Questions tagged [unruh-effect]
This tag is for questions regarding to the Unruh effect (also known as the Fulling–Davies–Unruh effect), the hypothetical prediction that an accelerating observer will observe a thermal bath, like blackbody radiation, whereas an inertial observer would observe none. It was described by Stephen Fulling in 1973, Paul Davies in 1975, and William Unruh in 1976.
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Will gravitational waves decay into photons? (and by how much?)
We know intense regions of curvature, for example near a black hole horizon, induce a flow of electromagnetic waves (and, less so, other particles). aka Hawking radiation.
By contrast, curvature in ...
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Boulware and Unruh vacuum in Schwarzschild spacetime
I am studying quantization in Schwarzschild spacetime. In class the Boulware vacuum $\left| B \right>$ has been defined using the o.n. modes $u_I(x) = \frac{1}{4\pi \sqrt{\omega}}e^{-i\omega v}$, $...
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Does accelerating blackhole grow in size due to constant infalling unruh radiation?
Unruh effects stipulates that an accelerating observer will observe a thermal bath, like blackbody radiation, whereas an inertial observer would observe none. Now assume a constantly accelerating ...
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Path Integral for Unruh Effect
In derivation of Unruh effect, according to arxiv 2108.09188, we have
$$
\langle\phi_L|\exp(-\pi H)|\phi_R\rangle=\int_{\phi=\phi_R}^{\phi=\phi_L} D\phi e^{-S_E}\propto \int_{lower\space half\space ...
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How does Unruh detector work?
It is often said that an inertial observer in flat spacetime vacuum will see an accelerating observer thermalize (Unruh Effect). If an accelerated observer takes a particle in a box coupled with the ...
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Is it possible to explain radiation of an accelerated charged particle via the Unruh effect?
From the point view of a noninertial observer, if a charged particle accelerates then it can catch the Unruh particle and excite. After that, the charged particle emits it and falls back to its ground ...
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Role of horizon in Unruh effect
I’m reading this on the Unruh effect and it is derived by calculating the Bogoliubov coefficients between the Minkowski and Rindler observer. Rindler observers use a different set of modes to describe ...
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Why is the Unruh effect observer dependent?
Why Unruh radition is observer dependent why Hawking radition is not observer dependent?
I know hawking radiation is caused by the creation of a pair partice and antiparticle in two different sides ...
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Bogoliubov coefficients between inertial frames
The Klein–Gordon Equation in Minkowski space says $\partial_\mu \partial^\mu \phi+ m^2 \phi = 0$.
The solution has modes $e^{ikx}$, $e^{-ikx}$ scaled by creation and annihilation operators $a^{\dagger}...
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How is Hawking radiation formally derived?
[EDITED] I'm a postdoc working in cond-mat/quant theory, and I've heard some explanations of Hawking radiation that strike me as inconsistent or silly (e.g., in terms of pair production). I'm hoping ...
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Does String Theory predict things like Unruh effect and Hawking radiation?
I've seen the other post about this, but the answer only discusses Unruh effect rather than String theory.
Hawking radiation and Unruh effect solidify fields as the universe's fundamental objects. ...
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Does the Unruh effect assume its conclusion?
Unruh effect says that accelerating observers see the single particle states of inertial frames as thermal baths.
But it proves it by defining the particle states in the accelerating observer's frame ...
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Might the tiny Hawking radiation from our cosmic event horizon (CEH) be additive, since my CEH is not your CEH?
Concerning our cosmic event horizon, an interesting question arises
from the seemingly innocent statement, "My cosmic event horizon is
not your cosmic event horizon." Ie: Since 'you' and 'I'...
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Informal derivation of the Unruh temperature
Imagine a charged particle of mass $m$ at rest in the electromagnetic vacuum.
The particle interacts most strongly with zero-point modes that have a wavelength $\lambda_C$ similar to the Compton ...
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Unruh effect origin of particle
I have a little confusion about where from the particle are coming in Unruh effect. Vacuum fluctuation is always there and does not depend on whether the frame/detector is moving or not. Vacuum ...
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Calculation of expectation of number of particle using Bogolubov transformation [closed]
we have two bases connected by Bogoljubov transformations. In the first basis, creation and annihilation operators are ($a,a^\dagger$) and in the second basis ($a',a'^\dagger$). They are connected by
\...
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Proof probability distribution of number of particles seen in different basis connected by Bogoljubov transformation is Poissonian
Let we have two bases connected by Bogoljubov transformations. In the first basis, creation and annihilation operators are ($a,a^\dagger$) and in the second basis ($a',a'^\dagger$). They are connected ...
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Significance of non-zero cross energy-momentum tensor in Fulling Davies Unruh effect
In the Fulling Davies Unruh effect We can get the outgoing particle flux from the asymptotic future region $\mathscr{I}^+$ from the mirror trajectory as the following
$$
\mathcal{F}=\int_0^\infty \...
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An example of the vacuum emitting photons?
Imagine we have two parallel wires with a potential difference of $V$ volts that form the opposite sides of a square of size $\lambda$.
Any virtual electron-positron pairs that form between the wires ...
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Does an electric field cause the vacuum to emit photons?
As I understand it electron-positron pairs pop in and out of the vacuum on a time scale $T$ inversely proportional to the electron mass.
Imagine we put a static electric field across the vacuum.
...
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Deriving Hawking temperature "from" Unruh effect and their relation
Let me recall some basic computational facts (the meaning of which I am trying to understand).
In flat space, an adapted coordinate $(\tau, \xi)$ associated with an observer with constant proper ...
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Do the null geodesics of photons emitted by Hawking radiation arise from the event horizon?
It is a well-known explanation of Hawking radiation that it originates from the quantum fluctuations near the horizon. Does it mean that one can look at the photons (part of the radiation) and follow ...
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Symmetry restoration in accelerated frames
I am trying to understand the symmetry restoration in accelerated frames. I was reading 1 and 2. Can somebody help me to understand how they got Eq. 7.12 in 1 or Equation just after Eq.3.3 in 2? In ...
user336310
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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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Lowering the Schwinger limit with superconductors while considering the Unruh effect?
Unruh Effect is often left out in calculations regarding the Schwinger limit.
I've been looking at different mechanisms for more easily attaining the Schwinger limit. So far, the only thing I have ...
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Rindler decomposition using Euclidean path integral
In section 3.3 of Jerusalem Lectures on Black Holes and Quantum Information (arXiv:1409.1231), Daniel Harlow wants to calculate the following Euclidean path integral
$$\langle\phi |\Omega\rangle\...
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How to derive the Unruh effect (or the thermofield double state) from the path integral?
I have been reading about the path integral approach to deriving the thermofield double state for the Minkowski vacuum in terms of the Rindler states:
\begin{equation}
\left|0_{M}(t=0)\right\rangle=\...
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Questions about the Unruh effect derivation in Wald's QFT in curved spacetime
So I'm currently reading chapter 5 of Wald's book on QFT in curved spacetime and I'm terribly confused with the notation in the last steps of his Unruh effect derivation.
Context:
In eq. 5.1.26, he ...
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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?
user85598
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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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Does the count of particles depend on the observer?
The Lagrangian and Action, say in QED, is invariant to Lorentz boosts and independent of observers.
(It’s possible to convert from a Lagrangian to the Hamiltonian view via a Legendre transform $H=vp-L$...
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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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Why Unruh temperature is the temperature measured by observer with $\xi = 0$?
My coordinate transformation is:
\begin{align}
t=\frac{1}{a} e^{a \xi} \sinh (a \eta), \quad x=\frac{1}{a} e^{a \xi} \cosh (a \eta).
\end{align}
The free scalar field is quantized under this ...
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Doubts about the "periodicity trick" to compute temperature
The "periodicity trick" is a mysterious way to compute some sort of temperature associated to a Rindler-like spacetime.
Suppose there exist coords $R\in(0,\infty), \eta\in(-\infty,\infty)$ ...
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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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Davies & Unruh: vacuum temperature is proportional to acceleration. But $T$ is not a vector
Davies and Unruh showed that vacuum temperature is given by acceleration:
$$T = \frac{\hbar a}{2 \pi k_\mathrm B c}.$$
But acceleration is a vector, temperature is not. If vacuum temperature produces ...
user85598
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What is the physical interpretation of negative Unruh temperature?
Actually the Unruh temperature is vectorial since it is proportional to acceleration but derived for only one space dimension so at least positive and negative. What can negative Unruh temperature ...
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Unruh effect derivation
I was going through the derivation of the Unruh effect in chapter 5 of these lecture notes ("Lecture Series on
Relativistic Quantum Information" by Prof Ivette Fuentes). On p.26 the author ...
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Can Quantum Field Theory not handle accelerated frames of reference?
Since Quantum Field Theory can't handle gravity, and gravity is mathematically equivalent to acceleration (equivalence principle), does this mean Quantum Field theory can't handle accelerated frames ...
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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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Does the Unruh effect need the accelerating observer's Hilbert space to be smaller than the inertial one?
I've encounter two different approaches to the Unruh effect and I feel like they are not consistent with one another.
Bogoliubov Transformation
In this approach the basic statement is that the vacuum ...
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Firewall in Rindler horizon
In arXiv:1409.1231 in section 3.5 above equation (3.34) Daniel Harlow says
More precisely if the left and right wedges are completely uncorrelated, as in
the state 3.33, then the typical difference ...
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Usage of Rindler coordinates in studying Unruh Effect
When studying the Unruh Effect, Rindler coordinates are being used for the observer with constant acceleration. I am confused as to why Rindler coordinates are used as I do not see the motivation for ...
user161157
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How can Unruh radiation ever be real?
It is speculated that Unruh radiation exists for accelerating observers in flat spacetime. A thermometer in the frame will point at a higher value than for someone in a stationary frame. In the ...
user303670
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Flux and radiation pressure from Unruh radiation?
A collection of accepted answers on Physics Exchange paint a seemingly inconsistent picture of Unruh radiation and it's isotropy. One of the most sophisticated answers, from Lubosz Motl, to the ...
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Unruh temperature appears to depend on reference frame, how is this resolved?
I am wondering about observer-(in)dependence of Unruh temperature. Specifically, consider two observers, A and B, initially at rest in the same position. Then, at some point, A starts uniformly ...
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How do you show that the Unruh Temperature between two inertial observers is zero?
As part of my undergraduate thesis, I'm trying to show that using massless scalar field, the Unruh effect between two inertial observers is zero. I'm using this book: "Introduction to Quantum ...
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Interpretation of the nonuniqueness of vacuum of QFT in flat spacetime for a given inertial observer; No Lorentz transformation; No accelerated motion
Consider an inertial observer in flat spacetime with a choice of coordinates $(t,{\vec x})$. This observer can expand a quantum field $\hat{\phi}$ in more than one complete set of orthonormal modes. ...
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What is the interpretation of non-uniqueness of field expansion in flat spacetime?
Scalar field expansion in terms of plane wave modes is given by
$$\phi(x)=\int\frac{d^3{\vec p}}{\sqrt{(2\pi)^{3}2\omega_{\vec p}}}\left(a_{\vec p}e^{-ip\cdot x}+a_p^\dagger e^{+ip\cdot x}\right)$$ ...
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Unruh effect on rotating galaxies?
According to the Unruh effect, an accelerating observer will experience a thermal bath. This is equivalent to Hawking radiation.
If we applied this to a spinning galaxy, I wonder if this thermal bath ...
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