Original subtitles

Perhaps that American politician was right.

There are indeed things we know we don’t know.

For instance, cosmologically speaking, we know we don’t know much,

and certainly not nearly enough,

about two of the enduring mysteries of the universe...

dark matter and dark energy.

It’s little wonder that scientists are devoting

so much grey matter and energy of their own

to finding out as much as they can.

Seen any big birds recently?

IceCube has. If you think that’s a cool name, you’re right.

IceCube is an observatory at the South Pole,

and it saw Big Bird back in December 2012.

IceCube is a neutrino telescope located at the South Pole,

or to be more precise, under it.

It consists of over 5,000 detectors

that are spread out into a cube about a kilometer on each side.

It's the world's biggest and it's coolest telescope.

IceCube has detected a handful of extremely energetic neutrinos.

One of them, which is called Big Bird,

has an energy of about two peta-electron volts.

To give you an idea of how much energy that is,

it is about a million, million times the energy of dental X-ray.

Scientists have been using the names of critters

from the popular TV series Sesame Street

to designate major events that may help us better understand

the particles that emanate from space... particles like neutrinos.

So a neutrino is an incredibly small particle,

it moves almost at the speed of light, it is nearly massless,

it's incredibly plentiful, but, it's very, very hard to detect

because it will not interact with just about anything.

If you could detect them though,

because they have traveled through the universe essentially undeflected,

they have information that you could not access in any other way.

The theory is that neutrinos are caused by violent events in space.

In 2012, light from such an event began reaching Earth.

This was a year-long outburst which happened ten billion years ago

in the unromantically named galaxy PKS B1424-418.

What we have been able to establish, for the first time,

is an individual blazar as a potential birthplace of an individual neutrino.

The Fermi Gamma Ray Space Telescope has an instrument

called the Large Area Telescope,

which we use to monitor the gamma ray sky,

the highest-energy electromagnetic band.

And we just noticed that there was a tremendous increase

in the amount of gamma ray light coming from this one extra-galactic blazar.

A blazar is an extremely powerful, variable galaxy

that is powered by a supermassive black hole.

It went up not by a little bit, not by a few percent.

It went up, like, 15 to 30 times its average flux.

So we knew something was afoot.

Later on it turned out to be coincident, both in time and in space,

with the neutrino that was detected by IceCube.

Working in conjunction with NASA’s Fermi X-ray telescope,

IceCube was able to link the cosmic neutrino it observed

with that outburst from the gamma ray blazar,

the first time such a causal link

between neutrinos and a single extragalactic object had been established.

The enormous increase in gamma ray flux seen by LAT

and radio flux by other TANAMI telescopes

let us finger the exact blazar which is responsible for Big Bird.

This is the first time that we can point and say,

that blazar is where this neutrino came from.

Neutrinos and gamma rays are what Fermi is all about.

It has already made some startling discoveries.

One of its latest is finding the most distant and oldest blazars.

Blazars are a type of galaxy whose intense gamma ray emissions

are powered by supersized black holes.

These distant objects emitted their light

when the universe was 1.4 billion years old,

or just ten percent of its present age.

That they developed so early in cosmic history

challenges current ideas of how supermassive black holes form and grow.

Fermi has received an upgrade to improve its capabilities.

We see gamma rays,

which are are the highest-energy form of light,

and with each object that we see these gamma rays from,

what we're doing is exploring some of the places in the universe

with most extreme environments.

The kinds of objects that it can study

are pulsars and neutron stars, black holes, as well as dark matter.

So, to analyze these events

we have written a very long and complex program

that basically uses all the information that was recorded by the instrument

and figures out what is the direction of the gamma ray, its energy,

and whether or not it's a real gamma ray

and not a charged cosmic ray.

So, obviously, software is really important for the LAT.

The software that we use to analyze the LAT data

has gone through many revisions over the course of the mission,

but Pass 8 is really the first revision of the software

where we took into account all the experience that we gained

from operating the LAT in its orbital environment.

Pass 8 has made everything better,

but one of the things that it's made better

is that it's allowed us to open our gamma ray eyes

to higher energies before, so that's a completely new view,

and it's allowed us to open our gamma ray energy eyes too--

at energies lower than before, so that's another completely new view,

in addition to improving everything across the entire energy range.

The improvements that we've made to the software

retroactively apply to all the data that we've collected.

And so, these improvements significantly enhance

what we can do with the data that we already have, as well as the data that we'll collect in the future.

Fermi’s talents have also been concentrated

on the search for dark matter. And in doing so,

it has observed unusual behavior in objects that remain unexplained. For instance, Fermi has discovered a gigantic structure in our galaxy,

with what looks like bubbles extending above and below the galactic center.

these enormous gamma ray emitting lobes.

Each lobe is 25 light years tall,

and the entire structure may be only a few million years old.

Within these clouds, extremely energetic electrons

are interacting with low energy light to produce gamma rays.

But no one knows the source of these electrons.

When studying these massive objects,

scientists must look at the other end of the size spectrum for answers.

Those at CERN in Switzerland

are expecting great things from the Large Hadron Collider

after it too received an upgrade, an increase of power by 40 percent.

In its new, improved form,

it is due to produce far more data than it previously did.

The LHC has already revealed the Higgs boson particle,

one of two types of fundamental particle,

fermions are the other, in our Standard Model of the Universe.

What other secrets might it be about to unearth, as it were?

With an increased luminosity,

we gain sensitivity at the highest energy,

so suddenly we will explore energies that hitherto were not really reachable.

So, if new physics is hidden there, this is the chance to see it.

Some indications that created a lot of excitement with the theorists

were seen with the experiments.

They may be fluctuations, they may be real particles.

As a physicist, of course, I hope that this is new physics already,

but maybe that would be too simple.

The Higgs boson was the last puzzle piece

in the Standard Model of fundamental particles

and the forces which govern them throughout the universe.

What we really want is to understand the universe

and why it looks and acts the way it does today.

Our role as particle physicists are to figure out

what the elementary particles are and how they fit together and interact,

kind of like puzzle pieces, in the way the puzzle pieces fit together

to give us a picture of the universe.

Over the last 120 years or so,

we've discovered all the individual puzzle pieces

that build up to give us a theory called the Standard Model,

which is kind of like the picture on the box.

But we know that it’s an incomplete theory.

What we’ve essentially got is a small section of a puzzle picture

that fits together very nicely and gives us all the particles that we see today,

but we have no idea what the bigger picture is.

The Higgs boson that we discovered in 2012

was the final piece in our Standard Model puzzle,

and it was a fantastic discovery because it completed that small picture.

Now what we can do, is possibly use this Higgs boson

to access the other parts of the puzzle.

So, our Higgs boson becomes like a Rosetta Stone

to talk between the Standard Model particles

and these new, what we call dark sector or hidden sector particles.

So we're going to need to create many, many more Higgs bosons

to be able to start seeing hints of this,

and that’s where the higher energy is useful.

When we go to higher energy, it's almost as if we’re getting a microscope

to look on what we've discovered so far.

It’s possible that there are some very small differences in that Higgs boson

like the way that it decays, that we haven’t noticed yet

because we haven’t had a strong enough microscope.

But with a higher energy collider, with the LHC running at 13 TeV,

maybe that is going to give us a strong enough microscope

so we can see some small differences

between our Standard Model theory and the Higgs boson that we have today.

Maybe that'll give us some hint of some new physics that we can expect to come.

But it doesn't explain why nature prefers matter to antimatter

or what dark matter is.

One theory that has been developed to answer these questions

is what is called supersymmetry.

So, one of the problems that supersymmetry could resolve

is the mystery of dark matter.

So, this is something where astronomers and cosmologists tell us

that there’s an additional source of gravity in the universe

which cannot be attributed to things we can see...

the stars, the nebulae and other things like that.

And so at the moment, this has the mysterious name dark matter.

I think that is, at least partly, because we don't really know what it is.

It's quite reasonable to think that it’s a particle

of a kind that we could potentially produce at the LHC,

and supersymmetry, or at least some forms of supersymmetry,

can... could explain that matter

and predict its properties.

So the main problem, if you ask most physicists, I think,

that supersymmetry would explain is the mass of the Higgs boson.

With the Standard Model as it stands,

we cannot explain why the Higgs boson has the mass it has.

It should be many, many times... many, many times heavier than it actually is,

so heavy that we would have no chance at all of seeing it

in any foreseeable experiment.

And this currently has no explanation.

Supersymmetry would provide a very neat solution to that problem,

but it remains to be seen whether that’s the correct solution or not.

So does dark matter?

It certainly does. It makes up about a quarter of the universe.

What is it? The short answer is, we don’t know.

The phrase was coined in the1930s by Swiss scientist Fritz Zwicky.

Four decades later, Vera Rubin’s studies of galaxy rotation confirmed his thinking.

Galaxies have more mass than observable light would lead us to suspect. One suspect suggested by supersymmetry are the neutralinos,

sometimes called WIMPs, or weakly interacting heavy particles.

These particles act as their own anti-particle...

They annihilate each other

and release a flurry of secondary particles and medium energy gamma rays.

The LHC experiments are very capable to find dark matter.

If, for example, supersymmetry is the symmetry which nature has realized,

then I'm very, very confident that maybe even very quickly

we can find, with the LHC experiment, supersymmetry.

And that would be great.

Imagine we have taken roughly 40, 50 years

in order to find and to really discover the Standard Model of particle physics.

but that only explains four to five percent of the energy

and meta density of the universe.

I think the LHC is the right machine to bring the first light,

to shed the first light into the dark universe.

There are more and more connections

between space research and particle physics,

but on the methodology, for example, and such things,

but also on the science itself there is a very strong connection,

especially through dark matter.

I mean, astronomers and astrophysicists will tell us

in the next, I don't know, ten, 20 years with their modern...

With their new telescopes,

they will tell us how dark matter, for example, has shaped the universe.

And with the LHC, we will find what type of matter that really is.

These are some of the things we know that we don’t know.

But what if new physics tells us there are things we don’t know that we don’t know?

The latest LHC data has turned up some interesting results.

In the data we took last year

we started to see a clustering of events, of diphoton events,

events with two photons at a particular region of mass.

The significance of that is not at this point very high.

With more data, we don't know what's going to happen.

There's a chance it could stay,

but there's also a bigger chance that it will go away again.

But, which is going to happen? We don't know.

Physicists are keen to explore any glitch in the data.

The most exciting thing would be to find something

that is completely outside the Standard Model.

Just... even if it's just a hint that there is something more within our reach,

just to give us an idea of where to look for new physics.

There's gotta be something out there.

We know that our picture is incomplete

and we just have to find the right place to look for it.

For this year... this year's running,

we are running again at 13 TeV center mass energy,

but the big difference this year is we're going to run at a lot higher intensities

and expect to get a much bigger data sample.

So the experiment itself is ready and starting to take the data that's coming,

and it really is ship shape waiting for the new data.

At that point, of course, then we're looking in great detail and great depth

at the data to try and understand what the physics is in the new data.

And there's many different things we will be looking at.

With this new data sample, we will look again

at the known processes of the Standard Model

which we've already seen at lower collision energies,

and we started to understand and to measure with last year's data,

but we will also, of course, look hard at places

where we might be able to see new physics starting to occur.

From the tiniest of subatomic particles

to the immensity of galactic clusters,

scientists and astronomers are looking into the past so as to see the future.

But when you think again about what we're exploring,

when you think about the images that we're going to take,

when you think about how far away and how far back in time we're going to look,

you can't help but feel like you're a part of something that's really important,

that's helping us see, not just about the past of the universe but the past of us,

where we've been and really, where we're going to go.

If discovering the true nature of dark matter is successful,

then we will have put together a picture of about 30 percent of the universe.

There is still a lot more stuff missing, and it's called dark energy.

Scientists have labeled dark energy one of the biggest mysteries in physics.

Dark energy is the name attached to the force

that appears to account for as much as 70 percent of the universe.

Our fixation with dark energy dates from the late 20th century,

when Hubble’s brilliant revelation of supernovae

showed us that the universe, approximately half its lifetime ago,

was expanding more slowly than it is in our time.

It started to speed up around 7.5 billion years ago.

Why? Dark energy is the working name for the amorphous answer

to that specific question.

Is it a property of space itself? Does empty space contain its own energy?

Does that energy increase as more space comes into existence?

Dark energy has negative pressure.

As dark matter is inimical to light, so dark energy repels gravity...

At least, that’s how the theory goes.

And to back it up, one major international effort

is nearing the end of its scheduled working plan.

Begun in 2013, the Dark Energy Survey, or DES, is an international project

linking 400 scientists from 25 institutions

in the United States, Australia, Brazil, Spain, the UK, Germany and Switzerland.

Its chief instrument is a 570-megapixel digital camera, DECam,

attached to the Blanco telescope at Cerro Tololo in Chile.

I'm a member of the Dark Energy Survey collaboration

and I'm here on Cerro Tololo working to help commission the new Dark Energy Camera

that we've just installed on the Blanco Telescope.

The whole purpose of our are project is to understand what is dark energy.

Dark energy was discovered just... less than fifteen years ago,

actually, in fact, using, in part, this this very telescope,

and it was discovered by its effect on the universe.

So dark energy is our name...

and it's just a name that we give to the phenomenon

that's causing the universe's expansion to accelerate.

We're not trying to figure out if dark energy exists.

We're not trying to find it. We know dark energy exists.

We're trying to characterize it.

We're trying to understand what it does to us,

what it does to the universe, to its expansion rate,

and to the gravitational attraction of things like galaxies.

Over five years, the dark energy survey will scan

five thousand square degrees of sky far back in time and far away from us,

in order to measure the distances of supernovae

and the distributions of galaxies.

In some sense, the purpose of our experiment

and what we'll learn by understanding more about what dark energy is,

is to find out about the fate of the universe.

What is going to happen into the future?

Is the universe really gonna keep expanding faster and faster and faster,

or not?

Covering 5,000 square degrees of southern sky,

the DES project is due to complete its search in 2018.

Like the DES, some other exciting discoveries lie, potentially,

just around the corner.

While space-based telescopes continue their tireless scouring of the skies,

their ground-based counterparts are poised on the brink of a dramatic new age.

More than 3,000 meters above sea level, at Cerro Armazones near Paranal in Chile,

ESO’s ELT... that’s Extremely Large Telescope to you and me,

is nearing the start of its working life.

With its stunning five-mirror system, its diameter is an unprecedented 39 meters,

making it the largest optical and near-infrared telescope in the world.

Extremely Large Telescopes are currently

one of the highest-priority areas of development in ground-based astronomy.

On ESO’s ELT’s job list will be the continuing search for exoplanets,

examining the possibility, for example,

of establishing contact with Proxima Centauri b,

one of the likeliest candidates for Earth-like biological conditions.

The ELT, attracting 15 times more light

than the largest telescopes in operation today,

will help detect water and organic molecules,

a major step forward in our quest for extraterrestrial life,

and make possible direct measurement of the speed of acceleration

of our universe’s expansion.

Will it provide some of the answers we seek,

or will they show us, collectively, that we don’t yet even know what we don’t know?

Is gravity an illusion?

Do we need a new theory of gravity on a cosmic scale?

As Einstein himself observed,

the most beautiful thing we can experience is the mysterious.