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Nanotubes Form The Darkest Material Yet Created
toxcspdrmn writes "Bad news for Spinal Tap fans. The BBC reports that researchers at Rensselaer Polytechnic Institute in Troy, New York, have produced the darkest known material by manufacturing "forests" of carbon nanotubes. This forms a surface that absorbs or scatters 99.9% of all incidental light."
The summary seems to be wrong. No where in the article does it say the material "scatters light". Rather, it absorbs light.
http://www.news.com.au/story/0,23599,23060778-13762,00.html not to be confused with: http://www.imdb.com/title/tt0134847/
I guess the article should really define "light" a bit more tightly. From your link:
Although Planck's formula predicts that a black body will radiate energy at all frequencies, the formula is only applicable when many photons are being measured. For example, a black body at room temperature (300 K) with one square meter of surface area will emit a photon in the visible range once every thousand years or so, meaning that for most practical purposes, the black body does not emit in the visible range.
My, possibly incorrect, interpretation (assumption?) of the article was "light" in the broad sense of all electromagnetic radiation. This, however, does not make your link less interesting; in fact, in makes it more interesting. Thank-you.
Yes, we would. No incoming photons doesn't mean that our brain furiously tries to make our pattern filling work 1000% beyond what it normally does. It would mean a big black spot. Just because a person wearing a suit made out of this would look completely flat doesn't mean he'd be invisible.
Even if your brain couldn't handle pure blackness, the rods still fire randomly, ensuring that some form if input is always present. You can verify this by closing your eyes in a very dark room - you should see a color that is not black. This color is called eigengrau.
I think this will be of limited value for personal stealth measures - being that dark, you'd stand out even aginst regular dark surfaces. However, as another article pointed out, a stealth plane could profit from being able to absorb radar beams. Research into the absorption of non-visible wavelengths is already underway.
USE HOT GRITS WITH STATUE OF NATALIE PORTMAN (NAKED AND PETRIFIED)
This story has a photo (seriously)
Pretty cool stuff. The sample on the left is carbon black, which is reasonably black, but the surface still texture stands out clearly with the flash. The sample of the new material looks like a black hole - which I guess it almost is. Except for the suckage.
You are wrong here. The 1366 W/m2 is indeed at the upper atmosphere. Lower in the atmosphere it is less, how much depends on the current state of the atmosphere. About 1000W/m2 is the right value.
The 100W/m2 is the energy output of a not so good photovoltaic module.
Nyh
Well, let us do some math on the trivial boiling of water with black containers.
Take a container with 1 kg of water. For ease of calculation we will take a 0.1 m x 0.1 m x 0.1 m container.
Let us assume one side of the container faces the sun. Area is 0.1 x 0.1 = 0.01 m2
The staring temperature is 20C, boiling temperature is 100C. Delta t is also 80 C. Specific heat of water is about 4200 J/K/kg.
To make the 1 kg of water boil you need 80 x 4200 = 336 kJ.
Energy received on the side of the container is 0.01 x 1366 = 13.66 W.
Time needed to get 336 kJ with this power is 336000/13.66 = 24597 s (=6 hours and 50 min).
Oops, not so trivial after all...
If you make a large area (1m2) container containing 1 kg water you need get a container of 1 m x 1 m x 0.001 m. This container would boil water in 336000/1366 = 245 s (about 4 min). Problem with such a container is a large area at the cool side of the container and the specific heat of the container is a lot higher than the specific heat of the water it contains. So you need to design a container with a very low specific heat compared to the specific heat of the water it contains, a large surface area to collect the solar energy and good isolation at the shade side to minimize heat losses. Welcome to the interesting world of designing solar collectors.
And for the very black material: going from 99% black to 99.9% black gives only (99.9-99)/99 = 0.9% increase of efficiency. The problem of solar collectors is not the black not being black enough. A new blacker black won't revolutionize solar collectors.
Nyh
Your eyes sensitivity to light is logarithmic, so yes, it is significant.
love is just extroverted narcissism