AuthorTopic: Black and white  (Read 11102 times)

Offline sharprm

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Re: Black and white

Reply #10 on: April 11, 2007, 07:57:01 am
A hole is black because the light that enters has to reflect off the surface of the hole so many times that it is mostly absorbed. I thought that was a cool fact.

Adrias I don't think what you say about quantisation of a photon of energy is correct. When electrons become excited, they had to absorb a photon with energy equal exactly to the energy they gained. When the electrons return to the ground state, they release a photon with the same energy as the incoming photon. So why something appears black doesn't fit with you're explanation.

Another thing you said was that it is wrong to say that there is always a little bit of visible light. I think that there will always be a little bit of visible light, even if you had a totally dark room with no light source. This is because all objects emit electromagnetic radiation as their vibrating atoms are accelerating charge. This phenomena can be seen when a hot object glows, because the greater temperature results in the atoms vibrating faster. However, even at low temperatures, there should be some visible light emitted. Even if the intensity is too low for our eyes to register, there would be some visible light.   
http://en.wikipedia.org/wiki/Black_body_radiation

I donít know if visible light can pass through all objects. Even though an electron canít absorb and emit light unless its of correct energy, what about the atom itself? Even if the energy of an atom is restricted to multiples of h (h being plank's constant), as the photons themselves will have energy equal to a multiple of h (E=hf), they can all be potentially absorbed. I donít think you can say that because most of an atom is mostly Ďspaceí, its unlikely light will be able to interact with an electron or atom. This is because there would be so many atoms in a small piece of material, so even if the probability of it being absorbed by a single atom is small, the probability of it being absorbed by the material will be much greater. Also, electrons wonít be simple billiard balls circling the nucleus with a neat path but occupy a much larger space over time. Even in transparent objects the atoms absorb the light (but re-radiates it).That is why light effectively travels slower in a material and why we get refraction.
http://en.wikipedia.org/wiki/Atomic_orbital

Anyway, I don't think I'm making a point at all but I think Physics is confusing and annoying and people who think they get it donít really get it so we should all stick to drawing. Post your idea on "ask a scientist" for an expert opinion on youíre statements.
http://www.madsci.org/
Modern artists are told that they must create something totally original-or risk being called "derivative".They've been indoctrinated with the concept that bad=good.The effect is always the same: Meaningless primitivism
http://www.artrenewal.org/articles/Philosophy/phi

Offline Dusty

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Re: Black and white

Reply #11 on: April 11, 2007, 11:47:12 am
Except it was never intended to be a scientific question? We all learn about colors in art. The question was, what were you taught in art about black and white? Were you taught they're colors or just the absence, or presence of color? I had no intention in getting physics answers when I posted as I already know about absorption of colors.

Offline Rox

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Re: Black and white

Reply #12 on: April 11, 2007, 03:18:18 pm
I also had no intention on getting answers on my obviously rhetorical question!


As for artsy stuff regarding black and white... Umm... I don't feel I've been taught anything. I can remember a buncha worthless mumbling from art classes back in school, but nothing I found useful. I also don't really know how I use the two. I guess I don't really think of black and white as black and white when I do art, I just make things lighter or darker if needed, and sometimes they appear to be black or white? I dunno. Just another tool in the arsenal.

Offline Helm

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Re: Black and white

Reply #13 on: April 11, 2007, 05:13:09 pm
Black is magic, the spell is cast! Discordant piping of heralds to the blind idiot god above, beyond! Menstrual blood and semen marks the circle that contains the eldritch horror, what is our demand? Absense of light, absense of life, within the darkness the goat births her thousand young. Devourer of dimensions, in killing blight we summon you!

Offline Xion

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Re: Black and white

Reply #14 on: April 11, 2007, 08:51:40 pm
What color are mirrors? I know that reflectivity deals with the texture of the surface and not the color, but...are mirrors technically white?

Offline Helm

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Re: Black and white

Reply #15 on: April 11, 2007, 08:54:29 pm
What color is the cosmos?

Offline Xion

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Re: Black and white

Reply #16 on: April 11, 2007, 09:05:13 pm
It is all colors.

Offline Darien

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Re: Black and white

Reply #17 on: April 11, 2007, 09:10:26 pm
What color are mirrors? I know that reflectivity deals with the texture of the surface and not the color, but...are mirrors technically white?

I suppose it would be white if it scattered the light that hits it, but because it's a smooth surface reflects lights at the angle that the light hits it and keeps the light it reflects in relatively the same beams at the same wavelengths.

And also I believe black holes are really the only pure black things out there. †Anything else that is black isn't really black because we can still see it, we can't see black holes. †Though, don't they even give off x-ray radiation? †So, technically, even black holes aren't pure black.

Offline AdamAtomic

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Re: Black and white

Reply #18 on: April 11, 2007, 09:11:13 pm
What color are mirrors? I know that reflectivity deals with the texture of the surface and not the color, but...are mirrors technically white?

Most of them are dark gray or dark brown I think, just with insanely high specularity and reflectivity.

Offline Skull

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Re: Black and white

Reply #19 on: April 11, 2007, 10:04:00 pm
What color are mirrors? I know that reflectivity deals with the texture of the surface and not the color, but...are mirrors technically white?

Most of them are dark gray or dark brown I think, just with insanely high specularity and reflectivity.

I would have gone with no colour at all.