There's no speed limit in a superfluid universe. Now we know why. - Livescience.com

A foreign object travelling through the medium could exceed a critical speed limit without breaking the fragile superfluid itself.

These 'super-atoms' form just one type of superfluid, though.

When cooled below a certain temperature, fermions become bound together in what are called Cooper pairs, each made up of two fermions that together form a composite boson.

These Cooper pairs behave exactly like bosons, and can thus form a superfluid.

And yet, in a 2016 paper, researchers from Lancaster University found that a wire rod moving through a helium-3 superfluid could exceed this velocity without breaking the pairs.

In their follow-up experiments, they measured the force required to move the wire rod through the superfluid.

They measured an extremely small force when the wire started moving, but once it was moving, the force required to keep going was zero - just give it a nudge and off it goes.

The team concluded that the initial force comes from the Cooper pairs moving around a little to accommodate the motion, exerting that small starting force on the wire rod.

But, after that, the wire can move freely, essentially camouflaged in a coat of Cooper pairs.