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 Hawking Radiation



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Title: Hawking Radiation as a Mechanism for Inflation
Authors: Sujoy Kumar Modak, Douglas Singleton

The Friedman-Robertson-Walker (FRW) space-time exhibits particle creation similar to Hawking radiation of a black hole. In this essay we show that this FRW Hawking radiation leads to an effective negative pressure fluid which can drive an inflationary period of exponential expansion in the early Universe. Since the Hawking temperature of the FRW space-time decreases as the Universe expands this mechanism naturally turns off and the inflationary stage transitions to a power law expansion associated with an ordinary radiation dominated Universe.

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Title: Fading Hawking Radiation
Authors: I. Sakalli, M. Halilsoy, H. Pasaoglu

In this study, we explore a particular type Hawking radiation which ends with zero temperature and entropy. The appropriate black holes for this purpose are the linear dilaton black holes. In addition to the black hole choice, a recent formalism in which the Parikh-Wilczek's tunnelling formalism amalgamated with quantum corrections to all orders in \hbar is considered. The adjustment of the coefficients of the quantum corrections plays a crucial role on this particular Hawking radiation. The obtained tunnelling rate indicates that the radiation is not pure thermal anymore, and hence correlations of outgoing quanta are capable of carrying away information encoded within them. Finally, we show in detail that when the linear dilaton black hole completely evaporates through such a particular radiation, entropy of the radiation becomes identical with the entropy of the black hole, which corresponds to "no information loss".

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Title: Near-extremal black holes
Authors: Bhramar Chatterjee, Amit Ghosh

We present a new formulation of deriving Hawking temperature for near-extremal black holes using distributions. In this paper the near-extremal Reissner-Nordstrom and Kerr black holes are discussed. It is shown that the extremal solution as a limit of non-extremal metric is well-defined. The pure extremal case is also discussed separately.

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Ed ~ The simple solution for Luminosity:

luminosity.gif
A = Surface Area
T = Temperature (Kelvin)


Temperature.gif
And
Stefan-Boltzmann.gif
And
surfacearea.gif

---->

luminositySub1.gif
---->

luminosityFinal.gif



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If you drive a motorised wheelchair, you can derive based on QFT in curved space that stationary BH's radiate like black bodies with temperature T = k/2*pi . This holds true even though the relationship between T and other BH parameters (q, M, J) is different for different types of BHs.
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It has been previously known that black holes are not completely black. But a weak emitters of black body radiation generated near the event horizon-a place where light can not exit from the pull of gravity. Horizon can separate pairs of virtual photons. Where when one sucked, then the others will escape. As a result, the black hole loses energy. This theory was first proposed by Hawking. However, the evidence of the theory is very difficult. Because almost impossible to measure it.
However, the proof of the analogue of Hawking's theory might be done. The key requirement is simply That the interaction the between waves and the medium in the which They propagate Causes there to be a boundary zones where the between the wave and the medium have different velocities. A study conducted by Francesco Belgiorno (Universitą degli Studi di Milano), using a high intensity of light filaments in the glass that interfere with optical propagation environment in a manner analogous to the way the light affects the gravitational field near black hole horizon. This perturbation creates an optical equivalent of the event horizon that allows Belgiorno et al. to make a convincing measurement of analogue Hawking radiation at optical frequencies.

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Black holes and pulsars could reveal extra dimensions

Black holes are predicted to fritter away their mass over time by emitting particles, a phenomenon called Hawking radiation. Without extra dimensions, this process is predicted to be agonisingly slow for run-of-the-mill black holes weighing a few times as much as the sun, making it impossible to measure.
Extra dimensions would give the particles more ways to escape, speeding up the process. This rapid weight loss would loosen a black hole's gravitational grip on any orbiting objects, causing them to spiral outwards by a few metres per year, the team calculates

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Research sheds new light on black holes

The quantum phenomenon which is thought to cause black holes to leak energy and ultimately explode is more common than first thought according to Victoria University researchers.
Physicist Stephen Hawking famously discovered in 1973 that black holes are not entirely black. Instead, a subtle quantum effect results in them losing energy and particles into space, causing them to shrink and, over trillions of years, disappear. Until Hawking's discovery, black holes were considered to have such a strong gravitational field that nothing could escape.

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Quantum Tunneling
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Title: Comment on "Quantum Tunnelling Beyond Semiclassical Approximation" by R. Banerjee and B. R. Majhi (and many others!)
Authors: Alexandre Yale

We discuss recent work which has found, using a tunnelling approach, higher-order terms in the Hawking temperature. We highlight a few important issues in the derivation, such as a misleading definition of energy, and criticize some of the conclusions that have been reached. In particular, we conclude that contrary to many recent claims, the tunnelling method yields no higher-order corrections to the Hawking Temperature.

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Title: Quantum tunnelling beyond semiclassical approximation
Authors: Rabin Banerjee and Bibhas Ranjan Majhi

Hawking radiation as tunnelling by Hamilton-Jacobi method beyond semiclassical approximation is analysed. We compute all quantum corrections in the single particle action revealing that these are proportional to the usual semiclassical contribution. We show that a simple choice of the proportionality constants reproduces the one loop back reaction effect in the spacetime, found by conformal field theory methods, which modifies the Hawking temperature of the black hole. Using the law of black hole mechanics we give the corrections to the Bekenstein-Hawking area law following from the modified Hawking temperature. Some examples are explicitly worked out.

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