The International Space Station will soon become the coldest place in the known universe… for science!

Here’s one of the coolest sentences you’ll ever read:
The International Space Station will soon be the coldest
place in the known universe. A new instrument that will
be sent to the ISS, called the Cold Atom Lab, will reach
temperatures as low as 100 picokelvin — 100 trillionths
of a degree above absolute zero. As matter approaches
absolute zero, it starts to exhibit some very odd, rather
quantum behavior. Because it’s so hard to reach these
temperatures, and because the material universe acts so
weirdly when you get down that low, no one actually
knows what the Cold Atom Lab will discover — but
NASA seems to be pretty certain that the findings will
be fascinating, in any case.
As you probably know, space is already very, very cold
— roughly 2.7 Kelvin (-270.45 Celsius, -454.81
Fahrenheit). This is mostly due to a lack of atmosphere
and the vacuum-like nature of space — with very few
molecules to energetically bounce around, there can be
no heat. At 2.7 Kelvin, though, nothing weird happens;
classical physics are still completely in control. To go
quantum, you need to go colder — a lot colder.
(Read: Negative temperature: Understanding what
happens below absolute zero.)
Now, getting to say, 1 Kelvin (-272C) isn’t all that hard.
A multi-stage dilution refrigerator (pictured right), which
mixes helium-3 and helium-4, will happily get you to
around 0.3 Kelvin. This is the method that most
quantum computers currently use. Another option is
laser cooling — but here on Earth, where the nagging
force of gravity on the cooled sample has to be
counteracted with strong magnetic traps, there are fairly
strict limits on just how cold you can get. In the
International Space Station’s microgravity climate,
however, laser cooling can be very effective indeed. Only
weak traps are needed to hold the sample in place while
the laser cools it — and less power means lower
temperatures can be reached. 100 picokelvin in this
case, or 100 trillionths of a degree above absolute zero.
Click to zoom in
NASA says the Cold Atom Lab, which will launch to the
International Space Station in 2016, will be the coldest
place in the known universe. To be fair, one group hit
100 picokelvin way back in 1999. That experiment isn’t
running any more, though, and it also had a very
different purpose — while they were looking at the
magnetism of rubidium atoms, NASA will be
investigating something far more interesting: Bose-
Einstein condensates. Basically, when you cool a very
dilute gas of bosons (force-carrying particles, as
opposed to matter-carrying fermions), a large number of
the bosons start to exhibit quantum behavior on the
macroscopic scale. That’s the important part —
macroscopic scale means that these quantum effects
will be visible to the naked eye.
In short, this coldest spot in the universe is expected to
be the first time that quantum physics makes the jump
from the realm of quarks and gluons and other
phantasmal forces, into the real world that you and I
occupy. The crazy thing is, though, no one even knows
what this Bose-Einstein condensate will actually do
once we cool it down to 100 picokelvin. No one’s ever
done it before, and no one knows where it will lead.
How exciting!