Physicists capture 'second sound' for the first time — after nearly 100 years of searching

Physicists capture 'second sound' for the first time — after nearly 100 years of searching

First theorized in 1938, heat's wave-like flow through superfluids, known as "second sound", has proven difficult to directly observe. Now, a new technique has finally done it, and could be used to study neutron stars and high-temperature superconductors.

In most materials, heat tends to disperse. If heat does not stay on a pan, it will gradually dissipate as it warms up its environment. But in exceptional states of matter, heat can behave like a wave, moving from one side to the other in a way similar to a sound wave that bounces from one end to the other from a room. This wavy heat is what physicists call “second sound.” Now, a team of MIT scientists has captured for the first time direct image…