UFO'S of UAP'S, ASTRONOMIE, RUIMTEVAART, ARCHEOLOGIE, OUDHEIDKUNDE, SF-SNUFJES EN ANDERE ESOTERISCHE WETENSCHAPPEN

Are Black Holes Truly Black? Lab Test Supports Stephen Hawking's Theory — **Jeff Steinhauer stands with a machine capable of simulating black-hole conditions in the laboratory.**
**Credit: Nitzan Zohar, Technion Spokesperson's Office**

Are black holes truly black? A new laboratory experiment points toward "no."

Using a simulated black hole made from soundwaves, scientists have observed a phenomenon known as Hawking radiation: a faint energy emission that, in theory, is created right at the edge of a black hole's event horizon, or the point beyond which even light cannot escape.

If Hawking radiation comes from astrophysical black holes (not just those created in a lab), it would mean these objects are not entirely dark. It could also help scientists solve a paradox posed by black holes, and perhaps shed light on one of the most significant problems facing modern physics. [The Strangest Black Holes in the Universe]

Black holes are strange regions where gravity is strong enough to bend light, warp space and distort time. [See how black holes work in this SPACE.com infographic.]

Credit: Karl Tate, SPACE.com contributor

Jeff Steinhauer, an experimental physicist at the Technion — Israel Institute of Technology in Israel, and lead author on the new study, told Space.com.

According to Steinhauer, earlier calculations bycosmologist Stephen Hawking (who came up with the theory that bears his name) combined the theories of quantum physics and gravity. The current experiment tests those calculations, providing the first strong evidence that they are correct, Steinhauer said.

"A black hole is a testing ground for the laws of physics," Steinhauer said.

Swimming against the current

There's a tricky concept in physics that says that pairs of particles constantly blink into existence throughout space. One is a particle of normal matter and the other is its exact opposite, or antiparticle, so the two annihilate one another, and there's no change to the universe's energy balance sheet. These are called virtual particles. When this happens near the edge, orevent horizon, of a black hole, the particles can avoid complete destruction; one can fall inside while the other escapes.

But observing such interactions in nature has remained difficult, the Hawking radiation around a black hole (if it exists) is so faint that it can't be seen from Earth around known black holes (most of which are very far away). In addition to the distance, the Hawking radiation is likely overwhelmed by radiation from other sources, Steinhauer said.

"It makes it seemingly almost impossible to see this very slight radiation coming from the black hole," he said.

The same problem applies in a laboratory, where any heat can create background radiation that overwhelms the lab-produced Hawking radiation. To eliminate that problem, Steinhauer's experiment ran at less than a billionth of a degree above absolute zero.

In the analogue black hole, a line of cold rubidium atoms stream from a laser to create a form of matter known as a Bose-Einstein condensate. The cold gas flows faster than the speed of sound in one direction, so that a sound wave trying to go against the flow can't manage to move forward. In this respect, the slower moving sound wave is like a particle trying to escape from a black hole.

"It's like trying to swim against the river," Steinhauer said. "If the river is going faster than you can swim, you go backwards, even though you feel like you're going forward."

The upstream attempt is analogous to light in a black hole trying to escape, he said. Sound waves trying to move forward instead fall backward. If two virtual particles were created near the edge of the event horizon, one particle could be consumed by the black hole (the fast-moving stream), while the other escapes, avoiding destruction. The escaping particles are called Hawking radiation.

A method of creating a black hole using sound waves was proposed in 1981, and since then scientists have struggled to simulate Hawking radiation in the lab. Two years ago, Steinhauer performed an experiment that measured Hawking radiation after something was deliberately crashed into the event horizon of the analogue black hole. This new experiment took more of a wait-and-see stance, waiting for the particle-antiparticle pair to appear without external stimulation, more like what happens in the depths of space.

Just as Hawking theorized, the simulated black hole spit out the predicted particles, a sign of Hawking radiation.

"What I saw suggests that a real black hole might emit something," Steinhauer said.

The new finding also has larger implications for the field of physics, he said. One of the biggest mysteries in physics is why Einstein's theory of gravity (which describes large-scale interactions in the universe) doesn't seem to be compatible with quantum mechanics (which describes very small-scale interactions).

"Combining gravity with quantum physics is one of the main goals of physics today," Steinhauer said. "Hawking made the first steps toward that."

The simulated black hole tested Hawking's equations.

"His calculations predicted there should be light from a black hole," Steinhauer said. "It turns out his calculations were correct."

Solving a paradox?

One intriguing result of the artificial black hole involved insight into theinformation paradox. According to Einstein's theory of general relativity, everything that crosses the event horizon of a black hole is consumed, including information. As the escaping particle steals energy from a black hole, the massive object can shrink over time, eventually evaporating into nothing. Of course, this assumes it has stopped consuming nearby materialand thus isn't putting on new weight. Theoretically, a black hole can shrink into nothing, taking with it the information carried by or about the particles it consumed.

"Information has vanished," he said. "It's like it goes into the black hole and disappears."

Since quantum mechanics suggests that information can't be lost, that raises a paradox.

According to Hawking's calculations, the surviving particles contain no useful information about how the black hole formed and what it consumed, suggesting that information vanished with the black hole itself.

Steinhauer's black hole revealed that the higher energy particle pairs remained entangled, even after one was swallowed by the event horizon. Entangled particles are able to share information instantaneously, even when they are separated by great distances, a phenomenon sometimes described as "spooky action at a distance."

"Some of the solutions to this [paradox] probably rely on entanglement," Steinhauer said.

Scientists not associated with the research who were interviewed by Nature News and Physics World both said that while the experiment appears to have measured Hawking radiation, it does not necessarily prove that Hawking radiation exists around black holes in space.

The research was published online in the journal Nature Physics.

Follow Nola Taylor Redd on Twitter @NolaTRedd or Google+. Follow us at@Spacedotcom, Facebook or Google+. Originally published on Space.com.

{ http://www.space.com/ }

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

Augusto Carballido, Baylor University; Jorge Carmona-Reyes, Baylor University, and Truell Hyde, Baylor University

In 1981, the Voyager 2 space probe took intriguing images of Saturn’s rings as it passed by the giant planet on its way to Uranus.

The images showed what looked like ghostly “spokes” moving on the rings, much like the spokes of a bicycle wheel as it turns. After some head-scratching, scientists realized that the Saturnian spokes most likely were tiny specks of dust moving around the rings due to electric and magnetic forces. These forces result from electrically charged gases known as plasma.

Even though you might not realize it based on our daily experiences, researchers think that 99 percent of the matter in our universe is in a plasma state. Many processes that occur in the universe are due in part to the presence of plasma.

Here on Earth, industry uses techniques that involve manipulating these ionized gases for microchip production, as well as for welding materials such as aluminum. Research facilities study plasma in hope of hitting on an efficient nuclear fusion process for energy production. In all these instances micron-size dust is present – which can be a good or a bad thing, depending.

The presence of dust in plasma makes it tricky to study them in a laboratory setting. Here at Baylor University’s Center for Astrophysics, Space Physics and Engineering Research (CASPER), we’ve built a sophisticated experimental facility to investigate these dusty plasma systems. We hope to answer fundamental questions related to dust-plasma interactions both on Earth and in space, in the process advancing our understanding of physics and astrophysics. Our investigations will allow us to untangle issues like the role of dust buildup in super-high-speed crashes in space, the formation of planets, and even areas belonging to life sciences, such as double-helix molecular interaction.

Solid swimmers in an electrical sea

Dusty plasma, also called complex plasma, contains small, solid particles distributed throughout the ionized gas. These particles can have the shape of a sphere, a rod or an irregular “pancake.” The reason dusty plasma are very interesting, and even technologically valuable, comes down to the fact that the dust particles themselves can become electrically charged.

We can think of dust particles as swimmers in a sea of electrons and ions – negative and positive charges, respectively. Electrons are so tiny compared to the dust that they easily stick to the particles' surfaces. When that happens, a dust particle will become negatively charged.

Because like charges repel each other, that bit of dust will now feel a push from other negatively charged dust particles. Likewise, that same negatively charged dust particle will feel a pull by the positive ions in the plasma, because charges of opposite signs attract each other. The net result is that dust particles will be pushed and pulled in many different directions, making them move in complex and fascinating ways.

Dusty plasma ‘in the wild’

One place to find dusty plasma is in Earth’s atmosphere, where they’re generated when meteoroids enter the atmosphere’s upper layers at speeds of several kilometers per second. Researchers study them with specialized radars that can detect the ball of plasma that forms around the meteroids as they heat up due to friction with the air.

**Photo taken by astronauts of noctilucent clouds in Earth’s atmosphere above the midnight sun (above the blue layer).**
**Credit: NASA**

At high geographic latitudes (between 50° and 70° north and south of the equator) an intriguing phenomenon occurs. Clouds made of tiny ice crystals and dust appear at an altitude of about 80 kilometers during the summer months. Known as noctilucent clouds, they are too thin to be visible in daylight, but they glow before sunrise or after sunset when the sun is below the horizon.

The clouds' icy dust particles are thought to play a role in the chemical composition of the atmosphere at those altitudes. In particular, their presence may be related to depletion of sodium and potassium. And since noctilucent clouds reside in an ionized region of the atmosphere (specifically, the lower ionosphere), their icy dust particles become electrically charged by electrons. These conditions give rise to a variety of electromagnetic phenomenaresearchers are actively investigating.

**Artist’s concept of a comet, with solar wind blowing back the coma into a tail.**
**Credit: NASA, CC BY-ND**

Farther from home, but still within our planetary neighborhood, comets can put on an amazing showthanks to dusty plasma effects. As a comet approaches the sun, the sun’s heat transforms part of the comet’s ice into vapor. This vapor, which contains many tiny dust grains, engulfs the comet nucleus to form a “coma.” The solar wind, which is a plasma made mostly of electrons and protons, pushes the cometary coma away from the sun and forms the spectacular tail with which we are familiar.

Even farther from us still, at distances of hundreds of light-years, dust particles embedded in huge, donut-shaped gas clouds move in orbits around young stars. These disks, known as protoplanetary disks, arewhere planets are formed. Portions of protoplanetary disks may be electrically charged and perhaps threaded by magnetic fields. The dust grains that have been detected in many of these disks are small enough to soak up plasma electrons, and it’s likely that grain charging affects how easily grains can grow to form planet precursors.

**Illustration of a star surrounded by a protoplanetary disk.**
**Credit: NASA/JPL-Caltech, CC BY-ND**

Astronomers detect these dusty plasma in space by capturing the light dust particles re-emit after being illuminated by stars. It requires extremely sophisticated instruments, such as the Hubble Space Telescope. From these observations, one can infer things like the dust size and chemical composition.

Dusty plasma in the lab

From a long distance, we can obtain only a limited amount of information about natural dusty plasma. By carrying out controlled experiments in laboratories, we can learn more about dusty plasma properties. For example, by directly manipulating the amount of ionization, we can control the arrangement of the dust particles. In contrast, at this time it is generally not possible to infer the precise arrangement of dust particles in space from telescopic observations.

To experimentally study dusty plasma, a lab must be capable of producing, confining and manipulating an ionized gas – that is, one that contains electrically charged particles. This is possible here at Baylor’s CASPER, where we use advanced instrumentation to investigate the behavior of dusty plasma. For example, we use an instrument called an inductively driven plasma generator – basically a wind tunnel containing electrically charged gases – to study a plasma’s interaction with lunar dust.

We’re also interested in what happens in the plasma when very fast dust particles collide with different targets. Understanding more about these collisions could help with designing better protection for spacecraft from micrometeorite impacts.

CASPER is one of a very few experimental facilities in the world that has three operating complex plasma cells – the chambers into which different gases can be injected to be ionized. Two are Gaseous Electronics Conference radio-frequency reference cells, a standardized plasma-producing chamber. The third is a custom-built device designed here that allows for the formation of much larger complex plasma systems than normally possible. The laboratory within which these cells reside was built from the ground up specifically for them. It’s a highly stable environment with regard to temperature and vibration, making it possible to produce extremely low-noise systems.

**A typical experimental setup for studying dust structures in plasma.**
**Credit: Truell W. Hyde, Jie Kong and Lorin S. Matthews**

A typical experiment looks like this: a glass box can be placed between two electrodes to create an electric potential that will confine the dust-plasma system. The dust particles, which are made of melamine formaldehyde and have a diameter of less than 9 micrometers (about a thousandth of a centimeter in size), are introduced into the box through a dust shaker. Once the system power is turned on, the electric forces will change the arrangement of the dust particles, which will form linear or helical chains, depending on the amount of power used. Images of the dust structures can be captured by telescopic cameras.

**Top and side views of different dust structures formed in a Gaseous Electronics Conference radio-frequency reference cell.**
**Credit: Truell W. Hyde, Jie Kong and Lorin S. Matthews**

These experiments open a window into the way the universe works, whether we are looking for improved efficiency of industrial processes or trying to understand how our solar system formed.

Augusto Carballido, Assistant Research Professor, Baylor University; Jorge Carmona-Reyes, Assistant Director of Educational Outreach and Research, Center for Astrophysics, Space Physics, and Engineering Research , Baylor University, and Truell Hyde, Professor of Physics and Vice Provost of Research, Baylor University

This article was originally published on The Conversation. Read the original article. Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook, Twitter and Google +. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Space.com.

{ http://www.space.com/ }