Hawking Radiation

Simulating a black hole

40 years ago Stephen Hawking predicted that black holes emit a special kind of radiation. Consequently black holes are theoratically able to shrink and even vanish. This radiation arises when virtual particles (pairs of particles developing because of quantum fluctuations inside the vacuum; usually they nearly instantly destroy each other) are near the event horizon. Then the virtual particle pair gets divided: one disappears in the black hole (and its quantum mechanical information) and the other one becomes real. Thus the black hole radiates but unfortunately this radiation is so low that astronomical observations are nearly impossible.
Therefore scientists have to simulate black holes to get empirical evidence. The physicist Jeff Steinhauer of the Technion, the University of Technology of Haifa in Israel exactly did this. He realized an idea of physicist Bill Unruh with an acoustical event horizon. He uses a fog made of rubidium atoms which is only slightly above the absolute zero. Because they are trapped inside an electromagnetic field these atoms become a Bose-Einstein Condensate. Inside of this condensate the acoustic velocity is only a half millimeter per second. With the help of accelerating some above this speed an artificial event horizon is created. The low temperatures lead to quantum fluctuations: pairs of phonons develop. In the simulation these pairs also get divided: one gets caught by the supersonic event horizon; the other one becomes some kind of Hawking radiation.
It is still not sure if this experiment really simulates black holes. According to Ulf Leonhardt it does not proof for sure that the two phonons are entangled. Thus it is not sure if the pairs arised out of one fluctuation. Leonhardt even doubts that the fog of atoms is a real Bose-Einstein Condensate. Leonard Susskind thinks this experiment does not reveal the mysteries of black holes: for instance it does not explain the information paradox, because acoustic black holes do not destroy information.

thegayngerzone  asked:

Are black holes infinite, or will they eventually, I dunno how to phrase this, really, but cease to exist?

Well hypothetically, a black holes life should end. But for most black holes we have discovered and observed it doesn’t have much effect due to the large amount of mass present.

Stephen Hawking (in 1974) discovered that black holes radiate energy, as it radiates energy it is losing energy. While a black hole is infinitely dense, it does not have infinite mass, so it will eventually cease to exist, the scientific term for this is “evaporation.” For most black holes this would take a really really really long time — but it could be an explanation to why there are no really tiny black holes! They evaporate and die. I read somewhere that a black hole with the mass of a car would evaporate in a time under like a hundred billionth of a nanosecond.

If you go here, you can find an explanation on the lifetime of black holes explained way more in depth. 

Black holes aren’t black

They’re very dark, sure, but they aren’t black. They glow, slightly, giving off light across the whole spectrum, including visible light.

This radiation is called “Hawking radiation”, after the former Lucasian Professor of Mathematics at Cambridge University Stephen Hawking, who first proposed its existence. Because they are constantly giving this off, and therefore losing mass, black holes will eventually evaporate altogether if they don’t have another source of mass to sustain them; for example interstellar gas or light. (Source)

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Ask Ethan #103: Have We Solved The Black Hole Information Paradox?

“How is Hawking’s theory of black holes storing information on the shell of an event horizon different than what Susskind said decades ago about black holes storing information on the shell of an event horizon? Did Hawking just pull a Steve Jobs and proclaim something new that Android figured out years before? Or is this actually new stuff?”

Stephen Hawking is claiming that the black hole information paradox has now been resolved, with the information encoded on the event horizon and then onto the outgoing radiation via a new mechanism that he’ll detail in a paper due out next month, along with collaborators Malcom Perry and Andrew Strominger. Only, that’s not really what’s happening here. While he does have a new idea and there is a paper coming out, its contents do not solve the information paradox, but merely provide a hypothesis as to how it may be solved in the future.

A black hole is a mathematically defined region of spacetime exhibiting such a strong gravitational pull that no particle or electromagnetic radiation can escape from it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of the region from which no escape is possible is called the event horizon. Although crossing the event horizon has enormous effect on the fate of the object crossing it, it appears to have no locally detectable features. In many ways a black hole acts like an ideal black body, as it reflects no light. Quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is on the order of billionths of a Kelvin for black holes of stellar mass, making it essentially impossible to observe. Objects whose gravitational fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. The first modern solution of general relativity that would characterize a black hole was found by German physicist and astronomer Karl Schwarzschild in 1916, although its interpretation as a region of space from which nothing can escape was first published by David Finkelstein in 1958. Long considered a mathematical curiosity, it was during the 1960s that theoretical work showed black holes were a generic prediction of general relativity. The discovery of neutron stars sparked interest in gravitationally collapsed compact objects as a possible astrophysical reality. 

Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle. After a black hole has formed, it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses (M☉) may form. There is general consensus that supermassive black holes exist in the centers of most galaxies. Despite its invisible interior, the presence of a black hole can be inferred through its interaction with other matter and with electromagnetic radiation such as visible light. Matter falling onto a black hole can form an accretion disk heated by friction, forming some of the brightest objects in the universe. If there are other stars orbiting a black hole, their orbit can be used to determine its mass and location. Such observations can be used to exclude possible alternatives (such as neutron stars). In this way, astronomers have identified numerous stellar black hole candidates in binary systems, and established that the core of the Milky Way contains a supermassive black hole of about 4.3 million M☉.

Hawking radiation mimicked in the lab

Sound waves used to imitate light particles predicted to escape black holes.

Scientists have come closer than ever before to creating a laboratory-scale imitation of a black hole that emits Hawking radiation, the particles predicted to escape black holes due to quantum mechanical effects.

The black hole analogue, reported in Nature Physics1, was created by trapping sound waves using an ultra cold fluid. Such objects could one day help resolve the so-called black hole ‘information paradox’ - the question of whether information that falls into a black hole disappears forever.

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Yes, they do—Stephen Hawking discovered that according to quantum mechanics, black holes should radiate energy. In the quantum world, space is filled with tiny particles that flash in and out of existence, and Hawking predicted that energy fluctuations would generate particle-antiparticles near a black hole’s event horizon. Before they can annihilate each other as would normally happen, the black hole pulls in the particle with negative energy and “emits” the particle with positive energy. For this reason, black holes aren’t completely black—they glow faintly.

This is called Hawking Radiation, and it results in the black hole losing energy and therefore mass according to E=mc^2. As a black hole radiates, it shrinks. The nature of the radiative process means that the more a black hole shrinks, the more it radiates—so eventually the black hole will disappear. This will take an incredibly long time, though. A black hole of the mass of the Sun will take a billion times a billion times a billion times a billion times a billion times a billion times the age of the universe to evaporate completely.

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Could the LHC make an Earth-killing black hole?

“There are a number of theories that predict the existence of extra dimensions. Not merely the three spatial and one time dimension we know to be present in our four-dimensional spacetime, but at least one additional spatial dimension that exists in our Universe. While we can’t quite access those dimensions at the energies we’ve probed, it’s conceivable that at scales that are smaller than those we’ve examined — which corresponds to higher energies — these extra dimensions exist.

And if these extra dimensions exist, one theoretical possibility is that it might be possible to create tiny, miniature, microscopic black holes!”

One of the more exotic scenarios associated with the LHC — a scenario inspired by extra dimensions — would be the production of tiny, microscopic black holes that arise from super-energetic particle collisions. As the LHC is now operating at the highest energies ever created on Earth, 13 TeV or just a hair over, this has a better chance of coming to fruition now than ever before. But black holes have a reputation of sucking everything they encounter into them. If we created one here on Earth, would this potentially be dangerous? And if so, are the timescales of danger something that humans should worry about? Even if you’re willing to violate (or extend) the laws of physics to allow the production of these black holes and force them to be stable against decay, it would still take timescales many times that of the age of the Universe for them to devour even one kilogram of matter, much less the entire Earth.

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We’re back after a short break, and decided to start the New Year off with something light. You know, black holes, Hawking radiation, the theory of everything, the Hadron Collider. The typical post-holiday chitchat.

The topic today? Stephen Hawking and his contributions to science. Guest: science writer Kitty Ferguson. She’s worked extensively with Hawking and just published a new biography about him.

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Hawking radiation   

n.

A form of radiation believed to emanate from black holes, emerging from the region just beyond the black hole’s event horizon (from which no radiation can emerge). Pairs of virtual particles and anti-particles, created naturally in the vacuum fluctuation near the black hole, are split apart, one particle falling into the black hole and the other radiating away. The energy lost to such radiated particles is believed to come from the mass of the black hole.

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Strange atomic behavior, intense radiation, and destruction that leads to formation? This excellent video gives insight into black holes and the phenomenon of Hawking Radiation!

In this dream, I was reading about a discovery that in significantly large systems of language (long sentences, long books, printings, the internet), there was a mathematically describable probability that adverbs would be randomly switched as an apparent “accident”.

I loved this, and was explaining it to someone else, along with the idea that has been discussed in real life that populations are surveyed and studied, as systems of knowledge become more certain, that the old formulas cease to apply and behavior in those systems becomes random. A kind of Heisenberg Uncertainty of Everything. This was similar, but in my mind I think I was comparing it to Hawking radiation? AH! NO! This is what that was.

I was discussing this article over coffee with Z, and explaining why I believed this strange equation was true, not because I liked it but because it seems to be how the world works. Then I started talking about how the duality between reason and dialectical thought was rooted in the same paradoxical dualism that makes the universe indescribable by a Unified Field Theory (screw you Higgs Boson).

What we call negation is what is described by probabilities in the sciences. The concept of time is nullified by the constant presence of the totality, and the dialectic follows from the structure hidden below in the mathematics. And the absolute negative acts as a kind of Hawking radiation from the void of thought. A mysterious energy that allows us to sense singularities-in-thought.

Earlier in the dream, someone from The Music Box asked me to evaluate some scripts. 

unknownconstellation-deactivate  asked:

Imagine the void of space. It looks empty, but quantum theory tells us that space is full of "virtual particles"; pairs of positive and negative particles that come into existence, then annihilate one another. Imagine this happened right at the boundary of the event horizon of black hole. One particle would fall in, and the other would escape into space. The black hole would, in effect, lose that bit of energy. This would happen over time, and the black hole would eventually evaporate.

Hey, y'all! This is Hawking Radiation. Cool stuff! Thanks unknownconstellation!

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Neil deGrasse Tyson on Creating Mini Black Holes on Earth

A fan asks whether you could actually create a miniature black hole on Earth? Your own personal astrophysicist, Neil deGrasse Tyson, explains to co-host Chuck Nice that even though you could create a microscopic black hole in the lab, you wouldn’t want to. Best scenario: it evaporates due to Hawking Radiation before it eats the Earth.

By: StarTalk Radio.

Hawking radiation formula

E=m*a*d

m: mass

a: gravitational acceleration d: distance the mass mfalls

The mass is the mass of a virtual photon in our case and the distance is the distance a virtual photon moves in its lifetime. Since virtual photons have such a short lifetime they won’t get very far during that (24 nanometers for a virtual photon of orange light). So we can assume the gravitation to be constant and therefore use this formula.

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A Brief History of Time resumido en dos minutos y medio. 

Por: Miguel Angel Estrada / January 11, 2015. 

Sabemos que Stephen Hawking es uno de los físicos más reconocidos de la actualidad, en gran parte debido a su enfermedad motoneuronal relacionada con la esclerosis lateral amiotrófica, pero aún más importante que ésta son sus trabajos sobre agujeros negros junto con Roger Penrose lo que le han dado el mote de uno de los mejores físicos de la segunda mitad del siglo XX. Bueno, también sabemos que recientemente salió en los cines la película The theory of everything, la cual está basada en la vida del Físico, y para aprovechar el boom del filme, el diario inglés The Guardian, realizó un vídeo de un brevísimo resumen del libro best seller de Stephen Hawking, Breve historia del tiempo, publicado en 1988. El libro fue tan exitoso que ha tenido varias reediciones, y estuvo en la lista de los más vendidos del diario The Sunday Times durante 237 semanas. Particularmente este libro marcó mi vida, o aún sigue marcándola debido a que fue una pieza inicial para acercarme al gusto por la Física, y una fuerte influencia para que decidiera estudiar esa carrera, debido a esto recomiendo que a quien le apasionen estos temas pero no tenga el suficiente adentramiento al mundo científico le dé una oportunidad a éste libro.