Questions tagged [hawking-radiation]

Radiation that comes from pair production quantum effects in close vicinity to an event horizon, leading to the potential for eventual evaporation of black holes. Two mirror particles are created with one falling behind the horizon, becoming casually lost to the rest of the universe, including its neighbor, allowing it to escape the gravitational potential.

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What would an external observer see happen to objects entering an evaporating black hole?

As I understand it, objects passing the event horizon of a black hole from their perspective will, from an external perspective, seem to keep approaching but never reach the event horizon. Given this, ...
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Hawking radiation and mass annihilation [duplicate]

Now, i just heard that the particle anti particle pairs that zip in and out of existence every planck second both have positive mass. if that is so, how does hawking radiation work? black holes lose ...
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Black hole horizon states in standard derivations of Hawking Radiation

In all standard derivations of Hawking radiation given e.g. by Hawking, Parker and Wald, one has the so-called horizon states. The point is that when one is quantizing a scalar field on a black hole ...
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Death of a black hole? [duplicate]

Is there a death of black holes? If yes, what is the average lifetime of a black hole and what happens when a black hole dies?
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How can one of the particles on a pair of virtual particles created by vacuum fluctuations have negative energy? How does it lower black hole mass?

Assuming Stephen Hawking’s 1975 “Particle Creation by Black Holes” : “One might picture this negative energy flux in the following way. Just outside the event horizon there will be virtual pairs of ...
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Why is this the probability that an incoming wavepacket is absorbed by the black hole?

I'm reading Parker's book "Quantum Field Theory in Curved Spacetime: Quantized Fields and Gravity" and when talking about Hawking radiation, there's a claim that I've not been able to understand. He ...
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Quantum tunneling into a black hole

The currently accepted answer to Throwing a micro black hole into the sun: does it collapse into a black hole or does it result in a supernova? states that a small black hole of mass approximately $10^...
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What does Hawking mean by “in empty space the field can’t be fixed at 0 because then it’d have both a precise value and a precise rate of change of 0”

Slightly modified the language in the title to make it fit in 150 characters. The above comes up in the part leading up to the explanation of how black holes emit particles.. My impression was that ...
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Why was it cold during inflation?

During inflation, spacetime is approximately de Sitter and there is a cosmological horizon; in analogy with Hawking radiation, there should be a de Sitter temperature $T \sim H$. This temperature has ...
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Advanced and Retarded Coordinates for Hawking Radiation

I am trying to solve the Klein Gordon equation near the horizon of a black hole. For a more accurate result I am using the Vaidya Metric in which the mass is a function of retarded time u. When ...
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By what mechanisms, other than Hawking Radiation, do black holes lose mass? [closed]

The equation for the luminosity of a black hole is: $\frac{1}{m^2}\frac{ħc^6}{5120G^2}$. However, if you take the mass of your black hole, and divide it by the lifetime, the equation you get is: $\...
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Why does Hawking radiation outside the Schwarzschild radius decrease a black hole's mass? [duplicate]

When a pair of virtual particles is created outside the event horizon of black hole, there is a chance for one of the particles to escape. Zero chance on the surface of the event horizon and my ...
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Why do macro black holes take ridiculous amounts of time to evaporate—unlike micro black holes which dissolve in even less than a second?

Why do macro black holes take ridiculous amounts of time to evaporate, considering that micro black holes dissolve in even less than a second? Does this mass-based behavior imply that the matter ...
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Why is the information paradox restricted to black holes?

I am reading Hawking's "Brief answers". He complained that black holes destroy information (and was trying to find a way to avoid this). What I don't understand: Isn't deleting information quite a ...
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What's the problem with Black Hole evaporation?

Black hole evaporation is not unitary because it takes a pure state to a mixed state. On the other hand, ordinary decay processes in Quantum Mechanics do not seem very unitary either. (For example, if ...
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Hawking Radiation from a Physical Black Hole

For distant observer, a physical black hole takes an infinite amount of time collapse, because time is redshifted near the Schwarzchild radius. Instead of the matter crossing the horizon, it will just ...
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Temperature due to the cosmological horizon during inflation

During inflation, the de Sitter space has a cosmological event horizon. This horizon exists because farther than the horizon distance the expansion carries light away from the observer faster than the ...
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Where does the time asymmetry come from in Hawking Radiation?

Taking General Relativity and Quantum Field Theory, Hawking predicts radiation emitted from a black hole. Both GR and QFT are time CPT symmetric. Taking just GR by itself, a black hole will stay the ...
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What if the usual predictability of the laws of physics fail in general relativity?

In Newtonian mechanics the future is predictable, If we know the initial state of a system exactly, then the laws of physics determine its state arbitrarily far into the future. What if the usual ...
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The Large Hadron Collider and Black Holes

Last week, I went to Switzerland and visited the LHC. I took a tour, and the guide told us that it is possible for black holes to appear in the LHC, but they will be so small, that they would ...
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How can both horizon and outgoing modes be kept together in this state if evaporation eliminates the horizon?

In the original computation of Hawking radiation one starts with a gravitational collapse spacetime (like the Vaidya geometry with $M(v)=M_0\theta(v-v_0)$). Then one introduces three complete sets of ...
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From emission probability to black body spectrum. (Hawking radiation as tunnelling.)

In the 1999 paper by Wilczek & Parikh (and in many subsequent papers) the "emission rate" (really the probability of tunneling) of a particle with energy $\omega$ from a static black hole (BH) is ...
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Based on black hole thermodynamics, shouldn't empty space contain infinite energy?

According to "Hawking radiation", Wikipedia [links omitted]: In SI units, the radiation from a Schwarzschild black hole is blackbody radiation with temperature $${\displaystyle T={\frac {\hbar c^{...
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Once a black hole is formed, is there anything other than Hawking radiation which shortens its life?

Hawking radiation is supposed to very slowly evaporate a black hole (terms and conditions apply :] ). Apart from Hawking radiation, is there any mechanism or effect that can make a black hole cease ...
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Does the Earth emit heat?

I'm reading my first book on physics "Seven brief lessons on physics" by Carlo Rovelli, and in his chapter on "Probability, time and heat of black holes", he mentions that Stephen Hawking showed that ...
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Stability of the Hawking-Hartle vacuum in semiclassical gravity

Consider a free quantum field theory defined upon a static Lorentzian spacetime possessing a bifurcate Killing horizon, such as Schwarzschild spacetime. These assumptions are sufficient to define a ...
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Hawking Black Hole Metric

What is the metric for a black hole which is emitting Hawking radiation? Does it depend on previous history or does it depend only on the current mass of the black hole? Are there multiple known ...
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Do white holes encode the future evaporation of the black hole?

In General Relativity, white holes arise when one formulates Maximal extensions (the process by which coordinate singularities are mapped to new non-degenerate coordinates) to a geometric solution (...
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Would you reach a singularity before evaporation of the black hole? [duplicate]

When going to a physics camp the other day, we discussed the Schwarzchild-metric for a rotational symmetric non-spinning black hole and its famous time-dilation properties. However, we know that ...
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How to understand Hawking's interpretation of the quantization of the field?

In Hawking's paper "Particle Creation by Black Holes" he says the following: The operator $\phi$ can be expressed as $$\phi=\sum_i f_i a_i+\bar{f}_ia_i^\dagger.$$ The solutions $\{f_i\}$ of ...
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Hawking Radiation specific clarification [duplicate]

If virtual particles on the edge of a black hole pop into existence randomly, wouldnt the likelyhood of a antiparticle generating on the inside of the black hole equal to a particle doing the same? So ...
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Can an Observer Distinguish between Unruh Effect and Hawking Radiation by Measuring Temperature?

In Unruh effect, the temperature of background appears to be proportional to acceleration. On the other hand, the temperature of a black hole is inversely proportional to its mass. If the two ...
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Matter generation during cosmic inflation (Hawking radiation like…)

Is there any estimation of how much of the matter in the observable universe was not created during the big bang, but later during cosmic inflation? My thought is as follows: Suppose we are in the ...
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Effects of negative energy density on properties of black hole horizon (and nearby spacetime)

Some background: Hawking's radiation (https://en.wikipedia.org/wiki/Hawking_radiation) is counter-intuitive in at least two sense. First is that it leads to a complete evaporation of the black hole in ...
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What and why is quantum information?

Can someone explain to a muggle like me what is "Quantum Information" concretely? I'm asking this because I don't get it why the Hawking radiation "destroying information" is so controversial. Quoting ...
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What is the role of an event horizon in Hawking Radiation?

I got to know that the particle anti-particle pair idea of Hawking Radiation isn’t completely accurate. Hence I went on to learn what the phenomenon actually is, but got stuck on how the horizon ...
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Hawking Radiation as $M(t) \rightarrow 0$

The luminosity $P$ of a Kerr-Newman black hole with charge $Q$ and angular momentum $J$ is given by \begin{equation} P = \frac{1}{240} \frac{\hbar c^6 \left( 1 -\frac{Q^2 }{ 4 \pi \epsilon_0 G M^2}...
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Should each and every black hole decay?

Is it necessary that black holes should always decay, say if we have a potential for not letting the Hawking radiation escape?
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Null Energy Condition Violation in QFT and Area Theorem

The Area Theorem by Hawking assumes the null-energy condition (NEC) holds, however, it seems QFT in curved space-time violates NEC. I tried to explicitly observe the NEC is indeed violated when there ...
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What effect would result from always keeping Page time >> Age of universe?

A thought experiment: I imagine, similar to early theories (eg: Hoyle), that the universe’s mass is not constant, but increases over cosmic time, in such a way that even the thinnest vacuum will ...
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Has Hawking radiation and black hole evaporation been observed by astronomers?

Has Hawking radiation ever been observed or has there been any attempt of observing them? Do we have any evidence that black holes can evaporate? I wonder how would one distinguish between Hawking ...
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What is the most likely/favoured theory put forth explaining the Black hole information paradox?

What is the most likely/favoured theory put forth explaining the Black hole information paradox? Is there any theory that is most favoured that has no flaws, or most likely explains how black holes ...
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Computation of Hawking radiation without explicit Hamiltonian?

I've observed that computation of Hawking radiations is mostly done without explicitly computing the Hamiltonian, which would require integration over spacetime that would seem to cause problems with ...
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Hawking radiation calculation breaking apart with mass density $M_{planck}$?

Hawking radiations are predicted from semiclassical quantum field theory, and it is sometimes said that calculations break apart at mass density $M_{planck}$. The question is, is this true only for ...
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Existence of Black hole radiation (through conservation) and Analysis of classification of black holes in classical dynamical system

I was taking nonlinear dynamical system where I found a confusion with black hole. (The dependency here was with respect to single $t$ and space was "flat", in a sense that the metric does not carry ...
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What is the effect of the locality condition if a „Rindler observer“ hovers close to a black hole?

Consider a „Rindler observer“ hovering close to the event horizon of a black hole, whereby flat spacetime is assumed locally. Does this observer see the same Unruh radiation like a Rindler observer ...
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Black Hole rotation and acceleration

I have been reading some about the black holes and the rotation about it, and have also heard about the fastest spinning black hole (NGC 1365), which as I understand, its rotation is 86% the speed of ...
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Is there a local source of Hawking radiation?

Suppose a black hole is formed at time $t_0$, and after that even more energy falls in, in what we are calling mass shells. I'm inclined to believe that the initial black hole starts radiating before ...
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Why are there negative energy particles inside a black hole?

In quantum field theory in flat spacetime, there are both positive and negative frequency solutions to the classical field equations, but upon quantization we get only positive energy particles. But ...
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Escaping a Blackhole

On reading hawking radiation, I know that either a matter or an anti-matter is able to escape a black hole, causing it to evaporate away soon. On this thought, I am curious that would it be possible ...

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