Researcher shows that black holes do not exist

Researcher shows that black holes do not exist: 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.

Black Holes Aren’t Black After All, Say Theoretical Physicists — The Physics arXiv Blog — Medium

Black Holes Aren’t Black After All, Say Theoretical Physicists — The Physics arXiv Blog — Medium: Stephen Hawking proposed a potential solution earlier this year. His idea is that gravitational collapse can never continue beyond the so-called event horizon of a black hole beyond which information is lost. Gravitational collapse would approach the boundary but never go beyond it...

White holes: Hunting the other side of a black hole - space - 20 July 2014 - New Scientist

White holes: Hunting the other side of a black hole - space - 20 July 2014 - New Scientist: Perhaps the fact that we have found no signs of a white hole, despite peering ever deeper into space, is a more fundamental problem. Enter a space telescope called RadioAstron whose wildly elongated orbit takes it out to a distance of 350,000 kilometres – nearly as far as the moon and 30 times wider than Earth's diameter. Launched from Kazakhstan's Baikonur Cosmodrome in 2011, its dish is only 10 metres across. But when its signals are combined with those from radio telescopes on Earth, the resulting images are as sharp as those from a dish 350,000 kilometres wide...

"...once we spot a gigantic powerful gamma-ray burst with a lot of radio radiation, we will take a close look with RadioAstron and try to determine its shape and size for the first time." That could provide important clues about its source. "It may be a white hole or a wormhole. Maybe the flashes are coming from another universe."

Quantum bounce could make black holes explode : Nature News & Comment

Quantum bounce could make black holes explode : Nature News & Comment: The theory suggests that the transition from black hole to white hole would take place right after the initial formation of the black hole, but because gravity dilates time, outside observers would see the black hole lasting billions or trillions of years or more, depending on its size. 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.

Cosmologists Prove Negative Mass Can Exist In Our Universe — The Physics arXiv Blog — Medium

Cosmologists Prove Negative Mass Can Exist In Our Universe — The Physics arXiv Blog — Medium: Today, Saoussen Mbarek and Manu Paranjape at the Université de Montréal in Canada say they’ve found a solution to Einstein’s theory of general relativity that allows negative mass without breaking any essential assumptions. Their approach means that negative mass can exist in our universe provided there is a reasonable mechanism for producing it, perhaps in pairs of positive and negative mass particles in the early universe...

The crucial breakthrough by Mbarek and Paranjape is to show that negative mass can produce a reasonable Schwarzschild solution without violating the energy condition. Their approach is to think of negative mass not as a solid object, but as a perfect fluid, an otherwise common approach in relativity...

Are Black Holes All Shaped Like Doughnuts?

Are Black Holes All Shaped Like Doughnuts?: Black holes appear to have several different kinds of shapes. The unified model posits that the reasoning behind this is not that they are shaped differently, but that the perspective we're seeing them from shifts.

Turbulent black holes grow fractal skins as they feed - physics-math - 28 April 2014 - New Scientist

Turbulent black holes grow fractal skins as they feed - physics-math - 28 April 2014 - New Scientist: "We showed that when you throw stuff into a black hole, the surface of the black hole responds like a fluid – and in particular, it can become turbulent...  More precisely, the horizon itself becomes a fractal..."

To investigate what the horizon of a black hole looks like at mealtime, Adams took advantage of a mathematical duality between Einstein's equations of general relativity – which describe gravity near black holes – and fluid dynamics...

Led by Paul Chesler, who is a post-doc researcher at Harvard, the team first modelled a turbulent fluid system. They then translated it into the black hole regime and let it develop with time. When they looked again, the horizon of the black hole appeared to have developed an infinite surface area.

A black hole in a bath: Big physics on a bench-top - physics-math - 10 March 2014 - New Scientist

A black hole in a bath: Big physics on a bench-top - physics-math - 10 March 2014 - New Scientist

Supersymmetry...  One of its central predictions is that there should be more than one Higgs particle... they might have found some clue as to where those extra particles might be – in superfluid helium-3... The discovered Higgs weighs in at around 125 gigaelectronvolts (GeV). Studying the spectrum of excitations in the superfluid helium suggests Higgs particles should also exist at energies of 210 GeV and 325 GeV. These possibilities are not excluded by results collected so far at the LHC...

By concentrating laser light into a very small spot within a waveguide made of a glass block, he can temporarily change the refractive index of the glass so that it slows down subsequent laser pulses and ultimately repels them. "What makes these analogue experiments so powerful is that from a photon or a water wave's perspective, it has no way of distinguishing whether it is crossing the event horizon of a real black hole or is in a waveguide under some weird constraints," he says.

Stephen Hawking: 'There are no black holes' : Nature News & Comment

Stephen Hawking: 'There are no black holes' : Nature News & Comment: Now Hawking proposes a third, tantalizingly simple, option. Quantum mechanics and general relativity remain intact, but black holes simply do not have an event horizon to catch fire. The key to his claim is that quantum effects around the black hole cause space-time to fluctuate too wildly for a sharp boundary surface to exist.

In place of the event horizon, Hawking invokes an “apparent horizon”, a surface along which light rays attempting to rush away from the black hole’s core will be suspended. In general relativity, for an unchanging black hole, these two horizons are identical, because light trying to escape from inside a black hole can reach only as far as the event horizon and will be held there, as though stuck on a treadmill. However, the two horizons can, in principle, be distinguished. If more matter gets swallowed by the black hole, its event horizon will swell and grow larger than the apparent horizon.

Curved Spacetime Mimicked on a Chip: Scientific American

Curved Spacetime Mimicked on a Chip: Scientific American: Liu and his collaborators simulated the gravitational lensing of a star on an integrated photonic chip. A layer of clear plastic on the chip acted as a waveguide, confining light to the chip’s surface. To change the index of refraction of the plastic, the researchers had to vary the plastic’s thickness. They did so by heating the plastic and adding polystyrene microspheres before the plastic cooled. Because the plastic rose upwards around the microspheres on cooling, the thickness of the waveguide increased near these miniature balls. The varying index of refraction the team achieved happens to be very similar to the bending of space-time geometry around a massive star...

“This is indeed the first time an exact solution of Einstein's equations was mimicked” using an optical model, says Leonhardt.

'Black holes' of the ocean could curb climate change - environment - 26 September 2013 - New Scientist

'Black holes' of the ocean could curb climate change - environment - 26 September 2013 - New Scientist: Swirling masses of water in the ocean are mathematically the same as the warped regions of space-time around cosmic singularities...

In this so-called photon sphere, light is trapped in loops that spin around the black hole forever.


"The boundaries of water-carrying eddies satisfy the same type of differential equations that the area surrounding black holes do in general relativity..."

Did a hyper-black hole spawn the Universe? : Nature News & Comment

Did a hyper-black hole spawn the Universe? : Nature News : ...in the bulk universe the event horizon of a 4D black hole would be a 3D object — a shape called a hypersphere. When Afshordi’s team modeled the death of a 4D star, they found that the ejected material would form a 3D brane surrounding that 3D event horizon, and slowly expand.


The authors postulate that the 3D Universe we live in might be just such a brane — and that we detect the brane’s growth as cosmic expansion. “Astronomers measured that expansion and extrapolated back that the Universe must have begun with a Big Bang — but that is just a mirage,” says Afshordi.

The model also naturally explains our Universe’s uniformity...

Black Holes Feed On Quantum Foam, Says Cosmologist — The Physics arXiv Blog — Medium

Black Holes Feed On Quantum Foam, Says Cosmologist — The Physics arXiv Blog — Medium: “Quantum fluctuations in the form of mini black holes can couple to macroscopic black holes and allow the latter to grow exponentially...”

He says this kind of growth can easily account for the observed size of relatively young supermassive black holes. And he goes on to predict that this mechanism could allow smaller black holes to grow too. In fact, he suggests these smaller objects, which would be difficult to observe from Earth, could make up a significant fraction of the mysterious dark matter that astronomers believe the universe must contain.

...He says that this quantum feeding mechanism must apply to the supermassive black hole at the centre of our galaxy and that consequently, it must be growing at the rate of about 10^-3 solar masses per year.

Oddball space neutrinos may be spawn of dark matter - physics-math - 15 August 2013 - New Scientist

Oddball space neutrinos may be spawn of dark matter - physics-math - 15 August 2013 - New Scientist: ...apart from those seen after a 1987 supernova explosion, none had been detected from beyond the solar system...

Then, earlier this year, the IceCube collaboration...reported two deep-space neutrinos...

...expected sources of such neutrinos... should also produce neutrinos of energies different from those seen by IceCube so far...

They calculate that heavyweight dark matter particles of about 1 PeV would decay either directly into neutrinos of about 1 PeV, or into other particles and then into neutrinos with energies of tens of TeV. "It exactly reproduces the features that you see in IceCube," says Serpico...

'Holographic Duality' Hints at Hidden Subatomic World - Wired Science

'Holographic Duality' Hints at Hidden Subatomic World - Wired Science; If strongly correlated matter is thought of as “living” on the 2-D surface of a pond, the holographic duality suggests that the extreme turbulence on that surface is mathematically equivalent to still waters in the interior. Physicists can get at the surface-level behavior by studying the parallel, but much simpler, situation below...

In the mathematical parlance of the holographic duality, certain strongly correlated matter in 2-D corresponds, in 3-D, to a black hole.... “These very complicated quantum mechanical collective effects are beautifully captured by black hole physics... For strongly correlated systems, if you put an electron into the system, it will immediately ‘disappear’ — you can no longer track it.” It’s like an object falling into a black hole.


To determine a formula for the conductivity of cuprates, Horowitz and Santos had to study how light would interact with the complicated horizon of their black hole... In the new work, they extended the calculation down to the temperature range in which cuprates become superconductive, or conduct electricity with no resistance, and again found a close match with experimental measurements of real cuprates.

Tabletop accelerator shoots cheap antimatter bullets

Tabletop accelerator shoots cheap antimatter bullets

http://www.newscientist.com/article/dn23748-tabletop-accelerator-shoots-cheap-antimatter-bullets.html?cmpid=RSS%7CNSNS%7C2012-GLOBAL%7Conline-news&

A tabletop device just 10 square metres in size can spit out energetic bursts of positrons as dense as those kicked out by the giant particle-factories at CERN...

Instead, Gianluca Sarri at Queen's University Belfast, UK, and colleagues used rapid laser bursts to make positrons in their smaller, budget device. The laser pulse ionises inert helium gas, generating a stream of high-speed electrons. This electron beam is directed at a thin metallic foil so that it crashes into metal atoms, releasing a jet of electrons and positrons. These particles are separated into two beams with magnets...

Wormhole entanglement solves black hole paradox - space - 20 June 2013 - New Scientist

Wormhole entanglement solves black hole paradox - space - 20 June 2013 - New Scientist:  First, the pair showed that these space-time tunnels, usually described by the maths of general relativity, also emerge from quantum theory, if two black holes are entangled. It's as if the wormhole is the physical manifestation of entanglement.

The pair then extended this idea to a single black hole and its Hawking radiation, resulting in a new kind of wormhole (see diagram). Crucially, they suggest that this wormhole, which links a black hole and its Hawking radiation, may not be a problem for quantum monogamy in the way that normal entanglement is. As a result, the firewall needn't appear, preserving relativity

Using black holes to measure the Universe's rate of expansion

Using black holes to measure the Universe's rate of expansion: By adding together measurements of the amount of energy being emitted from the vicinity of the black hole to the amount of radiation which reaches Earth, it's possible to infer the distance to the black hole itself and the time in the history of the universe when the energy was emitted.
Getting an accurate estimate of the radiation being emitted depends on the properties of the black hole. For the specific type of black holes targeted in this work, the amount of radiation emitted as the object draws matter into itself is actually proportional to its mass, say the researchers. Therefore, long-established methods to measure this mass can be used to estimate the amount of radiation involved.

Gravity-less toy black hole solves cosmic puzzles

Gravity-less toy black hole solves cosmic puzzles: His team modelled a minimal black hole, defined only by having an inside and an outside, using quantum theory. To their surprise, they found that this object reproduces a lot of the features of real black holes that are thought to rely on gravity, including Hawking radiation, which could occur via a process called quantum tunneling.

This chimes with suggestions that gravity is not a fundamental component of the universe but an emergent property of quantum mechanics, just as waves are an emergent property of water molecules.

Physicists Find a Backdoor Way to Do Experiments on Exotic Gravitational Physics

Physicists Find a Backdoor Way to Do Experiments on Exotic Gravitational Physics: But what about running the dualities in the other direction, using laboratory measurements of extreme materials to probe exotic gravitational physics?...
The experiments in question entail smashing gold or lead nuclei together to create plasmas of quarks and gluons...
The plasmas must actually be liquid...

They equated the viscosity of a fluid to gravitational waves caroming off a black hole in higher-dimensional space—which, even for a physicist, is not an analogy that springs to mind...

The answer: 1/4π, in the appropriate units. The viscosity measured by RHIC comes close. Water, some 400 times more viscous, is molasses in comparison.

Surprisingly, the minimum value is the same for all fluids, whatever they are made of. Through the logic of duality, this universality has a simple explanation: Viscosity is equivalent to a gravitational phenomenon, and according to Einstein’s general theory of relativity, gravitation is blind to compositional details.