Narrator: The white hole.
One of the strangest objects in the universe.
Oluseyi: Black holes are weird,
but white holes... They're way weirder.
Narrator: Science predicts they should exist.
But these astronomical wonders are so mysterious,
no one is sure what they really are.
How do you start looking for something that you have no idea
what it might possibly look like?
Narrator: Today, astronomers race to find the clues
that can unlock the secrets of white holes.
Can unexplained energy bursts deep in space
be a sign of these enigmatic objects?
To this day, we still don't know what caused it.
Narrator: And could a white hole be a gateway to a different time
and space?
Tremblay: White holes sound like pure science fiction,
but they could be science reality.
Narrator: We venture to the farthest reaches of the universe,
go back in time to the moment of its creation,
and journey through the monster at the center of our galaxy
to hunt for the truth about white holes.
♪♪
Our universe is home to a mind-boggling array
of mysterious objects.
Stars so magnetic that they rip apart atoms.
Planets where diamonds fall as rain
into oceans of liquid hydrogen.
Threads of dark matter, billions of light-years long
that weave the entire universe into a vast cosmic web.
Astronomers have unlocked many of the secrets
of these weird cosmic creations.
But one theoretical object in the vastness of our cosmos
confounds the greatest minds in science.
It's called
the white hole.
A white hole is a super powerful stream of energy.
That pours from an intensely bright point in space.
It emits radiation so powerful that nothing can venture near.
A white hole certainly has to be
one of the most mysterious objects
that the universe could possibly conjure up,
but you wouldn't want to get too close.
I think if one went off anywhere near in our galaxy
and it was pointed at us,
you wouldn't even know it was coming.
The earth would be fried by the light coming out in an instant.
Narrator: No astronomer has ever seen a white hole.
[ Explosion ]
Does this galactic monster really exist?
A clue lies inside the brilliant mind
of the world's most famous physicist.
Thaller: Einstein is truly a cultural icon.
If somebody said the word "genius" to you,
one of the first things you might think of
is the face of Albert Einstein, his crazy hair and all that.
But all of that overshadows just what a profound effect
he had on modern science.
Narrator: Over a century ago, Einstein comes up with a theory
that changes everything we know about the universe.
Plait: Einstein's general theory of relativity
tells us that the universe is not as it seems.
It puts limits on what we can do in space and time,
how fast we can travel.
It basically affects everything we understand
about the universe itself.
Narrator: Einstein's theory stretches space, literally,
and predicts the existence
of one of the strangest objects in the universe.
General relativity combines space and time into space-time,
the fabric of the cosmos,
which is flexible.
Extremely heavy objects can actually warp space-time
to create gravity Wells around them.
The more massive the object,
the bigger and deeper the gravity well.
But the theory predicts one object
that could stretch space-time to its limit,
a point so dense that nothing escapes its thrall.
The name for this bottomless gravity well is a black hole.
It is an object that transforms physicist's ideas
of what's possible in the universe.
Einstein's theory also predicts another mind-bending object.
The equations of general relativity
allow us to push the limits of the universe as far as we can.
What if there's something that's like the opposite
of a black hole... a white hole?
Well, the mathematics of general relativity
allow for that, as well.
Narrator: Einstein's equations make it possible
for white holes to exist.
How would they work?
Clues to how they might operate could lie
in the extreme physics of their theoretical opposite.
A black hole.
In the 100 years that follow Einstein's theory,
definitive proof of a black hole's existence,
a photograph, eludes astronomers.
Thaller: Up until now,
really what we've had is indirect evidence.
Wouldn't it be amazing
to actually see the black heart of it itself?
Narrator: How can astronomers see a black hole
to take a picture of it?
Fortunately, Einstein's theories predict
that black holes and white holes both share a common feature.
Tremblay: Out of these complex theories come these
mathematical predictions that sound like science fiction,
but in reality, they give us actual things
to search for in the universe.
One of those science-fiction-sounding ideas
is something called the event horizon,
this purely mathematical boundary
that is the prediction from the theory.
And yet this is an actual physical surface
that we can search for.
Narrator: The event horizon of a black hole is
the invisible boundary beyond which nothing,
not even light, can escape.
In theory, it should leave a Mark that astronomers can see.
As matter falls into a black hole,
it gets superheated and when he gets superheated,
it glows and it gives off light,
so we can find it.
Narrator: If this direct evidence for the existence
of black holes is out there in space,
then it is possible to unlock what makes black holes tick
and use this information to unravel how white holes work.
Photographing a black hole is a huge challenge.
Plait: The strength of a black hole
doesn't come from its size.
It comes from its density.
You actually want to compress as much matter as possible
into a very, very small volume of space.
And what happens is that makes black holes very small
and that makes them hard to see.
And in fact, even the biggest black holes,
if you want to see them,
you're going to need a telescope the size of the earth.
Narrator: In 2017,
eight radio telescopes across the globe joined forces
to take a first picture,
from Arizona to Hawaii
to Europe,
even the south pole.
All aim at the exact same spot...
The heart of a galaxy 55 million light-years away.
This is the picture that the telescope captures,
the first ever photograph of a black hole.
This image just makes my jaw drop.
It's not some myth. It's not some story.
It's real data.
Oluseyi: Now that we have this image, that's it.
How can you be a black-hole denier?
That would be as crazy as saying the earth is flat.
Narrator: The image proves that black holes exist.
It also reveals how the event horizon
of a black hole works.
And this is the first step
to unlocking how a white hole operates.
Plait: That circle is actually from a disk of material
swirling around the black hole.
Any light inside of that region circles around the black hole
a few times and then falls in.
So it actually can't escape to reach our telescope,
and it looks dark.
Narrator: The photograph shows that the event horizon really
is the point of no return for both energy and matter.
What does reverse-engineering the event horizon
of a black hole tell us
about how their theoretical opposite, a white hole, works?
And could an unexplained burst of energy
lead astronomers to the first ever sighting of a white hole?
♪♪
Narrator: Astronomers are on the hunt
for the most elusive object in the cosmos...
The white hole.
Einstein's theory of general relativity predicts
that it can exist.
Can reverse-engineering its twin, the black hole,
reveal how a white hole works?
Physicists believe that a simple stream of water
unlocks the mystery of how a white hole behaves.
It turns out that you can demonstrate the rough behavior
of a white hole in your kitchen sink.
So if a black hole is a region of the universe
that something can only ever enter and never leave,
a white hole is the opposite of that.
It's a region that something can only ever leave
and nothing can ever enter.
Narrator: The falling water makes a circle
of fast-moving liquid when it hits the plate.
Outside is an area of slow-moving water.
The boundary acts like the event horizon of a white hole.
It creates this continuous,
outward-flowing cascade of water that serves as a kind of barrier
for anything trying to enter.
Narrator: Energy or matter
from inside the white hole gets flung out.
Energy or matter outside the event horizon
can never enter the white hole.
Tremblay: It just can't.
There's this outward-flowing barrier of water
that's preventing it from doing so.
Narrator: Flipping the physics of black holes 180 degrees
unlocks how a white hole should work.
What would this look like in the depths of space?
A black hole's immense gravity draws in
everything that gets too close.
As a planet approaches the dark sphere
of the event horizon,
it stretches out and disintegrates.
Once inside,
it's a one-way trip towards the black hole's
infinitely dense heart.
A white hole works in the opposite way.
Energy and matter accelerate outwards from its center.
Once outside the event horizon, nothing can return.
The science of white holes works,
but finding one in space is a big challenge.
Plait: The problem with white holes is the equations
allow for a lot of different conditions for these things,
and so we can look all over the sky,
but we don't really know what we're looking for.
If white holes exist, they might last a long time
or a short time, they might give off
one kind of light versus another kind of light.
All of these things, all of these variables
make them very hard to search for.
Narrator: Where might white holes be hiding
in the universe?
What are the signs that will help us find them?
♪♪
Astronomers believe that tracing the energy a white hole shoots
out into space could pinpoint its position.
And it's possible that we might have already seen one.
In June 2006, the swift space telescope
detects a massive release of energy...
[ Explosion ]
...in a distant galaxy around 2 billion light-years away.
It is a super intense beam of radiation
called a gamma-ray burst.
Gamma-ray bursts are some of the most extreme
and luminous events in the universe.
They are hyper-energetic.
The amount of energy
that these events liberate is extraordinarily high.
Narrator: The gamma-ray burst that swift sees
lasts over 100 seconds.
[ Explosion ]
A burst this long likely comes from gamma rays
released by a star going supernova.
NASA tasks the Hubble space telescope
to search for the aftermath of this probable stellar explosion.
Hubble spends weeks hunting for the telltale glow of light
that a supernova always produces
after the initial gamma-ray burst.
But Hubble finds no such glow.
Plait: When we followed up and looked at this galaxy,
there wasn't anything there.
There was no supernova associated with it.
Narrator: It's as if the gamma-ray burst
appeared from nowhere.
To this day, no one knows for sure what created it.
But one object could, in theory, be able to blast into existence,
release a vast amount of energy,
and then simply vanish.
♪♪
An explosion of light appears from seemingly nothing.
Twin beams of intense gamma radiation
traveling at almost the speed of light
shoot out across space.
The gamma-ray burst.
Turning down the brightness on this cosmic light show
reveals the possible source of the fireworks.
A perfectly spherical ball spewing out so much energy
that nothing can enter it, not even light...
A white hole.
The swift space telescope spots
a number of similar unexplained blasts
over the next 15 years.
Are these the signs that astronomers
searching for white holes are looking for?
Since 2006, there have been several gamma-ray bursts
that aren't really well-explained
by the standard models out there.
Perhaps they could be the long-sought white holes.
Narrator: A single gamma-ray burst releases more energy
in 10 seconds than our sun will emit in 10 billion years.
If this mysterious gamma-ray burst is from a white hole,
where does this energy come from?
And how does it get inside the white hole in the first place?
♪♪
Narrator: Unexplained mega blasts of radiation
could be evidence of elusive white holes.
How this energy gets inside them in the first place
puzzles scientists.
Can unraveling this mystery help astronomers pinpoint
the location of a real-world white hole?
The solution to this puzzle may lie inside the super dense
heart of the white hole's twin, the black hole.
♪♪
Black holes are so dense and warp space so much,
they work like cosmic car crushers.
Matter falling in first gets stretched,
then so extremely compressed, it almost ceases to exist.
Einstein's theories predict that inside a black hole,
matter squashes to an infinitely hot, small, and dense point.
But the problem with infinity is
that what works in theory may not work in practice.
It's one thing to mathematically express infinity.
It's another thing to realize infinity in our actual universe.
And there has been no observations
of an actual infinite density of anything.
Narrator: Physicists are now evolving Einstein's theories
to explore what really happens inside a black hole.
These new ideas put a limit on how small
and how dense the heart of a black hole can get.
And that limit could unlock where the energy pouring out
from a white hole comes from.
Plait: Well, the idea now is that
there is a smallest amount of volume in space.
You cannot get any less than that.
It's not zero. Very tiny, but it's not zero.
That's like a brick wall.
When that black hole collapses down and hits that volume,
it basically has to stop.
Narrator: One radical theory explains what that brick wall is
and what it is made from.
Inside the nucleus of every atom are two types of particles...
Protons and neutrons.
Inside these subatomic particles
are even smaller entities called quarks.
Some scientists believe if we could peer deeper,
we would find the fundamental building blocks
of both matter and space...
Tiny quantum loops.
These are the threads that weave together
the fabric of the universe.
♪♪
These quantum loops are the building blocks
of more than just matter and energy.
They make up space itself.
The theory says that it is impossible
to compress anything smaller than the size of the loops.
That means the loops put a limit
on how dense a black hole's heart can get.
This idea could unlock the mystery
of where the energy blasting out from a white hole comes from.
It's likely that there is no infinitely small point
at the center of a black hole.
Instead, there could be a ball of super dense matter.
It contains everything that the black hole
has swallowed in its lifetime.
Eventually, this ball reaches a point
where it can contract no further,
and so it goes into reverse.
It releases matter and energy, swallowing up its event horizon.
What was once a black hole has bounced into a white hole.
♪♪
The theory of quantum loops unlocks where
the energy blasting from a white hole comes from
and how it got inside in the first place.
It states that a white hole is one stage
in the evolution of a black hole.
If everything in this theory adds up,
then what this means is a collapsing and bouncing
black hole could be a path to a white hole.
[ Explosion ]
Narrator: It is possible that bouncing black holes
unleash the mysterious gamma-ray bursts
that astronomers detect.
But what type of black hole could we actually see live
as it transforms into a white hole?
And where in the sky should astronomers point
their telescopes to capture the moment of eruption?
♪♪
Narrator: Astronomers are on the hunt for elusive white holes.
One theory states that they release vast amounts of energy
when a quirk of quantum physics throws black holes into reverse.
This change is called a bounce.
No astronomer has ever seen this dramatic transformation.
Where should we point our telescopes to witness it live?
Oluseyi: If we're gonna look for black holes
that are becoming white holes,
then we have to look in the right places
and for the right things.
Space is big. It's huge.
So this is very important
if we're gonna find these things.
Most of the black holes in our galaxy
are stellar black holes.
Each one weighs around 10 times more than our sun.
A stellar black hole forms when a star dies.
It leaves behind its super dense core
after it goes supernova.
This core collapses under its own extreme gravity.
This gravity well is so large
that it eventually turns into a black hole.
Our milky way contains around 100 million stellar black holes.
In theory, seeing one bounce into a white hole
is just a matter of time.
If there's this idea
that black holes do eventually come to the end of their lives
and turn into white holes,
couldn't we just wait for that to happen?
There are black holes all around us.
♪♪
Narrator: But there's a problem with waiting for
stellar black holes to turn into white holes.
The transformation could take so long
that it will probably never happen.
Tremblay: We, as flesh-and-blood human beings on our tiny
little planet earth, think of time as some constant force,
but it's actually not.
One of the fundamental tenets of general and special relativity
is that time and space are fundamentally the same thing.
And because black holes warp the fabric of space-time so much,
they do really crazy things with time.
So in a way, observing anything close to a black hole
is like watching time in really, really slow motion.
And so a black hole could, in principle,
take trillions of years to evolve in any real way.
Narrator: The milky way is around 13.6 billion years old.
The rules of relativity
mean that the stellar black holes in our galaxy
are too large and too young to bounce into white holes.
The telescopes on earth could watch the black holes
in the milky way for billions of years
and never see one collapse into a white hole.
Plait: When we think of a black hole, and we think of one
that's like 10 times the mass of the sun
as sort of a typical stellar-mass black hole,
that takes far longer than the age of the universe
for this thing to rebound.
Narrator: Astronomers think that black holes must be very small
and very old
to even stand a chance of bouncing into white holes.
Where in the cosmos can they find them?
♪♪
A clue could lie in the images
taken by the Spitzer space telescope
that studies some of the oldest objects in existence.
Spitzer takes this image of a portion of the universe.
It shows a one-degree-wide strip of the sky
and the great bear constellation.
This tiny sliver of space contains
50,000 visible galaxies.
The image offers a possible glimpse of objects
that could bounce into white holes.
To see extremely far back in time,
astronomers must first remove all the bright points of light
that come from closer stars and galaxies.
The technique leaves behind this...
A background infrared glow coming from the ancient cosmos.
The glow comes from something very old and very distant.
What is emitting this huge amount of infrared energy?
Another space telescope could unlock the mystery.
The Chandra telescope sees the universe in x-rays.
X-rays sit at the opposite end of the light spectrum
to infrared.
They reveal the hidden light
coming from super violent events like supernovae.
Astronomers direct Chandra's X-ray camera
to the exact same patch of sky as Spitzer.
It shows that the ancient universe also
has an uneven X-ray glow.
Astronomers use computers to compare the two images
from the two telescopes.
They make an extraordinary discovery.
20 percent of the bright patches of infrared light
match up with bright patches of x-rays.
Thaller: Way, way down, deep in the noise,
you need a computer to pull out the statistics.
There's a correlation between this background glow
in the x-rays and infrared, and that's very mysterious.
No object should be able to glow
in both those types of light brightly at once.
Narrator: Astronomers believe that there is one object
in the early universe that could glow in this way.
Remember, we're looking eons back in time here
at some of the earliest moments of our universe,
and we're seeing objects that are emitting a huge amount
of energy across the electromagnetic spectrum.
And what's a kind of object that could do that?
It's a black hole.
Narrator: The telescopes see back in time
to before stars were even born.
How is it possible for black holes to exist
if there were no dying stars to make them?
And could white holes be the missing ingredient
of theoretical tunnels through time and space?
♪♪
Narrator: White holes are cosmic oddballs
born from Einstein's theory of relativity.
One idea is that a white hole
is the last gasp of a dying black hole,
a burst of energy released in one giant cosmic belch.
But the only black holes ancient enough to bounce like this
date from when the universe contained only energy.
How is it possible for them to exist
if there were no dying stars to make them?
Thaller: We know that black holes
took an unimaginable amount of gravitational power to make,
and the only way we know how to make that is an exploding star.
But is it possible the universe
had another way to make black holes,
something that only existed in conditions
just after the big bang?
Narrator: The big bang unleashes forces so powerful,
they could, in theory, bend space and time
enough to make small black holes.
[ Explosion ]
Milliseconds after the big bang,
the universe is a tangled web of pure energy.
Super dense pools of this energy condense and collapse
under their own gravity to rip deep Wells in space-time.
These primordial black holes are born small.
They mature and shrink further over billions of years.
In theory, many could now be old enough and dense enough
to bounce into white holes
just in time for us to spot them.
♪♪
Tremblay: So, this type of black hole is
really, really small, and because it's so small,
we might be in this sort of Goldilocks zone
in our history of the universe
in which just enough time has passed for us
actually to be observing this transformation now.
Narrator: A tiny, primordial black hole
could be astronomers' ticket
to witnessing the birth of a white hole.
But is there something even weirder out there
waiting to be discovered?
Einstein's theory of relativity predicts a mind-blowing link
between black and white holes,
a tunnel to a different place and time
known as a wormhole.
What Einstein showed us
when he invented general relativity
is that space is not just this background against
which everything takes place.
Space is a part of the game.
It expands, it contracts, it warps, it waves.
And it can actually have tunnels.
Narrator: A wormhole might sound like science fiction.
But in theory, a shortcut through space and time
isn't a great leap in the upside-down world
of white and black holes.
Matter and light cross the event horizon of a black hole.
The extreme gravity inside stretches space into a funnel.
It is theoretically possible for something that survives
the crushing gravity to pass through a wormhole
and emerge from a white hole
in a different part of the universe.
So, you have a black hole on one side
and a white hole on the other.
Now, it sounds crazy because you can enter a black hole
at some place or time
and exit the white hole at another place and time.
Narrator: But Einstein's theory states that a wormhole
only works as a closed system.
The problem is when you look at the mathematics
of how a wormhole exists, they're unstable.
If even a single atom of hydrogen enters one,
they collapse.
Narrator: A tunnel between a black hole and a white hole
must be fed an exotic form of matter to stay open.
Humans will need to generate this weird material
to stop a traversable wormhole from collapsing.
Thaller: In order to make them stable,
you'd have to have some sort of matter
that actually has a negative energy,
and I don't think we even really understand what that means.
So while Einstein's theories led to the idea
that you could build these Bridges,
how exactly they would stay open is still a complete mystery.
Narrator: But when Einstein speaks, astronomers listen.
How can scientists find a wormhole in deep space?
And is it possible that one exists in our own galaxy?
♪♪
Narrator: Astronomers hunt for a wormhole,
a theoretical tunnel between a black and white hole
that traverses space and time.
Their quest begins with the black hole
that they believe lies at the heart of our own galaxy...
Sagittarius a-star.
Every year, the European southern observatory in Chile
takes a photograph of the same spot
at the center of the milky way.
The data from 16 years of observations
creates this four-second time lapse.
It shows stars 26,000 light-years away from earth,
circling the heart of our galaxy.
But what they orbit appears completely invisible.
You can see these stars, and they're moving around nothing.
You look to the center where these stars are orbiting around,
and there's nothing there.
There has to be mass there because it's telling these stars
how to move in this really, really well-defined orbit.
But there's nothing there.
Narrator: Astronomers believe that only a giant black hole
has enough mass for stars to orbit in this way.
One theory states that charting the orbit of one of these stars
could reveal the presence of a wormhole.
S2 is the closest star to the likely location
of the black hole, Sagittarius a-star.
The idea is to identify
all the different influences on s2's orbit
to see if something unknown affects the way
the star moves through space.
Astronomers think that the main influence on s2's orbit
is the huge gravity of Sagittarius a-star.
But s2 moves in a very crowded corner of space
where other stars and black holes
could affect its motion.
Astronomers are studying the effects of all these objects
to calculate the path of s2 with extreme accuracy.
They're looking for a tiny deviation
that they can't explain.
Which could be gravity leaking through a wormhole.
The theory sounds fantastical,
but physics supports it as a potential way
to identify the presence of a wormhole.
Collisions between massive objects like neutron stars
and black holes generate gravitational disturbances.
These huge distortions in space-time are the one thing
that could potentially pass into white holes.
In theory, a disturbance from a violent event
at the other end of the universe
might enter a nearby black or white hole,
travel through a wormhole,
and emerge from Sagittarius a-star.
This disturbance from an unknown time and place
could then alter the orbit of the star s2.
Thaller: What if we get better and better observations
over time and look very carefully
at the way the star's accelerating.
We might be able to just tease tiny little clues
out of the orbit that there's something else in there,
some more gravitational exotic things,
perhaps even a wormhole.
Narrator: Future telescopes will be able to track
s2's movements with greater precision.
If they do spot something unusual,
Einstein's incredible wormhole theory
could be proven correct.
Oluseyi: If we find out that wormholes actually do exist
and there is one in our stellar neighborhood,
then this opens up a whole new realm of research.
This tells us that we can now understand space and time
in ways that we never could have before.
So even though humans may not be able to go
at any time in the near future, we could start along the path
and send probes to see what happens.
Narrator: White holes are one of the weirdest ideas in science.
They could be responsible for unexplained blasts of radiation
that shoot across our universe.
It is possible that they are born at the moment
super ancient black holes died.
What started as an idea triggered by the mind
of the world's most famous physicist
could really exist.
Oluseyi: If Einstein turned out to be right about white holes,
man, I would just say, "there he is again.
He did it again. Albert Einstein, right?"
My hero.
Narrator: In the future, we could discover a real white hole
that is a portal to a different time and space.
All of a sudden access not only all the space of the universe,
but the entire history and future of the universe, as well.
And from there, your imagination can take you
pretty much anywhere.
Narrator: New telescopes promise
to unlock the mysteries of these cosmic wonders.
White holes could exist.
And they could be out there, just waiting to be discovered.
♪♪