17 January 2008

A Darker Shade of Black

With a reflective index of 0.045 per cent--the new standard for "dark" captures 99.955 of incident light. Darker darks and whiter whites are not just for laundry detergents, painters, and interior designers. The ability to control radiative energy is useful to scientists, engineers, and industrialists.
An ideal black object absorbs all the colours of light and reflects none of them. In theory, it should be possible to make something that approaches the "perfect absorber"...But it has proved difficult to construct an object that does not reflect light at all...Researchers at Rensselaer Polytechnic Institute in Troy, New York, turned to carbon nanotubes - structures made from carbon, billionths of a metre across, that have unique properties.

...A team led by Dr Pulickel Ajayan, who is presently at Rice University in Houston, Texas, built an array of vertically aligned, low-density carbon nanotubes. Dr Shawn Lin measured the optical properties....The roughness of the material's surface was tuned to minimise its optical reflectance....Experiments showed that this "forest" of carbon nanotubes was very good at absorbing light, and very poor at reflecting it.

Reporting their findings in the journal Nano Letters, Dr Ajayan, Dr Lin and colleagues say the reflectance of the material is three times lower than previously achieved.

Here is the key to the image above-- "uses of nanotech" (BBC):
1 - Organic Light Emitting Diodes (OLEDs) for displays
2 - Photovoltaic film that converts light into electricity
3 - Scratch-proof coated windows that clean themselves with UV
4 - Fabrics coated to resist stains and control temperature
5 - Intelligent clothing measures pulse and respiration
6 - Bucky-tubeframe is light but very strong
7 - Hip-joint made from biocompatible materials
8 - Nano-particle paint to prevent corrosion
9 - Thermo-chromic glass to regulate light
10 - Magnetic layers for compact data memory
11 - Carbon nanotube fuel cells to power electronics and vehicles
12 - Nano-engineered cochlear implant

Of course, those are only a very few of the uses of nanotech.

H/T Bayou Renaissance Man

This nanotube material absorbs well within visible wavelengths. What is needed is material that absorbs well across the entire electromagnetic spectrum. From X-rays to long wave radio. That would be a stealthy material.

It is still a very useful discovery--giving a way to capture almost all visible light will allow manipulating radiative energies in ways never before possible.

When Maxwell invented his famous "daemon", he did not anticipate the discoveries in nanotechnology that would allow humans to get down to the scale of atoms and molecules. Humans are looking for ways to cheat entropy.

Any sufficiently advanced technology becomes indistinguishable from magic--acording to Arthur C. Clarke. We are standing on the verge of sufficiently advanced technologies.

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Blogger Will Brown said...

Isn't it a great time to be alive?

And, I think "Humans are looking for ways to trim the limits of entropy" would be a better descriptive. "Cheating" implies some sort of entropic rebound resulting from nanotech advances, which I don't believe would be the case.

Finally, Sir Arthur's famous quote only applies to those who don't have any understanding of the technology being used, surely not a condition under which any Al Fin reader labors. :)

Friday, 18 January, 2008  
Blogger al fin said...

Thanks for the comment, Will.

I fear that all of us labour under such a condition at one time or another, perhaps without knowing it.

Friday, 18 January, 2008  

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“During times of universal deceit, telling the truth becomes a revolutionary act” _George Orwell

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