Here I am at the IceCube Laboratory, which
is part of the larger IceCube Neutrino Detector. Which is the biggest, most expensive experiment
here at the south pole, and one of the largest in the world. If you're thinking that there is no way this
little building could be a world-class physics experiment, I wouldn't blame you. But looks are decieving; the real magic of
IceCube isn't in this building. It's deep in the ice of Antarctica. Here, deep in the ice below the south pole
station, you'll find the workhorse of the IceCube Observatory: the Digital Optical Module,
or DOM. The DOM is an advanced sensor designed to
detect effects of neutrinos in the ice. The DOM is constructed of many different parts. There's the glass pressure sphere that protects
the DOM from the crushing pressure of the ice, and the pressure band that holds the
two halves of the sphere together. There's the photomultiplier, which is basically
a light sensor that is really really sensitive, which is important for detecting neutrinos. Then there's what's called the mu-metal cage
which helps cut down interference with the sensor. There's the main circuit board, and then there's
the "flasher board" which has light on it so that DOMs can signal each other within
the ice and help calibrate the experiment. This function is pretty important, because
there are over 5000 of these DOMs deep within the ice, that all need to be coordinated and
calibrated. All the DOMs are strung together on a cable,
and the first DOM is at a depth of 1450m, or nearly a mile deep. The deepest one is at 2450m, or one and a
half miles deep. Each string of DOMs is taller than the Burj
Khalifa, and the whole array encompasses about a cubic kilometer of ice... hence the name,
IceCube. Okay so what are neutrinos, where do they
come from, and how does IceCube detect them? To put it in very simple terms, a neutrino
is a fundamental physical particle, like an electron or a photon. It travels very fast, at nearly the speed
of light. And it almost never interacts with normal
matter; the vast majority of the time, neutrinos just pass right through matter without leaving
a trace. In fact, right now there are trillions of
neutrinos passing through your body every second, but you can't feel them. This last quality is what makes neutrinos
so difficult to study. If a particle almost never interacts with
matter, then you need a very large amount of matter to give you the best chance of detecting
it. Also, on the rare occasion that a neutrino
does interact with matter, the reaction produces light. So you need the matter in your detector to
be very very clear, because if you can't see the light, you can't detect the neutrino. That's why IceCube is designed the way it
is; thousands of detectors, in a large amount of very clear ice, in a dark place. So where do neutrinos come from? Well they can come from a number of sources,
like the sun and nuclear reactors... but what IceCube is looking for, is something special. It's looking for high-energy neutrinos that
come from outside our solar system, and I'm going to tell you the story of one that turned
out to be kind of important for astronomy. Like so many great stories, we have to start
a long long time ago, in a galaxy far far away. But not this galaxy, this one's too nice,
I'm looking for a fuzzier one. Here we go. This is the galaxy TXS O506, and although
you've probably never heard of it, it holds one of the most powerful objects in the universe.... a blazar. Blazars are basically supermassive black holes
that gobble up matter around them, and in turn start spewing out high energy particles,
like neutrinos, in powerful jets. So this blazar TXS 0506 gobbles up a star
or something and spews out all these high energy neutrinos. Now the unique thing about blazars compared
to other supermassive black holes is that their jet of particles is pointed right at
our solar system. So our neutrino speeds off towards from the
blazar and heads toward earth at almost the speed of light, but even so, it still takes
a few billion years to get here. Finally, in September 2017, the neutrino passes
through the earth and into the ice of IceCube's detector field, and lucky for us, it decides
to smash into a hydrogen atom there, resulting in shower of light within the ice. Within seconds, the IceCube computers were
able to create a model of its path through the ice, and get an idea of where it came
from. This triggered an automatic alert sent out
to telescopes around the world to look at that area of the sky, and when they did, they
saw a burst of radiation from the blazar, which basically confirmed that that's where
the neutrino came from. This whole event was important for 2 reasons:
For one, it was the first time scientists could say with some confidence that we had
found the birthplace of a high energy neutrino, and two, it was one of the earliest demonstrations
of what's called multi-messenger astronomy, which just means taking two very different
experiments, like a neutrino detector and a conventional telescope, and using them together
to study the stars. But lets get back to the laboratory. Because there are over 5000 optical sensors
running 24/7, IceCube is constantly generating a massive amount of data, and that data needs
to be processed and refined before being sent back to the primary host of the project, the
University of Wisconsin. That refinement process is the main function
of the building, which is called called the IceCube Laboratory. So when you first walk in to the IceCube Laboratory,
it actually looks kind of unassuming, despite it being one of the biggest physics experiments
in the world. This first room is just a workshop for building
maintenance, etc, but through here is where we have the electronics workshop, where the
scientists can do small repairs to the electronics if they need to. And then here we have an example of one of
the many many sensors that are down in the ice. All the data they're collecting goes upward
through this cable and upstairs to the server room, which I'll show you right now. You might have seen the snacks I was standing
next to, and those are there because you never know when you're going to get hit with bad
weather. There's also a bed in the building for the
same reason. So I've come up to the server ante-room, which
has all the readouts of all the data that are coming in. Also, the sensors that monitor the temperature
in the server room. And then this screen right here tells them
the status of all the sensors in the ice. And then through here is the server room. But first I got to get anti-static jacket
on. OK, so this is the server room. This is probably one of the biggest power
draws on station because all these computers are going all the time, getting all the data
up from the sensors, filtering it, refining it. As you can see tons of server racks here. This whole entire row going all the way down
is just all servers. And if you look above me, there's actually
these giant cables coming in from each side of the building. And these are cables coming in from the sensors
feeding all that data upward so you can see how big and thick these cables are. There's two layers of them, and they're coming
in from two different sides, so a ton of data. The first time I walked through here, I was
just overwhelmed by the just terabytes of data. They're just flowing around me all the time. A couple other unique things about the IceCube
server room. It's actually the only actively cooled room
on the entire South Pole Station Complex; every other room is actively heated. It also uses an FE-13 fire suppression system
to protect the electronics, so if you hear the alarms go off, it's probably smart to
leave as quickly as possible. Besides being a world-class experiment, IceCube
is also one of the furthest buildings away from the elevated station. So it's nice to go up on the roof on a nice
sunny day and take in the views of the plateau. That's all for IceCube. Remember to like and subscribe if you'd like
to see me make more of these videos, and keep an eye on my channel for the next video where
I tell you all about the South Pole telescope.
