I was staring at a black camera today, thinking about what exactly I was seeing. it's not a perfect black body or anything, but i can still see it just as well as a white object. it seems that there would be a slight difference of visibility, maybe it'd be a little harder to make out what shape it is, but no i can make it out fine. unlike a perfect black body which you could only make out the outline of the object. so is our vision cover such a small spectrum that in reality a marginally different amount of light is being reflected? what light is being reflected at me anyway? there's no such thing as "black light" so is it just a small amount of white light? what do you guys think?

Tags: light, physics

Views: 23

Reply to This

Replies to This Discussion

There cannot be pure black light, as black is the absence of light.
I think it's probably due to two things:
1) If the surface is refletive at all then it allows us to see the shape from the way light bounces off of it.
2) Most things are not 100% black, black is the absence of light while colors all come from white light refracting in different ways. But since we cannot completely subtract some form of light when making the "color" black then we cannot get a true black therefore it's still visible. Does that make sense?
it does, but why isn't there a differential in our ability to make out 3 dimensional shapes depedning on color and reflectivity?
could it be that a body in full shadow isn't necessarily a black object, but something that all of its rivets and shapes have no light to reflect off it; whereas an object that is a black color to begin with but has light shining on it has places where we can see the light reflected?
Does this make sense?
yea, but by definition black absorbs this light
There is.

There's even a differential in our ability to see movement depending on color and reflectivity.

It's why flies are black.

Instead of asking silly questions on the forums and answering every answer with more silly questions maybe you could read a book?
i'm going to have to say that's total bull. theres no evidence of that, and if there is, provide it.
Take a gray object, move it really fast in a circle, it will become a black circle...
Point proven.

Now about your theory.
(Side note before I discuss what your saying: PLEASE type better. Your incredibly lucky I had the time to re-re-reread your original post... and my girlfriend had the time to help me, for without doing this I would have no idea what the hell your saying. So please, when discussing things like this... be as clear as possible. Use grammar, and for gods sake re read the post before you hit submit)

Ok So, from what I gathered your saying that light has some sort of color and when it reflects off of something this color changes so when it hits your eye you see the color of the item it reflected off of. That's why you ask about the idea of black light...
You have to read a lot more on how the eye operates. More or less every sense is done by touch and vibrations. Light has (Simplified to the extreme) a vibration to it. When light hits something that is brown the vibration changes and has the properties that your eye distinguishes as the color brown. Your eye then absorbs said light, your eyes measure said vibrations, and your brain goes through the whole process of ending up with brown.

So a fun idea to think of would be... does anything actually have color, or just the property that changes the frequency of light to give you the illusion of color.

(But I am by far NO EXPERT on this subject and am still in need of much teaching)
that's not quite what I was saying, my actual question was more along the lines of "if two intricate identical, non reflective, 3d objects, one white, one black, placed in equal lighting are looked upon from the same angle in such a way that no shadows can be seen, why is it that they can both be made out just as easily even though more of the light is being absorbed by the black object?" for an example lets say we took tool two identical sculptures and shined a light straight at them then looked from the same angle as the light source we could just as easily make out the black one and the white one. I did re-read the first post and it made perfect sense, alas the consequences of going to a magnet school for science and technology. on a side note, how fast is the grey object supposed to be spinning because i have never heard of such a thing, and it seems that flies are black even when stationary and do not get more black in flight.
The flies don't change color.

They're black because a black object moving fast is harder to see than a... let's say lime green object moving fast.

There's also differences in the speed of objects you can with light behind them.

To test this you can take a white-plastic pen and move it quickly in front of your face between you and the monitor. You should have little trouble seeing it. Do the same thing with a black object and it will seem to disappear.
that didn't work, can you explain the physics behind it? or maybe link to a wiki article or something
I'm sorry... but this post is nearly as illegible as the first one. I am no where close to a grammar Nazi, but I really don't know what you are saying...
"we took tool two identical sculptures"
What word were you trying to use when you said tool and where should it have been placed in the sentence? I don't follow why the word tool is there. This is not the only grammar mistake it's just the most ridiculous one.

But hey, about the color blurring and changing idea...
I know this activity is for first graders, but it can show how moving colors can be perceived poorly or wrong with movement. I know it's very scientific and hard to explain... but with some arts and crafts you too can make it happen.


Youtube Links!

Here are some YT links to channels related to Nerdfighteria and educational content!

*Can you think of any more? Pass along any suggestions to an Admin who will then add it to this list should it fit!

© 2015   Created by Hank Green.   Powered by

Badges  |  Report an Issue  |  Terms of Service