New findings from researchers at the Department of Energy Oak Ridge National Laboratory (ORNL) have supported a theory proposed by Albert Einstein in 1911, which explains how heat is moving through solids.
In a study published in the journal Science the researchers examined a class of materials called thermal insulators, which prevent heat transfer – a basic natural process.
"We saw evidence of what Einstein initially suggested in 1911, as heat pumps randomly from atom to atom in heat insulators," said Lucas Lindsay, a material researcher at ORNL, in a statement. "The jump is beyond the normal heat flow through the collective vibration of atoms."
In material that guides heat easily, this random energy hopping is not particularly noticeable, the researchers said. However, it can be seen in those who can not transfer heat.
The results will help researchers to better understand how the heat travels in heat insulators. This can lead to the development of new materials that restore waste heat or prevent heat transfer. These materials have the potential to drastically reduce energy costs and carbon dioxide emissions, says the ORNL team.
In order to make their discoveries, researchers used advanced vibration sensor equipment and supercomputers to detect the motion of atoms and simulate how the heat moves through a crystal made of the Thallium thermal insulator chemical element.
They found that the vibrations of crystals ordered in a grid did not contain enough energy to transfer much heat. However, they still observed evidence of heat transfer that was not reported in their predictions.
"Our predictions were two times lower than we observed from our experiments. We were initially confused," said Lindsay. "This led to the observation that a other heat transfer mechanism must be at stake ".
This "other mechanism" is the heat hopping described by Einstein.
At present, this process can only detect race in strong insulating materials, says Lindsay, but it can also be present in other crystalline solids, which will create new heat management options.