NASA is planning to send an ice chest-sized box to the International Space Station (ISS), where it will freeze gas atoms to create the coolest spot in the universe, an advance that may provide new insights into gravity and dark matter. Inside that box, lasers, a vacuum chamber and an electromagnetic “knife” will be used to cancel out the energy of gas particles, slowing them until they’re almost motionless.
The suite of instruments, developed by NASA’s Jet Propulsion Laboratory in the US, is called the Cold Atom Laboratory (CAL). It is set to ride to space in August aboard the SpaceX CRS-12. CAL’s instruments are designed to freeze gas atoms to a mere billionth of a degree above absolute zero – more than 100 million times colder than the depths of space.
“Studying these hyper-cold atoms could reshape our understanding of matter and the fundamental nature of gravity,” said CAL Project Scientist Robert Thompson of JPL. “The experiments we’ll do with the Cold Atom Lab will give us insight into gravity and dark energy – some of the most pervasive forces in the universe,” said Thompson.
When atoms are cooled to extreme temperatures, as they will be inside of CAL, they can form a distinct state of matter known as a Bose-Einstein condensate. In this state, familiar rules of physics recede and quantum physics begins to take over. Matter can be observed behaving less like particles and more like waves.
Rows of atoms move in concert with one another as if they were riding a moving fabric. These mysterious waveforms have never been seen at temperatures as low as what CAL will achieve.
NASA has never before created or observed Bose-Einstein condensates in space. On Earth, the pull of gravity causes atoms to continually settle towards the ground, meaning they are typically only observable for fractions of a second. However, on the ISS, ultra-cold atoms can hold their wave-like forms longer while in freefall. That offers scientists a longer window to understand physics at its most basic level.
Thompson estimated that CAL will allow Bose-Einstein condensates to be observable for up to five to 10 seconds; future development of the technologies used on CAL could allow them to last for hundreds of seconds.
Bose-Einstein condensates are a “superfluid” – a kind of fluid with zero viscosity, where atoms move without friction as if they were all one, solid substance. “If you had superfluid water and spun it around in a glass, it would spin forever. There’s no viscosity to slow it down and dissipate the kinetic energy,” said Anita Sengupta of JPL, Cold Atom Lab project manager.
“If we can better understand the physics of superfluids, we can possibly learn to use those for more efficient transfer of energy,” said Sengupta.