Researcher shows that black holes do not exist

This artist's concept depicts a supermassive black hole at the center of a galaxy. 

The blue colour here represents radiation pouring out from material very close to the black hole. 

The grayish structure surrounding the black hole, called a torus, is made up of gas and dust. 

Credit: NASA/JPL-Caltech

Black holes have long captured the public imagination and been the subject of popular culture, from Star Trek to Hollywood.

They are the ultimate unknown, the blackest and most dense objects in the universe that do not even let light escape, and as if they weren't bizarre enough to begin with, now add this to the mix: they don't exist.

By merging two seemingly conflicting theories, Laura Mersini-Houghton, a physics professor at UNC-Chapel Hill in the College of Arts and Sciences, has proven, mathematically, that black holes can never come into being in the first place.

The work not only forces scientists to reimagine the fabric of space-time, but also rethink the origins of the universe.

"I'm still not over the shock," said Mersini-Houghton. "We've been studying this problem for a more than 50 years and this solution gives us a lot to think about."

For decades, black holes were thought to form when a massive star collapses under its own gravity to a single point in space, imagine the Earth being squished into a ball the size of a peanut, called a singularity.

So the story went, an invisible membrane known as the event horizon surrounds the singularity and crossing this horizon means that you could never cross back.

It's the point where a black hole's gravitational pull is so strong that nothing can escape it.

The reason black holes are so bizarre is that it pits two fundamental theories of the universe against each other.

Einstein's theory of gravity predicts the formation of black holes but a fundamental law of quantum theory states that no information from the universe can ever disappear.

Efforts to combine these two theories lead to mathematical nonsense, and became known as the information loss paradox.

In 1974, Stephen Hawking used quantum mechanics to show that black holes emit radiation.

Since then, scientists have detected fingerprints in the cosmos that are consistent with this radiation, identifying an ever-increasing list of the universe's black holes.

But now Mersini-Houghton describes an entirely new scenario. She and Hawking both agree that as a star collapses under its own gravity, it produces Hawking radiation.

However, in her new work, Mersini-Houghton shows that by giving off this radiation, the star also sheds mass. So much so that as it shrinks it no longer has the density to become a black hole.

Before a black hole can form, the dying star swells one last time and then explodes. A singularity never forms and neither does an event horizon.

The take home message of her work is clear: there is no such thing as a black hole.

The paper, which was recently submitted to ArXiv, an online repository of physics papers that is not peer-reviewed, offers exact numerical solutions to this problem and was done in collaboration with Harald Peiffer, an expert on numerical relativity at the University of Toronto.

An earlier paper, by Mersini-Houghton, originally submitted to ArXiv in June, was published in the journal Physics Letters B, and offers approximate solutions to the problem.

Experimental evidence may one day provide physical proof as to whether or not black holes exist in the universe, but for now, Mersini-Houghton says the mathematics are conclusive.

Many physicists and astronomers believe that our universe originated from a singularity that began expanding with the Big Bang.

However, if singularities do not exist, then physicists have to rethink their ideas of the Big Bang and whether it ever happened.

"Physicists have been trying to merge these two theories, Einstein's theory of gravity and quantum mechanics, for decades, but this scenario brings these two theories together, into harmony," said Mersini-Houghton. "And that's a big deal."

More information: Mersini-Houghton's ArXiv papers: Approximate solutions: arxiv.org/abs/arXiv:1406.1525 Exact solutions: arxiv.org/abs/arXiv:1409.1837

Black Holes: Seeking proof for the no-hair theorem

According to general relativity, a black hole has three measurable properties: mass, rotation (angular momentum), and electric charge.

That's it. If you know those three things, you know all there is to know about the black hole.

If the black hole is interacting with other objects, then the interactions can be much more complicated, but an isolated black hole is just mass, rotation (angular momentum) and electric charge.

In general relativity this is known as the no-hair theorem.

The basic idea of the no-hair theorem is that the material properties of any object (referred to as "hair" because a physicist named John Wheeler once coined the phrase "a black hole has no hair") become unmeasurable (hence unknowable) as the object collapses into a black hole.

On the surface this seems fairly reasonable. If a neutron star collapses into a black hole, for example, all the neutrons and their interactions become trapped inside the black hole's event horizon when the black hole forms.

The same would be true for an object that was lopsided (say with a mountain range on one side). As it collapses into a black hole, any irregularities would be squashed flat as it approaches the black hole limit.

But there are also difficulties with the no-hair theorem. For one, even though it's referred to as a theorem, it has never been proved in general relativity. So it really should be called the no-hair hypothesis.

There have been lots of demonstrations that the theorem is reasonable, and computer simulations tend to agree that black holes stabilise to a structure defined by mass, rotation (angular momentum) and electric charge, but none of these reach the level of proof.

Then there is the problem that if a black hole really is just defined by mass, rotation (angular momentum) and electric charge, then it has no temperature, and that means that its entropy is zero.

This violates the principles of thermodynamics. Of course when we try to include quantum theory into our black hole description we know that black holes do have a temperature.

In Stephen Hawking's theory, the temperature of a black hole depends upon its mass, so even a Hawking black hole would be definable by mass, rotation (angular momentum) and electric charge.

It's possible that the no-hair theorem is valid even for a quantum black hole.

But there is a more subtle mystery that hides within the no-hair theorem, because it would seem that a black hole is much simpler than other massive objects such as planets, stars and the like.

If you think about an object like the Sun, it has a certain chemical composition, and it's giving off light with different wavelengths having varying intensities.

There are sunspots, solar flares, convection flows that create granules, and the list goes on.

The Sun is a deeply complex object that we have yet to fully understand, and yet, if our Sun were compressed into a black hole, all that complexity would be reduced to mass, rotation (angular momentum) and electric charge.

So what happens when a complex object like a star collapses into a black hole? Where does all that complexity go?

In physics we refer to that complexity as the physical information of a system. According to quantum theory, physical information is never lost, but according to general relativity and the no-hair theorem, physical information that enters a black hole is lost forever.

This contradiction is known as the black hole information paradox, or sometimes the 'firewall paradox.'

Now you might think that the easy answer is just to presume the no-hair theorem is wrong but it's not that simple, and if we started exploring that paradox, things would get a bit hairy.

Black holes exploding into 'white holes'

The collapse of a star into a black hole could be a temporary effect that leads to the formation of a 'white hole', suggests a new model based on a theory known as loop quantum gravity.

A new scientific theory suggests that when black holes reach the end of their lifespan, they explode into "white holes" and release all of their matter into space.

If true, the theory could help put to rest the debate over whether or not black holes actually destroy the matter they end up devouring.

As noted by Albert Einstein's theory of relativity, when a dying star ends up collapsing under its own weight, at some point the collapse becomes irreversible, resulting in a black hole that consumes light and anything else within its surrounding area.

Although black holes do slowly leak radiation over time, ultimately draining the black hole completely, this doesn't account for all the other matter that the dying star has consumed.

Since quantum theory does not allow for the possibility that information can be lost, though, two researchers from France's Aix-Marseille University believe they've discovered an explanation for this so-called "information paradox."

Carlo Rovelli

According to physicists Carlo Rovelli and Hal Haggard, a black hole eventually reaches a point where it cannot collapse any further and the internal pressure begins to push outwards.

This essentially turns the black hole inside out and expels everything it once consumed back into space.

Notably, the scientists believe that these white holes are created not long after the black hole's original formation, and we humans can't see it because gravity dilates time and makes the black hole's lifespan seem to last for billions or trillions of years.

Their current calculation is that it only takes a few thousandths of a second for a black hole to turn into a white hole.

Hal Haggard

Importantly, the process is very long seen from the outside, but is very short for a local observer at a small radius," the researchers wrote in a paper on the subject.

Ron Cowen, a science writer at Nature, explained further.

If the authors are correct, tiny black holes that formed during the very early history of the Universe would now be ready to pop off like firecrackers and might be detected as high-energy cosmic rays or other radiation.

In fact, they say, their work could imply that some of the dramatic flares commonly considered to be supernova explosions could in fact be the dying throes of tiny black holes that formed shortly after the Big Bang.

Although Rovelli and Haggard aren't completely dismissing the idea that black holes leak radiation, they said the trickles of energy would not be sufficient enough to deplete the dying stars of all the energy they've consumed.

Radiation may very well seep out, but their work is primarily concerned with discovering what happens inside a black hole.

Both Rovelli and Haggard admitted that their theory needs to be tested further with more comprehensive calculations.

If research confirms their ideas, however, theoretical physicist Steven Giddings of the University of California Santa Barbara says, "It would be important. Understanding how information escapes from a black hole is the key question for the quantum mechanics of black holes, and possibly for quantum gravity itself."

Theoretical physicist Stephen Hawking of the University of Cambridge, UK, has recently suggested that true event horizons would be incompatible with quantum physics.

More Information: Black hole fireworks: quantum-gravity effects outside the horizon spark black to white hole tunneling - Authors: Hal M. Haggard, Carlo Rovelli - arXiv:1407.0989

NASA Swift: Black Hole event horizon

This illustration released by the journal Nature on shows an artist’s conception of the unusual gamma-ray transient Swift J164449.3+573451.

It shows the birth of a relativistic jet from a tidally disrupted star near the event horizon of a supermassive black hole.

This highly energetic event was serendipitously beamed towards the Earth. A black hole described as a "cosmic monster" lurking at the heart of a galaxy has been recorded as it tore apart a star.

On March 25, NASA's Swift orbital telescope captured a surge of X-rays from deep space, disgorged by what was clearly an immensely powerful source.

Picture: AFP PHOTO / NATURE - AMADEO BACHAR

Black Hole Devours Celestial Body

NASA's Swift satellite captured a gamma ray flash brighter than anything astronomers had previously witnessed.

The cause? Scientists believe a supermassive black hole at the center of a galaxy nearly four billion light-years distant has wrapped its gravitational tendrils around a star the size of our sun, spawning a high-energy jet of gamma radiation.

On March 28th the gamma ray burst was equivalent to the brightness of a hundred billion suns—or as the paper published today in Science describes it, "An Extremely Luminous Panchromatic Outburst from the Nucleus of a Distant Galaxy." It's believed that supermassive black holes lie at the heart of large galaxies.

"This burst produced a tremendous amount of energy over a fairly long period of time, and the event is still going on more than two and a half months later," says UC Berkeley astronomy professor and study lead Joshua Bloom.

The reason it's so bright? The energy jet is pointed directly at us. And instead of swallowing the star whole, the black hole is nibbling on it bit by bit, keeping the energy jet going.

"That's because as the black hole rips the star apart, the mass swirls around like water going down a drain, and this swirling process releases a lot of energy," explains Bloom.

Bloom surmises the black hole wasn't doing much until the star wandered by, causing a tidal disruption so violent it produced energy at never-before-seen gamma-ray levels.

Couple this with the likelihood of the jet angling in our direction, and you have a "once in 100 million years in any given galaxy” event, according to Bloom, who says he'd be surprised if another occurred "anywhere in the sky in the next decade."

Simulated view of a Black Hole

New Scientist Video of what it would be like to approach a Black Hole