You’ve probably heard of four states of matter:
Solid, Liquid, Gas, and Plasma,
but there’s a fifth ultracold state that is attracting a lot of attention:
the Bose-Einstein Condensate, discovered during the late 20th century,
and the object of intense research ever since.
This year, a condensate will make its way to the space station.
but why has this material suddenly rocketed to prominence,
and just what is a Bose-Einstein condensate?
BEC gets its name from the two scientists who proposed its existence.
Satyendra Nath Bose and Albert Einstein.
They suggested that when certain atoms are cooled to temperatures near absolute zero,
the atoms lose their individual identities and crowd into a single quantum state.
70 years after the proposal,
scientists finally achieved the temperatures needed to generate the condensate.
To get these atoms super cold, scientists use lasers.
Lasers can be tuned so that atoms preferentially absorb photons
when they move towards the laser.
Absorbing these laser photons slow down and cool the atoms.
Inside a vacuum chamber, an array of laser beams
cool a few atoms trapped within a magnetic field
to just fractions of a degree above absolute zero.
Just like Einstein predicted, when the temperatures get this low,
regular physics seems to break down.
This new matter forms into something called a superfluid.
Superfluids are fluids that have zero viscosity,
meaning they flow without any friction or resistance.
Not only that, but a BEC can behave much like a light wave.
a BEC can overlap and interfere with itself
to spontaneously develop a rippled, wavy distribution of atoms.
Such wave-like effects are rare among forms of matter,
so physicists are excited to study their intricacies.
But they only have milliseconds in which to study the BECs, after they release the atoms
from their magnetic traps and gravity brings them crashing
to the bottom of their vacuum chamber.
Now, scientists want to send BECs to space,
where weightlessness gives them more time to perform experiments.
On Earth, the best way to mimic the weightlessness of space
is by performing experiments during free fall.
In Bremen, Germany, scientists are dropping BEC experiments down a 146-meter tower.
But they need to get the cold atoms into space if they want to probe their BEC regularly
for more than a few seconds.
The Cold Atom Laboratory is a remote controlled device that will become operational in 2018,
after it is installed in the International Space Station’s Destiny module.
If all goes well, the CAL will be churning out data
for at least a year after it is switched on.
Being in space also means they can cool atoms to lower temperatures.
Scientists may reach record temperatures below 100 picokelvins:
colder than any spot in the universe.
Weightlessness also allows experiments to happen that wouldn’t be possible otherwise.
Some researchers are aiming to create BEC bubbles, a form of the condensate that wouldn’t
be possible back on Earth due to gravity.
Other scientists are looking into cooling not just atoms, but individual molecules.
While the space station is a better environment than Earth for maintaining BECs, vibrations
from the machinery on board keep it from being the perfect test bench.
In the future, space-based experiments
may be able to perform atom interferometry on the BECs.
Eventually, these atomic interferometers could be launched on purpose-built satellites,
and used to measure tiny variations in Earth’s gravity.
But for right now, there’s still a lot we need to learn about this fifth state of matter.