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A Superfluid Black Hole That Acts Like Liquid Helium


This ‘superfluid black hole’ is the result of physicists modelling a theoretical black hole that behaves in a way that’s mathematically identical to liquid helium when it enters a superfluid state, and they say it’s so strange, our entire Universe probably couldn’t support it.
A superfluid is an incredibly rare substance that has zero viscosity, which means it can flow without any loss of kinetic energy. It has amazing behaviours, like the ability to flow ‘upwards’ against gravity, or fit into spaces that are mere molecules wide.
And here’s why scientists particularly like superfluids – they can conduct electricity with no resistance.
As J. R. Minkel writes for Scientific American, we’ve known for decades that if you cool liquid helium to a few degrees below its boiling point of –269°C (–452°F), it will transition into a superfluid state.
“It will suddenly be able to do things that other fluids can’t, like dribble through molecule-thin cracks, climb up and over the sides of a dish, and remain motionless when its container is spun,” says Minkel.
It even does the opposite of remaining motionless in a moving container – if you get it spinning in a motionless container, it will stay that way forever. 
If it is set [down] a cup with a liquid circulating around, after some time of course it will stop moving.
“But if you did that with helium at low temperature, and came back a million years later, it would still be moving.”
Superfluids have been very difficult to identify in nature, but we do know it occurs in two isotopes of Helium (Helium-3 and Helium-4) when they’re liquified by cooling to cryogenic temperatures, and physicists think they could exist elsewhere in astrophysics, high-energy physics, and theories of quantum gravity.
Now, Mann and his team have observed the same kind of behaviour when they simulated a specific type of black hole – called an anti-de Sitter black hole – under the conditions of Lovelock gravity.
Also known as the Lovelock theory of gravity, this state is a hypothetical generalisation of Einstein’s theory of general relativity, so that in three and four dimensions, it coincides with Einstein’s theory, but in higher dimensions – such as the fifth, sixth, and seventh dimensions – the laws of physics differ. 
Such a state has not been seen in our own Universe, but physicists suggest that it could govern the laws of physics in other universes, and strangely enough, when you stick a model black hole in a universe with Lovelock gravity, you get the mathematical equivalent of a superfluid.
These model black holes are exotic, existing in a higher-dimensional space-time with properties.
“Given certain conditions for gravity’s interaction with matter, the switch to superfluidity could potentially happen in a wider set of black holes – but probably not ones in our Universe.”
So why is it important? Well, unfortunately, the research isn’t going to help us find a superfluid black hole IRL, because we’re not even sure that other universes even exist, let alone if they contain even more bizarre black holes than the ones we’ve got.
But the discovery does give physicists a unique opportunity to explore the properties of superfluids without needing to produce some in a liquid helium sample, and that could lead to new ways of manipulating them for zero-resistance energy.
The simulation also works in the opposite way – for the first time, it allows scientists to use superfluids to figure out how black holes in our own Universe might behave under certain conditions.
As physicist Jennie Traschen from the University of Massachusetts Amherst, who wasn’t involved in the study, tells Crane, “This could tell us something about superfluids which we can’t calculate by other methods, so that’s part of the excitement.”
Materials provided by Physical Review Letters via ScienceAlert.

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