These atomic physicists are about to create
an exotic state of matter in space. They’re sending commands to a special lab
currently installed aboard the International Space Station, that operates when the astronauts
are asleep. It’s engineered to trap gas atoms and cool
them to temperatures just a hair’s edge above absolute zero. When it gets this cold, a curious state of
matter called a Bose-Einstein condensate comes into existence. This isn’t your classic solid, liquid, or
gas, but an ultracool state of matter - that behaves like a wavy super atom. Making them in space is an opportunity to
hold a magnifying glass to the quantum world, but only for a brief period of time. It is incredibly challenging making something
ultra cold, because there is nothing in the natural world that wants to be ultra cold. Something like this is so rare, so unnatural,
so unlikely, that you're talking about the coldest spots in the known universe. The quest for colder temperatures has gone
on for over a hundred years. Scientists kind of steadily working to get
colder and colder temperatures. And by cold... We're talking seriously chilling. Nanokelvin is a billionth of a degree above
absolute zero, and picokelvin is now a trillionth. Strange and curious things happen when we
get atoms to ultra-cold temperatures. But to understand why colder regimes are an
exciting playground for scientists, we have to wade into some quantum mechanics:
Quantum mechanics tells us that everything has both a particle and a wave nature to it. And so at normal temperatures atoms just act
like little billiard balls. As we cool a gas of atoms, we lower its momentum
and each particle's wave nature starts to become more and more pronounced. And if you get cold enough... These wavelengths get so large, those atoms really start to blur
together. At that point, this strange new state of matter
occurs called the Bose-Einstein condensate. Bose is the person that really came up with
the breakthrough to show that particles called bosons behave in this collective way. Einstein predicted that this state of matter
would exist, but he thought it was at such a ridiculously low temperature that you would
never be able to actually observe it. This was back in the 1920s when quantum mechanics
was the new revolution on the scene. They didn’t have the technology to wrangle
atoms just yet. But eventually... Understanding quantum mechanics gave us lasers,
semiconductors, transistors. In the 1980s, people discovered ways to actually
use lasers to cool atoms to incredibly cold temperatures. Most people's intuition is that you shine
a bunch of lasers on something it makes it hotter. But by tuning a laser to a particular resonance
frequency, scientists can slow down the motion of an atom, which essentially cools it. Then in the 90s, people started developing
these techniques to move those atoms into magnetic traps, and then use this other technique
called evaporative cooling to get to still colder temperatures. Evaporation relies on losing atoms. They need atoms to go away to get out of the
trap and carry energy with them. After decades of technical progress, teams
finally made Bose-Einstein condensates in the lab. They last inside a trap for a glorious 15-20
seconds. It was clear that gravity had a big effect
on these systems, and it would be interesting to do these types of things in space, even
though it was totally crazy to even think about that. We were confining them with magnetic fields
and the magnetic fields themselves are changing and perturbing the atoms. We would like to turn off the fields, and
just study the atoms on their own, but of course in gravity, they just kind of go plop. And that’s why putting a lab in space offers
a unique advantage. You can shut the trap off and these matter
waves remain floating. We think we can get to a new regime of even
colder temperatures for even longer amounts of time, and make really sensitive measurements. And that’s where this engineered quantum
mechanics box comes in. CAL is a multi-user cold atom lab within the
International Space Station. The heart of it is what we call the science
module. Then inside that there's a vacuum chamber. There's computer to control everything, and
to store the data. There's electronics to drive magnetic field
coils. And then there is a whole suite of lasers. We have two species that we're trying to trap: both
Rubidium and Potassium. The reason we like to cool those is because
they've got one electron in their outer shell. You want to be able to continually drive,
excited state, ground state, excited state, ground state, while you cool these atoms. We have this little small vacuum that has
this little atom chip on top of it, and then that's mounted inside an assembly that steers
all our laser beams. For cold atom physicists who are used to tweaking
their experiments, building a lab that could operate remotely was a huge milestone. We sometimes call that last phase of a mission
the death march. We had a number of issues that last few months,
and things broke that we've been working with in the lab for decades and never had one break. This is sort of been my baby. It's something I've been working on for 20
years pretty much. And to finally see it all together, was just
wow. It was something that was amazing to go through. And wonderful to go through and you don't
want to do it again. The instrument is placed near the center of
mass of the ISS, that's important for the gravitational measurements that we eventually
want this kind of technology to be able to do. But it's right next to the astronauts exercise
bike, and it's pretty ludicrous when you see these videos of, you know, the shaking that's
going on nearby. So it runs during the crew sleep periods. When these LED lights switch on... We make the sample, and then we release it. We snap off our magnetic fields, and the gas
will start to expand. You shine in a final laser pulse that blasts
the cloud apart, and then you collect this light that includes the shadow of the atoms
on a CCD camera behind them. Tens of microseconds later, you send in another
pulse that's a reference image. You subtract the two and you get a density
profile of the atoms that were there. We're always anxious to see as soon as possible the images coming down. To detect that it is a Bose-Einstein condensation,
there's certain signatures that you look for. It's a very sharp transition. Virtually every day we go down there and we
turn it on, and we run a sequence to make Bose-Einstein condensates. We're sending up an upgrade up for CAL. And the new capability is going to allow us to
have something called an atom interferometer, which is a really, amazingly sensitive sensor
for things like accelerations, and gravity. And this is probably in the long term, the
most important thing to come out of using cold atoms in space. Interferometers use beams of light to make
precision measurements of a given environment. They’re great instruments to tackle some
of the universe’s most stubborn mysteries. Some of the teams are going to do studies
of tests of Einstein's equivalence principle. The Apollo astronauts did the first one of
those in space, they dropped a hammer and a feather and showed that on the moon, they
fall at the same rate.That might not actually be true. We're going to drop a Rubidium atom and a
Potassium atom. We can read them out with laser beams using
this atom interferometer technique to just a fraction of wavelength of light. As a general rule, you should never bet against
Einstein but there is this fundamental conflict between his theory, and what's called the
standard model of quantum physics. If there's a problem, that problem could be
all the way back in the assumptions that that theory was built on. And Einstein’s equivalence is a fundamental
tenet of general relativity. You're testing this fundamental tenet of
general relativity with quantum mechanics. Another experiment that I really like is trying
to study the quantum nature of collisions. It gets to one of these I think one of the
really profound questions in physics is that the basic laws of physics are simple, that
we have just a few fundamental particles and they interact by these few simple rules. And they also tell us that in this whole universe,
the only thing that's happening, really the only thing is, particles are coming together,
they collide and they are bouncing off, sometimes they change from one type to another. Sometimes they just go off in different directions,
but that's it. And then how do we get this complicated universe
that we see around us from that simple underlying physics? I think it's going to be a really important and again a kind of an iconic experiment, if we can pull it off.
