# Black hole darkness a result of gravity or temporal distortion?

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Please correct me if I am wrong as I may have made some incorrect assumptions.

Okay so we know that at some stage of "nearness to a black hole", light is no longer reflected back at us from the black hole itself. Some scientists have proposed the speed of light and it's relationship to relativity is natures way of adjusting the rate at which time passes seemingly to disallow "weirdness that could result"… for example the fast moving object would become more massive.

We also know that the mass of the black hole causes a nearby observer to behave as if he/she were moving at incredible speeds and subsequently slows time for the observer "relatively speaking of course".

I realize that from the perspective of the observer light is traveling to and away from him/her at it's normal rate even though effectively the observer is traveling very fast. Imagine however what would happen to the frequency of the light. The red/blue shift would undoubtedly be obscene.

Since we here on earth are "relatively speaking" experiencing time passing at our normal "earth rate". I can't help but imagine that immense gravity near a black hole is distorting time and its darkness is a result of either extreme red/blue shift or the light is somehow phased or altered by the temporal distortion. Yes gravity is the origin of the darkness but is the direct cause or an indirect relationship where the rate of time passing is the culprit?

Gravity is in fact a side-effect or result of spacetime distortion.

Consider this simple diagram:

The blue grid representing timespace, and the orange sphere being a high-mass object.

Moving through space means going from one tile to another, so when light passes into the distorted dip in spacetime it not only has to simply pass from square to square, but do so whilst those squares are being pulled in towards the massive object. For a planet or average star, this distortion is negligible as far as light is concerned, but the dip a Black Hole would make would be many, many times deeper than the above diagram - space would be flowing in to the hole as fast, or faster than light can travel along said space to pass through it.

Like trying to climb up a downwards escalator that always moves faster than you can climb it.

But spacetime flows, it should eventually be dragged out, like pulling a table cloth out from under a load of dishes, but the mass of a black hole is so great, timespace essentially becomes pinned, like jamming your fork into the tablecloth as your friend tries to pull it away; time comes to a standstill at the epicentre of the hole.

It's important to note that at no point does light slow down travelling through the vacuum of space here, it's just space is moving in the opposing direction preventing the light from escaping in any meaningful amount beyond the expected level of Hawking Radiation.

As an object falls towards a black hole, light emitted by the object will become red-shifted by the gravity. As photons rise out of the gravity well of the black hole they lose energy, they can't slow down but their wavelength is stretched. The object will go dark as it approaches the event horizon due to gravitational redshifting.

Photons starting from the event horizon would be redshifted to zero energy, and no photons can travel from inside the event horizon.

We also will observe gravitational time dilation, the last second before the object reaches the event horizon will be stretched out indefinitely. The two effects are all part of the same relativistic theory of gravity. You can't unpick the two effects.

The fact is, the gravity and the distortion of the rate of time are the same thing. A free-falling object follows a spacetime geodesic into the future, which just means a path that is as straight as possible subject to the curvature of spacetime. But "as straight as possible" translates to "the path in spacetime where the traveler experiences the most time passing over all possible paths". That's analogous to the way a geodesic on the Earth is the path with the shortest distance. (The geometry of spacetime is not just the natural 4D generalization of 3D geometry, but instead it's more of an analogue with special rules based on the way physics actually works.)

It turns out that the curve with the most "proper time" (time experienced by the traveler) is one that curves towards wherever time passes more slowly, and time passes more slowly near a massive object. That means that, as you move into the future, your path through spacetime curves towards the massive object. In other words, you move faster and faster towards the massive object. You fall.

And of course it makes sense that a slowing down of time will reduce the frequency of a clock or a beam of light.

And, what's more, the slowing down of time is a part of the curvature. Any time you have the scale of measurement changing as you move from place to place, if it does so in a way that causes geodesics to change, then we call that curvature. And curvature is arguably the fundamental phenomenon. And so I would say that it really is the slowing down of time (along with the deformation of space) that is the basic cause of light not being able to escape.

## Black hole darkness a result of gravity or temporal distortion? - Astronomy

Goddard Space Flight Center, Greenbelt, MD

### FIRST OBSERVATION OF SPACE-TIME DISTORTION BY BLACK HOLES

The phenomenon is distorting the orbit of hot, X-ray emitting gas near the black hole, causing the X-rays to peak at periods that match the frame-dragging predictions of general relativity. The research team, led by Dr. Wei Cui of the Massachusetts Institute of Technology, is announcing its results in a press conference today during the American Astronomical Society's High Energy Astrophysics Division (HEAD) meeting in Estes Park, CO. Collaborators in the research include Dr. Wan Chen of NASA's Goddard Space Flight Center, Greenbelt, MD, and Dr. Shuang N. Zhang of NASA's Marshall Space Flight Center, Huntsville, AL.

"If our interpretation is correct, it could demonstrate the presence of frame dragging near spinning black holes," said Cui. "This observation is unique because Einstein's theory has never been tested in this way before."

Black holes are very massive objects with gravitational fields so intense that near them, nothing, not even light, can escape their pull. This effect shrouds the hole in darkness, and its presence can only be inferred from its effects on nearby matter. Many of the known or suspected black holes are orbiting a close "companion" star. The black hole's gravity pulls matter from the companion star, which forms a disk around the black hole as it is drawn inward by the black hole's gravity, much like soap suds swirling around a bathtub drain. Gas in this disk gets compressed and heated and emits radiation of various kinds, especially X-rays.

The research team used these X-ray emissions to determine if frame dragging was present. The team found that the X-ray emissions were varying in intensity. By analyzing this variation, they found a pattern, or repetition, that was best explained by a perturbation in the matter's orbit. This perturbation, called a precession, occurs when the orbit itself shifts around the black hole. This is evidence for frame dragging because as the matter orbits the black hole, the space-time that is being dragged around the black hole drags the matter along with it. This shifts the matter's orbit with each revolution.

Einstein's Theory of General Relativity has been highly successful at explaining how matter and light behaves in strong gravitational fields, and has been successfully tested using a wide variety of astrophysical observations. The frame-dragging effect was first predicted using general relativity by Austrian physicists Joseph Lense and Hans Thirring in 1918. Known as the Lense-Thirring effect, it has not been definitively observed thus far, so scientists will scrutinize the new reports very carefully.

The possible detection of frame dragging around another type of very dense, quickly spinning objects, called neutron stars, was accomplished very recently by Italian astronomers, whose work led Dr. Cui's team to seek the effect near black holes. The Italians, Drs. Luigi Stella of the Astronomical Observatory of Rome, and Mario Vietri of the Third University of Rome, will report their findings at the November 6 conference in Estes Park. These observations also were made using the RXTE, which is available for use by astronomers throughout the world.

"This is exciting work that needs further confirmation, as for any seemingly major advance in science," said Dr. Alan Bunner, Director of the Structure and Evolution of the Universe Program at NASA Headquarters, Washington, DC.

The RXTE spacecraft is a 6,700 pound observatory placed into orbit by NASA in December 1995. Its mission is to make astronomical observations from high-energy light in the X-ray range, which is emitted by powerful events in the universe. These events are often associated with massive, compact objects such as black holes and neutron stars.

## How to hunt for a black hole with a telescope the size of Earth

Astronomers hope to grab the first images of an event horizon — the point of no return.

Here's how to catch a black hole. First, spend many years enlisting eight of the top radio observatories across four continents to join forces for an unprecedented hunt. Next, coordinate plans so that those observatories will simultaneously turn their attention to the same patches of sky for several days. Then, collect observations at a scale never before attempted in science — generating 2 petabytes of data each night.

This is the audacious plan for next month’s trial of the Event Horizon Telescope (EHT), a team-up of radio telescopes stationed across the globe to create a virtual observatory nearly as big as Earth. And researchers hope that when they sift through the mountain of data, they will capture the first details ever recorded of the black hole at the centre of the Milky Way, as well as pictures of a much larger one in the more distant galaxy M87.

The reason this effort takes so much astronomical firepower is that these black holes are so far from Earth that they should appear about as big as a bagel on the surface of the Moon, requiring a resolution more than 1,000 times better than that of the Hubble Space Telescope. But even if researchers can nab just a few, blurry pixels, that could have a big impact on fundamental physics, astrophysics and cosmology. The EHT aims to close in on each black hole’s event horizon, the surface beyond which gravity is so strong that nothing that crosses it can ever climb back out. By capturing images of what happens outside this zone, scientists will be able to put Einstein’s general theory of relativity to one of its most stringent tests so far. The images could also help to explain how some supermassive black holes produce spectacularly energetic jets and rule over their respective galaxies and beyond.

### LISTEN

Researchers’ bold effort to capture a black hole.

But first, the weather will have to cooperate. The EHT will need crystal-clear skies at all eight locations simultaneously, from Hawaii to the Andes, and from the Pyrenees to the South Pole. These and other constraints mean that the team gets only one two-week window every year to make an attempt. “Everything has to be just right,” says EHT director Sheperd Doeleman, an astrophysicist at Harvard University in Cambridge, Massachusetts.

“Radio astronomers relish the challenge of doing the almost impossible,” says Roger Blandford, an astrophysicist at Stanford University in California who is not part of the collaboration. And the EHT could present them with their toughest challenge yet.

Monsters of the Universe

Astronomers have known since the 1970s that an odd source of radiation lurks in the heart of the Milky Way. Radio telescopes had picked up an unusually compact object in the dusty central region of the Galaxy, within the constellation Sagittarius. They named the object Sagittarius A ∗ — Sgr A ∗ for short — and eventually gathered compelling evidence that it was a supermassive black hole, with a mass equal to that of about 4 million Suns. The black hole M87 ∗ in the centre of the galaxy M87 is even larger, at some 6 billion solar masses. In terms of angular size in the sky, these two have the largest known event horizons of any black holes.

Although scientists have a pretty good idea of how smaller black holes can form, no one knows for sure how these supermassive monsters develop. And for a long time, astronomers doubted that they could achieve the resolution required to image them in any detail.

The challenge comes down to basic optics. The resolution of a telescope depends mostly on its width, or aperture, and on the wavelength of the light at which it is observing. Doubling the width of the telescope allow scientists to resolve details half as wide, and so does halving the wavelength. At wavelengths of 1.3 or 0.87 millimetres — the only radiation bands that do not get absorbed by the atmosphere or scattered by interstellar dust and hot gas — calculations suggested that it would take a radio dish much larger than Earth to image Sgr A ∗ or M87 ∗ .

But in the late 1990s, astrophysicist Heino Falcke, then at the Max Planck Institute for Radio Astronomy in Bonn, Germany, and his collaborators pointed out that the optical distortion caused by a black hole’s gravity would act like a lens, magnifying Sgr A ∗ by a factor of five or so 1 . That was good news, because it meant that Sgr A ∗ might be within the reach of very-long-baseline interferometry (VLBI) on Earth. This is a technique that integrates multiple observatories into one virtual telescope — with an effective aperture as big as the distance between them.

The reason that there is any hope of imaging Sgr A ∗ , and the larger M87 ∗ , is that they are surrounded by superheated plasma, possibly the residue of stars that did not get swallowed up outright but got torn apart under the intense gravitational stress. The gas forms a rapidly rotating ‘accretion disk’, with its inner parts slowly spiralling in. Falcke and his colleagues reckoned that a VLBI network spread along the entire globe, and working at around 1 mm wavelength, should be just about sensitive enough to resolve the shadow cast by Sgr A ∗ against the halo of gas of the accretion disk.

The team also made the first simulations of what such a network might see. Contrary to most artistic depictions of black holes, the accretion disk does not disappear behind the object the way Saturn’s rings can partly hide behind the planet. Around a black hole, there’s no hiding: gravity warps space-time, and here the effect is so extreme that light rays go around the black hole, showing multiple distorted images of what lies behind it. This should make the accretion disk appear to wrap around the black hole’s shadow like a halo. (The 2014 hit Interstellar was the first movie to accurately depict this kind of warping of light around a black hole.)

But it won’t be a standard halo, of the type seen in many Renaissance paintings. The inner regions of the accretion disk orbit at nearly the speed of light, so one side of the disk — the side rotating towards the observer — should look much brighter than the other. The result should be something similar to a crescent Moon (see ‘Power of the dark’).

“ Radio astronomers relish the challenge of doing the almost impossible ”

In 2004, Falcke, who is now at Radboud University in Nijmegen, the Netherlands, was part of a team that made one of the first VLBI observations of Sgr A ∗ . The US-based network they used, set up by the National Radio Astronomy Observatory, spanned 2,000 kilometres, and took data at 7-mm wavelength 2 . This allowed them to get no more than a blob of light: it was like seeing the black hole through frosted glass.

Meanwhile, starting in 2007, a team led by Doeleman made its own VLBI observations of Sgr A ∗ (ref. 3) and M87 ∗ (ref. 4). Using VLBI networks of three observatories, the team made measurements at 1.3 mm, enabling them to close in towards the event horizon. Although the researchers didn’t capture an image of the event horizon, they were able to put upper bounds on its size.

Eventually, the two groups joined forces and merged with others to form the current EHT collaboration. And as the team grew, so did the number of telescopes enlisted for the imaging effort.

In April, the EHT will have a total of four, or possibly five, nights’ observing time — a limit set mostly by their use of the state-of-the-art, US\$1.4-billion Atacama Large Millimeter Array (ALMA) in Chile, one of the world’s most oversubscribed observatories. They plan to spend two nights on Sgr A ∗ and two on M87 ∗ . At each observing station, atomic clocks will tag the arrival time of every crest and trough of every electromagnetic wave to the nearest one-tenth of a nanosecond, explains Feryal Özel, a theoretical astrophysicist at the University of Arizona in Tucson.

In typical interferometry, the arrival times at different locations are compared in real time, and triangulated to their point of origin to reconstruct an image. But with so many observatories scattered around the globe (see ‘Global effort’), including in places with slow Internet links, the researchers will have to record the streams separately and compare them later. “We’re not going to have a picture appear before us on the screen,” Daniel Marrone, an astrophysicist at the University of Arizona, says. This means that the EHT will need to record data at a faster rate than any previous experiment of any kind, says Avery Broderick, an astrophysicist at the University of Waterloo in Canada. A typical night will yield about as much data as a year’s worth of experiments at the Large Hadron Collider outside Geneva, Switzerland.

The racks of hard disks containing the data will be flown to two central locations, where computer clusters will combine them into one picture, a task that could take up to six months. Only once that phase is completed will the data analysis — the actual scientific study — begin. The team will probably not have results to publish until well into 2018.

Astrophysicists have high hopes for the results from the EHT. They are particularly interested in data that could help to explain one of the most spectacular phenomena in the cosmos: the giant jets of particles that certain supermassive black holes spew out into intergalactic space at close to the speed of light. Some such black holes, including M87 ∗ , sport jets even longer than their host galaxies. But not all do: if Sgr A ∗ has any, they are too small or too feeble to have been spotted yet.

Scientists are not even sure what these jets are made of, but they seem to play an outsized role in cosmic evolution. In particular, by heating interstellar matter, jets can prevent that material from cooling down to form stars, thus shutting down galaxy growth, Broderick says. “Jets rule the fate of galaxies.”

The most likely explanation for the jets, astrophysicists say, is that they are produced by rapidly twisting magnetic fields just outside the black hole, but it is unclear where their energy comes from. In the 1970s, Blandford and his colleagues proposed two alternative models: in one, the energy comes from the accretion disk in the other it is drawn from the spin of the black hole itself (which is not necessarily aligned with the rotation of the accretion disk). In 2015, Doeleman’s group reported 5 the first hints of structure in the magnetic field around Sgr A ∗ , using VLBI at 1.3 mm. Their results suggest that black-hole spins are a more likely candidate than accretion disks for fuelling the jets, says Blandford, but the full power of the coming experiments could make that conclusion much more solid, as well as revealing whether Sgr A ∗ has any jets at all.

At a more fundamental level, looking at the size and shape of the event horizon will test Einstein’s theory of gravity for the first time in the extreme regime around a supermassive black hole. This will follow on from the historic discoveries announced last year by LIGO, the Laser Interferometer Gravitational-wave Observatory, which captured the signal of gravitational waves produced by the merger of black holes about as massive as large stars. Its findings were hailed as the most dramatic evidence yet for the existence of black holes, but they have not yet provided incontrovertible evidence. Moreover, supermassive black holes are millions or billions of times larger, Broderick points out. “What we’re looking at is a place where we don’t necessarily know how the physics works.”

There is even the chance that the EHT will find something different from a black hole in the target areas. Theorists have produced a number of alternative ideas to explain what happens when matter collapses under its own weight. In some of these theories, black holes never form, because gravitational collapse stops before the stellar remnants cross the point of no return. That could result in a super-compact star with a hard surface that might emit radiation detectable by the EHT.

But astrophysicist Carlos Barceló, of the Institute of Astrophysics of Andalusia in Granada, Spain, says that finding anything like that is a long shot. “I am a bit sceptical that this observation is going be able to distinguish between classical black holes and more exotic kinds of objects.” He and others say that LIGO might have a better chance of testing those models, for example by detecting echoes in the merger of two black holes.

As VLBI observations keep improving, however, they might reach the point at which scientists will be able to tell if the event horizon is as symmetrical as general relativity implies, says Alexander Wittig, a mission analyst at the European Space Research and Technology Centre in Noordwijk, the Netherlands. “A future version of the Event Horizon Telescope could reach resolutions that allow us to distinguish more intricate features in the shape of the shadow,” Wittig says. For that goal, Falcke is already dreaming up arrays of space telescopes that could make the EHT even bigger than Earth itself.

For now, though, astronomers will gladly settle for a few pixels that will give them their first peek at these elusive behemoths. They have had so many imaginary pictures swirling in their heads, often inspired by science-fiction books and movies like Interstellar. “To demonstrate that radio astronomers can catch up with Hollywood and show us pictures of black holes that actually exist,” says Blandford, “that is a magical idea.”

## University of California, San Diego Physics 7 - Introduction to Astronomy

The General Theory of Relativity is an expansion of the Special Theory to include gravity as a property of space. Start with this Gravity Tutorial.

The Theory of Special Relativity has as its basic premise that light moves at a uniform speed, c = 300,000 km/s, in all frames of reference. This results in setting the speed of light as the absolute speed limit in the Universe and also produced the famous relationship between mass and energy, E = mc 2 . The foundation of Einstein's General Theory is the Equivalence Principle which states the equivalence between inertial mass and gravitational mass.

Inertial Mass is the quantity that determines how difficult it is to alter the motion of an object. It is the mass in Newton's Second Law: F = ma

Gravitational mass is the mass which determines how strongly two objects attract each other by gravity, e.g. the attraction of the earth:

It is the apparent equivalence of these two types of mass which results in the uniformity of gravitational acceleration -- Galileo's result that all objects fall at the same rate independent of mass:

Galileo and Newton accepted this as a happy coincidence, but Einstein turned it into a fundamental principle. Another way of stating the equivalence principle is that gravitational acceleration is indistinguishable from other forms of acceleration. According to this view a student in a closed room could not tell the difference between experiencing the gravitational pull of the earth at the earth's surface and being in a rocketship in space accelerating with a = 9.8 m/s 2 .

nor could students in a similar room distinguish between free-fall under gravity and the weightlessness of space.

Curved Spacetime

 The second fundamental principle of General Relativity is that the presence of matter curves space. In this view, gravity is not a force, as described by Newton, but a curvature in the fabric of space, and objects respond to gravity by following the curvature of space in the vicinity of a massive object. The description of the curvature of space is the mathematically complicated part of general relativity involving "metrics", which describe the way that matter curves space, and tensor calculus. The Curvature of Space caused by a Massive Object.

The figure above represents a two-dimensional slice through three-dimensional space showing the curvature of space produced by a spherical object, perhaps the sun. Einstein's view is that the planets follow the curvature of space around the sun (and produce a tiny amount of curvature themselves).

Here are two fine astronomy course pages on General Relativity from Dr. Terry Herter at Cornell, from whom I stole the above images, and astronomers at the University of Tennessee.

Deflection of Light by Gravity: A direct consequence of the equivalence principle is that light should be deflected or bent by gravity. Einstein twice calculated the amount that light would be deflected passing by the sun, the largest "nearby" mass. His first calculation used only the Equivalence Principle and the equivalent mass-energy of a visible photon. In his second calculation, published in 1916, he included the space-time metric, which describes the curvature of space and time caused by gravity and got an answer twice as large as his first calculation. The second calculation predicts that light from a distant star passing by the limb of the sun would be deflected by 1.75 arcseconds (less than 1/2000th of a degree).

The first opportunity to test Einstein's calculation came with the Solar Eclipse of 1919. British Astrophysicist Sir Arthur Eddington mounted a pair of expeditions to West Africa and Brazil to observe the shift in position of the Hyades cluster stars behind the occulted sun. Eddington's measurements, though not perfectly precise clearly showed a deflection and favored the larger value. The result made Einstein world-famous. The test can now be made with greater precision. Every year the radio source 3C279 is occulted by the sun. Because the sun is only a modest radio-emitter, Radio Astronomers do not need to wait for an eclipse. Radio interferometry of 3C279 as it passes behind the sun has confirmed Einstein's calculation to better than 1%.

An exciting and only very recently verified prediction of the bending of light by gravity is the existence of gravitational lenses an optical lens focuses light be refraction, bending of light due to the change of the speed of light as it passes through a refractive medium. Because gravity can bend light, massive objects can act as lenses, focusing and amplifying images of distant objects. Gravitational lenses have rather different properties than "normal" lenses producing multiple images such as the Einstein Cross, a case of a distant quasar imaged by a galaxy between us and the quasar, discovered by J. Huchra & colleagues, shown to the left. If the alignment between us, the lensing galaxy, and the distant object, an Einstein Ring is produced. Distant galaxy clusters may also act as gravitational lenses. Astronomers are beginning to make use of the gravitational lensing phenomenon to study very distant galaxies and quasars. More about this in Lecture #17.

Twins Bill and Jill, born within minutes of each other, take differing career paths. Jill becomes an astronaut and Bill becomes a ground-based astronomer. On their 21st birthday Jill sets out on a space mission to Aldebaran, 32 light years away. Travelling at 99.5% of the speed of light, Jill measures a time of 3.2 years for her trip to Aldebaran and another 3.2 years for her return. (Incideltally, while she is travelling near the speed of light she also sees the distance to Aldebaran contracted to a mere 3.2 light years.) Bill finds that it takes her 32 years and 2 months for each leg. Upon Jill's return, she is 27 while her sibling is 85! Bizarre as these effects appear to us slow moving mortals, relativistic time dilation has been repeatedly confirmed in high energy particle accelerators, where particles travel near the speed of light, and by atomic clock on supersonic aircraft.

A similar process occurs in the presence of strong gravity a timekeeper in a strong gravitational field will measure a slower time than one in the absence of gravity. It is not just clocks, by the way, all physical processes: clocks ticking (however they measure their ticks), hearts beating, aging, etc., must slow down, but the only one who notices is the distant timekeeper. Everything seems "normal" to the person measuring the duration of events in his own frame of reference. Light waves travelling past the sun are slowed down by this time dilation by a small but measurable amount. In 197X the Viking Mars Lander performed the initial confirming experiment of gravitational time dilation by relaying radio signals back to earth from the Martian surface on the other side of the solar system. Although the effects of the intervening solar wind complicate the experiment, NASA scientists demonstrated clearly that the radio signals took longer on their round trip by just the amount predicted by the predicted slowing of time.

Predicted sources of strong gravitational waves in the Galaxy are supernova explosions, collapsing stellar cores as they form neutron stars or black holes, compact binary star systems, collisions of neutron stars & black holes, or possibly material falling into the blavk hole which may reside in the Galactic Center. Gravitational waves have not yet been detected directly, but we believe that they have been detected indirectly by radio astronomers in the binary pulsar system 1913+16. As the pulsar is accelerated around its companion, orbiting every 8 hours in this compact system, General Relativity predicts that gravitational waves should be produced. Although these waves are far too faint to be detected directly, the binary pulsar system is losing energy through this radiation, and the pulsar/neutron star and its companion are predicted to be slowly spiralling together. The rapid radio pulses permit precise timing of the pulsar orbit by doppler shifts of the pulse period as the pulsar moves toward or away from us. Since the discovery of the binary pulsar in 1974, timing of the pulsar has shown that the stars are indeed spiralling together just as predicted. In 300 million years the stars will coalesce - that should produce gravitational radiation that can be easily detected!

All of this amounts to pretty spectacular confirmation of General Relativity Theory.

So, Einstein was right and Newton was wrong!

1. developing theories or hypotheses,
2. testing them repeatedly by experiment and observation,
3. using them where they are shown to be applicable, and
4. revising & improving them when they are shown to disagree with experiment.
• Spacetime Wrinkles - National Center for Supercomputer Applications at U. Illinois has put together a superb Relativity site which includes History, Special Relativity, General Relativity, Tests of Relativity, Black Holes, Gravitational Waves, Relativistic Astrophysics, Relativistic Astronomical Objects, Spacetime Movies, and more. Many of the above links are to pages at this site. Strongly recommended!
• Jillian's Guide to Gravitational Waves

The French mathematician LaPlace first speculated about the existence of an object so compact that the escape speed would be greater than the speed of light. The first relativistic calculation was performed by Karl Schwarzschild (1916) shortly after Einstein published his theory. Curiously, Schwarzschild's result is the same as that of LaPlace an object with mass M which has a size

will have an escape speed equal to the speed of light. We call such an object a Black Hole. (Note that for the sun to be a black hole it would have to be compressed by a quarter of a million times down to a radius less than 3km.) A black hole is an object so compact that nothing can escape its gravity, not even light. Mathematically, a black hole is an object of zero size and infinite density (but finite mass) - a singularity. Schwarzschild's calculation shows that the gravitational radius, also called the Schwarzschild radius or event horizon, provides an effective size for a black hole because nothing can escape from inside the gravitational radius and there can be no communication from objects inside Rgrav and the outside world.
Curved Spacetime around a Black Hole.
Inside the horizon or gravitational radius space
is so strongly curved that nothing can escape.

First, perhaps we should dispel a prime misapprehension about black holes: Black holes are not gigantic vacuum cleaners sucking everything in the Universe into their darkness. And you would have to be pretty foolish to get caught in the strong gravity of a black hole hopefully our interstellar astronauts will get better training than the hapless space explorers in so many bad sci-fi stories. This is because black holes have finite mass and because everything in the Universe is so far apart. Black holes are produced by massive stars as a natural part of the stellar evolutionary process. A black hole from a collapsed 10M stellar core will have a mass of 10 solar masses. It will produce gravitational effects on neighboring stars just like a normal 10M star would. You need to get close to black hole (i.e. near the gravitational radius) for its strong gravity to "suck you in" or for General Relativistic effects to be important.

Similarly, if you were on a planet orbiting a star which became a black hole, you would not be sucked in by the Black Hole's gravity. If the star loses no mass, you would feel no change in the gravity and would continue to stay in the same orbit. (Lots of other bad things would happen, particularly if the star goes through a supernova explosion. In that case, cosmic rays & gamma rays would extinguish life on the planet and the mass lost in the explosion would decrease the gravitational pull of the remnant causing your planet to fly off into space.)

 We believe that we have found black holes in our galaxy in the form of X-Ray Binary Stars. In these star systems material may be transferred from a main sequence or red giant companion onto the black hole. (Remember that massive stars live fast & die young.) When a binary star system is formed, the more massive star will complete its life cycle first, becoming a black hole (or perhaps a neutron star). When the lower mass companion begins to expand, evolving toward the red giant phase, material may be pulled toward the black hole. Because of the angular momentum from the stars mutual orbits, the material cannot fall directly down the black hole, but spirals inward forming an accretion disk. The release of gravitational energy as material spirals into the black hole heats the accretion disk to millions of degrees so that it emits x-rays. Artists Conception of the Black Hole Binary Star System, Cygnus X-1. Material is pulled from the Companion into an Accretion Disk (shown in red) which is heated to millions of degrees as material spirals into the Black Hole.

Neutron stars in binary star systems may also be x-ray binaries. Material falling from a companion onto a compact neutron star may release just about as much gravitational energy as material falling into a black hole. Neutron stars will probably be pulsars in x-rays just like in the radio. Here is a JAVA x-ray pulsar animation courtesy of the Chandra X-Ray Observatory.

The best known black hole candidate is Cygnus X-1, an x-ray binary in Cygnus and one of the brightest x-ray sources in the sky. In 1972 Cygnus X-1 was identified with a 9th magnitude O supergiant, catalogued as HDE226868. HDE226868 is orbiting an unseen companion which orbital analysis indicates has a mass of about 20M , far too massive to be a neutron star or white dwarf. Cygnus X-1 also has unusual x-ray properties which lend support to the idea that this must be a black hole.

Stellar black holes have masses in the range of a few times the mass of the sun, up to a few tens of solar masses, but other processes may produce very massive black holes. There is increasing evidence that there may be a million solar mass black hole in the center of our Milky Way galaxy, and black holes with masses up to a billion times the sun's mass in the cores of other galaxies. Many astronomers also believe that black holes power quasars and other active galaxies.

• The best book asbout black holes is Kip Thorne's "Black Holes & Time Warps: Einstein's Outrageous Legacy" (W.W. Norton, 1994). This book is challenging, but worth the effort.
• Astronomy Pictures of the Day of Black Holes.
• Newton's Apple PBS series Black Hole Page.
• Black Holes from U. Tenn. Violence in the Universe Pages. from "Into the Cosmos".
• A Black Hole Tutorial from John Blondin, N. Carolina State U.
• Virtual Trip to a black hole which depicts distortion effects in the vicinity of a compact object.
• Jillian's guide to black holes
• Falling into a black hole
• Movies in a variety of formats of a Black Hole bending light.

Prof. H. E. (Gene) Smith
CASS 0424 UCSD
9500 Gilman Drive
La Jolla, CA 92093-0424

Last updated: 15 February 2001

## Stephen Hawking Black holes are. Grey Holes

I think Stephen Hawking is more concerned about creating a legacy for himself.

NASA Radio Telescopes Capture Best-Ever Snapshot of a black hole..

### #14 The Mighty Mo

I think Stephen Hawking is more concerned about creating a legacy for himself.

### #18 vickster339

Hawking is making the only move I left him to make. Now they are "seeing" gravitational waves yet we should already detected them. Just checking up on my ignorant demagogue astrologer savage buddies. Eat it and choke on it forever.

Any version of the Anthropic Principle eats itself at the temporally perceived gravitationally radius. This seemingly insurmountable problem undoubtedly influences the thinking of many. This would include my former roommate in college who is now a physicist. Professors at my Alma Mater doggedly denounced any possibility that such constructs existed within our universe. Thus, the gravitational radius was rendered the status of intellectual taboo. Such an approach forever bars the mind from the only possible path to the only possible answer. You will find the illusion of the infinite and Moore's Law are very much in my favor.

When Einstein looked through the Hooker 100 inch reflector at Mt. Wilson and realized his cosmological constant was incorrect I suspect his realization was accompanied by a creepy feeling that even he himself could not quite pin down.

Consensus and assumptions can be difficult to overcome even with good reasoning. One must consider many things collectively to get on a path to a final answer regarding the true nature of our perceived universe. While a high mental capacity is always helpful, knowing how to separate marketing information from actual data when considering observations is indispensable.

A short list would include:

1. The necessity of dark energy and dark matter to model an intelligible cosmology based on cold war age thinking.

2. The nearly 50% metallicity discrepancy between what the big bang predicts and what is actually observed in the universe.

3. The homogeneity necessary for big bang hyper-inflation as assumed before the CMBR has no means to explain the formation of large scale structures observed in the early universe. There is no structure to create structure with, nor a means for structure to be created.

4. Blatant violations of the M Sigma relation being revealed on a nearly daily basis. Dwarf galaxies harboring super massive black holes remain impossible to explain within any iteration of big bang cosmology. Not to mention recently discovered globular galaxies, I do not recall big bang cosmologist predicting those.

5. The G, K, and M dwarf problems combined with contradictory star populations in both open and globular clusters.

6. Problems inherent to forming a hydrostatic equilibrium of plasma from a localized thermal nuclear ignition. A problem particularly difficult when considering large stars.

7. Gamma Ray bursts of impossible power and duration within the context of big bang cosmology.

8. I could go on and on and on with this list. but this will suffice for now.

The individual expertise of the audience will be the determining factor in whether my ideas have any merit or lack of it. Please consider the following before continuing:

1. Inductive reasoning argues black holes exist. - Star S0-16 orbits within 600x the theoretical Schwarzschild radius of the Milky Way’s Super Massive Black Hole (SMBH) (Ghez, Salim, Hornstein, Tanner, Lu, Morris, Becklin, Duchene, 2004). The gas mass currently accreting into the Milky Way’s SMBH will come much closer and allow us to indirectly confine the Schwarzschild radius further. This would further strengthen the argument for the existence of black holes. Moreover, there is no currently known state of degeneracy pressure greater than that of Neutrons capable of halting a massive star core from collapsing into a black hole construct. While other states of degeneracy may yet be discovered preventing a black hole from forming, I choose to remain with current star mass and degeneracy scaling relationships as a guide.

2. Abductive reasoning suggests conserving physical information (quantum determinism and reversibility in the form of the quantum evolution operators) within the entropy of a black hole horizon occurs by a currently unknown method. Information conservation is necessary otherwise it could lead to information destruction whether by Hawking radiation (Hawking, 1975) or vanishing beyond the horizon forever. While a formal information conservation principle for the universe is still vigorously debated, I am clearly planting my flag in favor of one.

3. Based on this previous abductive reasoning I am making a further inductive argument. Specifically that there are implied consequences to conserving physical information in the entropy of a black hole horizon nobody has ever considered to my knowledge.

4. Following the inductive argument I make a number of deductions and a few predictions.

Assuming the existence of black holes, the number of possible quantifiable states of mass, entropy, and physical information within the construct seem fairly limited from our perspective as of now. It is indeed possible the worst case scenario in terms of human understanding turns out being the truth, that scenario being there is no hawking radiation, horizons do not have entropy nor do they preserve physical information, and that everything beyond the horizon is irretrievably lost. I have not yet resigned myself to such a level of pessimism. I am not yet willing to accept that a perceivable universe is indeed not fully understandable without requiring one to commit certain suicide in effort to gain further knowledge. Moreover, a universe requiring one to commit certain suicide as the sole path to attain further knowledge would prove to be inherently irrational to any sapient life form. Just to be clear I am promoting a Rational Universe Theory defined as such:

Rational Universe Theory: All physical laws, forces, and properties governing a perceivable universe are capable of being fully understandable by a sapient being without requiring a sapient being to commit certain suicide in effort to gain further knowledge.

There is currently a growing scientific consensus that black holes preserve physical information in the entropy of their horizons by some unknown method. This is a precept of various holographic universe models. Ideas promoted by Susskind and others regarding holography led to a thought experiment resulting in a black hole merger paradox.

By "Physical information" I am referring to quantum determinism and reversibility in the form of the quantum evolution operators via some as of yet undiscovered method. While I am unaware of the leading current theory for maintaining physical information in a black hole horizon, all seem to include concepts regarding quantum gravitational fluctuations of the horizon membrane as the primary method.

Even without a formal theory of quantum gravity, there is a huge problem looming even if we indeed had one. If black holes preserve physical information in the entropy of their horizons it would be in a constant state of change. Material is constantly being added to a black hole so the horizon would always be preserving new physical information over time. Meaning all black hole horizons are utterly unique entities based on the black holes ever changing entropy, physical information, and mass which is being represented.

Allow yourself to imagine the entropy and information of a black hole horizon as a simple dataset. If black holes preserve datasets in their horizons, those datasets would be in a constant state of change. New data is constantly being added to the existing dataset maintained in a black holes horizon over time. Every black hole horizon dataset is a unique entity based on the black hole horizon’s ever changing dataset and the mass which is being represented.

Setting localization issues of the black hole horizons aside (black hole horizon localization issues are largely the result of assumptions that will be dealt with later) allow us to consider a black holes ever changing dataset taking the form of a sphere. What would be the point of maintaining a dataset in the form of a sphere be if the black hole was not representing something beyond the horizon boundary of the sphere?

If mass or anything else is represented beyond the dataset sphere of the horizon it implies a spatial and temporal separation between the dataset being maintained in the horizon and what it is being representing beyond it. Black holes in this respect share the unique characteristic of maintaining a dataset or identity inside out from our perspective. If this is the case there are two possibilities with regard to theoretical black hole coalescence events or merger attempts.

In the event gravitational wave signatures of black hole coalescence and ring down are discovered, I do not envy those attempting to complete the following task. To describe binary black hole inspiral and eventual coalescence accurately we would need to do the following. First it would be necessary to develop a formal theory of quantum gravity. With a formal theory of quantum gravity we would then need to mathematically create a black hole using that particular models space time.

This black hole would need to have a changing dataset in its horizon and mass beyond the horizon being represented. Then we would need to mathematically explain how the unique datasets from the separate horizons would scramble, merge, or coalesce datasets without the mass being represented interacting since they are spatially separated from the horizon. With datasets in the horizons scrambling or scrambled, we then must mathematically describe how the mass being represented merges and how this new entity sorts everything out in the end. Moreover, the only means by which to verify such a theory would require the certain death of an observer in the effort to gain information.

It seems to me black holes cannot have their cake and eat it too. Intuition suggests this to be a seemingly impossible event and utterly irrational in requiring an observer’s suicide to verify. This is the "Black Hole Merger Paradox" or "Black Hole Merger Problem". It is also worth noting that Cosmological singularities will also need to be explained using the same quantum gravity theory derived in this model.

Black Holes can never merge and will opt for entropy and physical information conservation through reassignment over the corruption of coalescence. Binary black holes must surrender entropy, physical information, and mass before their unique horizons can interact in this scenario. If black holes must abort each other by their very nature because it is rational to do so, you can see exactly where I am going with this. The universe did not begin with a single cosmological singularity failure or irrational self-destructing black hole (I am doing the “Standard Model” a favor here, this is one consensus they do not have a consensus on) I argue it was generated in a process by the abortion or synthesis of 2 or more black holes. Producing everything we see and concealing a process that has been until now out of mankind’s collective perception. The purpose of the following is to establish a new philosophy or way of thinking regarding black holes as a construct in the universe. This philosophical argument will be followed by further papers including mathematical models based on the ideas put forward here.

The 8th possible solution to the black hole information paradox revealed here involves physical information being preserved within black hole entropy only to be deterministically assigned later. If black holes must preserve physical information within the entropy of their horizons, black holes must opt for physical information reassignment over the corruption of coalescence. I feel I have argued for this fairly convincingly with my "black hole merger paradox". Black holes must abort one another before their horizons can interact for that would allow for the corruption of physical information preserved within them this is how our perceived universe began. To verify this solution does not require the certain suicide of the observer, it can be simulated on the smallest theoretical scale possible. This brings into question, what exactly is a black hole?

Black holes are temporally neutral states of mass at temporally perceived infinite gravity simultaneously representing non temporal mass which is not governed by the inverse square law occupying a temporal volume. This is due to the fact that non temporal mass being represented by the temporally neutral black hole is outside our temporal horizon.

Moreover, non-temporal mass occupying a temporal volume and temporally neutral state of mass represented by the black hole are also both reflections of one another. The tidal interaction between 2 non temporal masses will be reflected in the temporally neutral horizon of the black holes represented.
Sufficient distortion of the temporally neutral horizon will lead to temporally perceived singularity failure and the synthesis of all elements currently attributed to primordial big bang Nucleosynthesis. Non temporal mass is the force we perceive as magnetism occupying a volume of vacuum space. If I am correct, there should be something left in the vicinity of a Type 1a supernova progenitor roughly 341,505,466 km in diameter. This transparent object will gravitational lens light for it is the unfurled dynamo of the star that once was. In addition, all gamma ray bursts originating from a mature elliptical galaxy should have some commonality.

What we temporally perceive as "dark energy" is actually resulting from black holes exiling temporal mass (temporally assigned magnetism) back into magnetism (non-temporal mass). A temporally perceived black hole gravitational radius will also not lens light, but the non-temporal mass (magnetism in a volume of space) which is represented and not governed by the inverse square law will. This is the temporally perceived galactic scale gravitational lensing currently attributed to temporally perceived dark matter. When black holes get to close to one another something special occurs and that is Singulosynthesis. The process by which physical information and entropy maintained in a black hole horizon is reassigned. It is how the universe began and is still occurring.

There are 2 possible paths to final solutions of the problem, first is a temporally centric version of the solution which was based on gravitational tidal effects of 2 or more temporally neutral horizons. The second is non-temporally centric version which is based on tidal effects of non-temporal mass being reflected into temporally neutral horizons. Reason suggests model 2 is the optimum path and is the one I am working on. Both will require simulation to verify which model is optimum. Regardless of which model is simulated, temporally neutral mass at temporally perceived infinite gravity has a mass density of roughly D = 2.56872778e^20 kg m^3 based on the best current observations and is the starting point. Some of the constants in physics really do need to be tightened up to make modeling easier. Nobody can really scoop this, but a collection of exceptional individuals could possibly figure it out together. The mass density figure listed above was derived in another paper of mine based on observation, reasoning, and no irrational assumptions.

The only path to a unified quantum theory of everything begins with a simulated replication of the deterministic process (Singulosynthesis) that governs the simulated universe we perceive and exist within on the smallest theoretical scale possible. I am well on my way in modeling this.
The Singulosynthesis universe began with 26.7865% dark matter (magnetism in a volume of space), 73.2135% matter (temporally assigned magnetism), and 0% dark energy. This accounts for the 46.427% metallicity discrepancy we observe based on predictions made by other more popular cosmological models. The universe never stopped producing big bang nucleosynthesis elements, we just never figured out how they were actually being produced. The universe has been converting mass (temporally assigned magnetism) into non temporal mass (magnetism in a volume of space not governed by the inverse square law) since its beginning. All while reassigning physical information and entropy periodically when black holes venture too close to one another. This leads to the current composition of the universe being 15.5% matter (temporally assigned magnetism), 84.5% dark matter (magnetism in a volume of space), and 0% dark energy.

1 solar mass x .267865 = .267865 solar mass non fusible compacted magnetized volume of space: 53266 X10^30 kg

Our Suns has .732135 solar masses of fusible mass: 1.45589 X 10^30 kg

A temporally perceived gravitational radius is a temporally neutral representation of non-temporal mass as well (magnetized volume of space):

(2 (6.67384e-11) (.53266 X10^30 kg)) / 299,792,458^2 = 791.069180m
7.10977523e19 / 299,792,458^2 = 791.069180m
Calculating minimum final degeneracy for temporal neutral mass at temporally perceived infinite gravity:
Volume of a Sphere= 4/3 Pi R^3
Volume of a Sphere = 4/3 Pi 495043536.1919463m
Volume of a Sphere = Pi 6.60058048e^8 m^3
Volume of a Sphere = 2.07363351e^9 m^3
Density = M/V
D = .53266e^30kg/2.07363351e^9 m^3
D = 2.56872778e^20 kg m^3

If you crushed the magnetic core dynamo at the center of our sun into a temporally neutral horizon D = 2.56872778e^20 kg m^3 would be the temporally perceived mass density. The geometry of non-temporal mass is not governed by the inverse square law and leads to a Vick Radius where 2GM/c. The geometry of non- temporal mass also governs the temporal assignment of energy states.
Take the CMBR map and apply it to a sphere. Distort the sphere until the thermal gradient reaches a state of equilibrium. The shape revealed is the geometry of non-temporal mass when temporal energy states are assigned.

This geometry will be the same for all synthesizing black holes regardless of mass. Improving our mapping of the CMBR will only help improve the model proposed. Ultimately, the geometry of non-temporal mass will be unified with the Higgs effect.
The only way to beat a black hole is simulation, but first you need to know what to simulate. Or, the universe inherently irrational to a sapient life form.

Ghez, A. M., Salim, S., Hornstein, S. D., Tanner A., Lu J. R., Morris M., Becklin, E. E., Duchene, G., Nov 2004, Stellar Orbits Around the Galactic Center Black Hole, UCLA Division of Astronomy and Astrophysics, Los Angeles, CA 90095-1574, http://arxiv.org/pdf. h/0306130v2.pdf (March 14, 2013)

Hawking, S.W., Particle creation by black holes, Commun. Math. Phys. 43 (1975), 199—220, http://prac.us.edu.p. /CMPhawking.pdf (March 8, 2013)
(I have another 500 references or so in a list, I considered many observations collectively while coming up with this)

"It's mercy, compassion, and forgiveness I lack not rationality." - Beatrix Kiddo

## Troll Combos

These are combos that are meant to not do as much damage, but are mostly meant to annoy players, or get rid of ones that target/follow you.

### Ozone Regeneration

Tip: This is best used if you are in the safe zone, and need healing, while someone is waiting for you to come out. Elements Needed: Wind, Spectrum (preferably), and Light

1. Use Rainbow Shockwave to launch up into the air. (Tip: If you flip out of spawn, and use this move right away a glitch can happen where there is no cooldown applied to rainbow shockwave allowing you to use it again.)

2. Use Wind Ascent to launch up into the air further.

3. Use rainbow shockwave again and launch yourself up and tward another safe zone.

4. While midair, use Scintillant Rejuvination and hold it until you have earned the full 250 HP

5 Use Wind Ascent one more time then Rainbow Shockwave into the nearest spawn. If pulled off right you should be in or near the targeted spawn

Usually after one use the player that was guarding you will give up.

Tip: Make sure to have lots of mana as this combo can drain it slowly.

### Sky Trolling

Elements Required : Space,Light,Spectrum

1.Use Comet Crash while facing the sky.

2.Heal yourself with Scintillant Rejuvination.

3.Use Comet Crash again while facing the sky.

4.Use Holobeam while in the sky.

After opponent moves use another blinding move ( low mana one) after using Genesis ray

### See Ya later, Alligator

1. Use any Travelling Spell to get close to your target.

3.Use Gravitational Exertion and aim at your opponent while they are still in the air. (Gravity)

## Black Hole Revealed: Into the heart of darkness

The image shows a bright ring formed as light bends in the intense gravity around a black hole that is 6.5 billion times more massive than the Sun. Credit: Event Horizon Telescope Collaboration

This remarkable glimpse of the heart of darkness of a black hole called M87 marks a major advance since I covered an attempt in 2008, when just three telescopes combined to gaze into the maw of the black hole that sits at the heart of our own galaxy, an enigmatic source of radio waves called Sagittarius A* (Sgr A*).

Today, in simultaneous global press conferences, Dr Sheperd Doeleman, Harvard University Senior Research Fellow, described how the Event Horizon Telescope, named after a black hole’s point of no return, combined signals from eight telescopes to create an Earth-sized virtual telescope capable of resolving a structure as small as an orange on the moon.

‘Black holes are the most mysterious objects in the universe,’ said Dr Doeleman, EHT Director, adding that in the case of M87, as a result of today’s ‘extraordinary scientific feat…we have seen the unseeable.’

The results are published in the Astrophysical Journal Letters.

M87 is at the centre of the Virgo galaxy, a behemoth with a mass 6.5 billion times that of the Sun, located 54 million light-years away from Earth, which also spews out a jet of energy thousands of light-years across space.

Dr Doeleman, Dr Jonathan Weintroub and colleagues used a technique called Very Long Baseline Interferometry to combine the data from eight observatories to study radio wavelengths that can penetrate the gas and dust that shroud the heart of galaxies.

They have also gathered data on Sgr A*, which is about the size of the orbit of Mercury, of mass about four million times that of our sun, and light from its surroundings takes 25,000 years to reach Earth.

However, because SgrA* is so much less massive (1500 times) than M87 ‘the timescale of variability for Sgr A* is about 20 minutes or variable over the time scale of an observation,’ said Dr Weintroub. ‘This makes the imaging more challenging because we depend on it staying static as the Earth rotates.

‘Which isn’t to say we’ve given up on SgrA*, very much to the contrary, but that’s why we focused on M87 first, which wasn’t easy either, but the better one on which to start.’

The existence of the Sgr A* black hole was predicted in 1971 by Lord Rees, Astronomer Royal, with Donald Lynden Bell. Today, the cores of largest galaxies are thought to harbour supermassive black holes and, though impressed by today’s M87 results, Lord Rees said he was disappointed not to see more details of the jet.

Nearby stars have been seen to orbit around black holes, an indirect clue to the existence of these gravitational monsters, while at the event horizon of the black hole space-time itself bends to the point where even light can’t escape.

The boggling gravity of a black hole gobbles up dust, gas and light from its surroundings into a disc around itself, eventually pulling this material over its event horizon and into oblivion.

The black holes are rendered visible as a shadow backlit by the accretion disk of material, where heat and light are generated, spiralling into the black hole.

The way a black hole wraps light around the event horizon in accordance with one of Einstein’s most famous predictions – the bending of starlight by a massive body in space – was first confirmed by Sir Arthur Eddington’s measurements during the 1919 solar eclipse, the results of which turned Einstein into a global superstar. In theory, space-time is warped so strongly that one can see behind the black hole.

At the most basic level, the 200 or more scientists of the Event Horizon Telescope want to answer two questions. The first is to take an image of a black hole, since ‘seeing is believing’. The second is whether Einstein’s predictions of the size and the shape of the black hole’s shadow hold up.

They might be circular, oval or some other shape, depending on circumstances which, if confirmed, is dull for theoreticians. However, if the Einsteinian equations describing them are askew, the research could open the door to new physics.

In the case of M87, the results were consistent but ‘this is just the beginning,’ said Dr Doeleman.

‘Once we were sure we had imaged the shadow, we could compare our observations to extensive computer models that include the physics of warped space, superheated matter and strong magnetic fields. Many of the features of the observed image match our theoretical understanding surprisingly well,’ remarked Paul T.P. Ho, EHT Board member and Director of the East Asian Observatory. ‘This makes us confident about the interpretation of our observations, including our estimation of the black hole’s mass.’

This ‘herculean task’ has resulted in a ‘historic moment,’ said National Science Foundation Director, France Córdova, explaining that it would ‘transform and enhance our understanding of black holes.’

One of the best simulations of what to expect can be found in the Hollywood movie Interstellar, which Kip Thorne, Feynman Professor of Theoretical Physics Emeritus at Caltech, worked with Paul Franklin of the British company Double Negative to show, as Thorne put it, ‘image distortion akin to a fun-house warped mirror.’

Thorne shared the Nobel Prize in 2017 for the observation of another prediction of Einstein’s general relativity, that gravitational waves – ripples in space-time – are generated by violent cosmic events, such as when two black holes collide. A prototype component of the Advanced LIGO (Laser Interferometer Gravitational Wave Observatory) gravitational wave detector made by the Rutherford Appleton Laboratory, Chilton, can be seen in the Science Museum.

Anticipated as ‘dark stars’ (stars so big that light cannot escape) in the 1700s by the English clergyman John Michell, black holes are among the more extraordinary predictions of Einstein’s theory of general relativity, one that links space, time and gravity, one of the greatest accomplishments of the human mind.

Originally, black holes were just one mathematical solution to Einstein’s field equations. But in the 1930s, the Nobel Prize winning astrophysicist Subrahmanyan Chandrasekhar showed that black holes were an inevitable consequence of a star’s death, and scientists started considering them real objects.

The late Stephen Hawking is another key figure in the story of black holes. He first caught the attention of his peers in the late 1960s, working with Roger Penrose on how general relativity sometimes breaks down, resulting in what is called a singularity. They showed that such singularities must occur inside black holes – and, most probably, at the start of the universe.

One of Hawking’s overarching goals was to take general relativity, which can be used to predict the large scale structure of the universe, and blend it with quantum theory, which rules the world of atoms and the very small, to produce a grand theory of everything, known as quantum gravity.

In his most famous work, Hawking raised the intriguing possibility that black holes are not as black as once thought. The reason is down to one strange consequence of quantum theory: empty space isn’t empty: pairs of particles are constantly popping into and out of existence. If they appear on the border of event horizon, they may find themselves on different sides, with one sucked in, and the other becoming ‘Hawking radiation’.

If the paradoxical glow of Hawking radiation had been detected from a black hole during his lifetime, Hawking could well have won the Nobel Prize. But, as Lord Rees remarked, this could not have been detected in the images released today because the effect is inversely related to mass and it ‘would only be seen from black holes smaller than an atom, which nobody really expects to exist.’

On his 70 th birthday, the Science Museum gave Hawking a special present, a ‘black hole light’, and at his memorial service at Westminster Abbey on 15th June 2018, his gravestone was unveiled which bears the Hawking’s equation that expresses Hawking radiation.

This is the memorial stone on Stephen Hawking’s grave in Westminster Abbey which carries his most famous equation, describing the entropy of a black hole.

### Roger Highfield

Roger Highfield is the Science Director at the Science Museum Group, a member of the UK's Medical Research Council and a visiting professor at the Dunn School, University of Oxford, and Department of Chemistry, UCL. He studied Chemistry at the University of Oxford and was the first person to bounce a neutron off a soap bubble. Roger was the Science Editor of The Daily Telegraph for two decades, and the Editor of New Scientist between 2008 and 2011. He has written or co-authored eight popular science books, and had thousands of articles published in newspapers and magazines.

This blog will take you behind the scenes at the Science Museum, exploring the incredible objects in our collection, upcoming exhibitions and the scientific achievements making headlines today.

## Black hole darkness a result of gravity or temporal distortion? - Astronomy

The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.

#### Fascinating ( Score: 5, Interesting)

I probably won't live to see it but I am looking forward to when we can directly observe in more detail the area surrounding the event horizon of black holes. There is so much we do not understand about the Universe and overall cosmology, but black holes by their very nature will probably be one of the last frontiers as we continue to peel back the layers of knowledge in our understanding of the nature of the Universe as a whole.

There are also potentially practical applications given far greater technology than we have now. Imagine using black holes to generate energy, or as massive particle accelerator laboratories!

#### Re:Fascinating ( Score: 4, Interesting)

Doesn't this point more to a possibility that a black hole is a solid physical body which manifests it's own physical rotation rather than some of the former mysticism explanations that have persisted to date?

Basically a continual increase in material density from neutron star densities to the point where gravitational forces are capable of attracting photons and other larger classifications of matter, either resulting in the fusion of matter to ever increasing densities of conventional matter or recombination of subatomic components in such a fashion of maximum compression density.

#### Re: ( Score: 3)

Do you think that black holes receive a notably more 'mystical' treatment than most other scientific phenomena that can only be usefully talked about in terms of fairly high level math? They certainly get their share of time whenever a SyFy special needs some sort of treknobabble to work with but by the standards of things that eat photons and defy direct observation they seem to be doing reasonably well.

#### Re: ( Score: 2)

phenomena that can only be usefully talked about in terms of fairly high level math?

A black hole is a ball of stuff with an extremely high density and an extremely small volume, which exerts an extreme gravitational pull that not even light can escape.

There, no high level math, and no mysticism, and only minor inaccuracies (volume vs mathematical point).

#### Re: ( Score: 2)

I believe the idea of black holes largely developed as a result of Einstein's General Theory of Relativity. In particular, the Schwarzschild solution to the equations Einstein proposed described a stationary black hole, and the Kerr solution described a rotating black hole. Several others contributed. The math associated with the General Theory of Relativity is fairly dense IMHO, with things like tensor calculus that are rarely addressed until graduate level classes.

We only get simple math if we apply Ne

#### Re: ( Score: 2)

Any mathematics, sufficiently advanced, is indistinguishable from magic.

#### Re: ( Score: 2, Interesting)

To me, I would think it suggests that high-intensity fields, in this case gravitational, can affect matter. Look at it from the opposite end of scale. Lets assume we have a point generating a magnetic field, the space surrounding that point can then be filled with free-floating, very fine iron particles. Ramp up the intensity of the field and set it spinning, it *will* affect the iron particles in the direction of its rotation, which would drag the particles around it.

At least, it sounds plausible.:D

#### Re: ( Score: 1)

Wow! You totally stole this from Will Wheaton off TNG. Ok, not really, but have you considered writing?

#### Re:Fascinating ( Score: 4, Interesting)

The media and a large percentage of the population treat *everything* with a degree of 'mysticism'. Anything that can't be understood in a sentence becomes ghosts, psychic phenomena, "god's hand", etc. etc.
Trained careers like medicine, law, and science become overly dramatic and so highly fictionalized in entertainment that the people who relate to the statement above assume that crimes really are solved in an 8 hour shift, deathly illnesses can always be cured with a single injection in the way we might treat something with epinephrine, and that all physics can be described in a few phrases by Deepak Chopra.
And there's a high level of resistance to combating that 'mysticism'.
Even recently I encountered someone who said that psychics/mediums are frauds. except HER medium.
Sigh.

#### Re: ( Score: 2)

Ha! "HER medium" must of been one of those certified psychics!

#### Re:Fascinating ( Score: 5, Informative)

It isn't really physically possible (at least, not so far as we know) for a black hole to be considered as a solid physical body. You see, the event horizon isn't the only place where the gravity prevents matter from escaping. Gravity increases until you hit the "outer" part of any body, which means if we assume for a second the event horizon occurs outside all the matter of the former star (which it does), gravity will be slightly more intense inside the horizon. That means that as you travel into the black hole until you reach the outer limit of the physical object itself, gravity will still increase and retain the property of inescapability. What that means is the outer shell of matter can't interact with everything inside, so the normal pressure from electromagnetic and nuclear forces can't keep the outer shell from collapsing inwards (the force literally can't push outwards, since gravity pulls it back).

That means the outer layer of matter will always collapse inwards, closer to the center, and as that happens, the body becomes more dense and the place where gravity forms a horizon extends ever closer to the center of the black hole. Normally, gravity would decrease after you entered the physical body, so near the center of the black hole there should still be a solid physical body where gravity is less than that required to form a horizon, but as the outer layer of the black hole continually falls downwards (it literally can't do anything else), the space near the center where the black hole retains normal physical properties of a star should diminish to nothing.

Another fascinating thing is that at the very center, there should be no gravity at all, by the simple rule of symmetry. But the black hole is ever shrinking towards that spot, so that the density approaches infinity and the entire matter of the star becomes condensed into a point with infinite gravitational force. So the center should also end up with infinity gravity. Which is impossible, or should be. That's why black holes are and always will remain a huge mystery, barring some incredible new scientific revelation that overturns the entire theory of. well, nearly everything.

In other words, for black holes to be treated as solid physical objects, a new force that defies the theory of general relativity (it would have to travel faster than light to allow the matter towards the center of the hole to interact with the matter towards the outer part of the hole) would need to be discovered. And that seems unlikely, although not impossible by any means.

#### Re: ( Score: 2, Informative)

Today's black holes allow for âoeevaporationâ and the making of âoejetsâ.

Jets aren't really escaping the black hole, that matter never actually fell in. And if by evaporation you mean Hawking radiation, those particles were never inside the black hole either, but they do steal energy, but not information.

#### Re:Fascinating ( Score: 5, Insightful)

The jets don't come from inside the black hole at all, they are a result of the interaction of the black hole and the disk of matter falling into it. The exact mechanism for their production isn't certain yet, but the simple explanation is that as the matter gets close to the disk, it spins faster and faster while losing energy (since it is falling into a negative gravity well) which can be focused into some few particles (through magnetic effects or possible relativistic "frame dragging") that are then propelled outwards well before they reach the event horizon. The evaporation is more complex and I don't understand it so I won't try to explain it.

Attempting to explain the universe through electro-magnetism alone is. a useful exercise, but also really not true, and demonstrably so. Gravitation effects are radically different from electrical ones. You can alter electrical theory to fit the observations, but only if you introduce arbitrary new rules and exceptions, which is, if not exactly forbidden in science, at the least extremely questionable (and the more complexities you have to introduce the less likely your theory is to be accurate). Gravitational theory, on the other hand, proceeds from and naturally fits with the observations. Now, it is well known in physics that our understanding of gravity is incomplete (classical and quantum theories do not agree, for one thing, despite both seeming to be true on their respective scales), but to argue that because gravity is "weak" it cannot also be the strongest force en masse (so to speak) is, well, faulty logic. There are numerous examples of weak things aggregating to provide effects well outside their individual strength. When we say electrical forces are "stronger" than gravity, we mean only on a certain scale (atomic, to be specific). Over they scale of a few feet, the nuclear force is nonexistent, despite the fact it is even stronger than the electrical force on small scales.

## Round IV: Conclusion

### What would you say to any student thinking of going for physics as studies, cosmology, particle physics, etc? Or to a student who is hesitating to choose Physics?

#### KMC

The field of physics has a reputation for being “difficult,” so students often hesitate to venture themselves into learning more about it or are worried that they are not “smart enough” to choose it as a career. These thoughts have certainly also crossed my mind.

It is my personal belief that nobody is a born genius and that, just like in any other career, hard work, perseverance, and the will to always be learning will get you far. I also believe that the picture of a scientist in academia is slowly but surely changing, and all kinds of people from all kinds of backgrounds should be able to pursue and succeed in a physics career.

A physics degree can open up the door to diverse careers information is always a reliable friend, so do not hesitate to look around and reach out for advice!

#### SI

I would say the most important aspect is to do something you enjoy. University is not easy, and it requires a lot of independence and self-discipline to get through and do well, no matter the subject. So it’s important to be motivated toward a goal, and to enjoy learning in your chosen study. I’ve always been interested in figuring out how things work. If, like me, you are a big fan of puzzles or brain tests, the fun you will have trying to solve problems or puzzles will make it very easy to enjoy doing science and push through hardships. Physics is a highly competitive field and requires a lot of self-discipline and creativity. Research needs a lot of independence and initiative, so it’s extremely important that you learn early on how to make efficient use of tools at your disposition, be it tutorials, classes, mentors, or networks.

#### LW

Choosing to study physics is not an easy choice. It comes with a lot of responsibility and work and determination. However, it also comes with so many surprises, fun challenges, and will give you more belief in yourself than anything else will. My road to physics wasn’t easy, but now that I’m nearing the end of my degree, I can proudly say that it has given me so much more confidence in my skills than anything else ever has. The most important thing to ask yourself is, “Am I curious? Am I inquisitive?” If the answer is yes and you have a passion for physics, then pursue it! It will teach you so much not just about Earth, the stars, and planets but also about yourself.

#### JW

I would encourage anyone with an interest in physics or astronomy to keep at it! Don’t let anyone tell you it’s too hard or you should try something else. All it takes is being passionate and willing to learn. In addition, do not fall into the trap of thinking Newton, Einstein, and Hawking are the only types of people who do physics. There is a diversity of people who pursue physics. Find someone who you relate to and learn more about their story. Physics is about a few big ideas and finding creative ways to apply them. As such, it has applications in many fields. Pursuing physics doesn’t mean you have to be a university researcher or academic (though you certainly can be!). I have friends who majored in physics or astronomy as undergrads and went on to become a NASA engineer, a Pixar animator, a university professor, technical writer, lawyer, copy editor, science consultant and more. Here is a good source to learn more. Mainly, have fun with it! Find a group of people who love physics and astronomy like you to connect with and support each other. Physics has the power to connect you in a deeper way with the world and the universe beyond!

#### JW

There are many good books and YouTube channels that interested readers can find. Some of my favorites are below. Some of the books may be a bit dated now, but they give great information.

Ferris, T. (1988). Coming of age in the milky way. William Morrow & Co.

Griffiths, D. (1995). Introduction to quantum mechanics (1st ed.). Pearson Education.

Hawking, S. (1988). A brief history of time. Bantam Dell.

Hawking, S. (1993). Black holes and baby universes and other essays. Bantam Dell.

Tyson, N., Gott, R., & Strauss, M. A. (2016). Welcome to the universe. Princeton University.

#### SI

We have lots of exciting research and useful information about black holes on our Event Horizon Telescope website and corresponding social media. I personally love the video with Dr. Janna Levin explaining gravity at different levels of expertise, and the talk by Dr. Brian Greene is great to understand a little bit about the quantum world.

Event Horizon Telescope. (2017). Event horizon telescope. https://eventhorizontelescope.org/

Wired. (2019, December 20). Astrophysicist explains gravity in 5 levels of difficulty | wired [Video]. YouTube. https://www.youtube.com/watch?v=QcUey-DVYjk

World Science Festival. (2018, February 16). Quantum reality: Space, time, and entanglement [Video]. YouTube. https://www.youtube.com/watch?v=BFrBr8oUVXU

#### LW

A book I highly recommend, which is usually also required reading if you study physics at university but you can also use during A-levels, is the Tipler and Mosca physics book. A YouTube channel I really enjoy is called Physics Girl. She has a lot of videos that explain some basic and more advanced concepts in physics in a fun way. Finally, I recommend finding any books on specific topics that you like! Are you interested in planets? Buy the book The Exoplanet Handbook by Perryman.

Perryman, M. (2011). The exoplanet handbook (1st ed.). Cambridge University.

Tipler, P. A., & Mosca, G. (2007). Physics for scientists and engineers (6th ed.). W. H. Freeman.

#### KMC

For Spanish speakers, some of the topics discussed here I first learned by reading popular science books from Mexico, specifically the books by Matos and Shahen. There are also tons of YouTube channels, with some of my personal favorites listed below.

Matos, T. (2004). ¿De qué está hecho el universo? Materia oscura y energía oscura [What is the universe made of? Dark matter and dark energy]. Fondo de Cultura Económica (FCE).

Shahen, H. (2012). Los hoyos negros y la curvatura del espacio-tiempo [Black holes and the curvature of space-time]. Fondo de Cultura Económica (FCE).

Karen Macías Cárdenas is a Mexican physicist who is a master’s student at Queen’s University. Their research area is astroparticle physics with a focus on dark matter (DM) phenomenology, specifically, studying the possibility of DM annihilation channels into Standard Model particles like neutrinos using constraints from current neutrino experiments and cosmological probes.

They have been an ARMY since 2017 when BTS released “Spring Day.” BTS encouraged them to stay true to themselves and be proud of who they are as a non-binary bisexual scientist and showed them the importance of elevating the voices of minorities in fields where they are historically underrepresented.

Love yourself, Speak yourself, ARMY!

Sara Issaoun is a PhD candidate in astrophysics at Radboud University and a member of the Event Horizon Telescope Collaboration, the team who, in 2019, imaged a black hole shadow for the very first time. Supermassive black holes generate the highest energy processes in the known Universe, ejecting jets of plasma affecting galaxy environments on large scales, but their fundamental properties remain shrouded in mystery. She makes use of global networks of radio-telescopes to image and study the immediate surroundings and gravitational pull of supermassive black holes.

Jessica Warren earned a BA in physics and astronomy from Vassar College and a PhD in astrophysics from Rutgers University, where she focused on X-ray spectra of supernova remnants. She has taught physics and astronomy at several institutions and is now a lecturer in physics at Indiana University Northwest. Warren is active in science outreach, having judged for local Science Olympiad competitions, hosted astronomy observing nights, and visited local schools. Currently, her research interests are in physics education, specifically looking at ways that students can employ self-evaluation strategies to develop expert-like attitudes toward physics.

Leonie Witte is a 23-year-old astrophysics student and big time ARMY! She is in her final year of her master’s at the University of Kent, UK and is hoping to go into a career looking at planets and their compositions. BTS’s music got her through a lot of the hard times during the pursuit of her degree, and even inspired her to visit Korea. In her spare time, she plays guitar and writes her own songs which she uploads to Spotify. She also loves dancing and mountaineering in the Alps.

Physics is everywhere you look: in your phone, in the nature surrounding you, and in the lyrics of BTS songs. Enjoy exploring and feed your curiosity!

Illustration By: Rachel Freeman @re_yichellart

### References

BANGTANTV. (2020, December 6). BTS (방탄소년단) black swan perf. + on + life goes on + dynamite @ 2020 MMA [Video]. YouTube. https://www.youtube.com/watch?v=PtaP4UkZKyc

Big Hit Labels. (2015a, May 10). BTS (방탄소년단) ‘I need u’ official MV (original ver.) [Video]. YouTube. https://www.youtube.com/watch?v=jjskoRh8GTE

Big Hit Labels. (2015b, November 29). BTS (방탄소년단) ‘Run’ official MV [Video]. YouTube. https://www.youtube.com/watch?v=wKysONrSmew

Big Hit Labels. (2016, October 9). BTS (방탄소년단) ‘피 땀 눈물 (Blood sweat & tears)’ official MV [Video]. YouTube. https://www.youtube.com/watch?v=hmE9f-TEutc

Big Hit Labels. (2017a, September 4). BTS (방탄소년단) Love yourself 承 her ‘serendipity’ comeback trailer [Video]. YouTube. https://www.youtube.com/watch?v=BEMaH9Sm3lQ

Big Hit Labels. (2017b, September 18). BTS (방탄소년단) ‘DNA’ official MV [Video]. YouTube. https://www.youtube.com/watch?v=MBdVXkSdhwU

Big Hit Labels. (2018, May 6). BTS (방탄소년단) Love yourself 轉 tear ‘singularity’ comeback trailer [Video]. YouTube. https://www.youtube.com/watch?v=p8npDG2ulKQ

Big Hit Entertainment. (2019a). 花樣年華 The notes 1 the most beautiful moment in life [ENG]. beORIGIN.

Big Hit Entertainment. (2020). 花樣年華 The notes 2 the most beautiful moment in life [ENG]. Big Hit IP Co., Ltd.

Blady, S. (2021). BTS from “N.O” to “ON” and beyond: Innovation in effective mental health messaging and modelling. Asia Marketing Journal, 22(4), 117-149.

Lazore, C. (2021). Success story: How storytelling contributes to BTS’s brand. Asia Marketing Journal, 22(4), 47-62.

Lee, J. (2019). BTS, art revolution: BTS meets Deleuze (S. Kim & M. Myungji & J. Won & S. Lee, Trans.). Parrhesia Publishers. (Original work published 2018)

Mnet K-POP. (2017, December 1). [2017 MAMA in Hong Kong] BTS_intro perf. + not today [Video]. YouTube. https://www.youtube.com/watch?v=2HboMs0vbsE

Studio XXX. (2015). 화양연화 The most beautiful moment in life pt. 2 [Album art]. Big Hit Entertainment.

Tegmark, M. (2003). Parallel universes. In J. Barrow, P. Davies, & C. Harper Jr. (Eds.), Science and ultimate reality: From quantum to cosmos. Cambridge University Press. https://space.mit.edu/home/tegmark/multiverse.pdf

Universal Music Japan. (2017, May 9). BTS (防弾少年団) ‘血、汗、涙 -Japanese ver.-‘ official mv [Video]. YouTube. https://www.youtube.com/watch?v=7OX7dIRReSA

World Science Festival. (2015, December 23). Black holes, wormholes, and time travel [Video]. YouTube. https://www.youtube.com/watch?v=LCgU7KZQCN8

### Conflicts of Interest

The creators have no relevant conflicts of interest to disclose.

### Suggested Citations

#### APA Citation

Etienne, L., Hulme, K., & Lazore, C. (2021). Beyond the stars: Astrophysics in the bangtan universe. The Rhizomatic Revolution Review [20130613], (2). https://ther3journal.com/issue-2/beyond-the-stars-astrophysics-in-the-bangtan-universe

#### MLA Citation

Etienne, Lyna, Hulme, Katie, and Lazore, Courtney. “Beyond the Stars: Astrophysics in the Bangtan Universe.” The Rhizomatic Revolution Review [20130613], no. 2, 2021. https://ther3journal.com/issue-2/beyond-the-stars-astrophysics-in-the-bangtan-universe.

## Deeper Details: The published papers

There is not one, but instead a related set of five scientific papers that go through it all in great detail. We shall take a very quick pass at each. They are all available within “The Astrophysical Journal Letters” and were published on 10th April 2019.

(Side note: These papers all have a vast number of contributors, and they are long, very long, very detailed, and quite technical).

### First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole

When surrounded by a transparent emission region, black holes are expected to reveal a dark shadow caused by gravitational light bending and photon capture at the event horizon. To image and study this phenomenon, we have assembled the Event Horizon Telescope, a global very long baseline interferometry array observing at a wavelength of 1.3 mm. This allows us to reconstruct event-horizon-scale images of the supermassive black hole candidate in the center of the giant elliptical galaxy M87. … Overall, the observed image is consistent with expectations for the shadow of a Kerr black hole as predicted by general relativity. The asymmetry in brightness in the ring can be explained in terms of relativistic beaming of the emission from a plasma rotating close to the speed of light around a black hole. We compare our images to an extensive library of ray-traced general-relativistic magnetohydrodynamic simulations of black holes and derive a central mass of M = (6.5 ± 0.7) × 10 9 M. Our radio-wave observations thus provide powerful evidence for the presence of supermassive black holes in centers of galaxies and as the central engines of active galactic nuclei. They also present a new tool to explore gravity in its most extreme limit and on a mass scale that was so far not accessible.

### First M87 Event Horizon Telescope Results. II. Array and Instrumentation

The Event Horizon Telescope (EHT) is a very long baseline interferometry (VLBI) array that comprises millimeter- and submillimeter-wavelength telescopes separated by distances comparable to the diameter of the Earth. At a nominal operating wavelength of

1.3 mm, EHT angular resolution (λ/D) is

25 μas, which is sufficient to resolve nearby supermassive black hole candidates on spatial and temporal scales that correspond to their event horizons. With this capability, the EHT scientific goals are to probe general relativistic effects in the strong-field regime and to study accretion and relativistic jet formation near the black hole boundary. In this Letter we describe the system design of the EHT, detail the technology and instrumentation that enable observations, and provide measures of its performance. Meeting the EHT science objectives has required several key developments that have facilitated the robust extension of the VLBI technique to EHT observing wavelengths and the production of instrumentation that can be deployed on a heterogeneous array of existing telescopes and facilities. To meet sensitivity requirements, high-bandwidth digital systems were developed that process data at rates of 64 gigabit s −1 , exceeding those of currently operating cm-wavelength VLBI arrays by more than an order of magnitude. Associated improvements include the development of phasing systems at array facilities, new receiver installation at several sites, and the deployment of hydrogen maser frequency standards to ensure coherent data capture across the array. These efforts led to the coordination and execution of the first Global EHT observations in 2017 April, and to event-horizon-scale imaging of the supermassive black hole candidate in M87.

### First M87 Event Horizon Telescope Results. III. Data Processing and Calibration

We present the calibration and reduction of Event Horizon Telescope (EHT) 1.3 mm radio wavelength observations of the supermassive black hole candidate at the center of the radio galaxy M87 and the quasar 3C 279, taken during the 2017 April 5–11 observing campaign. These global very long baseline interferometric observations include for the first time the highly sensitive Atacama Large Millimeter/submillimeter Array (ALMA) reaching an angular resolution of 25 μas, with characteristic sensitivity limits of

1 mJy on baselines to ALMA and

10 mJy on other baselines. The observations present challenges for existing data processing tools, arising from the rapid atmospheric phase fluctuations, wide recording bandwidth, and highly heterogeneous array. In response, we developed three independent pipelines for phase calibration and fringe detection, each tailored to the specific needs of the EHT. The final data products include calibrated total intensity amplitude and phase information. They are validated through a series of quality assurance tests that show consistency across pipelines and set limits on baseline systematic errors of 2% in amplitude and 1° in phase. The M87 data reveal the presence of two nulls in correlated flux density at

8.3 Gλand temporal evolution in closure quantities, indicating intrinsic variability of compact structure on a timescale of days, or several light-crossing times for a few billion solar-mass black hole. These measurements provide the first opportunity to image horizon-scale structure in M87.

### First M87 Event Horizon Telescope Results. IV. Imaging the Central Supermassive Black Hole

We present the first Event Horizon Telescope (EHT) images of M87, using observations from April 2017 at 1.3 mm wavelength. These images show a prominent ring with a diameter of

40 μas, consistent with the size and shape of the lensed photon orbit encircling the “shadow” of a supermassive black hole. The ring is persistent across four observing nights and shows enhanced brightness in the south. To assess the reliability of these results, we implemented a two-stage imaging procedure. In the first stage, four teams, each blind to the others’ work, produced images of M87 using both an established method (CLEAN) and a newer technique (regularized maximum likelihood). This stage allowed us to avoid shared human bias and to assess common features among independent reconstructions. In the second stage, we reconstructed synthetic data from a large survey of imaging parameters and then compared the results with the corresponding ground truth images. This stage allowed us to select parameters objectively to use when reconstructing images of M87. Across all tests in both stages, the ring diameter and asymmetry remained stable, insensitive to the choice of imaging technique. We describe the EHT imaging procedures, the primary image features in M87, and the dependence of these features on imaging assumptions.

### First M87 Event Horizon Telescope Results. V. Physical Origin of the Asymmetric Ring

The Event Horizon Telescope (EHT) has mapped the central compact radio source of the elliptical galaxy M87 at 1.3 mm with unprecedented angular resolution. Here we consider the physical implications of the asymmetric ring seen in the 2017 EHT data. To this end, we construct a large library of models based on general relativistic magnetohydrodynamic (GRMHD) simulations and synthetic images produced by general relativistic ray tracing. We compare the observed visibilities with this library and confirm that the asymmetric ring is consistent with earlier predictions of strong gravitational lensing of synchrotron emission from a hot plasma orbiting near the black hole event horizon. The ring radius and ring asymmetry depend on black hole mass and spin, respectively, and both are therefore expected to be stable when observed in future EHT campaigns. Overall, the observed image is consistent with expectations for the shadow of a spinning Kerr black hole as predicted by general relativity. If the black hole spin and M87’s large scale jet are aligned, then the black hole spin vector is pointed away from Earth. Models in our library of non-spinning black holes are inconsistent with the observations as they do not produce sufficiently powerful jets. At the same time, in those models that produce a sufficiently powerful jet, the latter is powered by extraction of black hole spin energy through mechanisms akin to the Blandford-Znajek process. We briefly consider alternatives to a black hole for the central compact object. Analysis of existing EHT polarization data and data taken simultaneously at other wavelengths will soon enable new tests of the GRMHD models, as will future EHT campaigns at 230 and 345 GHz.

1. Keenon

I join. And I ran into this. We can communicate on this theme. Here or at PM.

2. Alaric

chance coincidence

3. Gilvarry

Love ...

4. Darby

to you the wrong data

5. Dempsey

I am able to advise you on this issue and, in particular, are committed to participating in the discussion.