When bodies get very close together there is rapid heat transfer. But we knew that.

Planck's blackbody radiation law, formulated in 1900 by German physicist Max Planck, describes how energy is dissipated, in the form of different wavelengths of radiation, from an idealized non-reflective black object, called a blackbody. The law says that the relative thermal emission of radiation at different wavelengths follows a precise pattern that varies according to the temperature of the object. The emission from a blackbody is usually considered as the maximum that an object can radiate.

The law works reliably in most cases, but Planck himself had suggested that when objects are very close together, the predictions of his law would break down. But actually controlling objects to maintain the tiny separations required to demonstrate this phenomenon has proved incredibly difficult. . .

"Experimental confirmation has proved elusive because of the extreme difficulty in measuring temperature differences over very small distances," Pendry says. "Gang Chen's experiments provide a beautiful solution to this difficulty and confirm the dominant contribution of near field effects to heat transfer."

In today's magnetic data recording systems — such as the hard disks used in computers — the spacing between the recording head and the disk surface is typically in the 5 to 6 nanometer range, Chen says. The head tends to heat up, and researchers have been looking for ways to manage the heat or even exploit the heating to control the gap. "It's a very important issue for magnetic storage," he says. Such applications could be developed quite rapidly, he says, and some companies have already shown a strong interest in this work.

The new findings could also help in the development of new photovoltaic energy conversion devices to harness photons emitted by a heat source, called thermophovoltaic, Chen says. "The high photon flux can potentially enable higher efficiency and energy density thermophovoltaic energy converters, and new energy conversion devices," he says.

The new findings could have "a broad impact," says Shen. People working with devices using small separations will now have a clear understanding that Planck's law "is not a fundamental limitation," as many people now think, he says. But further work is needed to explore even closer spacings, Chen says, because "we don't know exactly what the limit is yet" in terms of how much heat can be dissipated in closely spaced systems. "Current theory will not be valid once we push down to 1 nanometer spacing."

And in addition to practical applications, he says, such experiments "might provide a useful tool to understand some basic physics."

The thermoelectric application potential intrigues me since a lot of heat is wasted that might be put to better use, and at the same time shunting that heat away would improve the efficiency and longevity of many devices that now suffer from heat fatigue and consume even more energy trying to get rid of excess heat.