MIT physicists just confirmed something wild: heat can move in waves, like sound, in superfluids! Imagine one side of a tank getting hot, then the other, back and forth, but the water itself looks totally still. This “second sound” was only a theory until now. Using ultra-cold lithium atoms and some clever radio tricks, they actually saw heat sloshing around. This could totally change how we think about energy and even help us understand neutron stars! #Science #MIT #SecondSound