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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Do black holes also exist on a quantum level? [closed]

I understand that quantum mechanics refutes the concept that black holes can not exist on a quantum level because matter can only be absorbed no emitted from a black hole. However, Hawking's radiation ...
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Does a (charged) black hole evaporate its charge? [duplicate]

There are basically two types of charged black holes, Reissner–Nordström, and Kerr–Newman. Next, Hawking radiation itself is mostly electromagnetic. The numerous popular articles which say that ...
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Does a free falling shell receive Hawking radiation?

According to the equivalence principle, a free radially-falling observer moving towards black hole does not see Hawking radiation. Does a free falling shell see Hawking radiation? If not, how does the ...
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Is Hawking radiation truly random or we just don't know that it is?

First off I am not a black hole scientist and my education is limited to special relativity so please treat this question appropriately. The way I understand the BH information paradox is that ...
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Does Hawking radiation never happen because a black hole takes an infinite time to form? [duplicate]

Consider the classical solution of a black hole and imagine some matter crossing the event horizontal so that it cannot escape the black hole. I don't remember in the case of a rotating black hole, ...
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On the necessity of an event horizon for the Hawking-Unruh effect

I first explain my reasoning. I know that a Schwarzschild metric is the right metric outside any spherical object, but I also know that it is correct in the empty space. So I thought: why we don't ...
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Hawking radiation in an eternal black hole background

This is a question about Hawking radiation in a fixed Schwarzschild background. The radiation does not back react on the metric and the black hole can not grow or evaporate. Now I've seen Hawking ...
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Hawking radiation and Unruh effect

I recently read about the Hawking effect and I noticed that formally, in its general lines, the derivation is very similar to that of the Unruh eff. In the latter case we write the Fock states in a ...
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Absorption of dark matter by black holes

Our Universe consists of about 22% Dark Matter (DM). Such matter is the main stuff of galaxies. Also, Black Holes (BH) live in galaxies. We know that DM is subject to gravitational interaction. So, ...
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Black hole Travel [closed]

Asking out of curiousity. All answers appreciated. You have a machine that generates micro black holes on the outside of it which evaporate quickly and then are immediately generated again upon ...
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Why is matter-antimatter asymmetry surprising, if asymmetry can be generated by a random walk in which particles go into black holes?

My understanding is the early universe was a very "hot" (ie energy dense) environment. It was even hot enough for black holes to form from photons. My second point of understanding is that black ...
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Why is the temperature of a black hole given by $T=E/2S$?

Naively, I would imagine that $$ T = \frac{E}{S} $$ However, for a black hole, $E=c^4 R / 2G$ and $S= A k c^3 / 4 G \hbar $, which yields $$ T = \frac{E}{2S} $$ Is there a simple explanation for the ...
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Can black holes really evaporate? [duplicate]

Stephen hawkings black hole evaporation theory assumes evaporation of black holes by losing mass through virtual particle radiation. As far as i know, the theory isn't based on mathematical ...
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Bogoliubov coefficient (not) being equal to zero

When discussing the nature and ambiguity of particles in curved space-times, one usually ends up at an expression for annihilation/creation operators that looks something like: $$ a_{i}=\sum_{j}(\...
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About black holes paradox [duplicate]

About the information paradox in the black holes, isn't it possible in principle, that the "singularity" itself doesn't really exists, and its just the horizon plane, where the particles that falls ...
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What would be the properties of an anti-black hole (concentration of negative mass)?

What would be the properties of an anti-black hole (concentration of negative mass)? Would it emit radiation? Would time go infinitely fast on its surface?
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Silly doubt on penrose diagram for evaporating black hole

This question is based on the naive ideia of evaporation of a black hole stated as, After sufficient Hawking emission the black hole loses it's mass and therefore it's area, until, as a result, the ...
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'Gauge invariant phase' - KG equation with EM potential in Hawking radiation

Given the massless scalar electromagnetism equation $$g^{ab}(\nabla_a -ie A_a)(\nabla_b -ie A_b)\phi=0, \quad \quad \quad \quad(3.5)$$ I include the following passage from Hawking's "Particle ...
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Do the apparent Black Hole dimensions contract as the observer falls into Black Hole?

According the Special Relativity, all objects contract their length if moving fast. As the observer falls into black hole, his relative speed to it increases up to the speed of light. But from his ...
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Entanglement of Black Holes with the outside universe

Black holes are thermal objects which means the density matrix of the black hole is in a thermal state. This means that the black hole has to be maximally entangled with the rest of the universe to ...
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How does the connection of constant-phase surface in Schwarzschild spacetime work?

I am stuck while following the calculation of constant-phase surface of Hawking radiation in Hawking's original paper (Particle Creation by Black Holes, S.W. Hawking, Commun. Math. Phys. 43, 199 (1975)...
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The change in mass of a black hole do to Hawking Radiation

Hawking radiation which is the result of virtual particles, which are always created in pairs,(particle/antiparticle) near enough to the event horizon of a black hole, that one of the pair falls in ...
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A quick clarification of Hawking Radiation

Good Morning, I have read the other posts on Hawking Radiation, and did not want to post a question to an older post... I just want a quick clarification of a point. Can you please clarify is this ...
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Feynman diagram for Hawking radiation?

I'm starting to wrap my head around Feynman diagrams, and the idea of "real" vs. "virtual" particles, but one area where this distinction seems to break down is in describing Hawking radiation, where ...
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Does an evaporating black hole violate conservation of angular momentum?

Angular momentum is supposed to be conserved, but when a rotating black hole evaporates the Hawking radiation comes out in straight lines. Doesn't this violate conservation of angular momentum? Does ...
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BH evaporation vs CMB

This is not a duplicate, I am not asking about how hawking radiation works or how CMB works or whether BHs can really evaporate, or not. My quesion is about how CMB (considering space expansion's ...
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When we are talking about black hole evaporation - what exactly happens?

According to Wikipedia: Hawking radiation reduces the mass and energy of black holes and is therefore also known as black hole evaporation. Because of this, black holes that do not gain mass ...
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Do Quarks decay into Photons at high enough temperatures?

At high enough energy, particles lose coherence and are ripped apart into a Quark-gluon plasma where the individual quarks can break free of the atomic nucleus and fly around unencumbered. A black ...
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Evaporation of large charged black holes

Black holes evaporate (Hawking Radiation) acting as black bodies with the temperature inversely proportional to the mass. No physical process, be it evaporation or any other "trick", can make a black ...
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Could the matter for a Big Bang come from the Hawking radiation of a super fast expanding universe?

If I understand it right, the universe will at some point in time expand so fast, that from any particular point in space, an observer will see an event horizon around himself. This event horizon ...
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What is the “explosion” caused by Hawking radiation, and how do you calculate its strength? [duplicate]

According to my limited knowledge of Hawking radiation, there is an "explosion" when the black hole fully radiates away. What is this explosion? Is it in the form of EM radiation only, or something ...
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Why isn't Hawking radiation of negative energy? [duplicate]

Hawking radiation is explained by particle-antiparticle creation. A particle with positive energy escapes away from the black hole while the particle with negative energy falls down. Why isn't that ...
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Does Hawking radiation violate baryon number conservation? [duplicate]

Throw two baryons into a black hole (baryon number +2), receive Hawking radiation out. Convert the resulting energy into one baryon and one anti-baryon (baryon number 0). Baryon number conservation ...
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Relation between maximally mixed state and thermal state

Hawking calculated the density matrix of the outgoing radiation to be a thermal state. I have heard people say this is a maximally mixed state. Is this because given a fixed average energy in the ...
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Violation of the Law of Conservation of Charge in black hole? [duplicate]

Hey I'm a noob to physics however after reading about black holes and Hawking radiation. If a black hole made entirely out of negatively charged particles (say this black hole is made entirely of ...
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How does Hawking Radiation not violate energy conservation? [duplicate]

If Hawking Radiation is produced by particle-antiparticle pairs forming from the vacuum, with one particle being absorbed by the black hole and one escaping, how is the original energy required to ...
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Do Rindler horizons evaporate?

It is thought that black holes radiate via Hawking radiation and consequently evaporate. Rindler horizons too emit radiation. Are they also thought to undergo a similar process of evaporation?
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Hawking radiation from black hole inside a Casimir cavity

Would a black hole inside a Casimir cavity emit Hawking radiation more slowly than a black hole outside a Casimir cavity? Various descriptions of each phenomena involve either virtual particles or ...
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Hawking Radiation and negative energy [duplicate]

Why is it that only the particle with negative energy is absorbed into the black hole on the event horizon during Hawking Radiation? What discriminates between the particle or antiparticle?
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Quantum tunneling through the event horizon (EH): Is the EH a potential barrier for Quantum tunneling?

This is not a duplicate. I am not asking whether anything can escape a BH, I understand nothing can. My question is whether the potential barrier in the definition of Quantum tunneling can be a BH EH? ...
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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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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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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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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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