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Knowledge_Seeker
2006-Dec-06, 07:14 PM
From what i know, black holes absorb anything around it, including light. So how can there be any color?

antoniseb
2006-Dec-06, 07:26 PM
Black holes got their name because the thought was that light would not escape. Hawking radiation wasn't imagined at the time. It is not correct to say that the 'absorb anything around them' Something has to go in before it has no hope of escape again.

The other aspect of your question is strange to me. Are you saying that black is the presence of all color, and so why should they be black, and not white (the absense of all color)?

Kaptain K
2006-Dec-06, 07:29 PM
From what i know, black holes absorb anything around it, including light. So how can there be any color?

Black is the absence of of all light (color).

jseefcoot
2006-Dec-06, 07:33 PM
Black is the absence of of all light (color).

And isn't white a blend of all colors (all wavelengths of light)?

BISMARCK
2006-Dec-06, 08:19 PM
It depends, because there are two sets of primary colors for humans:

Additive (what TV uses): Red, Blue and Green. When all 3 are combined, you get white.

Subtractive (things like oil paint): Cyan, Magenta, Yellow. When those are combined, you're supposed to get black, but sometimes it turns out as dark brown.

Click Ticker
2006-Dec-06, 08:28 PM
I've always heard it said that from the perspective of a scientist, white is the presence of all color and black is the absence of all color. From the perspective of an artist, black is the presence of all color and white is the absence of all color.

BISMARCK
2006-Dec-06, 08:33 PM
The difference is that additive primaries are based on the emission of light itself.

Subtractive primaries are based on reflected light, and what an object absorbs.

The Wikipedia articles are pretty good at explaining it. Interestingly, the human eye is most receptive to these three colors (http://en.wikipedia.org/wiki/Color_vision), none of which is red or yellow:

http://upload.wikimedia.org/wikipedia/en/2/2d/Rodcolours.jpg

The human eye is far more sensitive to greenish things than any other color, probably because it we evolved to look for food where plants are. This is why video cameras and TVs generally devote twice as much information to green than they do to blue or red.

Peter Wilson
2006-Dec-07, 06:31 PM
Why do we call them black holes when by-and-large, they are the brightest objects in the universe?

:think:

antoniseb
2006-Dec-07, 06:34 PM
Why do we call them black holes when by-and-large, they are the brightest objects in the universe?
The people who named them didn't know that. Why does current go in the direction the electrons are fleeing?

hhEb09'1
2006-Dec-08, 06:31 PM
John Archibald Wheeler made up the name in the '60s, didn't he?

publius
2006-Dec-08, 09:35 PM
John Archibald Wheeler made up the name in the '60s, didn't he?

Yes, he was the one who coined it as I understand it. According to some, interest in the subject didn't pick up until Wheeler came up with this name. "Black hole" has a certain omninous and very descriptive ring to it, which captured the imagination.


-Richard