In the Name of Allah — the Most Beneficent, the Most Merciful.
There is a place in the universe where the sky ends. Not in the sense of an edge, but in the sense of a boundary past which nothing returns — not light, not matter, not even a message. Astronomers call it a black hole, and it is the most extreme object physics has ever described: a region where so much mass has been packed into so little space that gravity wins completely. This post is about what happens to the biggest stars when the burning stops — and about the monsters that sit, quiet and unseen, at the centre of almost every galaxy, including our own. First the phenomenon as science understands it, then the argument for how it relates to the Qur'anic narrative.
1. The darkest objects in the universe
A black hole is not a hole in the ordinary sense, and it is not black in the ordinary sense either. It is a region of space where gravity has become so strong that the speed needed to escape it is greater than the speed of light — and since nothing can travel faster than light, nothing escapes. That is the whole definition, and everything else follows from it.
The strangeness is that we cannot see one directly. A black hole gives off no light of its own, and any light that falls into it never comes back. What we see, when we see anything at all, is the light of the things around it: gas heated white-hot as it spirals inwards, stars whipped around an invisible mass, a glowing ring with a dark shadow at its centre. The first photograph of a black hole, taken in 2019, was a photograph of that ring and that shadow — the hole itself is the darkness in the middle.
It is worth saying plainly at the start that black holes are not science fiction. They were predicted by mathematics before they were ever observed, they were doubted for decades even by the physicists who predicted them, and they are now among the best-confirmed objects in astronomy. We have photographed two of them, weighed dozens of them by the motion of their companion stars, and heard the ripples in spacetime made when two of them collided more than a billion light-years away.
2. How gravity wins: the speed of escape
The idea is older than the name. Escape velocity is the speed a thing must reach to leave a body behind and never fall back. For the Earth it is about 11.2 kilometres per second; for the Sun, about 617 kilometres per second. The heavier and more compact the body, the faster you must go. In 1783 the English clergyman and geologist John Michell asked a simple question: what if a star were so massive, and so compact, that its escape velocity exceeded the speed of light? Light itself could not leave it, and the star would be invisible — a "dark star". The French mathematician Pierre-Simon Laplace reached the same idea independently in 1796. Both men were working with Newton's gravity and with light imagined as tiny particles; both were right in outline and wrong in detail, and their idea was largely forgotten for a century.
It was Albert Einstein who gave the idea its real foundation. In 1915 he published the general theory of relativity, in which gravity is not a force pulling things together but a curvature of spacetime itself, shaped by mass and energy. Within months, the German physicist Karl Schwarzschild, serving on the Russian front in the First World War, found the first exact solution of Einstein's equations: the spacetime around a perfectly spherical, non-rotating mass. His solution contained a surface, at a certain radius from the centre, where the mathematics changed character — a boundary from which nothing could return. Schwarzschild himself died of illness in 1916, before anyone understood what he had found. For decades most physicists assumed the boundary was a mathematical curiosity, an artefact that real stars would never reach. The stars, it turned out, had other ideas.
3. How stars die: from white dwarf to collapse
A star is a balancing act. Gravity pulls its matter inwards; the pressure of the hot gas, and later the pressure of nuclear fusion, pushes outwards. As long as the fuel lasts, the balance holds. When the fuel runs out, gravity wins — and what happens next depends on how much mass is left.
A star like the Sun ends quietly. It swells into a red giant, sheds its outer layers, and leaves behind a white dwarf: a Earth-sized ember, about as massive as the Sun, held up not by heat but by the quantum-mechanical refusal of electrons to be squeezed into the same state. In 1930 the young Indian physicist Subrahmanyam Chandrasekhar calculated that this support has a limit: a white dwarf heavier than about 1.4 times the mass of the Sun cannot hold itself up, and must collapse further. Chandrasekhar was ridiculed for the result at the time; he was proved right, and won the Nobel Prize for it in 1983.
A heavier star collapses past the white dwarf stage. Its core is crushed until protons and electrons merge into neutrons, and it becomes a neutron star: a city-sized ball, about 20 kilometres across, with more mass than the Sun, so dense that a teaspoon of it would weigh about a billion tonnes. Its escape velocity is a large fraction of the speed of light, and it spins, sometimes hundreds of times a second, sweeping a beam of radio waves across the sky like a lighthouse — those are the pulsars. But even a neutron star has a limit. Neutron pressure, too, can only hold so much, and the best estimates put the maximum mass of a neutron star at roughly two to three times the mass of the Sun; the exact number is still uncertain, because the physics of matter at such densities is not fully known.
Above that limit there is nothing left to hold the star up. A star born with more than about twenty to twenty-five times the mass of the Sun, having burned through its fuel and shed some of its mass in a supernova explosion, leaves behind a core too heavy for any known pressure to support. It collapses — and keeps collapsing. The matter falls inwards, the density rises without limit as far as the equations can follow, and a black hole is born.
4. The point of no return: the event horizon
The defining feature of a black hole is its event horizon: the boundary around it past which escape is impossible. The horizon is not a surface made of anything. There is nothing to touch, no wall, no floor. It is a boundary in spacetime — the place where the escape velocity reaches the speed of light. Cross it, and every direction you could travel leads further inwards, the way that, past a waterfall's edge, every direction the water can flow leads down.
The size of the horizon is set by the mass alone. The Schwarzschild radius — the radius of the horizon for a non-rotating black hole — is about 2.95 kilometres for every solar mass packed inside. The Sun, if it were squeezed into a black hole, would have a horizon about 3 kilometres in radius — a ball the size of a small town, holding the mass of a star. The Earth, squeezed the same way, would have a horizon about 9 millimetres across: the mass of a planet inside a marble. A black hole of ten solar masses has a horizon about 30 kilometres in radius. The relation is strictly proportional: double the mass, double the radius — which means that the biggest black holes, though enormously massive, are not enormously dense. The supermassive black hole at the centre of our galaxy, with 4.3 million solar masses, has a horizon about 12.7 million kilometres in radius, and the average density inside that horizon is less than the density of water. A black hole is not dense because it is small; it is inescapable because its mass is great and its gravity is deep.
The Schwarzschild radius — the radius of the event horizon — is about 2.95 kilometres per solar mass. The Sun squeezed into a black hole would be 3 kilometres across; Sagittarius A*, 12.7 million kilometres; M87*, about 19 billion kilometres. Source: Schwarzschild radius formula, Rs = 2GM/c².
Around the horizon there are two more landmarks worth knowing. The photon sphere, at one and a half times the horizon radius, is where light itself can orbit the black hole in a circle — a ring of light going around and around, though the orbit is unstable, and any small disturbance sends the light spiralling in or flying away. And at the centre, according to general relativity, lies the singularity: a point where the density becomes infinite and the equations stop making sense. Physicists are the first to say that this is a sign the theory has reached its limit, not a description of a real thing. What actually sits at the centre of a black hole — whether some quantum object replaces the singularity — is one of the great open questions in physics, and it is the reason black holes matter so much: they are the place where our two great theories, general relativity and quantum mechanics, collide and neither one, alone, is enough.
5. What falling in would be like
No one will ever report back from inside a black hole, but relativity describes the journey precisely, and the description is stranger than any invention. There are two stories, and both are true — the story of the person falling in, and the story of the person watching from far away — and they disagree.
For the distant watcher, the falling person never quite arrives. As the faller approaches the horizon, the light from them takes longer and longer to climb out, and their clock, as seen from outside, appears to slow down. They seem to freeze at the horizon, growing dimmer and redder as their light is stretched, until they fade from view. They never appear to cross — though the light that reaches the watcher after a finite time is, in practice, too faint and too red to see.
For the faller, nothing special happens at the horizon at all — provided the black hole is large. They cross it in a finite time on their own clock, and if they are falling into a supermassive black hole they may not even notice the crossing: there is no flash, no wall, no jolt. What they would notice, sooner or later, is the tidal force. Gravity pulls harder on the parts of a body nearer the hole than on the parts further away, stretching the body lengthwise and squeezing it sideways — an effect physicists, with grim humour, call spaghettification. For a small, stellar-mass black hole the stretching becomes lethal long before the horizon: a person would be torn apart first. For a supermassive black hole the tidal forces at the horizon are gentle — an astronaut could cross the horizon of Sagittarius A* alive, and only be stretched apart much deeper inside. Either way, the end is the same: everything inside the horizon is drawn towards the centre, and there is no way back, because "back" would mean travelling faster than light.
Time itself behaves differently near a black hole. A clock held close to the horizon ticks more slowly than a clock far away — not because the clock is broken, but because time, in general relativity, runs at different rates in different places. This gravitational time dilation has been measured in the laboratory and in the satellites of the Global Positioning System, which must correct for it every day to keep their clocks accurate; near a black hole, the effect becomes extreme. It is one of the most thoroughly tested predictions in all of physics — and it is also one of the hardest to hold in the mind, because it breaks the everyday assumption that time is the same everywhere.
6. How we know they are there: weighing the invisible
For most of the twentieth century, black holes were a prediction without a specimen. That changed in 1964, when a rocket-borne detector found a powerful source of X-rays in the constellation Cygnus — Cygnus X-1. The X-rays came from gas being pulled off a blue supergiant star and heated to millions of degrees as it spiralled towards something dark, compact and massive. By 1971 the invisible companion had been weighed by the motion of its visible star: about 21 times the mass of the Sun, far too heavy to be a neutron star, packed into far too small a space to be anything else. Cygnus X-1 became the first widely accepted black hole, about 7,200 light-years away — and it is still there, still feeding, still shining in X-rays.
The method is the same in every case: you cannot see the black hole, so you watch what it does to the things around it. A star orbiting an unseen companion reveals the companion's mass from the size and speed of its orbit, by the same Kepler's laws that the Astronomy post used for the planets. Gas falling towards a black hole forms an accretion disk — a flattened whirlpool, heated by friction to millions of degrees, glowing in X-rays — and the brightness and flickering of the disk reveal the mass and the spin. Some black holes, fed greedily, fire jets of particles outwards along their poles at nearly the speed of light, jets that can stretch for hundreds of thousands of light-years, longer than a galaxy is wide. And when a star wanders too close, the black hole tears it apart in a tidal disruption event, a brief flare as the star's gas is swallowed — a flash that telescopes catch a few times a year across the sky.
Dozens of stellar-mass black holes are now known in our galaxy from X-ray binaries like Cygnus X-1, and the true number is far larger: most black holes have no companion star to betray them, and they drift through the galaxy unseen. Astronomers estimate the Milky Way may hold tens of millions of them, perhaps a hundred million — the collapsed cores of all the massive stars that have lived and died in the galaxy's ten-billion-year history, silent and dark, revealed only when something falls in.
7. The monsters at the centres: Sagittarius A* and M87*
The stellar black holes are the small ones. At the centre of almost every large galaxy sits something vastly larger: a supermassive black hole, millions or billions of times the mass of the Sun. How they grew so large, and so early in the history of the universe, is still an open question — but that they are there is now certain, and the evidence comes from the centre of our own galaxy.
The centre of the Milky Way, in the constellation Sagittarius, is hidden from ordinary telescopes by clouds of dust. In infrared light, which passes through the dust, astronomers have watched individual stars orbiting an unseen point for more than twenty-five years. One of them, called S2, completes an orbit in just 16 years, swinging to within about 120 times the Earth–Sun distance of the centre and reaching a speed of nearly 8,000 kilometres per second — the fastest star ever measured in the galaxy. The only object that can hold such an orbit is a mass of about 4.3 million Suns, packed into a region smaller than the Solar System. That object is Sagittarius A*. The two astronomers who led the decades of tracking, Reinhard Genzel and Andrea Ghez, shared the Nobel Prize in Physics in 2020 for proving it exists — the other half of that year's prize went to Roger Penrose, for proving mathematically that black holes must form.
Then, in April 2019, the Event Horizon Telescope gave the world its first photograph of a black hole: the supermassive black hole at the centre of the galaxy M87, about 55 million light-years away, with a mass of 6.5 billion Suns. The telescope was not a single dish but eight radio telescopes spread across the Earth — in Arizona, Mexico, Chile, Spain, Hawaii and Antarctica — linked together to act as one virtual telescope the size of the planet. The image showed a ring of glowing gas, brighter on one side where the gas is rushing towards us, around a dark shadow about 42 millionths of an arcsecond across: the silhouette of the event horizon itself, its size matching Einstein's prediction. In May 2022 the same collaboration released the second such image — Sagittarius A* itself, a smaller, quicker-flickering ring at the heart of our own galaxy.
Black hole masses, in solar masses, on a logarithmic scale: from stellar black holes like Cygnus X-1 (about 21 Suns) and the merged remnant of GW150914 (62 Suns), to Sagittarius A* (4.3 million Suns), M87* (6.5 billion Suns) and TON 618, the largest known, at about 66 billion Suns. Sources: EHT Collaboration; LIGO Scientific Collaboration.
The largest known black hole, TON 618, holds about 66 billion solar masses — fifteen thousand times the mass of Sagittarius A* — and it sits at the heart of a quasar, a galaxy whose central black hole is feeding so fast that it outshines all the stars of its galaxy put together. Between the stellar and the supermassive, there is a middle range — the intermediate-mass black holes, hundreds to hundreds of thousands of solar masses — whose existence was long suspected and only recently confirmed, when the merger detected as GW190521 in 2019 left behind a remnant of about 142 solar masses. The picture that emerges is a whole population, from a few Suns to tens of billions, with every size in between — and with the supermassive ones shaping the galaxies around them, their jets and winds regulating the birth of stars across billions of years.
8. When black holes collide: the sound of spacetime
For a century, black holes were known only by the light of the things around them. Then, on 14 September 2015, humanity heard them directly — not in light, but in gravity itself. The two detectors of the Laser Interferometer Gravitational-Wave Observatory, LIGO, in Hanford, Washington and Livingston, Louisiana, recorded a signal that swept upwards in frequency from 35 to 250 hertz over about two-tenths of a second: the chirp of two black holes, of about 36 and 29 times the mass of the Sun, spiralling into each other and merging, more than a billion light-years away. The merger left behind a single black hole of about 62 solar masses; the missing three solar masses had been radiated away as pure energy, in gravitational waves, in a fraction of a second. At its peak, the power radiated in those waves was more than ten times the combined light of all the stars and galaxies in the observable universe — and the signal that reached the Earth moved the detectors' mirrors by less than a thousandth of the width of a proton. The detection, announced on 11 February 2016, was the first direct observation of gravitational waves — ripples in spacetime predicted by Einstein in 1916 — and the first direct observation of a binary black hole merger. Rainer Weiss, Barry Barish and Kip Thorne won the Nobel Prize in Physics for it in 2017.
The detectors have since heard dozens more mergers, including the 2019 event GW190521, whose remnant of about 142 solar masses was the first confirmed intermediate-mass black hole. Each detection is a test of general relativity in the most extreme conditions that exist — two horizons colliding at a large fraction of the speed of light — and so far Einstein's theory has passed every test. Gravitational-wave astronomy has also done something no telescope could: it has weighed black holes that give off no light at all, and shown that stellar black holes heavier than astronomers once thought possible — thirty, fifty, even eighty solar masses — are common. The universe, it turns out, is full of collisions we never saw, because we were listening with the wrong sense.
9. Do black holes die? Hawking radiation and the open questions
A black hole is not quite eternal. In 1974 Stephen Hawking showed that quantum effects near the event horizon should make a black hole glow — very faintly, and very coldly. Pairs of particles flicker into existence at the horizon, in the quantum vacuum, and occasionally one falls in while the other escapes, carrying away a tiny amount of the black hole's energy. The black hole, in effect, evaporates: it loses mass, shrinks, and grows hotter as it does so. For a black hole of one solar mass the temperature of this Hawking radiation is about sixty billionths of a degree above absolute zero — far colder than the 2.7-degree afterglow of the Big Bang that fills the universe — so a real black hole today gains far more mass from that background radiation than it loses by evaporating, and its evaporation time is about 10^67 years: a one followed by sixty-seven zeros, vastly longer than the age of the universe. A supermassive black hole would take about 10^100 years to evaporate. Hawking radiation has never been observed directly — it is far too faint — and it may never be. But it is the best-tested idea we have about what happens when quantum mechanics meets gravity, and it leads to a deep puzzle: if a black hole evaporates completely, what happens to the information about the things that fell into it? Quantum mechanics says information is never truly destroyed; general relativity, in its classical form, says it disappears behind the horizon. This is the black hole information paradox, and fifty years after Hawking raised it, it is still unresolved — one of the sharpest open questions in physics, and the reason many physicists believe black holes will be the key to the next great theory.
There are other open questions. We do not know how the supermassive black holes grew so large so quickly — some already weighed a billion Suns when the universe was less than a billion years old, which is hard to explain by slow feeding alone. We do not know exactly where the line falls between a neutron star and a black hole. We do not know what, if anything, replaces the singularity. What we do know is more than enough to be sure the objects are real: their masses, their spins, their shadows, their mergers, their jets, and the stars that race around them — all measured, all consistent, all pointing to the same conclusion Einstein resisted and Schwarzschild first wrote down.
10. The Qur'an on the hidden stars
The Qur'an never uses the words "black hole" — the term was coined in 1967 by the physicist John Archibald Wheeler — and no honest reading can turn a seventh-century text into a modern physics paper. But the Qur'an does speak, in striking language, of a sun whose light is wrapped up, of stars that retreat, run and hide, of stars whose light is extinguished, and of a heaven that will be folded up — and those passages are the ones this section reads, with the classical commentators' readings kept in view.
The most direct passage is the opening of Surah At-Takwir: "When the sun is wrapped up" (81:1). The word is kuwwirat, from the root k-w-r — to wrap, wind, fold, roll up, as a turban is wound around a head or a scroll is rolled shut. The sun's light is folded away, wrapped up on itself. The classical commentators read it of the Day when the sun's light is taken away and extinguished — the light that has shone for the life of the world, folded up and gone.
That is, in substance, the death of a star — and it is the process by which a black hole is born. A star shines because its core burns; when the fuel is spent, the balance fails and the star collapses inward, and the light that once streamed outward is folded back in. For a massive star the collapse does not stop: the core falls in on itself, the outer layers are thrown off, and what remains is a region from which light cannot escape at all. A black hole is the most complete form of a star being wrapped up — a star folded so tightly into its own gravity that its light is wrapped inside the horizon, unable to leave. The event horizon is, in the most literal sense, a wrapping: inside it, every path leads inward, and the light is folded back toward the centre.
The limit must be stated plainly. The verse speaks of the sun, and our Sun will not become a black hole: as section 3 explained, it will end quietly as a white dwarf, its light fading over billions of years rather than collapsing. The verse is not a prediction about the Sun's fate. What it describes is a star's light being wrapped away — the death of a star, its light folded up on itself — and it is that process, the collapse and the extinguishing of the light, that is directly parallel to the birth of a black hole. The black hole is the extreme case of the same wrapping: a star whose light is folded away completely and permanently.
Light rays approaching a black hole are bent by its gravity. Rays that pass close enough loop around the photon sphere — the light is wrapped around the hole — and rays that cross the event horizon never return. The light is folded back toward the centre: a star's light wrapped up, as Qur'an 81:1 describes the sun being wrapped up. Computed from the Schwarzschild light-ray equation; distances in Schwarzschild radii.
The second passage in the same surah is the one most often discussed in connection with black holes: "I swear by the retreating stars, those that run and hide" (81:15–16). The words are al-khunnas — the ones that retreat, withdraw or hide — al-jawari — the ones that run or course along — al-kunnas — the ones that hide themselves away, the word used for an animal returning to its den. The classical commentators read these verses, in the main, of the five visible planets — Mercury, Venus, Mars, Jupiter and Saturn — which move against the background of the fixed stars, appear to slow, stop and move backwards in their retrograde motion, and then vanish in the Sun's glare. That reading fits the words well: the planets are the wanderers that run, retreat and hide. Some modern writers have also associated the verses with black holes: objects that run through space, and hide themselves — and everything near them — from sight altogether. The association is a modern one, and it must be named as such. It does not replace the classical reading, and it cannot be claimed as the verse's only meaning. What can be said is that the words describe, with precision, things in the sky that move and then disappear from view — and that a black hole is the most complete example of such a thing that science has found. It is a resonance, and a secondary one: the wrapping of the sun in 81:1 is the more direct parallel, because it is the star itself, and its light, that is folded away.
The same surah continues: "and when the stars fall" (81:2). Elsewhere the Qur'an swears "by the positions of the stars — and indeed, it is a great oath, if you only knew" (56:75–76), as though the places of the stars were themselves a thing worth swearing by — their positions, measured today to extraordinary precision, being exactly what revealed the black hole at our galaxy's centre, through the orbits of the stars around it. "And when the stars are extinguished" (77:8) speaks of a light going out; "when the stars fall and scatter" (82:2) of their dispersal. Surah An-Najm opens "By the star when it descends" (53:1), and Surah At-Tariq by "the night-comer, the piercing star" (86:1–3) — a star that knocks, that pierces the night. And the folding of the heavens returns more than once: "On the Day We will fold the heaven like the folding of a scroll for writing" (21:104), and "the heavens will be folded in His right hand" (39:67). The Qur'an's cosmos is not a static backdrop. Its lights move, hide, fall, are extinguished and are folded away — and the end it describes for the heavens is a physical unmaking, not a mere metaphor.
11. The argument: correspondence, not proof
The argument of this series has been the same from the first post, and it holds here too: the science and the Qur'anic narrative are in correspondence, and correspondence is not proof. Black holes stand on their own evidence — on the orbits of stars around Sagittarius A*, on the ring and shadow photographed by the Event Horizon Telescope, on the chirp of GW150914 — and they would stand if no scripture had ever mentioned a hidden star. What the Qur'an adds is not a measurement but a meaning: that these hidden things are signs, that their hiding is itself appointed, and that the order they belong to is temporary.
The correspondences are worth naming plainly, because they are real. First, the Qur'an opens Surah At-Takwir with a star's light being wrapped up (81:1), and science describes the death of a massive star as exactly that: a collapse in which the light is folded away, until, in the black hole, it cannot escape at all. The black hole is the most complete form of a star being wrapped up. Second, the Qur'an speaks of stars that run and hide (81:15–16), and science has found objects that do exactly that in the fullest sense — bodies whose gravity hides them, and everything that falls into them, from every observer. Third, the Qur'an swears by the positions of the stars (56:75–76), and it was precisely the measured positions of stars — their orbits, tracked year after year — that proved the black hole at the centre of our galaxy. Fourth, the Qur'an speaks of stars being extinguished and falling (77:8, 82:2, 81:2), and science describes stars dying, collapsing and vanishing behind horizons, and a universe whose stars will, over immense timescales, go out one by one. Fifth, the Qur'an speaks of the heaven being folded like a scroll (21:104), and physics describes spacetime itself being curved, stretched and folded by mass — the very curvature that makes a black hole possible.
The limits matter as much as the matches. The classical reading of 81:15–16 as the planets is well-grounded, and the black hole association is a modern reading offered as a resonance, not imposed as the only meaning. The verse of the wrapped sun, 81:1, speaks of the sun itself, which will not become a black hole; the correspondence is to the process — a star's light folded away in collapse — not to the Sun's own fate. The Qur'an does not give the Schwarzschild radius, the mass of Sagittarius A*, or the frequency of a gravitational wave; those are measurements, and they belong to science. The information paradox, the origin of the supermassive black holes, and the nature of the singularity are open questions in physics, and no verse settles them. To claim that the Qur'an proves black holes, or that black holes prove the Qur'an, would be to overstate both. What can be said, and is worth saying, is that a text revealed in a world that saw the stars as fixed lights in a dome speaks of stars that run, retreat, hide, fall and are extinguished — and that is, in substance, a universe in which the most extreme objects are the ones you cannot see.
12. Closing: the edge of the knowable
A black hole is, in the end, an edge: the edge of what light can do, the edge of what our theories can describe, and the edge of what any observer can ever know. We have learned to weigh what we cannot see, to photograph a shadow, and to hear the collision of two horizons a billion light-years away. We have also learned where our knowledge stops — at the horizon, where time slows and the equations break, and at the singularity, where a new theory is needed and does not yet exist.
The proper response, on the evidence of this post, is twofold. The scientific response is attention: to keep watching the stars that race around Sagittarius A*, to keep listening for the chirps of colliding holes, and to keep asking what happens to information, to time, and to matter at the edge. The Qur'anic response is the one the series has returned to each day: to read these hidden things as signs — ayat — that point beyond themselves. "When the sun is wrapped up" (81:1): the first verse of the surah is a light folded away, a star's shining brought to an end — and the sign is in that wrapping itself. The sign is not only in what shines. It is also in what is folded away — and in the fact that, even hidden, it can be known by what it does to everything around it.
Sources: Event Horizon Telescope Collaboration — first image of M87* (10 April 2019) and image of Sagittarius A* (12 May 2022); LIGO Scientific Collaboration and Virgo Collaboration — GW150914 (observed 14 September 2015, announced 11 February 2016; masses about 36 and 29 solar masses merging to about 62, about 3 solar masses radiated) and GW190521 (remnant about 142 solar masses); Nobel Prizes in Physics 2017 (Weiss, Barish, Thorne) and 2020 (Penrose; Genzel and Ghez); standard values: Sagittarius A* about 4.3 million solar masses at about 26,000 light-years, M87* about 6.5 billion solar masses at about 55 million light-years, Cygnus X-1 about 21 solar masses at about 7,200 light-years, TON 618 about 66 billion solar masses, Schwarzschild radius about 2.95 km per solar mass, S2 orbital period 16 years; Chandrasekhar limit about 1.4 solar masses; Hawking radiation (Hawking, 1974), evaporation timescales about 10^67 years (solar mass) and about 10^100 years (supermassive); Qur'an: 81:1–2, 81:15–16, 56:75–76, 77:8, 82:2, 53:1, 86:1–3, 21:104, 39:67. Verse renderings are the author's; classical commentators read 81:15–16 chiefly of the planets, as noted in the text, and the black hole association is a modern reading offered as a resonance.
