¿Qué es un agujero negro? Un agujero negro es una región del espacio en la que la atracción de la gravedad es tan fuerte que nada puede escapar. Es un "agujero" en el sentido de que las cosas pueden caer, pero no salir de él. Es "negro" en el sentido de que ni siquiera la luz puede escapar.
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00:00Something is hidden in the darkness. Invisible objects that empty the universe of color,
00:21that have the power to destroy worlds and stop time.
00:28To me, a black hole is the greatest exhibition of the mysterious powers of nature.
00:35You literally can't see them, and that's what makes them so mysterious.
00:41Black holes are strange whims of nature.
00:45Studying black holes is the limit of human knowledge.
00:50However, they are sculptors of the cosmos.
00:55The jets of black holes are so powerful that they can affect the whole shape and nature of a galaxy.
01:04And when you try to understand them...
01:07Fermi revealed something completely amazing and unexpected.
01:11We had never seen anything like it.
01:14Physicists have been forced to completely re-evaluate our most basic understanding of reality.
01:21Finding those little pieces of the puzzle that didn't fit is super exciting.
01:29If we want to understand the deepest questions of the universe, we have to understand the black holes.
01:36Can we take off and reveal their secrets?
01:41Forget about the return trip to Mars. I'm going to the black hole.
01:45The universe.
02:10Black holes.
02:25The heart of darkness. Black holes.
02:30When we look at the Milky Way, our eyes feel attracted to the light.
02:35Hundreds of billions of stars spinning serenely through the cosmos.
02:42When we look at the sky, the stars and the planets we see are beautiful.
02:47But it is in the space between them, in the dark areas, where some of the most fascinating things are found.
02:58In places where there is no light.
03:01Deeply mysterious objects await their moment.
03:07Amazing for their simplicity and perfection.
03:11The so-called black holes.
03:15A black hole is an infinitely dense point in space from which nothing can escape, not even light.
03:23It's extraordinary to think that there are black holes all over the universe that have existed for very old times.
03:33When they're inactive, they're almost impossible to detect.
03:38We're talking about a region of space where if something falls in, we'll never see it again.
03:44They have the power to destroy stars and planets.
03:50But also the potential to form galaxies.
03:55Black holes are the most fundamental objects that could dictate how galaxies form and evolve.
04:04It's natural to fear them, but we understand that they're essential.
04:08We can't live with them, but we can't live without them either.
04:14And they may keep the secret of the final destination of the universe.
04:19Black holes, at a fundamental level, challenge our understanding of physics and the way the universe works.
04:29Black holes are the most mysterious objects in the universe.
04:38To understand black holes, we have to start at the beginning.
04:44At the moment of their birth.
04:48Black holes, which have several times the mass of the sun,
04:53probably were formed from giant stars that had maybe about 20 or 30 times the mass of the sun.
05:02Enormous bright blue burning stars that emit intense heat.
05:09But the brightest stars are the shortest-lived.
05:14A star is a big ball of gas.
05:17Its gravity pushes it inward, trying to collapse on itself.
05:22But the fusion that occurs in its nucleus releases so much light
05:27that the pressure of the radiation it generates prevents it.
05:31Although in the end, it ends up collapsing.
05:36A star like this can exhaust its nuclear fuel in a few million years.
05:55And when its source of energy is exhausted, it collapses due to its own gravitational attraction.
06:03There are so many materials that are collapsing during their final moments
06:09that they create a dense and gigantic neutron ball that continues to collapse.
06:18A star with a mass 20 times or more superior to that of our sun.
06:25Crushed by the force of gravity.
06:29Until it disappears.
06:35Leaving behind only a ghost.
06:41A black hole.
06:47But this transformation is not the fate of all stars.
06:52The smallest, not as massive as our sun,
06:56end up becoming dwarfs that are consumed when their fusion stops
07:01in ashes that fade slowly.
07:06But it is possible that almost all the massive stars that dominated the primitive universe
07:11formed black holes when they died.
07:15Because a black hole is simply what happens when enough matter is compressed
07:21into a fairly small volume, drastically deforming the space around it.
07:28A river is a good analogy to understand the area that surrounds a black hole.
07:32Here I am above the river and the water is flowing pretty flaccidly.
07:37It's not going too fast.
07:39If I wanted to get to the water here and cross the river, I'd be able to do it fairly easily.
07:44In the same way, if you're far away from a black hole,
07:48you could move around with a normal spaceship without too many problems,
07:52with a basic propulsion.
07:58But the closer you get to the black hole, the stranger things become.
08:04The collapsed massive star becomes so small and dense
08:09that it ceases to have a physical surface.
08:14It becomes an infinitely small point in space
08:19that exerts a profound effect on the space-time that surrounds it.
08:25As the water gets closer to the waterfall, its speed increases.
08:31If I jumped into the water right here,
08:35the current would be so intense that I wouldn't be able to swim against it.
08:40So I would be gradually going towards the edge of the waterfall
08:44until I reached a point of no return.
08:46And the same thing happens around a black hole.
08:51On the edge of the black hole, the fabric of space itself stretches inwards, towards the center.
09:02Not even the stars, not even the planets, not even the light can escape the attraction of a black hole.
09:08It's like a waterfall in the fabric of the universe.
09:15But the gravitational reach of a black hole is not infinite.
09:20People have the idea that black holes suck, that they suck everything inwards.
09:25But that's not true.
09:27Black holes can only eat things within a certain distance away from them.
09:32If you're further away, then the black hole has no way of eating you.
09:39But once you've fallen into its clutches, you're lost forever.
09:45And that's the key to its mystery.
09:48The interior of the black hole is hidden from sight,
09:52isolated from the rest of the universe by a space limit.
09:57The horizon of events.
10:00Beyond this point, there is no escape.
10:09As we approach the horizon of events,
10:13we begin to become aware of the true rarity of black holes.
10:22Ever since Einstein, we've seen the fabric of the universe not as something static,
10:27but instead as something that's fluid,
10:30something that bends and deforms around objects of mass.
10:35We call this space-time, a combination of space and time.
10:40What Einstein did was realize that these two things are intimately connected,
10:46that when an object has mass, it not just bends space,
10:51but changes the passage of time itself.
10:54In particular, the effect of a mass is to slow time down.
11:00In the region that surrounds the black hole,
11:03the deformed space-time extends the waves of light, distorting color.
11:09The event horizon is the place where time stops when seen from afar.
11:15Someone who's outside the black hole will see you getting redder and redder,
11:20and your time will slow down,
11:23as if you crossed the horizon and disappeared forever.
12:00Black holes are like waterfalls in the fabric of the universe,
12:06where space is distorted,
12:10and time stops, catching the light,
12:14thus becoming strongholds of the great secrets of the universe.
12:30It is said that fact is sometimes stranger than fiction,
12:36but nowhere is that more true than in the case of black holes.
12:42Black holes are stranger than anything dreamed up by science fiction writers,
12:48but they are firmly matters of science fact.
12:54The vast majority of black holes are small,
12:58less than 30 kilometers in diameter,
13:01and usually wander alone through space.
13:06But if we turn our gaze to the center of the Milky Way,
13:11and travel inside it,
13:14we will find that the black hole is not only a black hole,
13:19it is a galaxy,
13:22and we travel inside it through the gas and dust that envelop the galactic core.
13:28There are signs of something totally different.
13:32If you see the stars that are in the very heart of our galaxy,
13:36for about 20 years,
13:38you'll observe them orbiting around nothing.
13:42At the center of this swarm of stars,
13:45there is darkness, it's a void.
13:48Scientists call this invisible enigma Sagittarius A Star,
13:54although it is not at all a star.
13:57Can you imagine how enormous that object must be
14:01to be able to put entire stars into orbit?
14:05It is believed to be a black hole with a mass equivalent to more than 4 million times the mass of our sun,
14:12thousands of times larger than any other black hole in the Milky Way.
14:17But how did this monster get to be in the heart of the Milky Way?
14:21Sagittarius A Star is a supermassive giant
14:26around which the entire galaxy revolves,
14:30which raises new and intriguing questions
14:34about the role of black holes in our galaxy and in the universe.
14:39How did it get there?
14:41How did it get so big?
14:43And what can you tell us about how black holes shape the cosmos?
14:48Would we be here today without Sagittarius A Star?
14:58There are a few minutes left for the 26th flight of the Columbia transborder with five crew members.
15:03A night launch is particularly exciting.
15:07All set for takeoff.
15:10We have ignition of the propellers and takeoff of the Columbia.
15:14Roger, Columbia, we are observing.
15:17Chandra is huge, the size of a bus.
15:21It is the largest telescope ever launched with a space transborder.
15:26SRB separation confirmed.
15:29You're stressed about the astronauts who risk their lives
15:33to help us get a better view of the universe.
15:42In the summer of 1999,
15:45NASA's Space Telescope lands on the moon.
15:51In the summer of 1999,
15:54the X-ray astronomy telescope takes off
15:57in the cargo section of the space transborder.
16:06Even two decades after its departure into space,
16:09Chandra remains by far the most powerful observatory
16:12we have to observe the high-energy universe.
16:20Almost 134,000 kilometers from the Earth's surface,
16:24in its highest orbit,
16:27Chandra scans the sky with eight high-precision mirrors,
16:31designed to detect X-rays
16:34emitted by extremely hot regions of the universe.
16:42For 14 years, it searches between the exploding stars
16:46and the clusters of galaxies.
16:51But suddenly, on September 14, 2013,
16:56Chandra finds something completely different.
17:02Chandra wasn't looking for anything like this.
17:05It happened while she was observing a nearby area.
17:08It was a total surprise.
17:13While the telescope is heading towards the Sagittarius constellation,
17:18it tries to observe a large hot gas cloud.
17:25But unexpectedly, it detects a X-ray flash
17:29a few pixels in diameter,
17:32coming from the apparently empty space of the galactic nucleus.
17:47When we see something heating up for a very short period of time,
17:50we get very interested.
17:52Something we can't see is causing it.
18:03Some scientists believe that the X-ray flash
18:06detected by Chandra was caused by an asteroid.
18:11It was so destructive that it caught fire
18:15hundreds of times brighter than the sun,
18:19producing a X-ray flash
18:22that Chandra can detect at almost 26,000 light-years away.
18:28When we see a level of X-rays so bright
18:31that it can't be explained by any other process,
18:34then we know that there's something going on.
18:37It's the giant that's in the center of our galaxy.
18:43Sagittarius A-star.
18:55With a telescope like Chandra,
18:58you can see how a small black hole
19:01takes a small step,
19:04like a human could take a cookie,
19:07and if it's like an asteroid,
19:10then that event will produce a sort of X-ray X-ray flash.
19:14So it's incredible that we can observe Sagittarius A-star,
19:18which is at 26,000 light-years away,
19:21as it devours something.
19:25But Chandra not only looks inwards,
19:28but also outwards, beyond the Milky Way.
19:32And in the center of almost all the big galaxies
19:35that Chandra looks at,
19:38she finds evidence that our galaxy is not unusual at all.
19:43We start to spot X-ray light sources everywhere,
19:47and we start to realize that something weird
19:50was going on in the center of the galaxies.
19:55At the heart of most galaxies,
19:58we think now there's supermassive black holes
20:01that weigh billions of times more than our sun.
20:05It's incredible that our modern X-ray telescopes,
20:08like Chandra,
20:11allow us to map where these fascinating black holes are
20:14across the universe.
20:17Supermassive black holes
20:20seem to be an integral feature of the cosmos.
20:23But these supermassive objects
20:26raise questions.
20:29How do they form?
20:32And why are they so big?
20:35These things form over billions and billions of years,
20:38so we can't see how it happens.
20:41We only see it at various stages throughout the universe,
20:44and so we have to sort of set it up like a puzzle.
20:48Some scientists support the theory
20:51that the largest and oldest black holes
20:54were not stars in their origin.
20:57In the primitive universe,
21:00we believe that supermassive black holes
21:03could have been formed by direct gas collapse.
21:06These are called direct gas collapse black holes.
21:10But there's still no consensus on that.
21:14It's possible that Sagittarius A-star
21:17was formed by direct material collapse,
21:20but what I think is more likely
21:23is that it was formed by the death of a star.
21:26But apart from how Sagittarius A-star was born,
21:29there's no doubt about one thing.
21:32It had to grow.
21:39The newly born Sagittarius A-star
21:42begins to give itself a feast,
21:45swarming not only with asteroids,
21:48but also with stars
21:51and massive gas clouds.
21:56As it feeds on these nearby objects
21:59that cross its path,
22:02it gets bigger and bigger.
22:07The black hole gains more mass
22:10and more gravitational power.
22:14Black holes, with just several times the mass of the sun,
22:17will never grow to become supermassive black holes,
22:20just biting gas and stars.
22:24But how did Sagittarius A-star grow?
22:30On September 14, 2015,
22:33an international team of astronomers
22:36found a clue.
22:40The effects of a truly titanic interaction.
22:44The collision of two black holes.
22:48So the merger of two black holes,
22:51is spectacularly energetic.
22:55It is so energetic that it causes ripples
22:58in the fabric of space-time
23:01that propagate at the speed of light.
23:04And we have detected those ripples here on Earth
23:07with something we call LIGO.
23:11LIGO is an instrument that works
23:14by sending laser beams that bounce off of mirrors.
23:17When a gravitational wave passes by Earth,
23:20what it does is change the interaction times
23:23of those laser beams.
23:27The stretching caused by a merger on Earth
23:30is tiny, but with the advances of technology,
23:33LIGO was able to capture it.
23:44Many scientists now think
23:47that mergers like this one are the key
23:50to how supermassive black holes like ours
23:53have grown so much.
24:09When another black hole approaches Sagittarius A-star,
24:12both are trapped in a gravitational embrace.
24:16At first it is a sort of intriguing dance.
24:19It's like they're dancing around each other.
24:22They're losing energy and slowly
24:25they form a spiral with each other.
24:31This dance gets faster and faster
24:34until they finally merge.
24:45Sagittarius A-star cannibalizes its cousin
24:52causing waves in the fabric of the universe itself.
24:58These mergers were fundamental to make Sagittarius A-star
25:01the monster we see today.
25:04This happened billions of years ago,
25:07right at the beginning of Sagittarius A-star's life.
25:11It keeps devouring stars,
25:16gas clouds,
25:19anything that gets too close.
25:24And as the mass and influence
25:27of our black hole grow,
25:30its environment also changes.
25:40The sea of stars and gas
25:43that surrounds the black hole continues to grow,
25:49evolving gradually
25:52until it becomes the familiar spiral disk
25:55that we recognize as our home.
25:58The majestic Milky Way
26:01with the supermassive Sagittarius A-star in its center.
26:11Sagittarius A-star
26:14When Sagittarius A-star becomes a supermassive black hole,
26:17it reaches the majority of its age
26:20and it acquires the ability to have a transformative impact
26:23across the entire galaxy.
26:26Black holes are the great engines of the universe.
26:29When you think about a car,
26:32the first thing you need to know is how it works.
26:35You open the hood and you look at the engine of the car.
26:38With a black hole, you're asking,
26:41I want to lift the hood of an entire galaxy.
26:44How does a galaxy feed into its core?
26:55The center of the young galaxy
26:58is full of gas and dust swirls,
27:02more matter than can be fed.
27:09This is a period of great voracity.
27:14A new era for Sagittarius A-star.
27:20It is when the invisible giant
27:23has the power to sculpt the galaxy.
27:31While Sagittarius A-star
27:35eats without stopping,
27:38everything it continues to devour
27:41swirls around that supermassive black hole
27:44forming a violent and energetic disk.
27:48And matter is being pulverized by gravity
27:51which causes protons and electrons
27:54to form twisted magnetic field lines.
27:58Everything is rotating and orbiting
28:01so that in the center of this black hole
28:04of that disc of accretion,
28:07there is a magnetic field that rotates almost like a tornado.
28:10Right before the material approaches
28:13that horizon of events,
28:16that eternal prison, so to speak,
28:19it can be redirected again.
28:22From this burning confusion,
28:25superhot materials come out
28:28Two high-powered jets
28:31heading for the cosmos.
28:34They can reach hundreds of thousands of light years
28:37from the black hole.
28:41Until recently, we have not begun to understand
28:44the enormous influence of Sagittarius A-star
28:47in our galaxy
28:50and the role that those super-powerful jets
28:53may have played.
28:561-0
28:59Take off!
29:03The Delta rocket carries a gamma-ray telescope
29:06to study the hidden physics
29:09of the stars of the galaxies.
29:21Just over a decade ago,
29:24astronomers made a completely unexpected discovery.
29:27It was a part of our galaxy
29:30that we did not know was there before.
29:33It was like we had found a new continent on Earth.
29:40The Fermi Space Telescope
29:43was designed to detect gamma rays,
29:46the most energetic radiation in the universe.
29:49Fermi is 100 times more sensitive
29:52than the previous gamma-ray telescopes.
29:55So it has the sensitivity to see things
29:58that we couldn't see before.
30:01While describing an orbit around the Earth every 96 minutes,
30:04Fermi builds a map of the cosmos
30:07and discovers an invisible landscape,
30:10the most energetic regions of the galaxy,
30:13illuminated through the sky.
30:17So we pointed the Fermi telescope
30:20towards our very own supermassive black hole.
30:23We had a vague idea of what that area looked like.
30:26But Fermi revealed something completely surprising
30:29and unexpected.
30:36Two huge bubbles protrude from the plane of the Milky Way.
30:39Each of them is a supermassive black hole.
30:43Each of them has an extension of 25,000 light years.
30:46Together, they are half the width of the galaxy.
30:57If we could see the gamma rays,
31:00Fermi bubbles would be the largest thing you could see in the sky.
31:03They look like huge thumbs
31:06going straight up and straight down from the center of the black hole.
31:12They coincide with the mark that scientists think
31:15would have left a huge eruption of Sagittarius in the galaxy.
31:21We had some clues that the Milky Way
31:24could have had an energetic and active past.
31:27But the incredible thing about Fermi bubbles
31:30was that they gave us concrete evidence
31:33that the Milky Way was much more energetic
31:36at some point in its history.
31:42Fermi bubbles
31:55While our black hole absorbs matter voraciously,
31:58it generates an infernal column of overheated matter.
32:07A supermassive black hole
32:10can emparse a billion trillion atomic bombs
32:13per second of energy.
32:16If we were in the line of fire of one of those jets,
32:19it would be catastrophic for us.
32:22We would be vaporized.
32:25Fermi bubbles
32:39Any planet that was in the trajectory of the jet
32:42could have been stripped of its atmosphere.
32:55Fermi bubbles
33:04But further into the galaxy,
33:10these violent eruptions of Sagittarius A,
33:13could have played a surprising role.
33:25Fermi bubbles
33:31Because the hot gas displacement
33:34that produces a supermassive black hole
33:37has a calming effect on the galaxy that houses it.
33:42In order for stars to form,
33:45you need very cold and very dense gas
33:48because stars are formed by the collapse of material.
33:51So, instead, if we have something like a black hole
33:54supermassive that is sending those hot jets
33:57into the galaxy that surrounds it,
34:00those jets are going to heat up the gas.
34:03Now the gas is no longer going to be cold enough
34:06to collapse and form a star.
34:09There is a symbiotic relationship
34:12between the supermassive black hole
34:15that is in the center and its host galaxy.
34:18And this relationship determines the speed
34:21in which stars form, planets form,
34:24and ultimately, in some sense, why we are here.
34:27Fermi bubbles
34:47After spending billions of years
34:50consuming gas, dust,
34:53and the stars that surrounded it,
34:56there is little left to devour.
35:02Our black hole is in a lethargic state.
35:10Now the Milky Way is living a calm era
35:13and Sagittarius A,
35:16is a sleeping giant.
35:19The huge bubbles detected by the Fermi telescope
35:22are echoes of a turbulent past.
35:27We live in a special moment in the history of the universe.
35:30Because, in fact, right now,
35:33the black hole is very calm,
35:36but it should have been much more active
35:39millions of years ago.
35:43As our understanding has increased,
35:46our image of black holes has transformed.
35:49They no longer seem sinister monsters,
35:52but agents of change and creation,
35:55sculptors of the cosmos.
35:58We are far from unlocking all the secrets
36:01of the supermassive black hole of our galaxy.
36:04And in fact, what we still have to know
36:07is probably the most important thing.
36:10What happens inside a black hole
36:13and in its event horizon?
36:24Black holes challenge the most basic principle
36:27about the predictability of the universe
36:30and the certainty of history.
36:34Nothing could get out of a black hole,
36:37or so it was thought.
36:46Black holes are the place
36:49where two of our most important theories collide.
36:52We have two primary forces in the universe.
36:55Gravity, which we all understand
36:58and feel in our bodies,
37:01and quantum mechanics,
37:04which governs the theory of the ultra-small,
37:07how atoms and nuclei are related.
37:10The black hole is where gravity
37:13and quantum mechanics are located.
37:16When we try to combine mathematics
37:19of the very large with mathematics
37:22of the very small, instead of coinciding,
37:25they get into a fight.
37:28And so we don't have a consistent way
37:31of describing them.
37:34We can begin to delve into this deep mystery
37:37by investigating the heart of Sagittarius A.*.
37:44Scientists have studied dozens of stars
37:47orbiting around it.
37:50Some of them pass just a few billion kilometers
37:53from the event horizon.
37:57Very close on galactic scales.
38:00And those approximations could have
38:03catastrophic consequences.
38:14Because some of those stars
38:17may have planets in orbit.
38:22Planets that could get too close
38:26like fleas to a flame.
38:32And be dragged from the orbit
38:35of their progenitor stars
38:38to the abyss.
38:41So imagine we are an alien civilization
38:44and we are looking at our star S2.
38:47And one day it begins to get closer
38:50to what we call the Sagittarius A.* tidal disruption radius,
38:53which is around 4 million solar masses.
38:58If we fell into a black hole,
39:01we would cross the event horizon
39:04and actually we would see nothing.
39:07There's no physical barrier.
39:10There's no great line in space
39:13that says no return.
39:16You would just slip very smoothly
39:19through the event horizon.
39:22If we were on a planet in that situation
39:25and we looked at the sky,
39:28we would see something spectacular.
39:37You would see a distorted universe.
39:40In fact, you would see it distorted
39:43in time and in space.
39:47You'd see it moving very fast
39:50and it would make an amazingly fast speed.
39:53The rest of the time we would play out
39:56from the very top in front of your eyes.
40:01But in the end,
40:04the tidal and gravitational forces
40:07would be too strong
40:10and they would end up stretching the space
40:13and everything in it.
40:16Your gravity would pull more gravity
40:19from your feet than your head.
40:22So you'd be stretched into a giant string
40:25and then you'd be one long string
40:28of one atom thick.
40:31It's what we call spaghettification.
40:34The big rocks become rocks.
40:37The rocks become sand
40:40whose atoms are separated.
40:47Gravity and the quantum world collide.
40:51And in front of it,
40:54the heart of the black hole,
40:57the singularity,
41:00where all the journeys end.
41:03Our idea of the singularity
41:06is that everything compresses beyond possible
41:09until it becomes nothing,
41:12but it still exists.
41:15Wow!
41:38Throughout billions of years,
41:41all the stars that surround Sagittarius
41:44will gradually cease to exist.
41:59Long after the last sun goes down,
42:02the black holes will continue to wander around the universe.
42:06The Dark Age
42:21If nothing can escape,
42:24if this is some kind of prison,
42:27is that the end of the story?
42:30Maybe not.
42:33Scientists believe that even Sagittarius A,
42:36the star, will die.
42:43And its death will come at the hands
42:46of what could seem an intrascending effect
42:49described for the first time
42:52almost five decades ago.
42:55So in 1975, Stephen Hawking
42:58published an amazing paper
43:01that showed that black holes
43:04are not absolutely black.
43:07They glow very, very faintly.
43:10They have a temperature associated with them.
43:13And you can write that temperature
43:16very simply in an equation
43:21that's just beautiful.
43:24It links together so many different parts of physics.
43:27It's got gravity.
43:30It's got the speed of light.
43:33It's got constants related to atomic physics,
43:36the microworld,
43:39and it's putting all of this together
43:42and giving us a temperature.
43:48So if something has a temperature,
43:51it's glowing, it's radiating.
43:54When you put your hand just by the fuel,
43:57and that whole extracting energy
44:00for a black hole like Sagittarius A,
44:03over time scales that are extremely long,
44:06it's going to evaporate.
44:09It's going to disappear.
44:12Very gradually,
44:15this radiation from Hawking
44:18is going to erode Sagittarius A.
44:21Until within billions and billions of years,
44:24in the future,
44:27it's going to disappear.
44:30It's going to disappear.
44:33It's going to disappear.
44:36It's going to disappear.
44:39In the future,
44:48in a final burst of light,
44:56our black hole will disappear.
45:01And then the Milky Way will be completely dark
45:04for all of eternity.
45:10So why do you care if these black holes
45:13disintegrate in the far future?
45:17Well, the discovery of Hawking's radiation
45:20raises some profound questions in physics.
45:23If I were to set fire to this piece of paper
45:26with Stephen Hawking's equation written on it,
45:31what happens to all of that information
45:34when it burns away?
45:37Do we lose it from the universe forever?
45:54Maybe if I could pick up all the ash,
46:00if I could find all the photons
46:04and reconstruct them,
46:07maybe I could reconstruct that piece of paper,
46:10even the equation written on it.
46:14So does this also apply to black holes?
46:17What happens to all the information
46:20contained on all the material
46:23that once fell into a black hole?
46:26And when a black hole evaporates,
46:29what happens to that information?
46:34Black holes ain't as black as they are painted.
46:38They are not the eternal prisons
46:41they were once thought.
46:47So, if you feel you are in a black hole,
46:50don't give up.
46:55There's a way out.
47:04If information escapes from Sagittarius A,
47:07while it evaporates,
47:10the implications are profound.
47:14Scientists now believe
47:17that every star,
47:20asteroid, planet,
47:23everything that once fell into Sagittarius A
47:26can continue to exist.
47:29Every aspect and position of every particle,
47:32everything encoded as information,
47:35everything that would theoretically be necessary
47:38to reconstruct the black hole.
47:42But how can something escape
47:45from the clutches of a black hole?
47:49The defining fact of a black hole
47:52is that nothing should be able to escape from it.
47:55And yet, if we examine Hawking's radiation,
47:58it seems to suggest that quantum physics
48:01does connect up the inside back to the outside.
48:04But we just don't know how.
48:08Black holes force us to consider
48:11nature in totally new and extraordinary ways.
48:16Maybe it gets sent to another dimension.
48:19Maybe it gets sent to another planet.
48:22Maybe it gets sent to another dimension.
48:25Maybe it gets sent to some kind of larger multiverse.
48:29Some people think that all the information
48:32that falls into a black hole
48:35is somehow encoded on its surface in a hologram.
48:39Whatever the explanation,
48:42its branches will go far beyond the black hole itself.
48:45This theory of quantum gravity,
48:48so difficult to formulate right now,
48:51is what we would need to describe
48:54what is happening inside the black holes.
48:57It could either be the most significant advance
49:00of the next decade,
49:03or maybe even of the next century.
49:06Or it could be a warning bell
49:09that maybe Einstein's theory of gravity
49:12is not the final word about gravity.
49:16Solving the mystery of the black holes
49:19could be our best opportunity
49:22to complete the image of nature
49:25that we have tried to build during the last century.
49:28It is possible that the important thing is not what the answer is.
49:31The important thing is that we will obtain
49:34a more complete understanding of the cosmos
49:37by studying these objects.
49:41We have to rethink everything over again.
49:44It's almost like breaking the universe we have now
49:47and writing a new one.
49:51We are still far from fully understanding
49:54the secrets of the black holes,
49:57but we are starting to lift the veil.
50:04Far from being a mere cosmic aberration,
50:07the black holes model our universe.
50:15It's extraordinary to think that we could be connected
50:18to something that we have not known existed
50:21since the dawn of humanity.
50:26The black holes are an incredibly rich source of information.
50:29We have learned so much about the universe
50:32by studying them.
50:35Space, time, the fundamental nature of reality.
50:40Little by little,
50:43the deepest mysteries of the cosmos are revealed to us.
50:47We are in a golden age of discovery of the black holes.
50:50We have understood how they merge.
50:53We have discovered their colossal jets.
50:56And we are beginning to see them not only as destroyers,
50:59but also as creators.
51:02And all that is just the beginning.
51:06Our story is happening now,
51:09but the black holes are going to help us survive
51:12trillions of years.
51:15Their story is just getting started.
51:32NASA Jet Propulsion Laboratory, California Institute of Technology