When you stir a liquid—like tea in a cup or water in a mug—you see slowing vortices that gradually slow down and stop due to friction between fluid particles. But in a superfluid, something astonishing happens: there is zero friction and zero viscosity. If you stir a superfluid once and return years later, it will still be rotating—forever. Such is the bizarre world of superfluid.
The Strange Properties of Superfluid
One of the most incredible properties of superfluids is their ability to climb up the walls of their container. Since they have no viscosity, they form a thin layer that spreads and completely covers the container. It is also possible to construct a superfluid fountain that can continuously jet upwards without any added energy, as there is no energy loss due to friction.
Do You Know Any Superfluid?
The answer is helium!
The Discovery of Superfluidity
Superfluidity was first marked in liquid helium at extremely low temperatures close to absolute zero (-273.15°C). In 1937, physicists Pyotr Kapitsa, John F. Allen, and Don Misener independently discovered that helium-4 exhibits odd properties when cooled below 2.17 Kelvin, known as the lambda point. Instead of behaving like a regular liquid, it could flow without friction, climb the walls of its container, and even pass through tiny pores that would usually block any liquid.
How Superfluidity Works
The phenomenon of superfluidity is deeply implanted in quantum mechanics. It occurs due to Bose-Einstein Condensation (BEC), where particles inhabit the same quantum state, behaving as a single entity rather than as individual particles. In this state, helium atoms move in a perfectly coordinated way, allowing them to flow indefinitely without losing energy.
Properties of Superfluids
- Zero Viscosity – A superfluid can flow without resistance, meaning it never slows down, making it an eternal motion phenomenon in a frictionless environment.
- Quantum Vortexes – When superfluids rotate, they don’t swirl like normal liquids but form quantized vortexes—tiny tornado-like structures dictated by quantum mechanics.
- The Fountain Effect – Superfluids can spontaneously rise against gravity in a fine tube, demonstrating their ability to defy normal fluid behaviour.
- Climbing Walls – Unlike ordinary liquids, superfluid helium can climb up and escape its container because it can spread in a thin film over surfaces.
Applications of Superfluidity
While superfluidity is a fascinating theoretical concept, it has practical applications in modern science and technology:
- Cryogenics & Space Exploration – Superfluid helium is used for cooling superconducting magnets in MRI machines and particle accelerators like the Large Hadron Collider.
- Quantum Computing – The study of superfluid behavior helps in advancing quantum mechanics, leading to breakthroughs in quantum computing.
- Astrophysics – Scientists believe that neutron stars may contain a core of superfluid neutrons, affecting their rotation and behavior.
The Future of Superfluid Research
Superfluidity continues to be an area of deep scientific inquiry. Physicists are investigating whether other substances can exhibit superfluid behavior and how it can be harnessed for futuristic technologies. With ongoing advancements in quantum mechanics, the mysterious properties of superfluids may unlock new frontiers in physics, computing, and even our understanding of the universe itself.