En el año 1610, Galileo Galilei construyó uno de los primeros telescopios y, observando al planeta Venus, se dió cuenta de que el centro del universo no era la Tierra, sino el sol y que entorno a él giraban los planetas.
Category
😹
DiversiónTranscripción
00:00A week earlier
00:09I can see everything so clearly.
00:12It's an inhospitable beauty.
00:24Magnificent desolation.
00:26Precioso. Precioso.
00:49La Vía Láctea seems like an impassable place.
00:57Hundreds of thousands of millions of stars,
01:00spinning serenely around the cosmos.
01:08But if we enter it,
01:10going through the gas and dust that envelops the galactic core,
01:18we will see a curious spectacle.
01:26Stars orbiting around an apparently empty place,
01:35but occupied by something dark and ancient.
01:40A hole in the fabric of the universe.
01:57The Vía Láctea
02:10Every one of those points of light in the night sky
02:13is a strange and fascinating place.
02:17Magnificent stars with countless planets orbiting around them,
02:21extra-solar worlds beyond imagination.
02:25But the strangest and most fascinating places are those that we can't see.
02:41There is an invisible monster lurking in the center of the Vía Láctea.
02:45A monster that absorbs the color of the universe.
02:54That has the power to destroy worlds
03:02and stop time.
03:16The Vía Láctea
03:29A monster that we have named Sagittarius A Asteriscus,
03:34and we believe it is a black hole.
03:38Sagittarius A Asteriscus
03:43Sagittarius A Asteriscus has been very relevant in the evolution of our galaxy,
03:48and it is possible that it has influenced the formation of other stars and planets like ours.
03:53But there is so much more,
03:56because black holes like Sagittarius A Asteriscus
04:00pose an intellectual and comparable challenge.
04:03They are part of nature,
04:05just like you and me,
04:07so we should be able to understand them.
04:09But they are holes in the fabric of the universe.
04:13They are gravitational prisons from which not even light can escape.
04:17And when trying to understand them,
04:20physicists have been forced to completely rethink
04:24the understanding of the most elementary reality.
04:29The answers are hidden in the void,
04:32waiting for the bravest to find them.
04:58Nowhere is that more true than in the case of black holes.
05:04Black holes are stranger than anything dreamed up by science fiction writers,
05:09but they are firmly matters of science fact.
05:21Received. We begin the deployment.
05:29When you look up, you realize how big it is,
05:32and that we have it above us.
05:37In the summer of 1999,
05:39the most important mission of NASA for X-ray astronomy
05:43arrived in orbit in the cargo bay of the transporter.
05:50There is nothing as beautiful as seeing Chandra
05:53navigating to his observation post.
05:59Orbiting around the Earth,
06:02Chandra scanned the sky,
06:04searching for some of the hottest regions of the universe,
06:10with explosions of stars and clusters of galaxies.
06:23But on September 14, 2013,
06:26after 14 years,
06:28Chandra found something totally different.
06:40The telescope was directed towards the Sagittarius constellation,
06:44to observe a huge cloud of hot gas.
06:57But in its place, it recorded a flash of X-rays,
07:01just a few pixels,
07:05coming from an apparently empty area in the center of the galaxy.
07:17Something had heated up a lot,
07:20in a period of time much longer than expected.
07:26Very short.
07:39It is believed that the flash captured by Chandra
07:42was an asteroid of tens of kilometers.
07:56Shattered and turned into a fireball,
07:59300 times brighter than the sun.
08:12The culprit, Sagittarius A.*.
08:27As if the black hole of our galaxy
08:30wanted to publicly announce its presence.
08:3520 YEARS LATER
08:4920 years ago, we didn't know for sure
08:52whether or not there was a black hole in the center of our galaxy.
08:56Now, thanks to the measurement of the radiation bursts,
08:59and the detailed analysis of the orbits of the stars
09:02close to the galactic center,
09:04we know without a doubt that Sagittarius A.* exists.
09:07We have even been able to measure its mass,
09:10around 4 million times the mass of our sun.
09:14This makes it a supermassive black hole,
09:17one of the strangest and most powerful objects in the universe.
09:21And we suspect that Sagittarius A.*
09:24is not just a strange element
09:26located in the center of the galaxy,
09:28tens of thousands of light years from Earth.
09:31Its role in the evolution of the Milky Way has been crucial.
09:36It is a story that begins with the death of a massive star.
09:42COSMOS
09:59Shortly after the beginning of time,
10:04the cosmos was the home of colossal stars.
10:12Hundreds of times more massive than the sun.
10:17Stars that burned with a blue color, and an intense heat.
10:28But the brightest stars are the ones that live the least.
10:33One of them had a fast and intense existence,
10:40burning all its nuclear fuel in a few million years.
10:55And the other star,
10:57the star of the Milky Way.
11:02And when the energy ran out,
11:05gravity took control.
11:08The star collapsed,
11:11getting smaller and denser,
11:17until it apparently disappeared.
11:21A star smaller than an atom,
11:24vanished in the universe.
11:29There was only one ghost left.
11:33A black hole.
11:45The genesis of Sagittarius A.*
11:48was not a special event.
11:51It is very likely that almost all the first stars disappeared,
11:55turning them into black holes.
11:59Black holes are simply what happens when gravity is out of control,
12:04compacting matter until it becomes something so dense
12:08that it opens a hole in the universe.
12:13In the vicinity of a black hole, space and time
12:17behave in a very unintuitive way.
12:20And this river provides us with such a beautiful and precise analogy.
12:24Close to a black hole,
12:27it seems that space itself is flowing towards it.
12:39Now, in this area, the current is not too fast.
12:43We could cross the river swimming faster than the current of space
12:47and escape from the galaxy.
12:50But as we get closer to the black hole,
12:53the current of space accelerates faster and faster and faster.
13:02A collapsed massive star is so small
13:05and at the same time so massive
13:07that it generates an immeasurable gravitational force.
13:13There is no limit to the speed at which the current of space can flow.
13:44And finally, we arrive at the place where the river becomes a waterfall,
13:48no matter how fast the current could never go back.
13:52That's what happens in the vicinity of a black hole.
14:01The river of space is a black hole.
14:04It is a black hole that is not a black hole.
14:07It is a black hole that is not a black hole.
14:11The river of space flows at the speed of light and exceeds it.
14:17Not even light has enough speed to escape.
14:25Sagittarius Asterix is precisely that,
14:28a waterfall in the fabric of the universe.
14:41Since the birth of the black hole,
14:44the seed of Sagittarius Asterix has had a heart of pure darkness.
14:53The interior has been hidden forever,
14:56isolated from the rest of the universe by a border in space.
15:03The horizon of events.
15:06The most extreme point of no return.
15:15As we approach the horizon of events,
15:18we begin to see the true singularity of black holes.
15:37Einstein taught us that space and time are not what they seem.
15:42They are mixed in the fabric of the universe,
15:45in what we call space-time.
15:48And he also taught us that the presence of massive objects,
15:52stars, planets and galaxies,
15:54curve and distort the fabric of the universe.
15:58That's what we perceive as the force of gravity.
16:07But that distortion is not exclusive to space.
16:11It also occurs in time.
16:18As you get closer and closer to a massive object,
16:22the speed at which time passes is reduced.
16:25And when you look at a black hole,
16:28time slows down and slows down more and more.
16:32Until, when you reach the horizon of events, it stops.
17:02ASTERISK
17:23Sagittarius Asterisk was born as a waterfall in the fabric of the universe,
17:29in which space flows faster than light,
17:33and time stops.
17:46But our black hole was just a baby.
17:53Smalled by the stars around it,
17:56it was nothing like the monster it became.
18:10Sagittarius Asterisk currently has four million times the mass of the sun,
18:16and there has never been such a massive star.
18:19That indicates that it was formed by the collapse of other smaller ones,
18:24and then it continued to grow throughout the life of the Milky Way, devouring things.
18:29Unfortunately, it had a lot of material to eat.
18:37The gravitational attraction of the young black hole was inexorable.
18:42There was no escape for anything that came too close.
18:54ASTERISK
19:02Sagittarius Asterisk began to grow,
19:05attracting the closest stars,
19:12and then breaking them into pieces and giving themselves a feast of hot plasma.
19:24The black hole was gaining more mass and more gravitational force.
19:36But we do not believe that there were so many stars nearby,
19:40as for the black hole to grow supermassively,
19:43following a monotonous diet of stars.
19:48It also developed a taste for more massive prey.
19:54ASTERISK
20:15When another black hole passed near Sagittarius Asterisk,
20:19they were anchored in a gravitational embrace,
20:30spinning in a spiral,
20:33accelerating and approaching each other at half the speed of light,
20:42until they collided.
20:50Sagittarius Asterisk cannibalized its cousin,
20:56generating waves in the fabric of the universe itself.
21:07And it kept devouring,
21:09black holes, stars, gas clouds,
21:13everything that ventured too close to its nest.
21:20As the power and influence of our black hole grew,
21:26its environment also changed.
21:32Around the galactic nucleus,
21:35hundreds of billions of stars orbited,
21:42spinning slowly around its common center of mass.
21:50And becoming this familiar spiral disk.
21:58The majestic Milky Way,
22:01with Sagittarius Asterisk in its center.
22:20Sagittarius Asterisk became what we call today
22:23a supermassive black hole.
22:26It is many tens or even hundreds of thousands of times more massive
22:30than any other star in the universe.
22:33But it is not a unique case.
22:35Now we believe that practically all large galaxies
22:38have a supermassive black hole in their heart.
22:50Chandra has directed his gaze beyond the Milky Way
22:54and has observed supermassive black holes
22:57in the nucleus of the myriad of galaxies scattered throughout the universe.
23:08These monsters are not rarities of nature.
23:13They are not secondary actors.
23:17They are fundamental elements.
23:20We are beginning to understand that black holes have enough power and reach
23:25to sculpt the galaxies that surround them.
23:47The center of our young galaxy was rich in gas and dust.
23:54More variety for the feast.
24:07It was a voracious period that marked a new era
24:10for the supermassive black hole of the Milky Way.
24:17The invisible monster became the sculptor of the galaxy.
24:22The Black Hole
24:43Creation and destruction in the universe usually go hand in hand.
24:47And black holes are no exception.
24:50Sagittarius Asterix is not just an agent of destruction.
24:53Not everything that falls under its influence
24:56vanishes on the horizon of events.
24:59There is a lot of material that stays orbiting around it.
25:07And it is a tremendously violent region.
25:10There are magnetic fields that twist and distort
25:15throwing material through the magnetic poles of the black hole
25:19like jets that cross the galaxy.
25:28Until recently we did not understand the true magnitude
25:31of the eruptions from Sagittarius to Asterix.
25:35And now
25:40Engines start.
25:43One, zero.
25:45Liftoff.
25:50The Delta rocket, transporting a gamma-ray telescope
25:53to investigate the physics of the invisible in the stars of the galaxies.
26:06Just a decade ago
26:09a totally unexpected discovery occurred
26:12comparable to the discovery of a new continent on Earth.
26:26The Fermi Space Telescope was designed to detect gamma rays
26:31the radiation with the most energy in the universe.
26:49Fermi's mission was to create a map of the firmament
26:52while orbiting around the Earth.
27:02And he saw that from the plane of the Milky Way
27:12two colossal bubbles of matter emerged
27:15with a length of 25,000 light years each.
27:32These bubbles are superheated gas.
27:36If our eyes were able to capture the wavelength of the light
27:40emitted by these bubbles
27:42we would see how they cover half of the sky that we see from Earth
27:46and converge in the center of the galaxy.
27:49So their origin could be Sagittarius to Asterix.
27:53Sagittarius to Asterix is large, but not too large on a galactic scale.
27:58Our solar system would fit comfortably in the orbit of Mercury.
28:06Although the size of our black hole is only a fraction of the size of the galaxy
28:12it has become the sculptor of the Milky Way.
28:29In a few million years
28:31the dense ring of materials that surrounded our black hole
28:41when accelerated by the torsion of the magnetic fields
28:45became overheated jets of matter.
28:50Jets so powerful that they destroyed the atmospheres
28:54of all the planets they encountered on their way.
28:59And radiation turned into inhabitables all the worlds similar to Earth
29:05in a radius of 1,000 light years.
29:08of all the planets they encountered on their way.
29:20And radiation made all the worlds similar to Earth
29:24into uninhabitable, in a radius of a thousand light years.
29:39But the magnitude of the explosions of Sagittarius A Asterisk
29:44made that at one end of the galaxy
29:53destruction became creation.
30:08And that's where we are today.
30:24When looking for explanations about how life on Earth came to be
30:28and how it evolved for 4 billion years
30:31until it turned the planet into the complex world we live in
30:35it seems a bit exaggerated to point to a supermassive black hole
30:39in the centre of the galaxy and say that's one of the reasons.
30:43But we are beginning to suspect that those huge discharges of energy
30:47from Sagittarius Asterisk were crucial to turn our little corner of the galaxy
30:53into a place where life could flourish.
31:00The hot gas expelled by Sagittarius A Asterisk
31:05had a balsamic effect on the galaxy.
31:08Now you might think that a hot gas cloud would produce more stars
31:13but in reality it's the opposite because with the heat everything moves faster
31:18and gravity can't hold and collapse matter to form stars.
31:22So Sagittarius Asterisk reduced the formation of stars in this region of the galaxy.
31:29And that's something good.
31:31Imagine if in this area there was a giant star.
31:35If it exploded as a supernova it would be a problem for an amoeba
31:40with the hope of evolving and becoming Einstein.
31:44So thanks to Sagittarius A Asterisk
31:47what could have been a violent region of our galaxy
31:50became a peaceful region.
31:54The hot gases expelled by Sagittarius A Asterisk
31:58reduced the rhythm of star formation.
32:08And around a small yellow star
32:11in a peaceful region of the extreme boredom of one of the spiral arms of the galaxy
32:184 billion years of this ability
32:21made everything different.
32:48The Big Bang
33:02Now of course there are many things to make life on a planet.
33:06The list is extraordinarily long.
33:09But I think it is interesting that the most interesting thing about that list
33:13is the presence of this strange object.
33:17A black hole, Sagittarius A Asterisk
33:20tens of thousands of light years from the center of our galaxy.
33:43After most of the gas, dust and stars around it disappeared
33:54there was almost nothing left to absorb.
33:59Our black hole stayed at rest.
34:06The huge bubbles discovered by the Fermi telescope
34:10are just echoes of a glorious past.
34:21Sagittarius A Asterisk today is a sleeping giant.
34:27A melancholic beast on fire.
34:32Sagittarius A Asterisk began as a violent destroyer.
34:36It became the sculptor of the galaxy and now it is a sleeping giant.
34:40In the last 20 years we have reconstructed its history,
34:43thanks to the discovery of the black hole
34:46and the discovery of the black hole.
34:49The black hole is a huge black hole
34:52and it is the largest black hole in the galaxy.
34:55It is the largest black hole in the galaxy.
34:58In the last 20 years we have reconstructed its history
35:01thanks to the observations of the Chandra and Fermi telescopes.
35:07But there is a big difference between knowing how a black hole interacts
35:12with its environment to sculpt a galaxy
35:15and understanding in depth what a black hole is.
35:23What is it really like inside?
35:29Black holes challenge the most basic principle
35:33about the predictability of the universe
35:36and the certainty of history.
35:42Nothing could get out of a black hole,
35:45or so it was thought.
35:59Looking to the future
36:02is the best way to explore the deep mystery of black holes.
36:12Around Sagittarius A Asterisk
36:15orbit dozens of stars,
36:18some of them a few thousand million kilometers
36:21from the horizon of events,
36:24on a galactic scale as if it were a hair.
36:29This proximity may have lethal consequences.
36:46It is likely that some of these stars have planets in orbit,
36:50planets that could be too close to the beast.
37:02And like a moth heading towards a flame,
37:05they could be dragged from their mother star to the abyss.
37:21If the planet survived its journey into the interior of the black hole
37:26and we could remain on its surface looking at the universe,
37:42we would see the growing distortion of space and time.
37:51The Black Hole
38:12Until the gravitational force was too strong.
38:20The Black Hole
38:39The singularity would approach inexorably.
38:44It would reach the end of time,
38:47where all paths end.
39:17Over billions of years,
39:20all the stars that surround Sagittarius A Asterisk
39:23will go out and die.
39:31And many worlds, more and more,
39:34will stop seeing the dawn.
39:37But our supermassive monster will continue there,
39:41with its interior full of sealed secrets,
39:45presumably forever.
39:54The day will come when the Black Holes
39:58will be able to return to their original form.
40:07The Black Holes will be the only thing left in the universe.
40:13It will be the final dark age.
40:16The Black Hole
40:35If nothing can escape a black hole,
40:38if Sagittarius Asterisk is really an eternal prison,
40:42then this is the end of the history of the universe.
40:46Darkness that is sprinkled with holes in space and time.
40:49But we don't believe that this is the end of history.
40:57We currently believe that the Black Holes also die.
41:02And that their death depends on something
41:05that was discovered 50 years ago,
41:08and that could seem like an intrascending detail.
41:16In 1975, Stephen Hawking published an extraordinary article
41:20in which he showed that the Black Holes are not completely black.
41:24They shine brightly,
41:27and they have a temperature.
41:30And here is his wonderful equation
41:33to calculate the temperature of a black hole.
41:43And you can see that this equation is so broad
41:46that it includes all of physics.
41:49This has got H bar, which is the constant of Planck,
41:53which belongs to quantum mechanics, the subatomic world.
41:57C is the speed of light.
42:00G is the force of gravity.
42:03K sub V is related to temperature and thermodynamics.
42:07And this M is the mass of the black hole.
42:10It even has circles, because it is also pi.
42:14Hawking's conclusion turned out to be irrefutable.
42:19And its implications are enormous.
42:23If an object has a temperature, then it emits radiation.
42:27That is why you feel heat when you bring your hand close to something hot.
42:31So, calculating the time on a scale of millions and millions and millions,
42:35longer than the current age of the universe,
42:38Sagittarius A asterisk will end up evaporating.
42:53Asterisk
43:03Hawking's radiation will gradually erode Sagittarius A asterisk,
43:13which will become smaller and smaller,
43:18until, within billions and billions of years,
43:29in a last burst of light,
43:33our black hole will die.
43:38And then there will be darkness for all eternity.
43:47Black holes
43:53Now, you may say, it's perfectly normal to think,
43:56well, why do we care?
43:58Why does it matter if black holes are going to evaporate in the distant future of the universe
44:03if no one will be able to see it?
44:05But the discovery that black holes evaporate
44:09raises in my mind the most profound question in the history of physics
44:13in the last 100 years.
44:15And that's no exaggeration.
44:17See, what happens if I set fire to this piece of paper
44:24where I've written Stephen Hawking's equation,
44:28to evaporate it,
44:30am I destroying something?
44:32When it burns, will I have eliminated from the universe all the information it contains,
44:36including the equation itself?
44:46The answer is no.
45:01If I could collect every bit of ash
45:04and every molecule of gas that burns off into the atmosphere,
45:09then in principle,
45:11I could reconstruct the paper with all its components,
45:16with all the information,
45:19including Stephen Hawking's equation.
45:24But that could also be true for black holes,
45:27the ultimate gravitational pressures
45:30from which not even light escapes.
45:36When they evaporate,
45:38do they return to the universe
45:41the information of everything that fell into it?
45:52Black holes ain't as black as they are painted.
45:57They are not the eternal prisons they were once thought.
46:02Things can get out of a black hole,
46:05both at the outside and possibly to another universe.
46:15So, if you feel you're in a black hole,
46:18don't give up.
46:23There's a way out.
46:26To get information from Sagittarius to Asterix
46:30by evaporation
46:34has very profound implications.
46:40Black holes aren't tombs.
46:43They're doors.
46:48Currently, the only way to get information
46:51from Sagittarius to Asterix
46:54is through evaporation.
46:59We currently believe that everything that falls into Sagittarius to Asterix
47:03will remain alive.
47:09Not as something physical,
47:12but as encoded information,
47:19in the form of Hawking radiation,
47:22from a distant future.
47:34The memory of all those worlds that fell into Sagittarius to Asterix
47:38throughout the history of the Milky Way
47:41is somehow written in the ashes of the universe of the future.
47:47But the real treasure lies in the explanation
47:51of how the information gets out of those eternal prisons.
47:55Now, what I'm going to tell you is going to sound very bizarre,
47:58almost science fiction, but it doesn't matter.
48:02When the black hole evaporates more or less halfway through the black hole,
48:07the interior becomes, in some sense,
48:11in the same place as the distant radiation emitted a few eons ago
48:16that's out there within the confines of the universe.
48:20If you open wormholes,
48:23spatiotemporal holes,
48:26between the interior of the black hole
48:29and those distant parts of the universe,
48:32we can read the information that's inside.
48:35Now, that is a bit of a weird sound.
48:38I must say that there is no agreement
48:41about what the physical image of what happens would be.
48:44But everyone agrees on something.
48:47The black holes tell us that the intuitive image
48:51that we have of the reality of space and time is wrong.
48:55The idea that this place is close to this other
48:59and that time is moving forward is wrong.
49:02There is a deeper reality
49:05in which space and time do not exist.
49:18The attempt to answer a seemingly simple question
49:22about the fate of the objects that fall into the black holes
49:26has led us to a conclusion as profound as disturbing.
49:32The concepts of space and time
49:35are fundamental in our way of experiencing the world,
49:39but they are not fundamental properties of nature.
49:46They arise from a deeper reality
49:49in which neither exists.
49:56What happens with the black holes
49:59is that no one really understands them.
50:02So don't worry if you don't understand what I'm talking about.
50:06I don't understand what I'm talking about either.
50:09And there's no one who understands it.
50:23We are still far from fully understanding
50:26the secrets of the black holes.
50:33But we are beginning to glimpse some details.
50:41Sagittarius A** is not a mere cosmic aberration.
50:47It is part of our history and our future.
50:57Our black hole has not only turned us into what we are.
51:03It is a master who is revealing to us, little by little,
51:07the mysteries of the universe.
51:12Secrets sealed inside a place
51:17beyond eternity.
51:27The moral of the story is very clear.
51:30Understanding the book of nature is very difficult.
51:33So the more nature we observe,
51:36the more chances we have of finishing the book.
51:39And the strangest objects in nature
51:42are the black holes, by far.
51:45And so it's totally unsurprising that when we look out
51:48into the horizon and into the darkness,
51:51we have glimpsed something deeply hidden,
51:54something that sustains reality itself.
51:59But to understand the meaning of all this,
52:02we cannot limit ourselves to the intellectually safe confines of our planet.
52:07We have to look out there, beyond our universe.
52:25A film by
52:29A film by
52:34A film by
52:39A film by
52:44A film by
52:49A film by
52:54A film by
52:59A film by
53:04A film by
53:09A film by
53:14A film by
53:19A film by
53:24A film by
53:29A film by
53:34A film by
53:39A film by
53:44A film by
53:49A film by
53:54A film by
53:59A film by
54:04A film by
54:09A film by
54:14A film by
54:19A film by
54:24A film by
54:29A film by
54:34A film by
54:39A film by
54:44A film by
54:49A film by
54:54A film by
54:59A film by
55:04A film by
55:09A film by
55:14A film by
55:19A film by
55:24A film by
55:29A film by
55:34A film by
55:39A film by
55:44A film by
55:49A film by
55:54A film by
55:59A film by
56:04A film by
56:09A film by
56:14A film by
56:19A film by
56:24A film by
56:29A film by
56:34A film by
56:39A film by
56:44A film by
56:49A film by
56:54A film by
56:59A film by
57:04A film by
57:09A film by
57:14A film by
57:19A film by
57:24A film by
57:29A film by
57:34A film by
57:39A film by
57:44A film by
57:49A film by
57:54A film by
57:59A film by
58:04A film by
58:09A film by