So we have lots of tools to study the universe.
We have very powerful telescopes that can
look out at galaxies and stars, and one of
the first puzzles that was discovered a few
decades ago is that stars move too fast.
People can add up all the visible matter of
the stars, hot gas, and so on, and it’s
not enough to explain how fast the stars revolve
around the center of the galaxy.
It’s as if there’s something there that
no telescope can see, and that’s dark matter.
So there’s really a wide consensus that
dark matter exists.
However, nobody to date has ever directly
detected dark matter.
What we do know is that there’s a lot more
dark matter than visible matter, and it must
permeate everywhere.
It must be moving through us right now.
There are many possibilities for what dark
matter might be and the prevailing theory
over the last few decades is that the dark
matter might consist of a weakly interacting
massive particle, called a WIMP.
So the way people have been searching for
these WIMPs is by building large detectors.
Picture a swimming pool roughly the size of
a house.
And if a WIMP were to pass by and interact
with an atom inside this swimming pool,
it would produce a little flash of light that
a bunch of photomultiplier tubes, which are
very sensitive light detectors, would detect.
But, after several decades of searching with
these detectors, people haven’t yet found
a WIMP.
However there’s another theory for what
dark matter may be.
And that’s a different particle called an
axion.
And that’s what we’re looking for.
Axions, if they exist, are very different
from a WIMP.
For starters they are much lighter.
So a WIMP is roughly the weight of a neutron
or a proton, and an axion is much lighter
than even a neutrino.
Because an axion is much lighter, it’s probably
easier to think of them as a wave rather than
a particle.
Searching for axions is very different to
searching for WIMPs.
We’re starting up on a much smaller scale.
So in a lab roughly the size of your kitchen
picture a bucket, and inside this bucket there’s
a few samples that basically act like little
magnets.
And if the axions exist what will happen to
the these little magnets is tiny little gyrations.
And we have very, very sensitive magnetic
field sensors that are designed to pick up
these gyrations.
Of course there are a lot of things that might
make these magnets gyrate, such as your cell
phone or a truck going by outside on the street.
And so a huge part of our job is to shield
out experiment well enough so that what we
detect is not some interference but could
only be caused by axions.
Our goal is to make a really, really sensitive
experiment so that eventually when everything
works correctly, hopefully we can hear this
axion field.
And we can see our motion through it.
It’s something that no one’s ever tried
before.
We’re really doing something that we as
a human race don’t know how to do.
Have never known how to do.
Have never tried.
