Go back
Why can I see the colour black?

Why can I see the colour black?

Science

3 edits
Vote Up
Vote Down

You might like to look at this...

Scientists Create a Black That Erases Virtually All Light

I heard this story on the radio and looked it up. The commentator suggested that the scientists will not give up until they achieve a blackness equal to Dick Cheney's heart...
But regardless of his intended political insert, it's a real story about scientists have made a material that only reflects 0.045 percent of visible light.


By Rick Weiss
Washington Post Staff Writer
Wednesday, February 20, 2008; Page A01

Black is getting blacker.
Researchers in New York reported this month that they have created a paper-thin material that absorbs 99.955 percent of the light that hits it, making it by far the darkest substance ever made -- about 30 times as dark as the government's current standard for blackest black.

The material, made of hollow fibers, is a Roach Motel for photons -- light checks in, but it never checks out. By voraciously sucking up all surrounding illumination, it can give those who gaze on it a dizzying sensation of nothingness.

"It's very deep, like in a forest on the darkest night," said Shawn-Yu Lin, a scientist who helped create the material at Rensselaer Polytechnic Institute in Troy, N.Y. "Nothing comes back to you. It's very, very, very dark."

"The newest black -- which when held next to something conventionally black, such as a tuxedo jacket, is noticeably blacker -- reflects just 0.045 percent of visible light."

http://www.washingtonpost.com/wp-dyn/content/article/2008/02/19/AR2008021902617.html?nav=hcmodule

Vote Up
Vote Down

Originally posted by uzless
If an object is blue because the object is absorbing all colours of the light spectrum but is reflecting the blue wavelength and white objects reflect all wavelengths consider this.

If black objects absorb all wavelengths, and therefore do not reflect any light, how come we can see the objects? Shouldn't they be invisible?

How do you "see" black?
You don't see it..you see the void...all the other colors reflecting around it and then nothing.

Vote Up
Vote Down

Originally posted by uzless
If an object is blue because the object is absorbing all colours of the light spectrum but is reflecting the blue wavelength and white objects reflect all wavelengths consider this.

If black objects absorb all wavelengths, and therefore do not reflect any light, how come we can see the objects? Shouldn't they be invisible?

How do you "see" black?
Most objects we call black are actually just very dark grey, just as objects we call 'white' are very light grey, though it is I suppose possible for an object to reflect all light (a good mirror for example, though it would only look white if it scatters the light).
We can however make the equivalent of a black object quite easily:
Simple make a whole and have a very large closed dark space behind it, virtually all light entering will not come out. Also almost any dark space viewed at night would appear identical to a truly black object.

1 edit
Vote Up
Vote Down

Originally posted by twhitehead
Simple make a whole and have a very large closed dark space behind it, virtually all light entering will not come out. Also almost any dark space viewed at night would appear identical to a truly black object.
Isn't this what we call a black body object?

The truly black thing - isn't it a black hole (if we disregard the Hawking radiation of course)?

Another question: Why can a black car be shiny? If it shines then it's not black...?

Vote Up
Vote Down

Originally posted by FabianFnas
Isn't this what we call a black body object?

The truly black thing - isn't it a black hole (if we disregard the Hawking radiation of course)?

Another question: Why can a black car be shiny? If it shines then it's not black...?
Black holes are different; they work via gravity.

A black body object can emit light if it's hot, but if it's cool it will be truly black.

Vote Up
Vote Down

Originally posted by AThousandYoung
Black holes are different; they work via gravity.

A black body object can emit light if it's hot, but if it's cool it will be truly black.
Oh, yes, a black body doesn't need to be black, sorry, my mistake.

But a black hole is truly black as no light can be emitted through the event horizon from inside. Is this the blackest body in the universe?

Vote Up
Vote Down

Originally posted by FabianFnas
Is this the blackest body in the universe?
I would guess so.

"It's like, how much more black could this be? and the answer is none. None more black."

Vote Up
Vote Down

Originally posted by FabianFnas
Oh, yes, a black body doesn't need to be black, sorry, my mistake.

But a black hole is truly black as no light can be emitted through the event horizon from inside. Is this the blackest body in the universe?
A Black Hole is not black...
Entirely different than what we are talking about. We are talking about how the colour black absorbs light waves. A Black Hole prevents light from escaping.

Vote Up
Vote Down

Originally posted by Arrakis
A Black Hole is not black...
Entirely different than what we are talking about. We are talking about how the colour black absorbs light waves. A Black Hole prevents light from escaping.
A black hole absorbs any incoming light, in any wavelength, and nothing is reemitted. It's black, alright.

Vote Up
Vote Down

Originally posted by FabianFnas
A black hole absorbs any incoming light, in any wavelength, and nothing is reemitted. It's black, alright.
depends on how you look at it. a black hole is simply so dense that it curves the space around it so that photons are trapped. that is why a black hole is "a different kind of black" than a black piece of paper. and if it is true that a black hole is a 0 volume point, you cannot perceive it optically. you only perceive the perturbations around it but not the hole itself.

Vote Up
Vote Down

Originally posted by Zahlanzi
depends on how you look at it. a black hole is simply so dense that it curves the space around it so that photons are trapped. that is why a black hole is "a different kind of black" than a black piece of paper. and if it is true that a black hole is a 0 volume point, you cannot perceive it optically. you only perceive the perturbations around it but not the hole itself.
As long as it is black, I'm satisfied.

I don't care if it is the central core of the black hole or the event horizon I'm calling black. Black it is, the blackest of all blacks there is.