Later this year, a small part of the International Space Station will become 10 billion times colder than the average temperature of the vacuum of space thanks to the Cold Atom Lab (CAL). Once it’s on the space station, this atomic fridge will be the coldest known place in the universe and will allow physicists to ‘see’ into the quantum realm in a way that would never be possible on Earth.
In a normal room, “atoms are bouncing off one another in all directions at a few hundred meters per second,” Rob Thompson, a NASA scientist working on CAL explained in a statement. CAL, however, can reach temperatures that are just one ten billionth of a degree above absolute zero—the point at which matter loses all its thermal energy—which means that this chaotic atomic motion comes to a near standstill.
CAL uses magnetic fields and lasers traps to capture the gaseous atoms and cool them to nearly absolute zero. Since all the atoms have the same energy levels at that point, these effectively motionless atoms condense into a state of quantum matter called a Bose-Einstein condensate. This state of matter means that the atoms have the properties of one continuous wave rather discrete particles.
Although Bose-Einstein condensates have been made in labs on Earth, gravity causes the particles to sink to the bottom of the device. Yet in the microgravity of low earth orbit, the Bose-Einstein condensate can hold its wave form for much longer—up to ten seconds—which allows researchers to better understand its properties.
CAL will also allow researchers to study Efimov physics, which is concerned with the interactions among three particles. Isaac Newton first described the rules governing interactions between two planetary bodies, but as physicists later discovered, this interaction becomes remarkably more complex when a third body is introduced. (This strange effect plays a central role in Cixin Liu’s phenomenal science fiction trilogy The Three Body Problem.)
Efimov physics is concerned with similar effects, but on the scale of particles, not planets. When three atoms interact, their behavior appears erratic because it is governed by quantum mechanics. CAL will allow researchers to form molecules consisting of three atoms, but which are one thousand times larger than a normal molecule in CAL’s ultracold environment. Using CAL to create molecules in this “fluffy” state will allow physicists like Eric Cornell at the National Institute of Standards and Technology to better understand their strange properties.
“The way atoms behave in this state gets very complex, surprising, and counterintuitive,” Cornell, who received the Nobel Prize in 2001 for creating Bose-Einstein condensates, said. “That’s why we’re doing this.”
Ultimately, the researchers collaborating on CAL think the lab will give them major insights into the relationship between quantum mechanics and gravity. CAL successfully produced Bose-Einstein condensates on Earth last year and now just needs to be delivered to orbit.
CAL was originally scheduled to launch in early 2017, but a series of testing setbacks at NASA’s Jet Propulsion Laboratory has pushed its launch into 2018. Although NASA hasn’t announced a final date for its delivery to the ISS, it is expected that the atomic fridge will be delivered sometime in the next few months.