# Black Hole - energy and matter

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Can someone explain what is happening with energy (e.g. light) and matter which was collected by a black hole?

I suppose that matter builds a black hole's mass and size, but what about light? Does it just disappear? But to generate light, the star consumed matter (mass).

No, the light doesn't just disappear, it adds to the black hole's mass in accordance with $$E=mc^2$$. So if a star produced light from $$m$$ kilograms of mass and all that light fell into a black hole, the black hole's mass would increase by $$m$$ kilograms.

## How physics breaks down in a black hole

An artist's conception illustrates one of the most primitive supermassive black holes known (central black dot) at the core of a young, star-rich galaxy. Credit: NASA/JPL-Caltech

One of the most cherished laws of physics—the conservation of charge—has come under fire in "startling" research by physicists.

The paper by Dr. Jonathan Gratus from Lancaster University and Dr. Paul Kinsler and Professor Martin McCall from Imperial College London demonstrates how the laws of physics break down in a black hole or "singularity."

"As the place where physics 'breaks down' in a black-hole, we have the sense that anything might happen at a singularity. Although perhaps most useful as a plot device for science fiction stories, should we as concerned physicists nevertheless check what conservation laws might no longer hold?"

The physicists investigated the behavior of charge conservation which is the principle that the total electric charge in an isolated system never changes.

To their surprise, they found that they could overturn this "usually sacrosanct principle of standard electromagnetism."

Dr. Kinsler said: "By dropping an 'axion-bomb' into a temporary singularity, such as an evaporating black hole, we can create or destroy electrical charge."

Axions are a hypothesized particle that are a candidate for dark matter, although their exact properties are still debated, and they have not yet been detected.

Professor Martin McCall said: "This so-called axion-bomb is a mathematical construct that combines electromagnetic fields and axion particle fields in the correct way.'"

Dr. Jonathan Gratus said: "The construction shrinks and disappears into the singularity, taking electrical charge with it. And it is the combination of a temporary singularity and a newly proposed type of axion field that is crucial to its success."

Dr. Kinsler added: "Although people often like to say that physics 'breaks down," here, we show that although exotic phenomena might occur, what actually happens is nevertheless constrained by the still-working laws of physics around the singularity."

The researchers said: "Our conclusion appears to be at once startling and undeniable: global charge conservation cannot be guaranteed in the presence of axionic electromagnetic interaction."

## Can energy and matter coexist in a black hole?

In other words, is it possible to distinguish between energy and matter in a black hole singularity? How about time?

Who knows black holes have a lot in common with the early days of the universe.

### #2 deSitter

Actually no - according to the theory, all that can exist for a black hole are its total mass (energy content divided by speed of light squared), its angular momentum, and its charge. So whatever goes over the horizon is lost in all but these terms.

The complication is - there is no strict conservation law for energy in GR so at some point, the whole issue becomes a large problem and points to issues with GR itself. This so-called "no hair" result depends on coupling electromagnetism to gravity in the most naive way, namely to simply paste electromagnetism into curved spacetime without allowing it to be essentially coupled to the gravitational field (EM warps spacetime but spacetime does not alter the form of EM).

Actually no - according to the theory, all that can exist for a black hole are its total mass (energy content divided by speed of light squared), its angular momentum, and its charge. So whatever goes over the horizon is lost in all but these terms.

I still don't see why that is not sufficient to get a magnetic field. An electron has basically the same properties - mass, charge, and spin. From these, we get magnetism. What is it that I am missing? Is it simply the assumption that a black hole would tend to have close to zero net charge?

### #5 deSitter

Actually no - according to the theory, all that can exist for a black hole are its total mass (energy content divided by speed of light squared), its angular momentum, and its charge. So whatever goes over the horizon is lost in all but these terms.

I still don't see why that is not sufficient to get a magnetic field. An electron has basically the same properties - mass, charge, and spin. From these, we get magnetism. What is it that I am missing? Is it simply the assumption that a black hole would tend to have close to zero net charge?

Because you can't identify a current of charge that would lead to a magnetic field. All you can say about a BH is that is has a given total charge - you can't say where it is or how it is moving. Since magnetism is just an aspect of charge in motion in 4d, it has the same restriction from escaping the horizon as does light.

A BH moving through space could generate an external magnetic field like any other moving charge.

Note that a charged rotationg BH will have a magnetic moment proportional to its charge and angular momentum. Classically the gyromagnetic ratio would have to be 1, but it turns out to be 2, just like the electron, in which the anomalous part is attributed to spin. Herein is a mystery.

Note that a charged rotationg BH will have a magnetic moment proportional to its charge and angular momentum. Classically the gyromagnetic ratio would have to be 1, but it turns out to be 2, just like the electron, in which the anomalous part is attributed to spin. Herein is a mystery.

Okay, that is what I was thinking of. And since a spinning black hole has a lot of angular momentum, it won't take a lot of charge to generate a significant magnetic moment.

Has anyone modelled the effect of the magnetic moment of a charged, spinning black hole on the accretion disk? If the black hole has a magnetic moment, and the accretion disk is ionized, then shouldn't it affect the movement of the disk? Could this selectively separate positive and negative ions, or have an effect on jet formation?

### #7 deSitter

Jarad, I am not very up on it - I was reading some "inverse" analysis about quasars, where the presence of magnetism was thought to be negative evidence for a central BH. A paper is here.

But the charge on a BH cannot be very high, as visible shells of ions around it would be obvious because EM is long range and vastly stronger than gravity.

Leiter's research is very interesting because the magnetosphere around a strongly magnetized collapsed object (e.g. a neutron star) can have the same physical effects seen from a distance as a hypothesized event horizon.

StarmanDan, the loss of physical information about the state of matter as it goes over the horizon is one of the main topics of BH theorizing. Read up on "black hole entropy and thermodynamics" for more information.

### #9 deSitter

Dave, I'm sure you are right. Along the same lines, there is every reason to believe that the long-range forces are related, and when something becomes gravitationally dense, as in, the effects of gravity become overwhelming, there is no reason to believe that the nature of EM will no also dramatically change. All the conclusions drawn about BHs are based on the simplest possible grafting of EM onto gravity - which for emphasis I'll repeat - one takes the flat-space form of EM and makes it compatible with existing on a curved spacetime manifold - example - the conservation of charge in flat space is

1/sqrt g d/dx_m ( sqrt g J_m) = 0

g is the determinant of the metric tensor, which is a constant in flat space.

By simply pasting EM into curved spacetime, one is making the enormous assumption that gravity does not alter the form of EM, that is, EM is not essentially coupled to gravity - EM can warp space, but warped space does not change the form of EM. Obviously such an assumption is just plain faith, as we have no possibility of actually testing it. "Gut feeling", "common physics sense", etc. whatever you want to call it, tells me that the long-range forces must be essentially connected at some level.

An article published in “The Astrophysical Journal Letters” reports a model of supermassive black hole formation that explains the rapid growth of the ones observed in the early universe. Wei-Xiang Feng, Hai-Bo Yu, and Yi-Ming Zhong propose a model in which the so-called seeds from which these gigantic black holes are formed are generated by a halo of self-interacting dark matter. According to this model, the collapse that forms the seed is accelerated by baryonic matter, common matter, a unified scenario between the two types of matter.

Observations made in recent decades indicate that it’s normal for a galaxy to have a supermassive black hole at its center whose mass can be millions or even billions of times the Sun’s. Various models have been proposed to explain the formation of black holes of such masses and the most difficult thing is to explain the ones discovered in the early universe. Some supermassive black holes we see as they were when the universe was less than a billion years old were formed in a very short time from an astronomical point of view but how? This new study proposes a solution based on dark matter.

The gravitational effects commonly found in galaxies are far too strong for the amount of matter detectable within them. Dark matter is the most accepted model to explain these effects. According to this model, a halo of dark matter allows common matter to gather in the galaxies that formed the universe as we see it today. According to this new study, there’s much more.

In the new model, the force of gravity attracts the dark matter particles of a halo inward but there’s a thermal pressure that pushes them outward. If the particles heat up when they’re attracted towards the center, their velocity increases, and the pressure also increases until they’re bounced back. If these particles interacted, their heat would transfer to nearby colder ones and would not be bounced back. This mechanism could be behind the formation of a supermassive black hole’s seed.

The halo’s rotation is also important because the self-interactions can generate a viscosity that dissipates the angular momentum. The collapse reduces the size of what is becoming a seed and also its rotation due to viscosity until it becomes a singularity, which is the seed. At that point, its force of gravity starts attracting the common matter nearby.

The amount of dark matter is much higher than common matter, so the process proposed in this new model could occur quickly from an astronomical point of view allowing the generation of supermassive black holes in the early universe. According to the researchers, the self-interacting dark matter model could also explain the motion observed in stars and galaxies.

This model is very interesting, the problem is to test it, like all models concerning dark matter. First of all, attempts are still underway to prove that dark matter really exists and there are alternative models that offer different explanations for the detected gravitational effects. The large amount of energy emitted by quasars, powered by supermassive black holes, allows to detect even the ones in the early universe, so it’s possible to study them. Perhaps, black holes will also help solve the mystery of dark matter.

## 'White Holes' May Be the Secret Ingredient in Mysterious Dark Matter

White holes, which are theoretically the exact opposites of black holes, could constitute a major portion of the mysterious dark matter that's thought to make up most of the matter in the universe, a new study finds. And some of these bizarre white holes may even predate the Big Bang, the researchers said.

Black holes possess gravitational pulls so powerful that not even light, the fastest thing in the universe, can escape them. The invisible spherical boundary surrounding the core of a black hole that marks its point of no return is known as its event horizon. [Images: Black Holes of the Universe]

A black hole is one prediction of Einstein's theory of general relativity. Another is known as a white hole, which is like a black hole in reverse: Whereas nothing can escape from a black hole's event horizon, nothing can enter a white hole's event horizon.

Previous research has suggested that black holes and white holes are connected, with matter and energy falling into a black hole potentially emerging from a white hole either somewhere else in the cosmos or in another universe entirely. In 2014, Carlo Rovelli, a theoretical physicist at Aix-Marseille University in France, and his colleagues suggested that black holes and white holes might be connected in another way: When black holes die, they could become white holes.

In the 1970s, theoretical physicist Stephen Hawking calculated that all black holes should evaporate mass by emitting radiation. Black holes that lose more mass than they gain are expected to shrink and ultimately vanish.

However, Rovelli and his colleagues suggested that shrinking black holes could not disappear if the fabric of space and time were quantum — that is, made of indivisible quantities known as quanta. Space-time is quantum in research that seeks to unite general relativity, which can explain the nature of gravity, with quantum mechanics, which can describe the behavior of all the known particles, into a single theory that can explain all the forces of the universe.

In the 2014 study, Rovelli and his team suggested that, once a black hole evaporated to a degree where it could not shrink any further because space-time could not be squeezed into anything smaller, the dying black hole would then rebound to form a white hole.

"We stumbled onto the fact that a black hole becomes a white hole at the end of its evaporation," Rovelli told Space.com.

Black holes nowadays are thought to form when massive stars die in giant explosions known as supernovas, which compress their corpses into the infinitely dense points known as singularities at the hearts of black holes. Rovelli and his colleagues previously estimated that it would take a black hole with a mass equal to that of the sun about a quadrillion times the current age of the universe to convert into a white hole. [Supernova Photos: Great Images of Star Explosions]

However, prior work in the 1960s and 1970s suggested that black holes also could have originated within a second after the Big Bang, due to random fluctuations of density in the hot, rapidly expanding newborn universe. Areas where these fluctuations concentrated matter together could have collapsed to form black holes. These so-called primordial black holes would be much smaller than stellar-mass black holes, and could have died to form white holes within the lifetime of the universe, Rovelli and his colleagues noted.

Even white holes with microscopic diameters could still be quite massive, just as black holes smaller than a sand grain can weigh more than the moon. Now, Rovelli and study co-author Francesca Vidotto, of the University of the Basque Country in Spain, suggest that these microscopic white holes could make up dark matter.

Although dark matter is thought to make up five-sixths of all matter in the universe, scientists do not know what it's made of. As its name suggests, dark matter is invisible it does not emit, reflect or even block light. As a result, dark matter can currently be tracked only through its gravitational effects on normal matter, such as that making up stars and galaxies. The nature of dark matter is currently one of the greatest mysteries in science.

The local density of dark matter, as suggested by the motion of stars near the sun, is about 1 percent the mass of the sun per cubic parsec, which is about 34.7 cubic light-years. To account for this density with white holes, the scientists calculated that one tiny white hole — much smaller than a proton and about a millionth of a gram, which is equal to about the mass of "half an inch of a human hair," Rovelli said — is needed per 2,400 cubic miles (10,000 cubic kilometers).

These white holes would not emit any radiation, and because they are far smaller than a wavelength of light, they would be invisible. If a proton did happen to impact one of these white holes, the white hole "would simply bounce away," Rovelli said. "They cannot swallow anything." If a black hole were to encounter one of these white holes, the result would be a single larger black hole, he added. As if the idea of invisible, microscopic white holes from the dawn of time were not wild enough, Rovelli and Vidotto further suggested that some white holes in this universe might actually predate the Big Bang. Future research will explore how such white holes from a previous universe might help to explain why time flows only forward in this current universe and not also in reverse, he said.

Rovelli and Vidotto detailed their findings online April 11 in a paper submitted to the Gravity Research Foundation's annual contest for essays on gravitation.

## Are black holes made of dark energy?

Objects like Powehi, the recently imaged supermassive compact object at the center of galaxy M87 , might actually be GEODE s. The Powehi GEODE s, shown to scale, would be approximately 2/3 the radius of the dark region imaged by the Event Horizon Telescope. This is nearly the same size expected for a black hole. The region containing Dark Energy (green) is slightly larger than a black hole of the same mass. The properties of any crust (purple), if present, depend on the particular GEODE model. (Photo credit: EHT collaboration NASA /CXC /Villanova University)

Two University of Hawaiʻi at Mānoa researchers have identified and corrected a subtle error that was made when applying Einstein’s equations to model the growth of the universe.

Physicists usually assume that a cosmologically large system, such as the universe, is insensitive to details of the small systems contained within it. Kevin Croker, a postdoctoral research fellow in the Department of Physics and Astronomy, and Joel Weiner, a faculty member in the Department of Mathematics, have shown that this assumption can fail for the compact objects that remain after the collapse and explosion of very large stars.

&ldquoFor 80 years, we’ve generally operated under the assumption that the universe, in broad strokes, was not affected by the particular details of any small region,&rdquo said Croker. &ldquoIt is now clear that general relativity can observably connect collapsed stars—regions the size of Honolulu—to the behavior of the universe as a whole, over a thousand billion billion times larger.&rdquo

Croker and Weiner demonstrated that the growth rate of the universe can become sensitive to the averaged contribution of such compact objects. Likewise, the objects themselves can become linked to the growth of the universe, gaining or losing energy depending on the objects’ compositions. This result is significant since it reveals unexpected connections between cosmological and compact object physics, which in turn leads to many new observational predictions.

One consequence of this study is that the growth rate of the universe provides information about what happens to stars at the end of their lives. Astronomers typically assume that large stars form black holes when they die, but this is not the only possible outcome. In 1966, Erast Gliner, a young physicist at the Ioffe Physico-Technical Institute in Leningrad, proposed an alternative hypothesis that very large stars should collapse into what could now be called Generic Objects of Dark Energy (GEODE s). These appear to be black holes when viewed from the outside but, unlike black holes, they contain Dark Energy instead of a singularity.

In 1998, two independent teams of astronomers discovered that the expansion of the Universe is accelerating, consistent with the presence of a uniform contribution of Dark Energy. It was not recognized, however, that GEODE s could contribute in this way. With the corrected formalism, Croker and Weiner showed that if a fraction of the oldest stars collapsed into GEODE s, instead of black holes, their averaged contribution today would naturally produce the required uniform Dark Energy.

Follow-up work that details the specific consequences of these results for Dark Energy surveys and gravitational wave observatories is presently in review.

## Black Hole: Conservation of energy

I don't exaclty understand where you see conservation of energy being violated. The energy still exists. in the black-hole and the space-time (gravity) around it---its not being 'dissipated' necessarily (although generally a good deal of energy is 'radiated' when material is consumed by a BH).

I don't see how you are relating this to the lifetime of blackholes, but what you are alluding to is correct: black-holes do not last forever---they slowly evaporate (but this gets very complicated, and large-black holes will essentially always being gaining more than they're losing). The micro-black holes which could hypothetically be created at the LHC would evaporate in the smallest fraction of a second. And if I recall the numbers correctly, a stellar-mass black hole would take about a Hubble-time (14 billion years) to evaporate.

General relativity doesn't have any preferred scales such as a mass scale or a distance scale, so there can't be any such limit.

What do you mean by "be destroyed"? Black holes evaporate. That is, they gradually lose mass over time until they disappear if they aren't constantly fed at a rate greater than the evaporation rate.

The rate of evaporation gets smaller (but never zero) as black holes get larger. The rate goes higher as the mass goes down. Really big black holes can 'feed' adequately on just the ambient radiation in the current universe (CMBR). Really small ones can't get enough mass down their gullets to sustain themselves. The 'end game' for black hole evaporation is a rapid flash of energy as the last of the mass within its minuscule event horizon is converted to particles and energy immediately outside of it. Boom!

ok, so once there done feeding, how are they releasing their mass energy?
would it be similar to a dying star? or supernova? there would have to be some fusion to release the energy in the event horizon and eventually become visible. otherwise there is no evaporation rate while its feeding

or become just a big chunk of mass that is stagnant or dead. That would mean it didn't evaporate?

ok, so once there done feeding, how are they releasing their mass energy?
would it be similar to a dying star? or supernova? there would have to be some fusion to release the energy in the event horizon and eventually become visible. otherwise there is no evaporation rate while its feeding

or become just a big chunk of mass that is stagnant or dead. That would mean it didn't evaporate?

Black Holes has a temperature any object that has a temperature emits radiation, emitting radiation=loosing mass. Black Hole radiations is also called as Hawking's Radiation.

Space around the black hole is usually colder. Hot flows into colder objects, therefor the space's heat flows into the black hole because black hole has a lower temperature. In addition with the black holes constant absorbing of matter, so therefor the black holes absorb more energy than they loose them.

When space is expanded enough, eventually the temperature around the black hole will become colder than the black hole. Remember hot flows to colder object? So black hole's heat will be carried into space, eventually the black hole will evaporate but this cycle will take a long time as described in the 1st post.

Small black holes= High Temperature=they die(evaporate) faster
Big black holes= Low Temperature=they die(evaporate) slower

I am not entirely sure, so experts please correct this if this is wrong.
(Excuse me for my bad English)

## Astronomers spy galaxies caught in the web of a voracious black hole

Astronomers staring out to the farthest reaches of the universe, and hence the deepest depths of time, have been puzzled to find supermassive black holes. How could such behemoths have had time to swallow up so much matter when the universe was so young? With new observations of one of these youthful giants—a black hole 1 billion times the mass of the Sun and less than 1 billion years old—astronomers now have a possible answer.

They found the black hole was connected to six nearby galaxies by filaments: feeding tubes for the monster in their midst. Assembling this family portrait (imagined above) took many observations—some lasting all night long—with some of the world’s largest telescopes, including the European Southern Observatory’s Very Large Telescope in Chile. This is the first time a tight-knit group of galaxies has been caught in the act of feeding a supermassive black hole, the researchers report today in Astronomy & Astrophysics .

And what bunched those galaxies together? The team suggests the culprit is an agglomeration of dark matter, the mysterious but unseen stuff thought to make up 85% of the universe’s matter. The dark matter may have pulled in huge quantities of gas and dust, allowing both the galaxies and the black hole to form.

### Daniel Clery

Daniel is Science’s senior correspondent in the United Kingdom, covering astronomy, physics, and energy stories as well as European policy.

## Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2006 April 27
NGC 4696: Energy from a Black Hole
Composite Image Credit: X-ray in red - NASA/ CXC/S.Allen (Kavli Inst., Stanford) et al.
Radio in blue - NRAO/G.Taylor (VLA) Infrared in green - NASA/ESA/W.Harris (McMaster Univ.)

Explanation: In many cosmic environments, when material falls toward a black hole energy is produced as some of the matter is blasted back out in jets. In fact, such black hole "engines" appear to be the most efficient in the Universe, at least on a galactic scale. This composite image illustrates one example of an elliptical galaxy with an efficient black hole engine, NGC 4696. The large galaxy is the brightest member of the Centaurus galaxy cluster, some 150 million light-years away. Exploring NGC 4696 in x-rays (red) astronomers can measure the rate at which infalling matter fuels the supermassive black hole and compare it to the energy output in the jets to produce giant radio emitting bubbles. The bubbles, shown here in blue, are about 10,000 light-years across. The results confirm that the process is much more efficient than producing energy through nuclear reactions - not to mention using fossil fuels. Astronomers also suggest that as the black hole pumps out energy and heats the surrounding gas, star formation is ultimately shut off, limiting the size of large galaxies like NGC 4696.

## My black hole white whole dark matter/energy reversed time theory.

I am new to this, and I would like to share my own theory of the description in the title.

Today we have almost come to the conclusion that black holes do exist, and that we also know that the universe is filled up by approx 73% dark energy and 23% dark material, that we don't know the origin of, we only know it has gravitational forces that interact with our own universe, that is expanding, faster and faster.

We also "know" that no matter that goes IN to a black hole ever goes out, all we see is the radiation trails from it, the actual large scale masses, just disappears, or stays there, indefinitely.

My theory is that what goes in to a black hole, goes out from a white hole and becomes dark energy/matter. The dark energy on the white hole side of the equation is what we see as the dark energy gravity force.

On a quark-level all that goes in to a black hole gets ripped apart down the building blocks quarks, and goes out of the white and is reassembled in a NATURAL way on that side of the black whole which is a white hole, which means the gravity force that is applied to the building block of the quarks being reassembled is anti-gravitational forces so the natural way for them to be reassembled is into anti-quarks.

Which then makes them increase the anti-gravitational force I label on the dark-energy.

What makes all of this seemingly possible is for our universe to be infinite, and made up of 2 or more universes in 2 or more dimensions. Our "white universe" in one dimension, and the "black universe" with white holes in another, where, to make this possible, TIME goes backwards. So from our point of view, our universe is expanding and sucked in to black holes. But from the "black universe" point of view OUR universe is the "black universe" that has white holes.

This is my theory of how it COULD be, and I am no physics student so I have no Idea about how many laws of thermodynamics I might have violated, but I would be grateful for any thoughts into the possibility of my theory.