Great and hilarious piece by Alan Bellows about a fascinating time in the history of physics. I will never again refer to James Dewar as simply the guy who invented the vacuum flask!
Here’s an excerpt:
Kamerlingh Onnes died in Leiden about three years later on 21 February 1926. He did so with the full awareness that he was among the last of a disappearing breed—the “classical physicists” who had the luxury of simply banging on matter until it did interesting Newtonian things. Science was thenceforth in the capable hands of quantum mechanics. His helium liquefaction apparatus remains on display to this day at Leiden University.
In 1937, researchers Pyotr Kapitsa and John F. Allen first formally observed and described the strange superfluid state of liquid helium that Onnes had lacked the foreknowledge to identify. They found that when one chills liquid helium below the lambda point—2.17 K—the boiling liquid falls suddenly, eerily still, and it takes on bizarre properties. The individual helium atoms blur into one another and become a single “superatom”, also known as a partial Bose-Einstein Condensation. This is a demonstration of Heisenberg’s Uncertainty Principle, which states that the more precisely the momentum of a particle is determined, the less precisely its position can be known. Since particles below the lambda point have almost no movement, their momentums are almost entirely “known,” therefore by necessity their positions become so inexact that they begin to overlap one another. In this situation atoms stop behaving like discrete things and become ambiguous smears of quantum probabilities. If one physically scoops up a portion of the superatom, the elevated portion acquires more gravitational potential energy than the rest, and since this is not a sustainable equilibrium for the superfluid, it will flow up and out of its container to pull itself all back into one place. It also flows with zero friction, as Onnes observed, since it has no energy to lose. Matter is indeed strange stuff—it’s just seldom so easy to tell.