Original subtitles

NARRATOR: Supermassive black holes,

the engines that power our universe.

Supermassive black holes are one of the major players

in the evolution of galaxies.

With no supermassive black holes, you have no Milky Way Galaxy,

no sun, no Earth, no you.

They're the driving force at the heart

of nearly every galaxy in the cosmos.

They are the most monstrous and scary and bizarre aspects

of our world, which just fascinates me.

Now, a new mystery has emerged

about the oldest supermassive black holes.

We see supermassive black holes in the very early universe.

And we don't understand how they grew so large so quickly.

We have clues about their formation.

But can we solve the mystery

of this supermassive growth spurt?

(ELECTRICITY BUZZING)

(EXPLOSION)

2017.

Scientists gazing deep into the distant universe

discover something completely unexpected...

..a vast supermassive black hole

dating from the earliest days of the universe.

CHIARA: This was 690 million years after the Big Bang.

The universe was about 5 or 6% of the age that it is now.

HAKEEM: Finding a supermassive black hole in the early universe

is like finding an NFL defensive lineman

playing in peewee football.

Something that big shouldn't exist that young.

The supermassive black hole wasn't just super early.

It was super big, 800 million times the mass of our sun.

PHILIP: In just a few hundred million years,

the universe has somehow been able to collapse

nearly a billion suns' worth of material

into a giant black hole.

And we honestly just don't know how that's possible.

We measure black holes by the mass of our sun...

Solar masses.

Regular, or stellar, black holes are a few

to a hundred solar masses.

Supermassive black holes weigh from 100,000 to billions of suns.

And scientists have now found over 100 of these monsters

in the early universe.

We were shocked to find even one of them existing

so early after the Big Bang.

It was kind of freakish, to be honest,

but then to find that there's whole populations

of these things that exist

and are well in place at the earliest times

that we can look at was truly shocking.

We believe supermassive black holes

might help explain the evolution and the destiny of the universe.

Astronomers are striving to understand them.

Understanding the origin of supermassive black holes

and how they could form so early in the universe's history

is something that would change all of astronomy and astrophysics.

How do you get something that massive

to form in such a short amount of time?

It's a big question. To begin to answer it,

we have to start small,

by asking how regular stellar black holes form.

ALEX: Black holes form through the collapse of stars.

Everyone knows that. You have a big enough star,

and it'll collapse to form a black hole.

(EXPLOSION BLASTS)

A really massive star dies in a violent supernova explosion,

and if they have sufficient mass, what's left over

collapses into a black hole.

MAX: The bigger the star was,

the bigger the black hole is to start with.

Were the stars of the early universe

big enough to collapse into supermassive black holes?

AMBER: The very early universe was much different

than the university you see around us today.

It was filled entirely with hydrogen and helium gas.

This gas amassed into giant clouds

which collapsed under their own gravity.

Nuclear fusion ignited the dense cores,

and the first stars were born.

GRANT: Now, we think that these earliest clouds of gas

probably made bigger stars than clouds of gas

do in our local or today's universe.

It was possible to get huge, giant stars

that we call Population III stars that were just utterly massive.

Population III stars are the oldest category of star.

Like stellar dinosaurs,

they dominated the universe a long time ago.

Now, they're extinct.

PHILIP: They'd be weird stars.

They would be incredibly bright in the ultraviolet

and have very unique signatures

that are very different from stars today,

but precisely because they're so big and so bright,

they would be very short-lived.

These first stars lived fast and died young...

(EXPLOSION BLASTS)

..exploding in supernovas, leaving behind black holes.

But were they supermassive black holes?

When a star blows up, when it goes supernova,

most of the mass is ejected away.

It just goes flying out,

leaving a dense neutron star or perhaps a black hole.

But it won't have much mass,

because most of that mass was blown away.

Even though Population III stars in the infant universe

were very large,

they weren't big enough to leave a supermassive black hole behind

when they exploded.

Perhaps if we can skip the supernova step,

that might be one pathway to understanding how supermassive

black holes formed.

Could a dying star's entire mass collapse

into a black hole?

A clue may lie in a galaxy nicknamed the Fireworks Galaxy.

The Fireworks Galaxy has that flashy name, because when you look at it,

there are all these supernova explosions going off

and, erm, making quite a show.

Recently, astronomers were keeping an eye

on one extremely bright star in the Fireworks Galaxy.

PHIL: This star is exactly the kind that we know explodes as a supernova.

Astronomers expected it to explode,

but then it did something even weirder.

Astronomy is so wonderful, because sometimes you see things

right in front of your eyes that you can't explain.

We saw an entire star just disappear.

In 2007, the star looked like this.

By 2015, it had completely vanished.

There was no flare or debris from a supernova explosion.

So what the heck is going on?

PHIL: It turns out that not every massive star blows up

with all the fireworks of a normal supernova.

You can get what's called a failed supernova.

A supernova fails when the shock wave

generated inside a collapsing star can't escape.

MICHELLE: In some cases, when the star is very massive,

the shock wave never has a chance to get all the way out of the star

by the time the star itself collapses into a black hole,

then you have a failed supernova.

The Fireworks Galaxy star may have been massive enough

to smother its own explosion before collapsing

to form a black hole.

Everything collapses into the black hole.

You can actually have a black hole

with all the mass of the original star.

Back in the early universe,

could the enormous Population III stars have died

as failed supernovas,

leaving behind supermassive black holes?

HAKEEM: These Population III stars don't seem to me to be

a good contender for the precursor to supermassive black holes...

they just would not have enough mass.

ALEX: Even the most massive stars are only

a couple of hundred times more massive than our sun,

whereas a supermassive black hole is millions or billions

of times the mass of our sun.

Early supermassive black holes

can't have formed from collapsing stars.

Even giant stars aren't massive enough.

So is there some other path to being supermassive?

Were stellar black holes

cosmic bodybuilders on a fast-track bulking program?

(OMINOUS MUSIC PLAYING)

How did supermassive black holes

in the early universe get so large so quickly?

We ruled out the idea that they were created

from the collapse of very large stars.

Maybe they started out as smaller,

stellar mass black holes and grew to be supermassive

by eating.

GRANT: Black holes are not fussy eaters.

They'll consume anything that comes in their path.

You know, gas, planets, stars.

It doesn't matter, and everything that they consume

adds mass to the black hole.

We've spotted a stellar mass black hole

currently eating in our Milky Way Galaxy.

Fifteen times the mass of the sun,

Cygnus X-1 is steadily feeding

off the material that swirls around it.

CHIARA: Some black holes are fed through things called accretion disks.

It's kind of like the rings around Saturn.

There's this thick or thin disk of material

around the black hole that feeds it.

Cygnus X-1's secretion disk

gets constant refills from a nearby source,

a vast star 20 times the mass of the sun called a blue supergiant.

The black hole has been feeding on gas

from this star for about five million years.

So if you ask, how do black holes eat or consume gas?

The answer is gravity, these are very massive objects,

and anything that comes within their sphere of influence

can be consumed by the black hole.

The more mass a black hole gains,

the greater its gravity and the more food it attracts.

PHIL: A black hole growing is a little bit

like a snowball rolling down a hill.

The bigger the snowball gets,

the more snow it can accumulate,

and so the bigger it gets. It's a runaway effect.

But even if Cygnus X-1 follows this runaway growth trajectory,

it still may never reach supermassive status.

The black holes of the early universe

must have fed at a much faster rate.

The biggest issue is how do you have enough time in the early universe

to go from a small black hole that's born from a star

to something that's supermassive?

GRS 1915 is another stellar mass black hole.

It's a greedy eater,

accreting at up to 40 times the rate of Cygnus X-1,

and when something gobbles food that quickly,

it can begin to overheat.

CHIARA: The black hole is accreting a lot of material,

and as it's eating, the accretion disc

really heats up to very high temperatures.

And at those high temperatures,

you can get a lot of light coming out of the system.

So the more material that a black hole eats and swallows,

the brighter it shines.

This stellar black hole sometimes eats so much so quickly,

its accretion disk pushes out radiation

almost a million times brighter than our sun...

..but this brightness has a serious consequence.

It stops the black hole from eating and growing larger.

If you wanted me to gain as much mass as possible as quickly as possible,

you would just keep feeding me hamburgers nonstop or whatever, but...

black holes have a problem that when they eat a lot,

they tend to just gobble up a lot of the food in the neighbourhood,

and then also, they start shining out so much stuff

that it pushes away much of the food.

The brightness, or luminosity, gets so intense,

it pushes away incoming material,

a sort of safety valve called the Eddington Limit.

So in many ways, the Eddington rate could be

a kind of a speed limit for the growth of black holes.

It could be a governor that prevents black holes

from growing even faster

by just dumping more and more gas onto it.

Eventually, you're gonna hit that Eddington limit,

and that more gas that you're dumping on

won't actually reach the black hole.

This cosmic method of portion control

means that stellar black holes in the early universe

couldn't have gained weight fast enough

to become supermassive.

PAUL: Black holes need time to grow.

They need to feed. They need to eat.

Maybe you need to skip a few steps.

Maybe you need to start at a medium size or bigger

in order to get to supermassive by the time we observe it.

So was there another type of black hole

in the early universe?

Something big enough to grow supermassive

in the time available?

In 2017, astronomers studied a dense star cluster

called 47 Tucanae on the outskirts of our own galaxy.

They detected 25 pulsars,

bodies that spin and emit radiation

like cosmic lighthouses.

These pulsars are all orbiting a central object.

And even though we couldn't see the central object itself,

we could watch the behaviour in the orbits of all these pulsars

around it, and we could figure out how big that central object was.

Well, when you do the math, you come up with something

that is about 1,500 to 2,000 times the mass of the sun

that's actually hidden in the heart of that globular cluster.

So what is the invisible object?

Whatever's lurking at the centre of 47 Tucanae

has to be big, and it has to be black.

Astronomers think it's a large black hole.

At 1,500 times the mass of the sun,

the object is much bigger than a regular stellar black hole,

but too small to be supermassive.

Could it be what's known as an intermediate mass black hole?

It's extremely hard to find any of these intermediate mass black holes.

This rare category of black hole

ranges between 100 and 100,000 solar masses.

At that size, they may have been large enough to become

supermassive very quickly.

Intermediate mass black holes could be what give

supermassive black holes a head start in life.

Astronomers search for intermediate mass black holes.

They may have been large enough to act as seeds

for the first supermassive black holes.

Yet so far, they've escaped discovery.

They're like the missing link.

And I mean that for real. They're missing.

Imagine you're an alien who's arrived on the planet Earth,

and you know very little about the human species,

and when you look around,

you only notice tiny, tiny little children

and grown adults. You don't see any adolescents, right?

And intrinsically, you know that the tiny little children

grow up to be full-size adults.

But you don't see how they got there, right?

You don't see the intermediate stages of growth.

That would be really, really weird, right?

That is the case for supermassive black holes.

So it's like a universe without teenagers.

Or that's how it looked, until September 2020.

Scientists studying gravitational waves

picked up the signal of an extreme event

in the distant universe.

What researchers are looking for are things called gravitational waves.

They're like ripples in space itself.

Most signals sound a little bit like a chirp.

It's a noise that's very characteristic.

It goes a bit, like, sort of whoop!

(WHOOPING NOISE)

But this particular event was so extreme

and so sudden, it just sounded more like a thud.

(FAINT THUD)

This faint thud from halfway across the universe

is music to the ears of intermediate black hole hunters,

because its pitch can mean only one thing.

This could only have been created

by two really massive black holes colliding into each other

and producing a combined black hole

with a mass that's 142 times the mass of our sun.

So that, is for the first time,

getting into this intermediate mass black hole regime.

This is the first confirmed observation

of an intermediate black hole.

Finding direct evidence like this

for an intermediate mass black hole is absolutely fantastic.

Now that we're certain intermediate black holes exist,

could they help explain the origin of supermassive black holes

in the early universe?

These intermediate black holes really could be the first seeds

of the supermassive black holes.

You would need something like that to form really big,

really early to even begin to explain these very massive,

supermassive black holes that have formed

just a short time after the Big Bang.

How do intermediate black holes form in the first place?

The recently discovered one came from the collision

of two smaller black holes.

They may also form in giant clouds of gas.

It could be that in the earlier universe,

you can just have large clouds of gas that can lose enough energy

quickly enough to just spontaneously collapse

and form a black hole of this size.

PHILIP: The enormous cloud of gas contracts and gets denser and denser,

the way it would if it was starting to form stars.

But it's somehow able to remain coherent

and collapse into one giant object

that forms an intermediate mass black hole.

A giant gas cloud undergoing a direct collapse

down to an intermediate mass black hole

would be a rare sight.

You think it would go giant cloud, slowly collapsing, black hole,

but instead, it's more like, giant cloud, ahhhh! Black hole.

So one day, you see this massive gas complex,

and then you blink, and it's collapsed,

and now you're face-to-face with a big black hole.

At least, that's the theory.

CHIARA: Getting a black hole to form from the direct collapse

of a gas cloud is very tricky.

Gas clouds tend to split up and collapse

into a multitude of stars...

Collapsing into one object would take unique conditions.

One possible scenario involves two neighbouring galaxies.

The first, a young protogalaxy,

a gas cloud yet to form stars.

Next door sits a larger galaxy.

It's forming so many stars,

radiation is bursting out all over its young neighbour.

Because they're in close proximity, the energy from the large galaxy

prevents the smaller galaxy from forming its stars,

so that means that it will continue to collapse in cloud form

before moving to star formation.

The gas cloud becomes large and dense enough,

the gravity eventually pulls it in on itself.

When it can't ignite into stars,

the collapse creates an intermediate mass black hole.

PAUL: I think this idea is very intriguing.

I don't know if it's physically possible,

but then again, there's a lot we don't know about the early universe.

2017, scientists simulated another way

that intermediate-mass black holes might form in the infant universe.

Under the influence of dark matter.

Dark matter was absolutely critical

for the evolution of structure in the early universe.

Without dark matter, there would be virtually nothing.

Dark matter is mysterious.

We know it has a gravitational pull on ordinary matter.

One idea is that it helped form very large stars in the early universe,

stars that later collapsed into intermediate mass black holes.

MICHELLE: The idea is something like this.

About a hundred million years after the Big Bang,

dark matter which dominated the gravitational early universe

was forming big clumps.

Then there might have been these supersonic streams

of regular matter after the Big Bang

and they were directed into these gravitational cores

where dark matter was gathering everything together.

When scientists simulated this,

they found that dark matter's strong gravity

could pull in huge clouds of gas.

You could actually accumulate as much as, say,

34,000 times the mass of the Sun into one gigantic star-like object.

That's big enough, it would just collapse into a black hole.

A black hole of 34,000 solar masses would sit squarely

in the intermediate-mass category.

It would be large enough to potentially become

a supermassive black hole.

It's possible that dark matter directing streams of gas together

about a hundred million years after the Big Bang

was the seed for these supermassive black holes.

Whichever way intermediate mass black holes form,

they seem like a good way to start explaining supermassive black holes

in the early universe.

The question is, then, how do they grow?

How do you start from this seed and end up,

you know, with something that's a billion times the mass of the sun?

Maybe early intermediate mass black holes

had enormous appetites,

gorging themselves to a supermassive state,

feeding on the biggest meals our universe can serve up.

(LIVELY MUSIC PLAYING)

Astronomers want to know how

the earliest supermassive black holes got so big so quickly.

Could they have started as intermediate mass black holes

that devoured super-sized meals?

PHILIP: It's possible that these intermediate mass black holes

could form in an exceptionally rare environment

where it can accrete new material at an enormously high rate.

So far, we only have direct evidence of one intermediate mass black hole,

and we can't yet detect how it eats and grows.

But we could look at much larger black holes for clues.

In 2019, astronomers searched for supermassive black holes

that are actively feeding.

They pinpointed 12 quasars from the beginning of the cosmos.

Quasars are among the brightest objects we know of in the universe.

And they're what happens when a supermassive black hole

at the centre of a galaxy is swallowing up gas and dust,

and that generates a tremendous amount

of energy and luminosity that we can see.

Surrounding these early galaxies

are enormous gas reservoirs called hydrogen halos.

PHIL: This is great, because that acts as fuel

for those supermassive black holes.

Cold gas can stream into those black holes and feed them.

These huge halos of cold gas are also the building blocks of stars.

GRANT: These enormous, pristine halos of hydrogen around early galaxies,

they're gonna be reservoirs to power star formation.

Star formation is a violent process

that can create turbulence in a galaxy.

That turbulence makes the gas fall toward the black hole,

and then that makes the black hole even bigger.

Hydrogen halos might have spoon fed early supermassive black holes.

This process may have also helped

intermediate mass black holes grow quickly.

Could the largest black holes show us other,

more drastic ways to put on weight?

In October, 2019, astronomers used telescopes

to explore a remarkably clear galaxy called M77.

Because this galaxy is so near to us,

we can study its central engine in really exquisite detail

at very, very fine resolution.

PAUL: Not only do you see the bright core, the bright nucleus,

but you can see spiral arms.

You can see structures in the galaxy.

You can see how the whole galaxy is arranged.

When we examined M77's central supermassive black hole,

we saw something extraordinary.

Its food was coming not from one,

but two accretion disks spinning in opposite directions.

Normally around a black hole, all of the gas is spinning in

roughly the same direction,

and that creates kind of a slow in-fall of gas and slow feeding.

Here, we've got a case where some of it's going one way,

the other is going the other way.

This is very unstable and can create opportunities

for lots of gas to get gobbled up by that black hole.

The material in the disks is one enormous ready-to-eat meal...

..but dinner will not be served until the outer disk slows down.

PHILIP: If there's a black hole at the centre of a galaxy,

and you're orbiting around it fast enough to maintain your orbit,

you're never going to fall in.

You're just going to orbit forever, and you're just going to spin around,

just like the way the Earth is going around the sun.

What needs to happen if you wanna fall in,

is to slow down your speed.

The outer accretion disk will gradually slow down

and orbit more tightly against the inner disk.

Dangerous collisions of the counter-rotating material

will start to occur.

The double accretion disk is like drinking

from two soda fountains at the same time.

It's great while it lasts, but you're building up some serious gas

that is just gonna blow the whole thing away.

In just a few 100,000 years,

the double disks will catastrophically collide,

and their entire contents will fall

into the central supermassive black hole.

It will devour everything in one gulp, generating a colossal cosmic burp.

In February of 2020, in the Ophiuchus Galaxy Cluster,

we saw the damage a cosmic burp can do.

PHIL: The Ophiuchus Galaxy Cluster is a collection

of a huge number of galaxies, all bound together by gravity.

And there's gas in between these galaxies.

And when astronomers looked at that gas in detail,

what they found was a huge arcing structure in it

that they realized was the edge of a cavity.

PAUL: There is a massive hole in the gas

that is over 15 times bigger than the entire Milky Way Galaxy.

Something frightening had to happen to carve this void out.

The size of this bubble is kind of stomping my brain.

We are talking about a hole in this gas

that is over a million light-years wide.

The burp that created this cavity must have been astoundingly powerful.

There are a lot of ideas about this,

but there's only one that really can explain it.

And that's a supermassive black hole.

A supermassive black hole that suddenly got very greedy.

In order to drive an energetic event like this,

the black hole needs to eat... Not just one meal.

It needs to eat thousands of meals at the exact same time.

It needs to go to an all-you-can-eat intergalactic buffet.

Sometime in the distant past,

this black hole must have had a huge episode of just gorging

on material falling in. That got super-hot,

blew out a tremendous amount of material in jets,

beams that shot out from the poles of the disk.

And that's what basically pushed its way out of that gas,

forming this enormous cavity.

The colossal cosmic burp pushed food far away

from the supermassive black hole,

ending its all-you-can-eat binge and stopping its growth.

If an intermediate mass black hole was this greedy,

it would come to a similar end.

It's no way to gain weight and become supermassive.

This is probably not the way

the earliest supermassive black holes grew to such enormous size.

Is there another way supermassive black holes could have formed

in the early universe without having to overeat?

Maybe black holes smashed their way to being giant-sized.

(EXPLOSION BLASTS)

November, 2018.

Astronomers scanning hundreds of nearby galaxies in infrared light

spot something extraordinary.

Some galaxies had not one supermassive black hole,

but two.

Are these pairs a clue to how supermassive black holes

in the infant universe got so big so fast?

Seeing these infrared images

showing pairs of supermassive black holes

at the centres of galaxies and showing that this could be very common

just is mind-blowing to me.

The reason we see pairs of supermassive black holes

is because two galaxies merged together.

CHIARA: In our picture of how the universe works,

galaxies start off as smaller galaxies

and grow by merging with other galaxies.

So they'll be whooshing around each other

and tearing each other up.

It's actually quite violent.

When galaxies merge,

we think their central supermassive black holes also merge,

smashing into each other and combining to build

a larger black hole.

GRANT: Galaxy-scale mergers can be one of the most

efficient growth mechanisms for supermassive black holes.

Maybe, in the early universe,

black holes of stellar or intermediate mass

merged repeatedly,

getting heavier and heavier until they became super massive.

AMBER: We don't really know how common

supermassive black hole mergers were in the early universe,

but we think they were more common than they are today,

because galaxies were closer together.

It would have taken millions of mergers

to build up the largest supermassive black holes we see today,

which could have been a tall order.

There's another problem, too.

We've never witnessed a supermassive black hole merger in the act.

We've seen supermassive black holes on their way to merging,

and we've seen ones that we think had gone through mergers.

But we haven't caught one in the moment.

As supermassive black holes start merging,

they spiral around each other,

getting faster and faster the closer they get.

But for them to finally merge together

into a single black hole,

they need to lose what astronomers call orbital energy.

The merger of supermassive black holes means that their orbits have to decay

for them to get closer and closer together.

So in order for an orbit to decay,

that orbital energy has to go somewhere.

To lose energy,

the merging supermassive black holes start disrupting

the orbits of nearby stars,

throwing them off their paths.

PHILIP: So something small and puny that weighs just one sun

like our own star will often get in the path of these two

and just get rocketed out,

potentially unbound and flung out of the galaxy entirely.

Each time the supermassive black holes fling out a star,

they lose more orbital energy.

They get closer and closer.

But eventually, they kicked out all the stars. There's nothing left.

The merger stalls.

Like two sweethearts at a high school prom...

..the supermassive black holes dance as close as they can,

but physical contact is not allowed.

So these two black holes could end up spiralling around each other

for billions and billions of years.

This is called the final parsec problem.

CHIARA: In 1980, there was a famous paper,

which addressed this issue that supermassive black holes

can only get to within about one parsec,

or three light-years, of each other

before they can't merge or they stall.

We believe that supermassive black holes must merge.

We know that galaxies merge,

and so if the black holes didn't merge,

we'd see lots of black holes floating around.

And we don't... There's always one in the middle.

So how do they merge?

In 2019, we found something that appears to solve

the final parsec problem...

A galaxy in the middle of a merger

that contains not two supermassive black holes,

but three.

Three supermassive black holes. Now that's really cool.

Sometimes you can have three galaxies

that are merging together in a galaxy cluster.

Then you have three supermassive black holes.

At this point is, it's virtually impossible

for there to be a final parsec problem.

Here's how a third black hole solves the final parsec problem.

Two of the black holes orbit closer and closer,

ejecting stars to lose energy.

Black hole number three joins the action.

Its gravitational pull takes even more energy from the orbiting pair.

Eventually, they lose enough orbital energy to collide.

HAKEEM: That third supermassive black hole is just what's needed

to transfer energy away from the two merging black holes

so that they can now merge into one single supermassive black hole.

Triple black hole events may explain

how the earliest supermassive black holes grew to such enormous size.

We've suspected that three black holes

may be necessary in order to get black holes to merge,

but we've never had any evidence for it.

But now, this might provide a direct picture

of three black holes caught in the act itself.

If we have a picture of this happening now,

then it certainly happened in the early universe

and might explain how the biggest black holes got so big so quickly.

Final proof will come when we witness a merger being completed.

But tracking mergers as they happen is challenging.

CHIARA: Supermassive black hole mergers can take billions of years

and therefore, it's impossible to witness

a supermassive black hole merger in action.

Mergers may take an incredibly long time

but the actual moment the black holes join is very fast.

Compared to the billions of years the black holes take to spiral together,

they might merge together in a matter of minutes or hours.

That means if we want to witness a merger happening,

we have to watch the skies very carefully.

No-one has ever seen a supermassive black hole merger

but I imagine it would be an absolutely spectacular event.

It's also possible that the merger is dark,

that there's no fireworks,

that there's nothing really special that happens

in terms of light being emitted from the system.

It could be a dark merger.

Whether dark or bright,

finally seeing a merger will help answer

how the very first supermassive black holes got so big so quickly.

AMBER: We think that mergers of supermassive black holes

in the early universe are one key way that galaxies and their black holes

could have grown in the early universe.

They're probably not the only way.

There are other ways that black holes could grow as well.

Scientists are also investigating invisible forces

at the beginning of the universe.

Did something we can't see

boost the size of the first supermassive black holes?

There's still so much we don't know about the early universe.

PAUL: The further out we look in the universe,

the less familiar the universe becomes.

And so the more and more interesting and new physics

you need to involve in order to explain

these very strange observations.

The puzzle of fast-growing, supermassive black holes

in the infant universe

now takes physicists somewhere new,

to the little understood realm of magnetic fields.

The thing about magnetic fields is they're hard.

They're hard to calculate, they're hard to understand.

They're sort of the elephant in the room for astronomers.

We know they're there, but we'd really rather not talk about them.

It's only recently that people are incorporating

magnetic fields into their models of galaxy formation,

and therefore, maybe it's under the influence of these fields

that somehow these supermassive black holes are formed.

To investigate how magnetic fields influenced

early supermassive black holes,

we must look back at the very beginning.

Soon after the Big Bang,

the first particles form, cool,

and become electrically charged.

Things were very different, radically different than they are now.

Particles were whizzing by each other.

Everything was charged. It was just a very different landscape.

There are no stars yet, not even atoms.

But some scientists think

moving charged particles created the first magnetic fields.

Magnetic fields were essentially everywhere in the early universe.

Those magnetic fields would have extended extremely large distances,

like a very finely spun web all through the early universe.

Gradually, atoms form and gather into clouds of gas.

These will become the first galaxies

and their supermassive black holes.

During this time, magnetic fields change.

They bunch together around the forming galaxies.

But we don't know how.

The thing with magnetic fields is they're extremely hard to predict,

and you need to do really hard calculations that, even now,

we're only just starting to do.

2017, scientists design a ground-breaking computer model

that simulates patterns of magnetism developing over time.

The images show lines of magnetic force getting stronger

and more focused across a vast region of space.

Some astronomers think these emerging magnetic field lines

help shape early galaxies

and the supermassive black holes at their cores.

Magnetic fields have this ability to push material around.

So one possibility is they could actually help push

or funnel material in towards a growing black hole

and help it grow faster than it would do otherwise.

In today's universe, we know magnetic fields around planets

can deflect dust particles.

On much larger scales, matter may also

have been channelled into the centres of galaxies

of the early universe.

Were the magnetic fields of these early galaxies a conduit

that you could get matter dumped more and more into the middle

and maybe build up a really big black hole?

Scientists are just starting to figure out

the effects of magnetism at the beginning of the universe,

but it could have been one of several mechanisms

that influenced the size of early supermassive black holes.

ANDREW: We have lots of ideas for how you might be able to form

supermassive black holes,

but until we see actual mechanisms in action,

we just can't really say which of them are the most important routes.

Maybe some other mechanism we haven't even thought of

explains how the early supermassive black holes got so big so fast.

Hopefully, one day, these monsters of the cosmos

will reveal their secrets to us.

Supermassive black hole research is utterly mind-blowing to me.

I mean, this is so cool.

CHIARA: It's important to explain

how these early supermassive black holes formed

in order to have a really concrete understanding

of how the universe works.

Supermassive black holes are the great engines of cosmic change...

they're enormous points of matter,

and because they're just so massive,

they can sculpt the evolution of galaxies.

They're the master key

to most of the unsolved mysteries in physics.

We have a chance here to understand super massive black holes

so that we can understand the formation of galaxies,

the generation of stars like our sun,

and maybe even the appearance of life.

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