La Verdad Sobre los Agujeros Negros： Misterios del Universo Revelados.

In the year 1990, the hope of a new era of scientific discoveries was put into orbit aboard the Hubble Space Telescope. A technical failure in its optics, which required a repair made by astronauts, delayed, but did not stop the beginning of a new era. In 1994, astronomers oriented the Hubble, recently repaired, towards one of its most important objectives, a giant elliptical galaxy 50 million light-years from Earth, called M87. As they deepened into the core of M87, they glimpsed a powerful superhot jet of gas that extended 5,000 light-years through space. Thanks to the impressive resolution of the Hubble, astronomers measured the speed of the gas surrounding its core. They concluded that the gravitational force that drives these movements is a black hole with a mass 6,600 million times that of our Sun. The news of M87 was joined by an avalanche of discoveries from the Hubble instruments. The public was fascinated by strange and majestic shapes captured in mysterious kingdoms far away from Earth. For scientists, the Hubble was part of an arsenal of fast-growing observation tools. An increasing fleet of space observatories captured the light of distant objects in the entire electromagnetic spectrum. On Earth, a new generation of giant telescopes with precision mirrors and dynamic optics allowed observers to study distant regions of the universe. Astronomers, used to long nights of meticulous camera exposures, were flooded with data from different corners of the cosmos. A new vision of the universe emerged, defined by enormous energy releases, titanic collisions, new mysterious forces, and the strangest phenomenon in nature, the black hole. The black holes, formerly considered mere curiosities, have become a central place in our understanding of the universe and its formation. The life of a black hole begins with the bright light of a dying star. Among the folds of our galaxy, the energy released by supernovae shakes the celestial composition. The shock waves of these explosions cause condensation and then the ignition of gases. And so stars are born, sometimes hundreds at a time. The intense stellar winds of these newly born stars sculpt majestic gas castles, the great nebulae admired by astronomers for a long time. However, for the giant stars that started this process, the consequences are disastrous. In the mid-19th century, sailors sailed the southern seas under the light of a bright star, right next to the plane of the galaxy, in the constellation of Carina. For more than a decade, it was the second brightest star in the sky. Since then, astronomers have studied it intensively. The star, called Eta Carinae, had suffered what we know today as the Great Eruption, an explosion that expelled two luminous gas bubbles that extend about 12 billion kilometers from one end to the other. Astronomers recently discovered that Eta Carinae are actually two giant stars that orbit each other at close range. To explain the extreme turbulence of this scene, scientists modeled the intense hot winds expelled by the two companions. The orbital movements of the two stars allowed them to calculate that the mass of the greater one is 90 times that of the sun. Eta Carinae will soon become a supernova. Over time, it will suffer convulsions, then it will collapse and explode. Some archaeologists believe that this drawing represents a supernova detected by observers of North American stars in the year 1054. The same event was also recorded in China, Korea and the Middle East. In Europe, supernovae sightings helped to dissipate the predominant belief that the skies are static and immutable. Astronomer Tigo Brahe saw one in 1572. I was so perplexed by how incredible that object was, he wrote, that I began to doubt what my own eyes saw. More recently, astronomers have studied intensely the remains of the explosion of 1054, the famous Crab Nebula. The radiation waves that arise from the explosion have drawn circular patterns in the surrounding gas, which we see here through radio waves, infrared, optical, ultraviolet and X-rays. You can see signs of a jet from the central region. This energy comes from a small rotating object located in the center and the size of a city. This neutron star is not formed by any element, but by subatomic particles gathered by gravity in an ultra-dense sphere. Physicists consider it a single and huge atom, approximately the equivalent of condensing Mount Everest into a sugarcane field. However, some dying stars face an even stranger fate. In 1796, the Marquis Pierre-Simon de Laplace imagined a kind of dark, heavy stars whose gravity prevented any light from escaping. This disconcerting idea was ignored for more than a century. Isaac Newton had described gravity as a force of attraction between two masses. At the beginning of the 20th century, Einstein's equations showed that gravity is the distortion of space-time caused by massive objects. Thus, a planet, a star or even a galaxy creates a gravitational well that modifies the trajectory of other objects and even the rays of light. As John Archibald Wheeler later expressed, space-time tells matter how to move. Matter tells space-time how to curve. In 1919, the now famous Eddington expeditions proposed trying this amazing idea during a solar eclipse. Their data showed that the gravity of the sun deviated the trajectory of stellar light as predicted by Einstein. But in Einstein's equations, there was also a strange idea that reminded Pierre-Simon de Laplace. If an object is dense enough, it will deflect a ray of light towards itself making that light disappear. The physicist Karl Schwarzschild, director of the Astrophysics Observatory in Potsdam, Germany, took this idea to its logical conclusion. While serving as artillery lieutenant on the battlefront during the First World War, he managed to study Einstein's new theory in detail. As you can see, Einstein wrote, the war treated me with enough kindness, despite the intense shooting, to allow me to move away from everything and take this walk through the land of his ideas. Schwarzschild realized that objects could become so dense that their mass would concentrate in an infinitesimal point, a singularity. He calculated that these strange creations must be limited by a greater spherical region beyond which no light can escape, the so-called event horizon. But how could such objects really exist? In 1939, Einstein himself wrote an article in which he tried to show that these strange objects were impossible. But just a few months later, physicist J. Robert Oppenheimer and his postgraduate students published their own article on the subject. With a new look at the mathematics of the collapse of stars, they proved that if the mother star is quite massive, the force of the collapse will literally crush its nucleus until it becomes a point, an infinitely dense and infinitely curved motte of pure gravitational energy. Oppenheimer would lead the design of the atomic bomb after setting the foundations of modern science on the black holes. The atomic era brought a totally new approach to the study of extreme physics. The bomb was a terrifying test, as Einstein conjectured that a small amount of mass could become a huge amount of energy. Researchers studied the enormous forces that are released when atoms are divided with chain reactions in the heart of atomic and thermonuclear bombs. Using new advanced computers developed to model and predict these explosions, astrophysicists began to probe what happens inside the stars, where the lightest elements burn and fuse to form other heavier ones. They saw how that can cause other larger stars to collapse and explode. This dark consequence of stellar death came to popular culture in 1967 when physicist John Wheeler called it the black hole. Astronomers were already looking for these monsters. In 1964, a rocket probe captured a source of X-rays of high energy in Cygnus, the constellation of the swan. Other later satellites captured a pulsating rhythm in its light, punctuated by unexpected bursts of energy. After determining its exact location, Earth observatories detected a giant star that could not emit X-rays on its own. Astronomers deduced that Cygnus X-1 is a star with an invisible companion that is devouring it alive. Wrapped in a bright halo of gas that flows from the star, that companion, with a mass 15 times that of our sun, is the first confirmed black hole. This computer simulation shows how we can recognize the presence of a black hole. The matter that falls in a spiral towards the abyss forms what we call an accretion disk. The rotating movement generates powerful magnetic fields that create a hurricane of particles and drive them from the poles almost at the speed of light. If we fell into a black hole the size of a star, the attraction of its gravity would increase so abruptly that it would stretch us until only our atoms remained, what physicist Stephen Hawking called spaghettization. The models of stellar evolution suggest that there could be up to a billion black holes only in our Milky Way. However, they are eclipsed by a much larger presence and much more powerful that lurks in the very center of the galaxy. The first indications of this presence arose in 1932. The telephone company Bell was concerned by the static that interfered with what it considered a new revolutionary technology, long-distance radio communications. The company commissioned radio astronomer Carl Jansky to find its source. Using this precarious-looking radio receiver, Jansky studied the radio waves methodically. He attributed most of the static to electric storms, some near and some far. But on September 16, 1932, he caught a noise that could not be explained. That concrete noise appeared when the antenna pointed to the Sagittarius constellation, towards the center of the galaxy. It returned every 23 hours and 56 minutes, exactly one terrestrial day in relation to the stars. Soon, Jansky's discovery was heard. He assured the population that it was not extraterrestrials trying to contact. But it would take the astronomers another 30 years to discover what it was about. In the 1960s, the most advanced radiotelescopes began to capture signals from distant space. Without knowing exactly what they were, the observers called them quasi-stellar radio sources, or quasars. These brilliant blue headlights emitted much more energy than a star. What cosmic engine propelled them? The radio astronomers discovered that some of them had brilliant extensions that originated in centers of galaxies and extended for millions of light years through space. By observing their luminous spectra, the researchers realized that in reality they were superhot jets that moved hundreds of thousands of kilometers per second. Could this feature finally explain Jansky's discoveries? It would take a new generation of giant telescopes to reveal the answer. To their sensational feat, several observatories were inaugurated in the mountains of Hawaii in the north and in those of the Andes in the south. Two rival teams of astronomers concentrated in the galactic center to see what was there. Each of these teams undertook a task of several decades to study a group of stars that seemed to orbit a concentrated source of energy emission called Sagittarius A-star. Finally, during the spring of 2002, a star called S2 approached, accelerating, until it reached a remarkable 18 million kilometers per hour. If its trajectory near Sagittarius A-star was erratic, astronomers would know that the galactic center would be full of multiple massive objects. But its path was not erratic. They concluded that S2 and its companions must be orbiting a single object that weighs several million times the mass of our sun, a supermassive black hole. This project, more than two and a half decades after its inception, was recognized with the Nobel Prize in Physics. Since that discovery, astrophysicists have continued to introduce additional observation data in their supercomputers to better understand how gas clouds flow around the monster and towards it, and how their immense gravity drives the movements of the stars in the center of our galaxy. The S2 star will inevitably return to the black hole. The gravitational attraction will cause its orbit to shrink, bringing it closer and closer. Astronomers recently foresaw what would happen then. A tracking telescope in the mountains of the Andes recorded the sudden brightness of a galaxy in the distant space. The astronomers of the European-Austral Observatory oriented their telescopes towards the source. The light came from a galaxy 215 million light-years away. The astronomers followed the event to its final outcome six months later. They deduced that a star had gotten too close to a supermassive black hole. The giant began to tear it apart, turning the star into a river of hot gas, feeding a jet of high energy that was bright enough to be detected from Earth. Astronomers have long hoped to see a black hole directly, to understand its properties and how it alters the space around it. In recent years, an international team of astronomers has been working on an equally bold goal. Like the Eddington expeditions, a century earlier, these scientists hoped to test Einstein's theories, but this time in the most extreme laboratory the universe can offer. A black hole. The idea was to adapt a technique developed more than 60 years ago, called long-base interferometry. By synchronizing radiotelescopes distributed all over our planet, a team of 400 scientists and engineers created a much larger virtual telescope with an opening the diameter of the Earth itself. Its resolution is equivalent to being able to read a newspaper that was in Paris from New York. They call it the event horizon telescope. Its goal is to capture the first image of a black hole, and its objective is the monster located in the center of M87. Deeply penetrating the luminous nucleus of M87, the astronomers achieved a delicate balance between filtering the interstellar dust and finding the contours of its objective. At a wavelength of about one millimeter, all the dust and gas that darkened the monster vanished, leaving this ghostly silhouette. A black hole. An object that, by its very nature, cannot be seen. The event horizon telescope is based on a tool that has transformed the study of the universe. To make sense of the immense amount of data captured by the numerous receivers, the researchers developed a series of computer simulations that visualize the complexity of the scene. These are some of the results. The dark nucleus is the event horizon, the shadow that remains when the object's immense gravity slows down all the light until it stops it. The singularity, the black hole itself, is hidden in the shadows. The visible ring marks the rotating accretion disk. One of its sides is brighter because there the gas spins in a spiral towards the telescope and its photons accumulate. The light from the material that moves away becomes thinner as its wavelength extends towards the red section of the electromagnetic spectrum. From a slightly further perspective, we can see how a part of the matter that flows towards the interior is expelled in a hot and pulsating stream. M87 is a black hole of truly cosmic proportions. It has been growing for thousands of millions of years with a constant diet of gas, dust, planets and stars. But it is not the only black hole of thousands of millions of solar masses. Not even the largest. The coma cluster is a dense cluster of galaxies at 321 million light-years from Earth. Its center is a colossal elliptical galaxy called NGC 4889. It houses a black hole whose mass is estimated to be 21 billion times that of the Sun. J2157 is even larger. With 34 billion times the mass of the Sun, this ultramassive black hole is 8,000 times larger than the one in the core of our Milky Way. The largest black hole discovered so far, TON 618, could weigh up to 66 billion times the mass of our Sun. It drives a superluminous quasar that shines 140 billion times more than our star. In theory, there is no limit to the size of a black hole. All it needs is time and the right circumstances. The rise of the construction of increasingly large telescopes has given astronomers a completely new perspective on the life cycle of ultramassive black holes. Here, in the deserts of northern Chile, they comb the primitive universe in search of faint signs of growing black holes. In the Leo constellation, they detected the most distant quasar observed so far, only 770 million years after the Big Bang. The red dot is light energized by a black hole whose mass is estimated to be 2 billion times that of the Sun. To find out, scientists have started an important international project to simulate the early evolution of the universe. The action begins a few million years after the Big Bang. Gravity begins to attract hydrogen gas forming large rings. And from them, to quite dense concentrations so that stars are formed. When some stars die, black holes are formed. These primordial monsters feed on the gas that reaches them and grow more and more as they hit their surroundings with fierce winds and jets. The scene changes to visible light when the universe reaches its middle point. Two galaxies are beginning to form, each with a densely populated central region of stars. Gravity begins to attract the two towards a cosmic embrace. The black holes in their centers will inevitably meet and merge. The final result? A galaxy similar to ours with a supermassive black hole hidden in its core. Now let's move on to a much larger scale. The action begins 500 million years after the Big Bang. Matter joins together following a pattern similar to a spider web with filaments and dense knots. As innumerable stars are formed, several larger galaxies are developed. As they merge, so do the black holes in their cores. A new perspective opens up. The quasars and the jets of black holes are among the most energetic phenomena known. This one, detected by the Hubble Space Telescope in the early universe, emits 600 billion times brighter light than our Sun. And yet, that barely begins to describe the power unleashed when two supermassive black holes collide. To know what it will look like from Earth, scientists have simulated the moment before the merger of two supermassive black holes. The magnetic and gravitational forces heat up the gas. The couple is surrounded by ultraviolet light. The superhot plasma that flows around and towards the black holes emits x-rays. The couple's intense gravity distorts and curves space-time, creating a lens. Albert Einstein insinuated that the energy of such a collision goes far beyond the emission of high-energy light. His equations predicted that when massive bodies like black holes accelerated or affected each other, they would alter the normally flat tissue of space-time. A series of powerful gravitational waves would move outward like the waves of a pond. When these waves travel across the universe and reach us, their energy will almost have dissipated. And yet, scientists believe they have detected them. In the observatory of laser waves known as LIGO, precision and high-power lasers and some of the most perfect large-scale vacuum chambers ever created. The idea is that the passage of a gravitational wave should stretch and narrow the distance between mirrors located at the ends of 4-kilometer-long tubes. This distortion of space-time, measured with lasers, is incredibly subtle, a thousand times smaller than the nucleus of an atom. This ambitious project, which took decades to develop, finally paid off in 2015. The instruments of LIGO and its European counterpart captured a coherent signal with the fusion of two black holes of 29 and 36 solar masses. Scientists calculate that the collision converted the mass of up to three suns into pure energy in the form of gravitational waves. The founders of LIGO received the Nobel Prize in Physics in 2017. This simulation shows the pattern of gravitational waves that the stellar couple would have emitted at the final moments of the fusion and just after. As the objects rotate together, the energy of each successive wave increases for a moment until it reaches 100 billion billion times the energy of our sun. This type of collision is extremely infrequent, but the universe is very large. As its sensitivity improves, LIGO and other similar instruments will detect more and more reverberations of this type in space-time. Surprisingly, all this barely begins to describe the force of a black hole. Let us imagine that a spaceship in the distant future approaches a supermassive black hole. Due to the immense size of the object, the force of the pull is small, which allows the ship to survive as it falls through the horizon of events, but not for long. As the ship descends in a spiral, it collides with an energy wall that scientists describe as the inner horizon. On the horizon of events of a black hole, matter accelerates to the speed of light. Then it is moved so fast that part of it is sent outwards and collides with the matter that enters it. On the inner horizon, the energy increases so abruptly that it could well reach the limit of nature, perhaps something equivalent to the Big Bang itself. Fortunately for us, gravity isolates those extremes behind the horizon of events of black holes. If we advance billions and billions of years, there could come a time in which, theoretically, all matter and energy would probably fall into the black holes. Gravity could well drag the entire universe into a single final black hole. Some theories suggest that it could explode like a burst of matter and antimatter, gases that cool down and fuse to form stars, explosions that cause black holes, galaxies that envelop and nourish them, while giving rise to solar systems like ours. And here we are, on a planet that is an infinitely small subproduct of the universe in general. Our imagination, however, lacks limits when we contemplate the strange and powerful forces that have shaped everything we see.