies with the individual. One of my best friends had a really hard time walking past the local Birks store at night. They had an ultrasonic alarm system, and he could (painfully) hear it.

 

[pallidin]

You want to wow your mind, look up tetrachromats.

I Googled tetrachromats and found the Wiki article most interesting! Thanks!

Also, I found a link in that Wiki which was also very interesting. Sorry for my long cut-and-paste, but here it is, from: http://www.independent.co.uk/news/science/you-wont-believe-your-eyes-the-mysteries-of-sight-revealed-439213.html

HOW MANY COLOURS ARE IN A RAINBOW?


Human colour vision is a relatively recent acquisition. It is, at most, 63 million years old, and it may be a lot younger. On a genetic level, it is a mess: misalignments and redundancies in the genes that code for our "red" and "green" colour perceptions account for 95 per cent of all variations in human colour vision, and it is quite usual for up to nine genes to cluster together in an attempt to code for these colours. This is why the perception of colours - especially blues and greens - varies so much between individuals.

Humans perceive colour through three types of colour-sensitive cell, called cones, but some have four types. Equipped with four receptors instead of three, Mrs M - an English social worker, and the first known human "tetrachromat" - sees rare subtleties of colour. Looking at a rainbow, she can see 10 distinct colours. Most of us only see five. She was the first to be discovered as having this ability, in 1993, and a study in 2004 found that two out of 80 subjects were tetrachromats.

WHY YOUR EYES NEVER STAY STILL

If our eyes did not move - if they simply "drank in" the view before them - we would go blind. Our retinas can only process contrast, and soon become exhausted looking at the same thing for too long. They must tremble constantly in order to bring still objects into view.

THE SIGHTS WE ALL MISS

Human vision captures only two degrees of the world with any clarity, so we tend to miss things that happen outside our focus of attention - and the more we concentrate, the more extreme our "attention blindness" becomes. This makes us easy prey for psychologists such as Daniel Simons and Christopher Chabris, whose notorious experiment of 1999 asked its viewers to score a three-a-side, 90-second basketball game. Afterwards, the viewers were told to relax, put down their score cards and watch the video again. Only then did the game's most remarkable feature come to light: the invasion of the court, a few seconds in, by a 7ft-tall pantomime gorilla.

 

[Danger]

we tend to miss things that happen outside our focus of attention

Excellent post, Squire. That principle also applies to combat shooting situations. In an emergency, the shooter sees nothing but the gunsights and the target. It's called 'tunnel vision', but not in the socialogical sense of the word. Something called 'auditory exclusion' also occurs, wherein the normally deafening report of a gunshot doesn't register.

 

[Gear300]

That ultimately everything is relative to human perception is a brilliant concept. Correct me if I'm wrong, but I think that's somehow related to the observer problem in quantum mechanics (in essence, a state changes merely by looking at it). That's quite puzzling.

It is quite interesting and puzzling.

 

[lightarrow]

see https://www.physicsforums.com/showthread.php?p=2143855

What I meant was: "I wish I knew the answer!"