Their Deepest, Darkest Discovery

Substances that absorb every smidgeon of incoming visible light could complement existing stealth coatings that absorb radar waves, Lin said. He and others emphasized, however, that there are also peaceful and more immediate applications for the blackest stuff on Earth.

Solar panels coated with it would be much more efficient than those coated with conventional black paint, which reflects 5 percent or more of incoming light. Telescopes lined with it would sop up random flecks of incidental light, providing a blacker background to detect faint stars.

And a wide array of heat detectors and energy-measuring devices, including climate-tracking equipment on satellites, would become far more accurate than they are today if they were coated with energy-grabbing superblack.

That helps explain why Lin has been fielding queries from solar-energy companies such as SolFocus of Mountain View, Calif., and the European Space Agency.

"The more black the material the better," said Gerald Fraser, a physicist at the National Institute of Standards and Technology, the federal agency that specializes in fine measurements and industrial standards.

That agency offers scientists a chemical mix it calls "standard black," which for years has been the defining measure of blackness. Photographers and printers use it to calibrate their gray scales. Industrial radiologists use it to calibrate X-ray imaging systems that detect radiation or hidden defects in building materials.

That black reflects about 1.4 percent of incoming visible light, and in recent years it has become somewhat outmoded. In 2003, scientists developed a substance made of nickel and phosphorus that reflected just 0.17 percent of visible light, winning it a Guinness World Records listing and kudos in Time magazine as one of that year's 300 "coolest inventions."

The newest black -- which when held next to something conventionally black, such as a tuxedo jacket, is noticeably blacker -- reflects just 0.045 percent of visible light.

It is made of carbon nanotubes: microscopic, hollow fibers whose walls are just one atom thick. Importantly, the fibers are widely spaced, providing plenty of space to allow light in and almost no surfaces to bounce it back out.

"There are a lot of materials that are very absorbing of light so that once the light gets in, very little is reflected. That is not the big issue," said John Pendry, a physics professor at Imperial College London. "The big issue is persuading the light to go in there in the first place" -- something the New York team accomplished by spacing the nanotubes so widely.

While Lin and his colleagues, including Pulickel Ajayan, now at Rice University, pursue applications for their superblack, Pendry and others are hoping to go further by perfecting complete invisibility. The big difference is that a superblack object, even if invisible to the eye, still casts a shadow behind it, while an object shielded by an invisibility cloak does not.

Pendry pioneered much of modern thinking about how to attain full invisibility using "metamaterials" -- substances engineered to manhandle light. Ordinary matter, such as glass or water, slows and bends light as it passes through. Metamaterials contain bits of metal or other substances embedded in precise patterns to make the light bend in an opposite direction from normal paths.