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Author Topic: Are objects colourless in the dark?  (Read 6870 times)

Abbey

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Are objects colourless in the dark?
« on: 14/12/2010 09:30:03 »
Abbey  asked the Naked Scientists:
   
If pigments show colour by reflecting light, does that mean, in theory, that an object in pure darkness is colourless?

What do you think?
« Last Edit: 14/12/2010 09:30:03 by _system »


 

Offline CliffordK

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Are objects colourless in the dark?
« Reply #1 on: 14/12/2010 09:45:29 »
If a tree falls in a forest and no one is around to hear it, does it make a sound?

If a pigment is a method to describe an object, that pigment would be permanent with or without light.

I suppose you could just as easily ask if in complete darkness, if the object is even there? 

Now, it may have a faint IR signature which is invisible to the naked eye, but can be picked up with IR sensitive tools like night goggles.  Since the IR is essentially monochrome, the display is also usually in monochrome, with the intensity displayed as brightness.

You would note, in your eyes, you have two classes of sensors.  The Cones are the color receptors.  The Rods are monochrome, but the rods are more sensitive to low light conditions.  Thus, in low light conditions, you actually see in monochrome.

If you can barely perceive a blue couch in low light, you may not be able to perceive the blue color, but you can remember the color it was when you last saw it during the daylight.
 

Offline Chemistry4me

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Are objects colourless in the dark?
« Reply #2 on: 14/12/2010 10:06:56 »
By colourless you mean black or...?
 

Offline JnA

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Are objects colourless in the dark?
« Reply #3 on: 14/12/2010 13:55:25 »
to my thinking colour exists even without perception.

Thus sound exists even without perception..

thus men are wrong even without a woman to tell them so..




(ok that last one might be taking things too far ;) )
 

Offline Geezer

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Are objects colourless in the dark?
« Reply #4 on: 14/12/2010 18:57:19 »
Unless the object has a built in light source, or it's very hot, the answer would be yes. Color is a function of the wavelengths of incident and reflected light. If there is no incident light there will be no reflected light and, therefore, no color.

We could also ask if a "white" object changes into a "red" object when we shine red light on it. I believe it does. It wasn't really white in the first place. It only seems to be white because it doesn't absorb certain parts of the visible light spectrum. In red light it's impossible to determine that it's not actually red.
 

Offline Bill S

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Are objects colourless in the dark?
« Reply #5 on: 14/12/2010 19:08:44 »
Quote from: JnA
Thus sound exists even without perception..

If a tree falls in a forest and there is no-one there to hear it, is there a sound?  As long as one interprets the “no-one” as meaning no creature capable of hearing, then the answer must be “no”.  Sound waves are vibrations; they become sound only when interpreted by the appropriate auditory organs.  No ears, (or ear substitutes) no sound!
 

Offline Geezer

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Are objects colourless in the dark?
« Reply #6 on: 15/12/2010 01:43:40 »
Bill,

Have you ever considered a career as a criminal defense lawyer? 

:D
 

Offline CliffordK

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Are objects colourless in the dark?
« Reply #7 on: 21/12/2010 12:15:15 »
Good point about color being dependent on the pigment and to some extent the wavelength of the light shining on it.

So, white will look white with a broad spectrum light.
It will look red with red light
Blue with blue light.

Although....
if you paint a wall red, and shine blue light at it, what do you get?  Black?
Or a blue wall with red light?  Black again?

Anyway, so no reflected light is colorless...
Unless you consider them an IR emitter.
 

Offline Don_1

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Are objects colourless in the dark?
« Reply #8 on: 22/12/2010 07:56:10 »
If you were to enter a totally light proof room with black walls, floor, ceiling and door, with a black table on which there are 4 coloured cubes, close the door and look toward the cubes, you would see nothing.

Strictly speaking, the cubes will not have changed their chemical composition, so any pigmentation remains unaltered. Similarly, your capability to receive light has not altered. What has changed is the total loss of light. Since colour is determined by the absoption and reflective nature of the chemical compounds of the cubes, then without light to absorb or reflect, I would estimate that it is fair to say that the cubes are now colourless, until light is reintroduced.
 

Offline Geezer

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Are objects colourless in the dark?
« Reply #9 on: 22/12/2010 08:00:38 »
If you were to ...... look toward the cubes, you would see nothing.


How would you know your were looking at the cubes?  ::)
 

Offline Don_1

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Are objects colourless in the dark?
« Reply #10 on: 22/12/2010 08:03:30 »

 

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