Your kitchen fridge cools everything to a single temperature. But in labs where quantum phenomena are studied, you often need two different levels of cold at once. Previously, that meant assembling two separate cooling circuits — bulky and heavy.
Engineers have proposed a three-stage refrigerator that acts like a smart conductor. It alternately switches thermal links between stages, so two spots on the device hold different temperatures: one at about 1 degree above absolute zero, the other even colder, at 0.3 degrees. All without extra hardware.
This approach saves mass and space, which is critical for spacecraft. For instance, detectors of distant galaxies must be kept very cold so they don't mistake faint starlight for their own heat. The new refrigerator already delivers 20 microwatts of cooling at 1 K and 4 microwatts at 0.3 K — enough for sensitive sensors.
It all comes full circle: the kitchen fridge cools your food, while this one cools the very possibility of seeing the edge of the universe.
At 0.3 K, helium becomes superfluid: it flows without any friction and can creep up the walls of an open vial and spill out.
In science fiction, ultra-low temperatures are often used for suspended animation, like in the movie Alien, where the crew sleeps in cryo-chambers.