'Winter is Coming' and So Are Superfluids

As helium-4 heads towards absolute zero it becomes a superfluid and can help us understand complex quantum physics. Understanding how elements react at sub zero temperatures can shed light on many lingering time/space related questions.
Jessica Miley

The PBS Space Time YouTube channel is an absolute must if you are even vaguely interested in the “the craziness of astrophysics, the possibilities of sci-fi, and anything else you can think of beyond Planet Earth” Hosted by the unflappable astrophysicist Matthew O’Dowd, the channel tackles issues ranging from White Holes to the Future of Space telescopes. In this issue, O’Dowd runs us through what happens in ‘absolute cold’. While absolute zero - where there is no atomic movement at all - is impossible. It doesn’t stop scientist trying, and along the way, they have discovered some really interesting things that happen to liquid as it gets very very cold.

Helium is one such element that displays some pretty weird characteristics as temperatures drop. For instance Helium-4, an isotope of helium, will remain in a liquid state even at absolute zero. Absolute zero is known as zero Kelvin or the equivalent of 273.15 °Celsius. At this temperature helium-4 changes into what is known as a superfluid. The superfluid has special qualities that allow quantum physics become visible to the naked eye. For instance, it is thought if you could shake a cup of the Helium-4 superfluid, the liquid wouldn’t settle down again even after a million years. We recommend watching the whole PBS video to get all the lowdown on just how wild HE-4 can get. We also love the way O’Dowd feels like the love child between Tyrion Lannister and Doctor Who.