They are objects of extreme density, with such strong gravitational attraction that even light cannot escape from their grasp if it comes near enough. Albert Einstein first predicted black holes in with his general theory of relativity.
Hawking radiation InStephen Hawking argued that, due to quantum effects, black holes "evaporate" by a process now referred to as Hawking radiation in which elementary particles such as photonselectronsquarksgluons are emitted.
Any primordial black hole of sufficiently low mass will evaporate to near the Planck mass within the lifetime of the Universe. In this process, these small black holes radiate away matter. A rough picture of this is that pairs of virtual particles emerge from the vacuum near the event horizonwith one member of a pair being captured, and the other escaping the vicinity of the black hole.
The net result is the black hole loses mass due to conservation of energy. According to the formulae of black hole thermodynamicsthe more the black hole loses mass, the hotter it becomes, and the faster it evaporates, until it approaches the Planck mass.
Thus, a thermodynamic description breaks down. At this point then, the object can no longer be described as a classical black hole, and Hawking's calculations also break down. While Hawking radiation is sometimes questioned,  Leonard Susskind summarizes an expert perspective in his book The Black Hole War: Such papers quickly disappear into the infinite junk heap of fringe ideas.
Such Planck-mass black holes may in effect be stable objects if the quantized gaps between their allowed energy levels bar them from emitting Hawking particles or absorbing energy gravitationally like a classical black hole.
In such case, they would be weakly interacting massive particles ; this could explain dark matter. Primordial black hole Formation in the early Universe[ edit ] Production of a black hole requires concentration of mass or energy within the corresponding Schwarzschild radius.
It is hypothesized by Zel'dovich and Novikov first and independently by Hawking that, shortly after the Big Bangthe Universe was dense enough for any given region of space to fit within its own Schwarzschild radius.
Even so, at that time, the Universe was not able to collapse into a singularity due to its uniform mass distribution and rapid growth.
This, however, does not fully exclude the possibility that black holes of various sizes may have emerged locally. A black hole formed in this way is called a primordial black hole and is the most widely accepted hypothesis for the possible creation of micro black holes.
Computer simulations suggest that the probability of formation of a primordial black hole is inversely proportional to its mass. Thus, the most likely outcome would be micro black holes. The small radius and high density of the black hole would allow it to pass straight through any object consisting of normal atoms, interacting with only few of its atoms while doing so.
It has, however, been suggested that a small black hole of sufficient mass passing through the Earth would produce a detectable acoustic or seismic signal.
This is far beyond the limits of any current technology. Stephen Hawking also said in chapter 6 of his A Brief History of Time that physicist John Archibald Wheeler once calculated that a very powerful hydrogen bomb using all the deuterium in all the water on Earth could also generate such a black hole, but Hawking does not provide this calculation or any reference to it to support this assertion.
However, in some scenarios involving extra dimensions of space, the Planck mass can be as low as the TeV range. It was argued in that, in these circumstances, black hole production could be an important and observable effect at the LHC      or future higher-energy colliders.
Such quantum black holes should decay emitting sprays of particles that could be seen by detectors at these facilities. Safety of high-energy particle collision experiments Hawking's calculation  and more general quantum mechanical arguments predict that micro black holes evaporate almost instantaneously.
Additional safety arguments beyond those based on Hawking radiation were given in the paper,   which showed that in hypothetical scenarios with stable black holes that could damage Earth, such black holes would have been produced by cosmic rays and would have already destroyed known astronomical objects such as the Earth, Sun, neutron starsor white dwarfs.
As a power source[ edit ] This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. March Learn how and when to remove this template message If a way to create artificial micro black holes were discovered, they could provide an abundant energy source by absorbing and converting their Hawking radiation.
The process may occur with a smaller mass black hole evaporating as a gamma ray burst immediately after creation. It may also occur in a zero-gravity environment, with a larger-mass black hole, that may emit radiation for years before becoming unstable and needing replacement, such as in a black hole starship.
This was explored in Arthur C Clarke's books such as Imperial Earth and in fact recent calculations[ which? It has also been theorized[ by whom? This raises the question whether human interest in and understanding of black holes could support attempts to improve the efficiency of light harvesting for green energy.
Black holes in quantum theories of gravity[ edit ] It is possible, in some theories of quantum gravityto calculate the quantum corrections to ordinary, classical black holes. Contrarily to conventional black holes, which are solutions of gravitational field equations of the general theory of relativityquantum gravity black holes incorporate quantum gravity effects in the vicinity of the origin, where classically a curvature singularity occurs.
According to the theory employed to model quantum gravity effects, there are different kinds of quantum gravity black holes, namely loop quantum black holes, non-commutative black holes, asymptotically safe black holes. In these approaches, black holes are singularity-free.A black hole formed in this way is called a primordial black hole and is the most widely accepted hypothesis for the possible creation of micro black holes.
Computer simulations suggest that the probability of formation of a primordial black hole is inversely proportional to its mass.
The simplest type of black hole, in which the core does not rotate and just has a singularity and an event horizon, is known as a Schwarzschild black hole after the German physicist Karl Schwarzschild who pioneered much of the very early theory behind black holes in the s, along with Albert urbanagricultureinitiative.com , David Finkelstein .
Black hole definition: Black holes are areas in space, where gravity is so strong that nothing, not even light, | Meaning, pronunciation, translations and examples.
contradictions in the definition, creation, and existence of black holes. It is proposed that the sum of the contradictions Shahriar Khan is in the School of Engineering and Computer Science of Independent University, Bangladesh. [email protected] outweigh the belief in this limiting solution of general relativity.
II. Black holes may answer questions about the beginning and the future of the universe. It seems likely that the early universe, in which very large, short-lived stars were the norm, was scattered with many, many black holes, which gradually merged together over time, creating larger and larger black holes.