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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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How exactly does black hole evaporate?

Reading about Hawking's Radiation I understood that black holes lose energy over time - which is logical in some way (otherwise they would be there forever and heat death would never technically ...
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Hawking radiation doubt [duplicate]

My question is that according to hawking radiation two particles pop near a black hole one goes into the black hole and one escapes from it so we get the impression that the black hole is radiating ...
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When GR is not valid passing the event horizon?

A test body crosses the event horizon of a black hole. When can we say that GR breaks down? Only at the singularity? At any point CLOSE enough to the singularity? How much close? In summary, do we ...
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Mass Loss per Unit of Time of a Black Hole of a Given Size

What is the equation which gives us the mass loss per unit of time, of a black hole (non-rotating) of a given mass? What does a graph of a range of [BH masses/(mass loss/t)^-1] (?) look like? Is ...
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Are 40 Kelvin interstellar gas clouds evidence of virtual positron and real electron annihilation

Given that Hawking radiation includes separation of a virtual electron-positron pair, then why cannot it be the case that in the vicinity of a real electron it annihilates with the virtual positron? ...
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Is my analogy on Hawking Radiation correct? [duplicate]

I just want to make sure what I know is correct. Let me explain and if there is anything wrong (any simple detail) with what I said, please, correct me. When the particle crosses the event horizon, ...
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What happens when a black hole evaporates?

I have read other articles here on the subject and I think my question is different.. When a singularity evaporates enough to reach just above the limit of mass required to make the singularity, what ...
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Why is Cosmic Microwave Background Radiation attributed to the Big Bang? [duplicate]

When searching for CMBR all articles start by stating as a fact that it is a remnant of the Big Bang. Why? Why is it well understood and accepted? Why sure that it's not an effect of something else ...
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Hawking radiation of massive scalar field

There are some calculations about Hawking radiation (expectation value of particle number operator, 2-point function, stress-energy tensor, and so on.), which are often done under the condition that ...
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Does the same hawking radiation mechanism of a black hole apply to all other event horizons, like the hubble horizon?

From my understanding of black hole evaporation, a pair of virtual particles manages to avoid annihilating itself when one of the particles in the pair passes the event horizon and the other escapes ...
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Using Hawking radiation to turn matter into antimatter and vice-versa

I asked this question on the astronomy stack exchange: https://astronomy.stackexchange.com/q/30477 and it was recommended to me that I instead ask it here. My question is related to the following ...
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At what point is a shrinking black hole unable to feed itself due to gravity?

Let's suppose that Hawking Radiation does occur. According to my limited knowledge, as the radius of the event horizon decreases, the emitted Hawking Radiation can (must?) assume ever-smaller ...
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When a black hole explodes due to hawking radiation, how does the curvature of space previously within the event horizon behave?

I'm thinking about the time dilation in terms of distance from the singularity, to the event horizon and outside it. After a black hole has lost its necessary mass to maintain its singularity through ...
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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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Hawking radiation inside a black hole [duplicate]

For a virtual particle pair is produced within the horizon, a mass of black hole decreased from the negative energy particle into the black hole or the positive-energy particle tunnel away from the ...
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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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Black Hole Evaporation with flux

I have a question regarding the black hole evaporation in dependency of the Schwarzschild radius $r_s = \frac{2GM}{c^2}$, flux $f = \frac{\partial E}{\partial t A}$ and the mass of the black hole. So ...
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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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Do these particles actually reach future null infinity, and if not where they end up?

In this paper by analogy with a process $e^+e^-\to e^+e^-$ Andrew Strominger proposes that in black hole evaporation there is creation of soft photons and gravitons. This can be argued by infrared ...
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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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Black hole evaporation and QFT scattering

In QFT we usually deal with scattering problems. On the asymptotic past we have free particles, they interact, and we compute the overlap with distinct free particle states on the asymptotic future to ...
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A question on firewall paradox?

In the firewall paradox, one considers a Hawking particle pair after the Page time. Assuming information conservation, the emitted particle must be entangled with early Hawking radiation. Assuming ...
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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 ...