Superfluid Surprise: MIT Physicists Capture Images of “Second Sound” for the First Time

MIT’s visualization of second sound opens new paths for understanding heat’s wave-like behavior in superfluids and its implications for various states of matter, expanding scientists’ understanding of heat flow in superconductors and neutron stars.

In most materials, heat prefers to scatter. If left alone, a hotspot will gradually fade as it warms its surroundings. But in rare states of matter, heat can behave as a wave, moving back and forth somewhat like a sound wave that bounces from one end of a room to the other. In fact, this wave-like heat is what physicists call “second sound.”

Signs of second sound have been observed in only a handful of materials. Now MIT physicists have captured direct images of second sound for the first time.