But diffraction does not create dark spots... it only results in a pattern with areas where there is no intensity. It's not as if there previously was intensity and now there is not... I was also thinking of a poisson (sp?) spot where a laser is aimed at a small opaque spehere. On a screen a distance away, there will be some intensity at the center of a dark shadow. If you turn off the laser, that shadow is still there with the same lack of intensity as before.
[Joke] In the 'Does anything eat wasps?' New scientist book one reader posits that we have misunderstood the whole light/dark argument and that it is light which does not exist. Lightbulbs are in fact 'dark suckers' which absorb darkness - hence their slight graying in their later lives as the dark absorbed begins to discolour the bulb. Candles are in fact 'primative dark suckers' which explains why even though the wicks start out white they end up black with all the dark they have absorbed. Thus a 'dark light' would simply be a dark sucker which worked within a given arc/cone - say 30 degrees through to 330 degrees leaving an arc of 60 degrees saturated with 'dark'. [/Joke]
/ can't be bothered to read everthing up there. The black on projector screens is actuall white. It's just that the contrast makes it look black, because the white screen is not illuminated, whereas the parts of the screen around it are lit brightly, making it seem black by comparison.
/ bangs head on table / cries Not entirely sure where this thread is headed, has this guy's question been answered?
But.. hang on.. wouldn't that in reality, just be.. err.. darkness? In the same way that exactly duplicated sound waves that are in exact opposite phase will completely cancel each other out, so will light. However, if we do that with sound, what we actually have is not non-sound, or some new hitherto unheard of form of sound, we just have silence. Wouldn't we just have darkness where there was previously light? You're not emmiting "black" light, but instead just not emmitting any light at all... you're right, Darkness. Hey I can emmit darkness too... in fact.. I'm holding up my pen right now.... can you see the darkness being emmitted from it? I don't care how convoluted, and brilliant the methods are you use to create the darkness, but going to those lengths to generate phase cancelled light (nothing in other words) is silly... like I said... I can create darkness with my pen.. or my finger.. or my egg whisk.
Hehe. "Brussel sprouts, what brussel spouts?" "Darn it Johnny, stop playing with your black hole and eat your dinner!! "I'm sorry teacher, my blackhole expanded out of control and absorbed my homework!"
Whats wrong with making a shadow i'm sure this will do the trick... sure you will have white light around it it and the shadow would probably be "out of focus" but meh
That would be brilliant shine a (black flashlight) at people and they woudl be like who turne dout the lights. It would be funny but that raises the point. You would have to generate light with a negative cefecient of every wavelength that exists in the light source yoru are using. Iono about you but I can't do that. O btw I don't liek this idea of making blackholes sooo close to earth or me. Take yoru hippy science away from me and MY earth.
Ima aggre with the first answer to the question. Magic. Come on guys! why do you have to make a big deal about it and just accept it! its just magic!
No - it's just that particular light which has been cancelled. There will still be ambient light reflected visible at that point. The same thing goes for your sound model. At the point of mirror image of the waves isn't silence - just that noise is cancelled. You'll still be able to hear everything else.
I guess I can be classified as a good magician and a clever scientist, everytime I mix up equal amounts of red, green and blue paint. Have any of you tried it lately? or do I have a bad memory of my nursery years. I think I shall risk an argument with the wife and open up couple of paint tins tonight!
Thats paint colours though, white *light* is made up of the rainbow, hence why you can split it using a prism. Black paint is essentially non reflective as it doesn't contain anyone one colour to a significant enough extent I belive
