For the first time in nearly a century, scientists have directly observed “second sound,” a wave-like flow of heat through superfluids. This phenomenon was predicted by physicist László Tisza in 1938 but remained elusive until now.
Researchers used a new heat-mapping technique to image heat behaving like sound within an exotic superfluid state of cold lithium-6 atoms. The study, published in the journal Science, reveals that heat moves as a wave, bouncing around its container and demonstrating properties similar to sound waves.
Understanding second sound could help scientists predict how heat flows inside ultradense neutron stars and high-temperature superconductors. This knowledge is crucial for developing near-lossless energy transmission systems, one of physics’ “holy grails.”
The researchers employed a novel technique that tracks the flow of heat through the resonant frequencies of fermion pairs in the lithium-6 atoms. By applying specific radio frequencies, they enabled the atoms to ring and track their movement frame by frame.
This breakthrough allows scientists to directly observe second sound for the first time, providing new insights into superfluid behavior and enabling the study of extreme objects like neutron stars. The technique also has potential applications in measuring conductivity and designing high-temperature superconductors.
Source: https://www.livescience.com/physics-mathematics/physicists-capture-second-sound-for-the-first-time-after-nearly-100-years-of-searching