An instrument capable of cooling matter to a smidgen above absolute zero is being readied for launch to the International Space Station, possibly uncovering new physics and answering some of our biggest cosmological questions.
This summer, a rather interesting experiment will arrive at the International Space Station. Called the Cold Atom Laboratory (CAL), this boxy instrument will be able to chill material down to unimaginably low temperatures — so low that it will become the coldest place in the known universe.*
At a temperature of a billionth of a degree above absolute zero, CAL will investigate a state of matter that cannot exist in nature. This strange state is known as a Bose-Einstein condensate (or BEC), which possesses qualities that, quite frankly, don’t make a lot of sense.
When a gas is sufficiently cooled and the subatomic particles (bosons) drop to their lowest energy state, “normal” physics start to break down and quantum mechanics — the physics that governs the smallest scales — starts to manifest itself throughout a material (on a macroscopic scale). When this occurs, a BEC is possible. And it’s weird.
BECs act as a “superfluid,” which means it has zero viscosity. Early experiments on supercooled helium-4 exhibited this trait, causing confusion at the time when this mysterious fluid was observed flowing up, against the force of gravity, and over the sides of its containing beaker. Now we are able to cool gases to sufficiently low temperatures, this superfluid trait dominates and gases move as one, apparently coherent, mass.
So far, BEC experiments have only been carried out in a gravitational environment and can only be observed for a very short period of time as gravity continually pulls the BEC particles to the bottom of its container, thereby limiting its stability. But remove gravity from the equation and we enter a brand new observational regime with the potential for brand new insights to fundamental physics, and this is why NASA built CAL — humanity’s first microgravity BEC laboratory that could unlock some of the universe’s biggest mysteries.
CAL works by trapping the BEC in magnetic containment and lasers will be used to cancel out energy in the gas, thereby cooling it (pictured top). The gas will then be further cooled through evaporative cooling (using a radio frequency “knife”) and adiabatic expansion. When sufficiently cooled, experiments can be carried out on the BEC — the first time a BEC has been tested in space. (The technical details behind CAL’s technology can be found on the experiment’s website.)
“Studying these hyper-cold atoms could reshape our understanding of matter and the fundamental nature of gravity,” said Robert Thompson, CAL Project Scientist from NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif., in a statement. “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.”
It is hoped that BECs will be observable inside CAL for five to twenty seconds and the ultra-low temperature technologies developed will allow for future experiments that could contain stable BECs for hundreds of times longer.
CAL isn’t a pure physics curiosity, even if it is pretty awesome just to observe quantum physics manifest itself across an entire mass of particles (in free-fall, no less). Producing stable BECs could have technical applications, such as in quantum computer development and improving the precision of quantum clocks. In addition, creating a stable BEC in a lab setting could, quite literally, give us new eyes on fundamental universal mysteries. Lower temperatures means more stability and more stability means boosted sensor precision. Astronomy is all about precision, so the spin-off technologies from the techniques developed in CAL could usher in a new generation of ultra-sensitive telescopes and detectors that could, ultimately, reveal the mechanisms behind dark energy and dark matter.
“Like a new lens in Galileo’s first telescope, the ultra-sensitive cold atoms in the Cold Atom Lab have the potential to unlock many mysteries beyond the frontiers of known physics,” said Kamal Oudrhiri, CAL deputy project manager also at JPL.
CAL is set for launch on a SpaceX resupply mission to the International Space Station in August and I can’t wait to see what new physics the instrument might uncover.
*Assuming there are no other intelligent lifeforms also playing with supercooled matter elsewhere in the universe, of course.