A discovery by scientists at the Department of Energy's Oak Ridge National Laboratory supports a century-old theory by Albert Einstein that explains how heat moves through everything from travel mugs to engine parts.
The transfer of heat is fundamental to all materials. This new research, published in the journal Science, explored thermal insulators, which are materials that block transmission of heat.
"We saw evidence for what Einstein first proposed in 1911—that heat energy hops randomly from atom to atom in thermal insulators," said Lucas Lindsay, materials theorist at ORNL. "The hopping is in addition to the normal heat flow through the collective vibration of atoms."
The random energy hopping is not noticeable in materials that conduct heat well, like copper on the bottom of saucepans during cooking, but may be detectable in solids that are less able to transmit heat.
This observation advances understanding of heat conduction in thermal insulators and will aid the discovery of novel materials for applications from thermoelectrics that recover waste heat to barrier coatings that prevent transmission of heat.
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