Черная дыра в лаборатории!

[cartesius]

http://newsru.com/world/18mar2005/hole_print.html

http://www.sky.com/skynews/article/0,,31500-13312730,00.html

Впечатляющего успеха сумели добиться американские ученые. Они создали черную дыру в лабораторных условиях.

Эксперименты с черной дырой считались всегда опасными, так как известно, что дыра поглощает всю материю вокруг себя, сообщает Sky News.

Черная дыра - это область в пространстве, возникшая в результате полного гравитационного коллапса вещества, в которой гравитационное притяжение так велико, что ни вещество, ни свет, ни другие носители информации не могут ее покинуть. Черная дыра окружена поверхностью со свойством однонаправленной мембраны: вещество и излучение свободно падает сквозь нее в черную дыру, но оттуда ничто не может выйти. Эту поверхность называют "горизонтом событий".

В земных условиях черная дыра просуществовала крайне мало времени: миллиардную часть наносекунды. Ее температура в 300 миллионов раз превысила температуру Солнца.

Для создания черной дыры ученые использовали ускоритель частиц в Брокхавенской лаборатории Нью-Йорка. Ученые столкнули друг с другом два ядра молекул золота, двигавшихся со скоростью света. Сила столкновения привела к том, что ядра распались на кварки и глюоны – мельчайшие частицы, из которых состоит материя.

Частицы затем сформировали шар кварк-глюонной плазмы, которая стала поглощать частицы, образовавшиеся в результате столкновения ядер, тем самым образуя черную дыру.

Ученые пока не знают, какую именно практическую пользу они смогут извлечь из своего открытия.

"Это, конечно, очень полезно, в том смысле, что стимулирует дальнейшие исследования в этой области, но будет ли это реально полезно, пока не понятно", - заявил известный физик Эд Шурьяк.

[cartesius]

http://www.ojenschina_legkogo_povedeniarev...=tech&id=188585

http://www.membrana.ru/lenta/?4415

Физики создали миниатюрную чёрную дыру

Горатиу Нэстес из американского университета Brown, участвовавший в эксперименте по столкновению ядер золота на околосветовых скоростях, вычислил, что получавшаяся в результате субстанция имела параметры, поразительно похожие на параметры чёрной дыры.

Эксперимент проводился на релятивистском ускорителе тяжёлых ионов (Relativistic Heavy Ion Collider).

При столкновении встречных пучков ядер золота образовывалась кварк-глюонная плазма с температурой в триста раз выше, чем на поверхности Солнца. По поглощению полученным плазменным "шаром" частиц, выделившихся в ходе столкновения, учёные судят о параметрах плазмы.

В ходе очередного опыта было поглощено в десять раз больше частиц, чем предсказывала теория. По расчётам Нэстеса, частицы "падали" в этот "шар" и выходили наружу уже в виде теплового излучения.

Это очень похоже на космические чёрные дыры, в которые падает материя, порождая излучение Хокинга, полагает исследователь.

[cartesius]

http://www.ojenschina_legkogo_povedeniarev...=tech&id=188585

Товарищи, а вы с фильтром не перебарщиваете? Уже и слово "обозреватель" нельзя написать? :hammer:

[cartesius]

http://www.bnl.gov/RHIC/black_holes.htm

http://qd.typepad.com/5/2005/03/public_service_.html

http://arxiv.org/PS_cache/hep-th/pdf/0501/0501068.pdf

Black holes at RHIC?

A statement from RHIC theoretical nuclear physicist Dmitri Kharzeev:

Horatiu Nastase, a member of the high-energy physics theory group at Brown University, has written a paper, posted on the preprint website arxiv.org, in which he claims that collisions at Brookhaven’s Relativistic Heavy Ion Collider (RHIC) produce the analog of a black hole.

Horatiu is referring to a mathematical similarity between the physics rules that govern black holes and those that govern RHIC collisions. That is, the two situations require similar mathematical wrangling to analyze.

The explanation for this begins with Einstein’s “Equivalence Principle,” which states that gravity and acceleration (or deceleration) are actually equal forces. The principle explains why a person going up in an elevator feels slightly heavier, just as they would if gravity on Earth were stronger.

In the same way, the rapid deceleration of RHIC ions as they smash into each other is similar to the extreme gravitational environment in the vicinity of a black hole. Thus, physicists see these situations as being very much alike, even though a black hole is very, very big and the amount of matter produced during RHIC collisions is very, very small. Horatiu uses the term “dual black hole” to express this relationship.

Moreover, the amount of matter produced at RHIC is so tiny that it is impossible to create a true, star-swallowing black hole.

For more information on this, see additional discussion from Kharzeev and the most recent Quantum Diaries blog entry from RHIC physicist Peter Steinberg.

See also: Statement on Committee Review of Speculative "Disaster Scenarios" at Brookhaven Lab's RHIC, October, 1999

[cartesius]

http://www.bnl.gov/RHIC/black_holes_kharzeev.htm

Black holes at RHIC?

Further discussion on black holes and RHIC by theoretical nuclear physicist Dmitri Kharzeev

Black holes are among the most mysterious objects in the universe. The gravitational field of a black hole is so strong that Einstein’s general relativity tells us that nothing, not even light, can escape from the black hole’s interior.

However, in 1974 physicist Stephen Hawking demonstrated that black holes must emit radiation once the quantum effects are included. According to the theories of quantum mechanics, the physical vacuum is bubbling with short-lived virtual particle-antiparticle pairs. Creation of a particle-antiparticle pair from the vacuum conflicts with the energy conservation, but energy need not be conserved at short times in quantum mechanics, according to Heisenberg’s uncertainty principle. The gravitational field of a black hole can resolve the intrinsic structure of the particle-antiparticle pair, and can therefore “suck in” one of the particles of the pair while the second particle is liberated and escapes.

The escaping particles have a thermal spectrum, reflecting the fact that no information can be extracted from the black hole (this latter assertion, however, is a subject of a lively debate at present — it may be possible that a spectrum does contain a small non-thermal correction, meaning that some information can be carried away from the black hole). The temperature of the thermal spectrum appears equal to the acceleration of gravity at the surface of the black hole divided by 2π. Einstein’s Equivalence Principle states that gravity is equivalent to acceleration in a non-inertial frame — and each of us has tested this principle by stepping into an elevator: Being in an accelerating elevator is equivalent to experiencing a stronger gravitational field. Therefore, the thermal radiation with a temperature equal to the acceleration divided by 2π should be a general feature of all processes accompanied by acceleration (or deceleration). Indeed, this was proved by physicist William Unruh in 1976.

What are the processes that accompany the largest deceleration that can be studied on Earth? The gravitational field of Earth is too weak, and leads to an unobservable thermal temperature of 10-20 degrees Kelvin (K). Electromagnetic fields also appear not strong enough. It appears that, at present, the strongest deceleration achievable in a laboratory is obtained in relativistic heavy ion collisions, where a sizable fraction of quarks and gluons is decelerated from the velocity of light down to zero velocity in a very short distance, about 0.2 femtometers. This deceleration thus must be accompanied by a burst of a hot thermal radiation with a temperature about 200 million electron-volts (MeV), or 1012 K (which is far h

otter than the Sun, which has a temperature of 107 K). A rapid deceleration also induces phase transitions in strongly interacting matter, similar to the ones that are believed to occur in the vicinity of a black hole. Indeed, a burst of hot thermal radiation of quarks and gluons has been observed at RHIC, where the abundance of the produced hadrons (hadrons are particles made of quarks and gluons) follow the predictions of thermodynamics, and there is growing evidence of a phase transition to the quark-gluon plasma.

Perhaps the greatest puzzle of RHIC physics is how this thermalization can occur so fast. The “black hole thermalization” scenario naturally explains this fact and provides a set of further predictions that can be tested at RHIC.

[cartesius]

http://education.guardian.co.uk/higher/sci...1440632,00.html

Scientists create 'black holes' on Earth

Alok Jha, science correspondent

Friday March 18, 2005

The Guardian

Thanks to a legion of science fiction stories, black holes are easily among the most terrifying objects in the universe. It is easy to understand why: these mysterious collapsed stars suck in and destroy everything around them. Get too close and nothing in the universe could save you from their clutches.

Fortunately, real black holes only exist in the depths of space, too far from the Earth to be of much concern. But an American physicist has put forward the idea that an experiment here on Earth regularly creates objects that bear a striking resemblance to real black holes, albeit tiny ones.

Horatiu Nastase of Brown University in Providence, Rhode Island, thinks that the intense fireballs created in an atom-smashing experiment at the Brookhaven National Laboratory in New York have remarkable similarities to the celestial phenomena.

But, worry not, the fireballs are nothing dangerous - they last for a mere 100,000 billion billionths of a second and do not seem to have much impact on the matter around them.

A real black hole is made from a massive star that has collapsed on itself - the gravitational force it exerts on the space around it means that matter is drawn towards it.

Prof Nastase's work is purely theoretical. But even if it proved to be completely correct, the amount of matter involved in typical particle accelerator experiments is so small that any gravitational effects of the mini "black hole" would be inconsequential.

"A black hole that can do interesting or scary things has to be quite large," said Andrew Jaffe, a cosmologist at Imperial College.

The Relativistic Heavy Ion Collider at Brookhaven throws the nuclei of large atoms, such as gold, together at close to the speed of light. The ensuing collision creates enough heat to produce a plasma 300 million times hotter than the surface of the sun.

For the briefest of moments, the nuclei break down into their constituent bits - particles called quarks and gluons - a state of matter that has not existed since a microsecond after the big bang that began the universe.

Analysing this process usually involves some horribly complicated quantum physics. But Prof Nastase decided instead to try a different tack and use string theory.

This bizarre idea is the prime candidate to solve the biggest problem in theoretical physics: how to describe the fundamental forces of nature in a single, coherent theory.

He showed that the core of the fireball had some of the characteristics of a black hole - 10 times more particles were being absorbed by the fireball than any quantum physics calculations could predict.

He said the particles were disappearing into the fireball before coming back out again as thermal radiation, rather as real black holes suck in matter from around them and re-emit "Hawking" radiation.

The problem for string theorists has always been that their work does not have experimental data to back it up, so many physicists are sceptical. But Prof Nastase's idea could begin to turn the tide.

Whatever happens, modern physics cannot create any damaging black holes here on Earth. "A few particles that you can push together in an accelerator ain't going to hurt anybody," Dr Jaffe said.