Questions tagged [hawking-radiation]

Radiation seen by static observers due to quantum effects in close vicinity to a black hole, leading to the potential for eventual evaporation of black holes. Pictorially, a particle-antiparticle pair is created, with one falling through the horizon, becoming causally lost to the rest of the universe, while its neighbor escapes the gravitational potential. Originally predicted by S. Hawking in the 1970s using quantum field theory in curved spacetime.

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Given the time dilation at the event horizon plus black hole evaporation, can anything really ever enter a black hole? [duplicate]

There are many thought experiments about what it would be like to fall into a black hole, spaghettififaction, the singularity at the center and so on. But to me it seems that no object could actually ...
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Temperature of a rotating/charged black hole

How do you calculate the temperature of a rotating or charged black hole? How will rotation/charge affect the lifetime?
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Carroll's derivation of Hawking radiation

In Carroll's Spacetime and Geometry: An Introduction to General Relativity, in his derivation of Hawking radiation Carroll makes the following statement: "as observed over length and timescales ...
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Hawking radiation: how can gravity rip a pair of virtual particles apart without creating another pair of virtual particles in the process?

To the best of my (limited) knowledge of theoretical physics you cannot rip a pair of virtual particles apart without investing enough energy to create another pair of virtual particles... If Hawking ...
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Can Hawking radiation decrease the area of the event horizon or not?

I have read this question: Null Energy Condition Violation in QFT and Area Theorem Can black holes shrink in classical general relativity, violating area theorem? And this one: When one considers ...
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${}$Hawking radiation and Einstein-Cartan theory

As I understand it, Einstein-Cartan theory predicts that inside every black hole, there is an einstein rosenbridge connecting to a new universe that forms due to a white hole. Where does hawking ...
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What is the equation for the mass of an evaporating black hole over time?

We predict that black holes will lose mass over time due to Hawking radiation. I want to find an equation for the mass over time $M(t)$ of a black hole with initial mass $M_0$ in an otherwise empty ...
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In Hawking's original Hawking radiation paper, how can we understand where the radiation comes from in the collapsing star spacetime?

In the original Hawking's paper "Particle creation by black holes" he first studies the collapsing star spacetime, and then the quasi-stationary phase of the black hole. In the collapsing ...
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What's the lightest possible black hole?

Is there, theoretically, a lower bound on the mass of a black hole? Or could you have a black hole that weights the same as an electron for example?
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Technical review article on black hole thermodynamics?

Can anyone recommend a resource on black hole thermodynamics for physicists who are not familiar with this area? I'd like to see a rough sketch of the derivations of black hole entropy and Hawking ...
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What's the current theory on final stages of black hole decay? [duplicate]

Okay, firstly, I know this question was asked here 11 years ago. And I know the correct answer is that we don't know because we haven't run the experiments and don't have a solid theory of quantum ...
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Paradox arising from using a black hole to go into the far future?

Let's say you have a very powerful spaceship and decide to travel to the event horizon of a supermassive black hole, but just before crossing you reverse your thrusters and escape. According to my ...
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Is the experimental evidence confirming black hole entropy or Unruh radiation?

The question says it all: how does Bekenstein–Hawking entropy or radiation fare when compared with observation? Or maybe just the idea of Unruh radiation?
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Hawking radiation temperature from dimensional grounds in Zee

In Zee's Einstein Gravity in a Nutshell he gives an argument for the temperature of Hawking radiation of dimensional grounds only (Introduction, p 15). It goes as follows. Both the black hole mass $M$ ...
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In the Unruh effect, where does the energy of the particles come from?

If you accelerate an object with constant acceleration, you will in effect create a black hole in the opposite direction in which you are traveling. This being due to light rays at a certain distance ...
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How can black holes evaporate into photons if they contain no anti-matter?

Hawking theorized the evaporation of black holes. Photons are pictured to slowly radiate their mass away. The higher the mass the longer it takes (due to smaller tidal forces). Which makes one ...
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Quantum pressure and chemical potential for a Schwarzschild black hole?

Just as Hawking showed that even Schwarzschild black holes have a temperature, shouldn't they also have a pressure and chemical potential? Are there any analytical formulae of those as well as $$ T_{...
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Why can't the information inside a black hole be reconstructed from what's left outside?

In trying to understand the significance of the black hole information paradox: regardless of what happens to information inside a black hole; how come it cannot, in principle, be reconstructed by ...
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Absorbing regions in Physics

How would you define an absorbing region (at the walls of a finite numerical simulation) in physics and how would you implement it? Can it be simulated by a high potential, low negative potential at ...
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Can the energy of a black hole's quantum field escape its event horizon?

From what I've read, Hawking radiation is produced far outside the event horizon. The radiation is produced by the quantum field of the black hole outside the event horizon. As more of these ...
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Question on the proof of Hawking radiation as done in "Quantum fields in curved space - Birrell,Davies"

In their proof of Hawking radiation, Birrell and Davies consider two dimensional model of a collapsing star with two set of coordinates, one outside the star: $$ds^2=C(r)du \space dv \tag{8.8}$$ $$u=t-...
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Physical significance of number operator in QFT

Does the expectation value of the number operator corresponds to any physical observable or has any significance in classical limit? This is probably a dumb question, but I'm struggling to identify ...
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Does wavefunction collapses near event horizon? [closed]

Picture an electron falling into an event horizon, so far from what I read gravity is either not a force or it is extremely weak therefore it doesn't cause wavefunction to collapse unless the strength ...
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Is Hawking Radiation Lorentz invariant?

Imagine an observer is very far from the black hole so that their local space-time is Minkowskian. In this case, we can apply special relativity to the derivation of the entropy of the black hole. We ...
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In Quantum Field Theory in Curved Spacetime, are particle states energy eigenstates?

I've been reading the paper Particle and energy cost of entanglement of Hawking radiation with the final vacuum state, by R. M. Wald (arXiv: 1908.06363 [gr-qc], DOI: 10.1103/PhysRevD.100.065019). It ...
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Is formation of a black hole thermodynamically favourable?

Isn't it like that the black hole is just swallowing suns and other parts of cosmos, and thus continuously absorbing matter. I know that it emits radiations also, which should be negligible in terms ...
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Is there a black-hole information equation?

According to some sources, black-hole information is proportionate to the surface area, and, the equation trotted out is $$S = \frac{A k}{4 l_p^2}.$$ But according to another source, the entropy and ...
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Black hole radiation

Black hole radiation in which particle and antiparticle pairs are separated which ultimately leads to the 'evaporation', but why does the negative particle always enters the black hole? Why do the ...
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In Hawking radiation, why don't the particles behind the event horizon contribute energy to the black hole?

This is all based on a cartoon understanding of Hawking radiation and black holes, so it wouldn't surprise me if there's a simple misconception behind my question. My understanding of Hawking ...
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Does Hawking radiation from micro black hole get redshift like it stellar counterpart?

In a stellar black hole the hawking radiation gets redshift as it escapes the event horizon, would the same phenomenon occurs with a micro black hole? If so what is the threshold for the redshifting ...
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Can we detect evaporating micro black holes?

The energy released by an evaporating black hole in its last instants (of duration $t$) is equal to $$E = \sqrt[3]{\frac{t \hbar c^{10}}{ 5120 \pi G^2}}$$ As the math shows, most of the black hole's ...
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Why must black hole have entropy?

From what I understand 2nd law of thermodynamics is just saying that information cannot be destroyed, ok got it. When a massive star collapses under it's own weight, it turns into a black hole and all ...
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Is there an explanation for why Hawking radiation causes a black hole to shrink *without* referring to particle/anti-particle pairs?

An observer far from a black hole sees thermal radiation at the Hawking temperature. As a consequence, we are told that the black hole loses energy over time: that is, it evaporates. This logical step ...
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Why is black hole information paradox a problem when there are no real black holes in the Universe?

We know stars take infinite time in our coordinates to actually collapse into a black hole due to time dilation. See, e.g., How can anything ever fall into a black hole as seen from an outside ...
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Why would the validity of UV/IR decoupling imply the explicit constructability of black hole remnants?

A paper written in 2020 by Harlow and Shaghoulian (reference 1) proposes a connection between unitary black hole evaporation and the non-existence of global symmetries in quantum gravity. In passing (...
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The entropy of Hawking Radiation

I am reading the review paper "The Entropy of Hawking radiation" by Almheiri et. al. They show the Page curve in the following figure: However, they do not show a formula of what they refer ...
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What's the big deal with information being lost in a black hole?

In the video here: https://www.youtube.com/watch?v=d_XuFkVdAYU (10:57), it is said that the loss of information when matter falls into a black hole is a paradox. He gives an example of throwing a ...
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Why is high energy required if we want to send a message in a short amount of time?

I am somewhat puzzled by the following statement "If Alice, after crossing the horizon, has less than a Planck time to communicate with Bob about the status of her qubits, then she is required to ...
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Hawking Temperature for a Given Metric

I want to calculate the Hawking temperature of the metric $$\mathrm ds^{2}=-\left(1-\frac{r^{2}}{l^{2}}\right)\mathrm dt^{2}\ +\frac{\mathrm dr^{2}}{\left(1-\frac{r^{2}}{l^{2}}\right)}+\ r^{2}\mathrm ...
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Age of a black hole

Is there a way to measure the age of a black hole by find Hawking radiation or calculating the stable orbits around the black hole?
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Is there a back-reaction in Hawking radiation?

Here, the following explanation for Hawking radiation in canonical quantum gravity is given: The local energy density is well-defined as the 00 component of the stress-energy tensor. It is frame ...
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Smooth Event Horizon and backreaction

If an observer falls into a black hole then gradually he will encounter higher and higher energy Hawking radiation. Assuming that Hawking radiation is created just outside the horizon (say at $r=2M+ \...
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What is the physical concept behind the standard explanation of the Hawking radiation? [duplicate]

The standard explanation of Hawking radiation says due to vacuum fluctuations near to event horizon of a black hole, a pair of virtual particles are created, one (with negative energy) falls to the ...
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Black holes and Hawking radiation

If Hawking radiation comes from outside the event horizon, how will it make the black hole evaporate? Also, how can the radiation be related to a blackhole's mass if it's coming from somewhere outside ...
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Quantum vacuum fluctuations and gravity

Stephen Hawking predicted Hawking radiation by studying what effect gravity would have on quantum vacuum fluctuations near the event horizon of a black hole. I wanted to ask, does gravity really ...
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Can an observer have zero time component of 4-velocity?

I’ve been working through Schutz’s First Course in GR. In chapter 11 (second edition page 324), he does a rough calculation relating to Hawking radiation. To calculate the energy relative to an ...
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Does Unruh radiation potentially explain the Paradox of 'apparent non-radiation of charged particles in a gravitational field'?

The Wikipedia entry on 'Paradox of radiation of charged particles in a gravitational field' does not mention Unruh or Hawking radiation, but I don't see why they wouldn't provide a solution.... ...
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When pressed together enough, matter annihilates with matter?

My question is a follow-up to this one: Interpretation of a black hole as an implosion in slow motion. It seems it is perfectly reasonable to think of a black holes as an implosion happening in slow ...
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Interpretation of a black hole as an implosion in slow motion

On Isaac Arthur's channel, he mentioned in one of his videos an interesting interpretation of Hawking radiation. Since the Black hole is going to evaporate eventually and all the matter contained ...
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Can Hawking Radiation occur at the Big Bang singularity or at the Big Crunch singularity?

While reading about Hawking Radiation which occurs due to quantum effects (quantum fluctuations) at the event horizon of a black hole, I was thinking whether this radiation can take place at the Big ...
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