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NARRATOR: Our world, our solar system,

our universe.

None of it would exist

without a ghostly particle called the neutrino.

They can pass right through a wall, right through a planet, through a star without even noticing.

They are our early warning system.

Whenever there's trouble in the universe

you can expect a flood of neutrinos.

Neutrinos trigger star killing explosions.

Supernovas.

Neutrinos can answer so many questions,

from why do we exist to how was the universe created.

These tiny particles save the infant cosmos from annihilation.

They cause destruction, you know, sometimes they blow up a star,

but at the end of the day,

they can be the very reason that we exist at all.

Neutrinos are the key to how the universe works.

(EXPLOSION)

In the 1960s, our sun appeared to be dying.

There was tantalising evidence

that our sun might be shutting down,

this question was a biggy for astronomers,

if the sun isn't undergoing nuclear fusion

at the rate we thought it was, then that's a big deal.

Was the sun's nuclear core shutting down?

Stars, including our own sun, are giant nuclear fusion reactors.

Inside these fusion reactors, hydrogen atoms smash together...

producing heat and light in the form of photons.

All the light and all the heat that we receive on Earth

comes from the sun,

if the sun were to suddenly start cooling off,

that would be seriously bad news for us.

How do we check if the sun is shutting down?

We have spacecraft monitoring the solar surface.

But they can't see into the heart of the reactor, the sun's core.

You can see the surface, and the sun is very bright,

that makes it very easy to study,

sadly, the core of the sun is under 400,000 miles of sun,

and that makes it pretty hard to look at.

Studying the light made in the core doesn't help.

By the time it gets to us, it's old news.

Imagine a photon, or this particle of light

that's born in the centre of a star,

and now imagine that it wants to reach the surface of the star,

it turns out that the star is so dense in the centre

and the star itself is so physically large,

that it will take it 30,000 years to escape the core.

It's like being at a cocktail party,

where you're trying to leave

and every time that you make another step towards the door

another group of people wanna talk to you.

And you also wanna talk to them.

And then it just takes 30,000 years to leave your cocktail party.

Any information we get from sunlight about what's going on in the core

is tens of thousands of years old.

If you want the current events,

the news headlines of what's going on in the sun's core,

right now, photons are not the way to do it, you want neutrinos.

So, what are these mysterious particles?

Neutrino literally means tiny neutral one, right?

We think they carry no net electrical charge,

and they're really, really small, so we call them neutrinos.

Neutrinos don't like to interact with matter.

They fly through almost everything.

The sun itself is generating enough neutrinos

to send 60 billion of them through your thumbnail

every single second,

and you will spend, this is the craziest thing,

you will spend your entire life without feeling a single one.

Neutrinos form during nuclear fusion reactions

inside the core of stars.

Hydrogen atoms collide, fuse into helium

and release photos of light and neutrinos.

In the core of the sun, nuclear bombs are going off,

and all of these nuclear reactions release neutrinos.

That's about ten trillion, trillion, trillion

neutrinos being created every second.

The trillions of neutrinos shoot out of the core

and up through 323,000 miles of the sun to the surface.

A neutrino basically doesn't even notice the sun is there,

it sails out at very close to the speed of light.

If you imagine a gridlocked highway,

the neutrinos would be the motorbikes

that are just zooming through the traffic.

The solar neutrinos race towards Earth.

Most pass straight through.

All the neutrinos, the trillions upon trillions of neutrinos

passing through the Earth every single second,

the entire Earth will only interact

with one neutrino out of ten billion.

Because they pass through anything, they're hard to detect.

I consider neutrino physicists

to be the ghost hunters of the particle physics realm,

because we study something so elusive,

and they're really, really hard to nail down and study.

Hard but not impossible.

While most neutrinos pass through Earth,

a few collide with atoms in the planet,

and we can detect those collisions.

To spot these tiny impacts, we built underground neutrino detectors

with giant sensors full of chlorine.

When a neutrino strikes this chlorine atom,

it transforms into argon,

and then we can pick out the argon atoms from the detector

and count them up to see

how many neutrinos actually struck our atoms.

The sensors detected neutrinos from the sun,

but the numbers were lower than expected.

Detectors were only detecting

about a third of the number of the neutrinos

that their models predicted.

This is called the Solar Neutrino Problem.

That is a big deal,

that either means we're doing something wrong

or our physics is wrong.

Where were the missing two thirds of the solar neutrinos?

They weren't AWOL, the detector had missed them

because neutrinos can change identities.

And it turns out neutrinos can change

what kind of neutrino they are as they're flying through space.

And we call this flavour changing.

Neutrinos come in three different flavours.

Think of them as different types of playing cards.

The king is the electron neutrino,

the muon neutrino is the queen, and the jack is the tau neutrino.

The sun produces electron neutrinos,

but by the time they reach Earth they could be a different flavour.

As they travel to the Earth

they constantly wave back and forth,

trading their identities,

so you never know exactly what you're gonna get

until it arrives at the Earth and we observe it.

It could be anything.

The detectors weren't seeing the different flavours.

But when we fine-tuned the sensors we saw all the solar neutrinos.

So, there were enough neutrinos coming from the sun,

but we were detecting a third of them.

Flavour changing neutrinos showed the sun was healthy.

The changing identities also answered an important question

about neutrinos, do they have mass?

Einstein showed that only particles without mass

can travel at the speed of light,

and these particles don't experience time.

But neutrinos can change their flavour,

so that must happen over time,

and that means neutrinos can't travel at the speed of light,

and so, they must have mass.

When scientists first started thinking about neutrinos

they thought that they were massless,

and if a neutrino has no mass

then it's bound to be one flavour or one type of neutrino forever.

Experiments proved the neutrinos have mass.

And if they have mass they must produce gravity,

which means, they can influence other things around them.

Neutrinos are also involved

in moments of huge, cosmic violence.

Whenever there's trouble in the universe

you can expect a flood of neutrinos.

These floods of neutrinos are the key

to some of the biggest bangs in the cosmos.

And new research suggests that without them,

there would be no solar system, no planets and no us.

Neutrinos are one of the smallest particles in the cosmos.

However, new research suggest they play a role

in some of the universe's biggest events.

Exploding stars, called supernovas.

The deaths of giant stars.

But there is a mystery surrounding their explosive ends.

Why do these giant stars end their lives so violently?

This is a major puzzle in astrophysics.

We got a lead when we detected a huge flash of light

in the Large Magellanic Cloud, a satellite galaxy of the Milky Way.

The light was a supernova explosion.

But three hours before the flash, astronomers spotted something else.

A burst of neutrinos coming from the same region of the sky.

This was the first time we have seen neutrinos coming from a source

other than the sun,

so, there must be some sort of connection

between neutrinos and supernova, but...but what is that connection?

To find a link we need to travel deep inside a giant, dying star,

where a battle is raging.

A star owes its existence to the careful balance

between the force of energy flowing out of the core of the star,

and the force of gravity pushing in toward the core of the star.

So, if these forces go out of balance something's gonna change.

That balance changes as the giant star starts to age.

When nuclear fuel runs out in the centre of a star,

fusion shuts down, gravity starts to take over.

Gravity makes the star collapse.

The extra pressure triggers a new burst of nuclear fusion,

making heavier elements and more energy to support the star, for now.

That process works fine

as you build up heavier and heavier nuclei

all the way to iron.

And then it tries to fuse that iron into heavier elements

to get some more energy out of it, but it can't.

Creating iron doesn't release energy, it uses it up.

That means that when a star gets iron in its core

it's like you've poisoned the nuclear process.

You have this massive,

crushing weight of the star with a core of iron,

and nothing left to support it.

So all that material crushes and squeezes that iron core down,

squeezes it so tightly

that all the electrons get shoved inside of the protons,

turning them into neutrons.

And very, very quickly you convert this massive ball of iron

into a very small, very compact neutron star.

When a star runs out of fuel, its core crushes down to a neutron star,

then the rest of the star collapses inwards,

hits the neutron star and bounces out,

triggering a supernova.

The computer models of supernovas reveal a problem,

the star doesn't explode.

When we run computer simulations of how supernova might work,

after this bounce the explosion stalls, it peters out,

the supernova isn't so super,

it needs another source of energy to propel it

to become an actual explosion.

Could the neutrinos that appeared before the explosion

be that energy source?

First, we need to understand what created the burst of neutrinos.

The core of the star collapses inward,

and eventually, the outer layers of the star fall in toward that star

at an appreciable fraction of the speed of light.

As the core rapidly collapses,

the intense pressure squeezes atoms together.

That core of iron gets squeezed down

to become a neutron star.

The electrons and protons that are part of its core

are under so much pressure that they fuse together

to form neutrons and neutrinos in the process.

The neutrinos shoot out from the newly formed neutron star core,

carrying an enormous amount of energy.

99% of the energy is carried by the neutrinos.

Neutrinos are the main event.

Trillions of neutrinos smash into the remains of the dying star.

And when those neutrinos are flying out of that core region,

a very tiny fraction of them interact with the gas.

And that fraction heats the gas.

Everything that's hanging around these new born neutron star

get heated to an unimaginable degree.

The heat creates pressures in the surrounding gas.

It builds and builds until it triggers an enormous shockwave.

And then the actual explosion, the actual firework show begins.

(EXPLOSION)

The star explodes

in one of the brightest events in the universe.

Powered by neutrinos.

We think that if it weren't for neutrinos,

supernovas might not even exist.

And we might not exist either.

Our bodies contain heavy elements

like calcium in our bones, and iron in our blood.

These elements form in supernovas

and are scattered across the cosmos by the blast.

Neutrinos are what kindle the fire

in the forges of these elements

and without the neutrinos you don't have the elements

and without the elements you don't have planets like the Earth

and without planets like the Earth, you don't have life.

There's this common phrase, you know,

we are stardust which is true,

but I like to think we're more like neutrino dust.

Neutrinos reveal how supernovas explode,

and they also warn us when one is about to detonate.

The neutrinos can even be these ghostly signposts

for something very violent that's happened in the universe, right?

We detect a sudden burst of neutrinos,

it could be that a star has gone supernova somewhere.

Neutrinos are an early warning system

because they barely interact with anything,

they race out of a dying star ahead of the light.

The neutrinos just slip right on through,

cos remember, they're ghosts, they're ninjas,

they get right through and they can arrive at the Earth

before the light does.

Supernovas happen suddenly, without warning,

so we rely on neutrinos to give us a heads up.

Neutrinos from supernova actually get to us faster than the light,

within tens of seconds we're seeing neutrinos hit our detectors.

If you have multiple detectors on the Earth,

they will all receive the same neutrino blast

as it washes over the Earth,

but different detectors

will receive that blast at different times.

And you can use that to triangulate on the sky

where that blast came from.

And we can use that as a warning signal

to alert our telescopes around the country

to look in this direction, in this portion of the sky,

because a firework display, supernova, is about to happen.

This gives us the time to focus our telescopes on the supernova

and watch the light show as it follows the initial neutrino burst.

Neutrino bursts are cosmic watchdogs alerting us to danger.

Neutrinos are definitely a sign

that something troubling is happening.

And in 2017, a single neutrino told us about something very troubling.

One of the most intense sources of radiation in the universe,

and it was pointing right at us.

Spring, 2017,

scientists at the South Pole are on the lookout for neutrinos.

These ghostly particles are extremely hard to detect.

Neutrinos are the biggest introverts in the universe,

they just don't like interacting with anything.

So if you wanna detect these things,

you need a lot of stuff and you need a lot of atoms in one spot.

So scientists built a facility with lots of available atoms.

It's called IceCube.

With neutrino detectors buried deep beneath sheets of ice.

It turns out that water is a very, very good detector of neutrinos.

To catch neutrinos, you need to build a very large target

for a reasonable cost.

Large areas of ice checks both boxes.

So you need a lot of water that's very, very clean.

What's the cleanest source of water on the planet?

The Antarctic ice sheet.

The Antarctic detector IceCube measures 3,280 feet across.

That's about the length of nine football fields.

It contains 5,000 sensors surrounded by more water atoms

than there are stars in the universe.

So if you wanna catch neutrinos colliding with other particles,

the thing you need to do is put a lot of targets

in front of that gun, right?

You need to pack a lot of particles in the path of the neutrino

to give it a higher probability of interaction.

The actual detectors are holes, drilled in the ice.

And these holes contain chains of detectors

that are three times longer than the tallest building in the world,

and these are sunk down into the ice

and use all that incredible volume of ice to detect neutrinos.

September 22nd, 2017.

IceCube detects a neutrino colliding with a water atom.

When a neutrino hits an ice atom inside of IceCube,

a charged particle flies out,

and it's this charged particle that makes a signal we can detect.

The ejected particle appears to fly out faster than the speed of light.

At first glance, this looks like

it violates something very important about physics,

that nothing can travel faster than light,

but light slows down

when travelling through a medium, like air or water,

and it is possible for other things,

other particles to outrun light in a medium.

As it hurdles through the ice,

the particle generates a burst of blue light

called Cherenkov radiation.

It's almost like a sonic boom,

if you travel faster than the speed of sound there's a boom.

When you hear that boom, you also see this cone of wind.

It's the same thing with Cherenkov radiation,

you get this cone of light.

Neutrinos carry different amounts of energy.

Some, like the 2017 neutrino, carried quite a punch.

And the energy of the neutrino depends on its source.

High energy neutrinos come from high energy events.

So we're looking for stuff blowing up,

we're looking for stuff colliding,

we're looking for stuff colliding and blowing up,

we're looking for awesome things.

The blue burst of Cherenkov radiation gives us a clue

about the fearsome origin of the neutrino.

We can follow the path of that blue light

and we can look backwards to see where the neutrino came from.

We tracked the neutrino to a galaxy nearly six billion light years away.

At its heart sits one of the most powerful objects in the universe.

A blazar.

A blazar is the biggest, baddest form of feeding, active,

super massive black hole out there,

where material isn't just falling into the black hole,

it's swirling around creating a high energy accretion disk.

The blazar's accretion disk spins at millions of miles an hour.

Charging particles of gas and dust.

The disk also generates magnetic fields that twist and tangle

as they swirl around the black hole.

Because you have magnetic fields that are twisted around,

they also generate electric fields.

The electric fields can then accelerate the charged particles

along the magnetic fields,

and thus produce a lot of both particles and radiation

coming out along jets.

The jets blast out of the poles of the black hole.

These are the most intense sources of radiation

that the cosmos can ever produce,

and they are pointed right at us from billions of light years away.

Do the jets create the powerful neutrinos?

It's a big of a mystery.

For a while it was thought that neutrinos are produced directly by the jet,

but now we think that matter, like protons,

come in from the accretion disk and they slam into each other,

and that's what produces the neutrinos.

Particles racing around the accretion disk

crash into the base of the jet.

The enormous energy there smashes the particles together,

producing neutrinos.

The jets focus the stream of neutrinos

and fire them straight towards Earth.

By just detecting one neutrino, we get to see a lot of information

from the inner workings of an object outside of our galaxy

and that's what's exciting about neutrinos,

is that it could peer into the unknown.

Now, we use neutrinos to probe even further into the universe.

Back towards the first second of the Big Bang.

To answer the biggest question of them all,

how, and why, do we exist?

The fact that our universe

appears to be filled with matter is puzzling.

There should have been equal amounts of matter and anti-matter in the beginning

and they should have annihilated one another, producing just pure energy.

So why do we exist?

This is a fundamental question, because this is a question

about why is there something rather than nothing?

To answer that question, we have to rewind the clock back

nearly 14 billion years to the birth of the universe.

A speck of energy sparks into existence.

This energy cools and forms tiny, primitive particles of matter,

including neutrinos.

The building blocks of everything we see today.

The early universe appears chaotic,

but it quickly establishes some ground rules, including symmetry.

Our universe is full of symmetries.

There are positive electric charges and negative electric charges.

There's the yin and the yang.

Well, there's also matter and anti-matter.

The Big Bang stuck to the rule of symmetry

and made the same amount of both forms of matter.

The mechanisms that we have

for creating matter in the early universe

create an equal amount of anti-matter,

that symmetry is baked into the laws of physics.

The laws of physics also say that when matter and anti-matter meet,

sparks fly.

So matter and anti-matter, when they touch they annihilate,

they just disappear in a flash of energy.

And as far as we understand, the earliest moments of the universe,

matter and anti-matter were created in equal amounts,

so they should have annihilated

leaving nothing but energy.

Which means no matter, no anti-matter, no gas, no dust,

no stars, no galaxies, no life, nothing.

Somehow, matter won the battle over anti-matter in the early universe.

In some ways, the universe ignored the rule of symmetry.

Something has to drive the universe off balance.

There has to be a violation

of this fundamental balance in our universe.

That way, when the matter and anti-matter met and annihilated,

because there was more matter,

there would be a residual of left over matter

and there would be no anti-matter.

How did the Big Bang break the symmetry

between matter and anti-matter?

So we're looking for any interaction, any process whatsoever

where matter behaves slightly differently than anti-matter.

We're trying to find a flaw in physics.

We can't look for that flaw directly because we can't see the Big Bang,

but we can recreate it, and we think neutrinos are involved.

This is incredibly complicated,

we are diving deep into the bowels of fundamental physics

and it is not a pretty sight.

Japanese scientists conducted an experiment called TK2.

They recreated part of the Big Bang by studying neutrinos

and their symmetrical twin, anti-neutrinos.

The goal? To see if anti-neutrinos change their identity, or flavour,

at the same rate as regular neutrinos.

Matter and anti-matter should behave exactly the same.

But we found something very interesting with this experiment.

The particles broke symmetry.

Neutrinos and anti-neutrinos changed flavour at different rates.

This was a clear cut example

of matter behaving differently than anti-matter.

And that has revolutionised our understanding

of the formation of particles during the Big Bang.

What could have happened in the universe

is that more of the neutrinos converted into matter

than there were anti-neutrinos became into anti-matter,

and in this way you end up with a surplus of matter over anti-matter.

Even though that surplus was just one particle in a billion,

it was enough to build the cosmos.

So neutrinos, in the early universe could possibly solve

the matter, anti-matter asymmetry problem we have.

Yes, they caused destruction,

you know, sometimes they blow up a star,

but at the end of the day they... they did save the entire universe.

Now, scientists hope that neutrinos

may solve one of the biggest mysteries in the cosmos,

the identity of dark matter.

Neutrinos have been around since the birth of the universe.

They may even be responsible for the formation of matter.

Now, we investigate if they play an even larger role

in the development of the universe.

The formation of the cosmic web.

At the very largest scales in our universe,

our galaxies are arranged in a very peculiar pattern.

We see long, thin threads of galaxies

and at the intersections we see dense clumps of galaxies called clusters.

In between them we have these vast empty regions

called the cosmic voids.

For a long time, how the cosmic web formed

and held together was a mystery.

One of the real mysteries about our existence

is why the universe was able to hold together at all.

All the matter was simply spread apart too sparsely

to ever form galaxies or stars.

Instead, something helped to hold it together.

We now think the glue binding the cosmic web

is a mysterious substance known as dark matter.

If it wasn't for dark matter in the very early universe,

there might be no structure at all.

But what is this architect of the universe?

This dark matter?

Dark matter is invisible matter that we can't see,

so you, me, all of the particles, everything that we see,

is actually only five percent of actual matter in the universe.

The rest is dark matter.

Dark matter is a fancy name for something we don't understand.

What we do know is that there is much more stuff than we can see,

but have no idea what it is.

It's one of the greatest open mysteries in science.

Dark matter hardly interacts with anything.

A bit like neutrinos.

Also, like neutrinos,

dark matter was abundant and active in the infant universe.

So, could neutrinos and dark matter be the same thing?

PHIL: We don't know what dark matter is but we kinda know how it behaves

and neutrinos sound like a pretty good candidate for it,

because, hey, they are dark, they are everywhere in the universe

and they have a little bit of mass.

And by little, we do mean little.

Neutrinos weigh around 10 billion, billion, billion times

less than a grain of sand.

But neutrinos are also exquisitely abundant

and so because they're so abundant,

their individual tiny mass can actually add up

to a large diffuse mass on very large scales.

To investigate if neutrinos and dark matter are the same thing,

we must return to the Big Bang.

As the universe expands and cools, primitive matter forms,

including dark matter and trillions of neutrinos.

The dark matter clumps together forming regions of higher gravity,

which pulls in regular matter.

It formed a structure of scaffolding that allowed regular matter

to gravitationally begin to come together

and collapse into galaxies, stars and planets.

Could the combined mass of neutrinos in the early cosmos

have produced the extra gravity to help structures form?

Could it be possible that this really is dark matter?

These tiny little particles, but in abundance across the universe.

And we know more, not all,

we know more about neutrinos than we do about dark matter,

but there's still a question around whether or not

neutrinos can be a specific type of dark matter.

To answer this question,

we have to work out what specific type of dark matter was around

in the Big Bang.

Hot, or cold.

People talk about hot dark matter and cold dark matter,

and really what you're saying is the speed of the particles themselves.

The cold dark matter is moving slowly,

and the hot dark matter is moving fast.

This speed difference is an important clue

to whether neutrinos make up dark matter.

With hot and cold dark matter,

the way they interact with regular matter has a lot to do with how fast they're going,

so it's a good analogy to think about a river.

With hot dark matter, you'd have a torrent,

basically it's going so fast it doesn't actually connect with anything,

it just goes right on past,

so there's no chance to form that larger structure.

If you have relatively slow moving dark matter, cold dark matter,

think about a slow moving river.

A slow moving river begins to deposit silt.

Think of that silt as the billions of galaxies

that make up the cosmic web.

We observed that galaxies formed very early in the universe

and this is good for cold dark matter,

but it doesn't work for hot dark matter,

so we think cold dark matter is really dominating structure formation in the early universe.

But cold and slow does not describe neutrinos.

They move very fast, close to the speed of light.

This is a problem with neutrinos,

because neutrinos would be hot dark matter.

That rules out neutrinos as cold dark matter.

The idea that neutrinos are dark matter, hit another set-back

when we weighed the universe.

If you add up the total mass of all the neutrinos in the universe,

it would wind up being about a half a percent to 1.5 percent

of the total mass of dark matter.

Neutrinos were a good candidate for dark matter

because they exist

and they're very shy just like the dark matter particles are.

But then, we were able to measure more accurately

how much dark matter there is and how much neutrinos there are

and there are just way less neutrinos than there's dark matter.

Neutrinos do have mass and there are a lot of them out there,

so it might be some tiny, tiny fraction

of dark matter is made up of neutrinos,

but we know that these things do not make up the bulk of dark matter,

it must be something else.

So neutrino scientists

hunt for a different contender for dark matter,

a completely new kind of neutrino.

We know about three flavours of neutrinos.

The electron neutrino, the muon neutrino and the tau neutrino.

But there could be a hidden fourth flavour of neutrino

that could solve the riddle of dark matter.

We call this a sterile neutrino.

So called because they interact even less than regular neutrinos.

A particle so tiny, so hard to detect,

could turn out to have lots of the secrets

wrapped up inside it as to how the universe works.

The first step to find out if sterile neutrinos are dark matter,

is to prove they exist and that's tough.

Even though sterile neutrinos are almost impossible to detect,

we can still hunt for them.

Back in the day, neutrinos were also said

to be difficult to detect.

Trying to find dark matter, trying to find these sterile neutrinos,

it's almost like using one invisible,

undetectable thing to find another, using a ghost to find a goblin.

We are definitely pushing the limits of science.

A team at Fermilab has an ingenious idea.

They can't spot sterile neutrinos directly

because they don't interact with atoms in the detectors.

So they're looking for neutrinos

as they change flavour into sterile neutrinos.

We know that normally neutrinos change type

as they move through space,

but they have to move far enough before that change happens.

So tracking neutrinos over a short distance

shouldn't show any flavour changing.

In this experiment they've constructed only a half mile long path,

it's not enough time for the neutrinos to change flavour in the normal way.

If they do see something, if they see something change,

this could be some interesting aspect,

perhaps evidence for sterile neutrinos.

So is it possible that over short distances,

regular neutrinos can oscillate into this sterile neutrino?

The team shoots beams of muon flavour neutrinos

along the detector.

In theory, they won't have time to change flavour.

We can see whether or not these muon neutrinos

morphed into a different type of neutrino.

They shouldn't change,

but if they do that points us towards sterile neutrinos.

The team compare the number of muon neutrinos reaching the detectors

to those fired along the beam.

Fewer muon neutrinos hit the detectors,

some neutrinos had changed flavour.

So we are seeing that oscillation of neutrinos

changing from one type to another.

We had an idea of how many we should have seen,

but we're seeing more, and that could be sterile neutrinos.

If sterile neutrinos do exist, would they be dark matter?

Right now, we don't know the mass of the sterile neutrino.

But if it's heavy enough, it could be a contender.

If it exists, it's prevalent enough

to account for all the dark matter in the universe.

Fermilab's results haven't been verified by other scientists.

So, it's too soon to say definitively

that sterile neutrinos are real.

Or that they make up dark matter.

Dark matter is probably one of the biggest questions of our time

and the fact that Fermilab may be one of the places to answer that question,

and the fact that I am working here, is really fantastic,

because we're attempting the impossible.

We have to wait to see if the impossible is possible.

We know neutrinos have played a vital role

in the history of our universe.

And even now, they refresh it by powering supernovas.

Without them, our sun...

our world and even our bodies, would not have formed.

Neutrinos are pesky little particles,

super elusive, difficult to study,

but when you can catch them they offer secrets to the universe.

The story of neutrinos has been interesting, it's like reading and you're on the last page,

and then you turn it and suddenly there's a hundred new pages.

Neutrinos are teaching us

that the universe is, in many ways, subtle and hard to figure out

and the more we learn about these things

they more we learn about the universe.

Neutrinos are the universe's great escape artists,

the Houdini of particles.

In fact, they may have helped us to escape the Big Bang

and end up existing.

At the end of the day, they're what saves us.

The more we understand these elusive particles,

the more we can gain insight into how the universe works.

So, it's really cool.

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