Questions tagged [holographic-principle]
The Holographic principle is a principle of string theories and a supposed property of quantum gravity that states that the information within a region is exactly described by that on its boundary. DO NOT USE THIS TAG for a photographic hologram.
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Definitions of Thermodynamics and Holography
There are many differences between the laws of thermodynamics and the laws of black hole thermodynamics (BHT):
Zeroth Law: In thermodynamics, the Zeroth Law establishes the notion of thermal ...
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Is the Ryu-Takayanagi (RT) formula calculating coarse-grained or fine-grained entropy?
I think it is computing the fine-grained entropy. However, I am confused by the case that when there is a black hole in the bulk. The Ryu-Takayanagi surface may include the horizon of the black hole ...
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Holographic microscopy: how 3d structure informations are contained within interference pattern?
I am studying holographic miscroscopy and it seems to me that the possibility of constructing the three-dimensional image of an object by irradiating it from one side only is given by the '...
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Nature of spacetime in the holographic boundary
My understanding from popular science articles is that the boundary is a field theory that has no gravity and has one less spatial dimension than the bulk.
However, I am not sure I understood this ...
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Resources for studying holography for someone with a long gap in physics
for the past 3 years I haven't been reading up on physics and I'd now like to get back into it by learning about holography. I have done courses on QFT and String theory but some concepts I've ...
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What do bulk Fourier modes look like in the boundary theory?
Suppose we have a bulk theory that has some holographic CFT dual at the boundary. Suppose we construct an operator that 'looks like' (whatever that needs to mean) a Fourier mode in the bulk ...
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Computing the entanglement entropy in non-abelian lattice gauge theory using superselection sectors
I have been trying to understand how the entanglement entropy of a non-abelian lattice gauge theory. This was discussed in the paper https://arxiv.org/abs/1510.07455, section 2.2.
First why is the ...
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Can you always write entropy as integral over space?
I am mostly interested in the entanglement entropy of the ‘‘outside region’’ (aka ‘‘$S_\text{out}$’’) in the holographic entanglement entropy formulation in arXiv:1408.3203 and arXiv:1307.2892. Take ...
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What does it mean for a quantum field theory to "live" on a manifold?
I was attending lectures om holography where the lecturer kept on mentioning that a QFT lives on a Cauchy slice. What does that mean?
Is it such that each point of the slice is associated to a unique ...
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Hawking Temperature for a hairy BTZ Black Hole
The metric of a hairy Black Hole is given by:
$$ds^2 = \frac{L^2}{z^2}\biggl(-g(z) dt^2 + \frac{e^{2 A(z)}}{g(z)} dz^2 +d\varphi^2\biggr), $$
where $L$ is the AdS length taken to be $1$,$A(z)$ is the ...
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Naive questions on AdS/CFT dictionary and alternatives?
I'm starting to become curious about AdS/CFT since hearing that condensed matter theorists use it as a 'dictionary' to find gravity duals of things from condensed matter physics. How exactly does this ...
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Holographic self-energy for a scalar field in a slice of AdS
I am confused about a key step in Gherghetta's "TASI Lectures on a Holographic View of Beyond the Standard Model Physics" in the derivation of the holographic self-energy in the strongly ...
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Why is the holographic encoding from Bekenstein-Hawking entropy remarkable?
The holographic encoding interpretation from the Bekenstein-Hawking entropy is due to it scaling with the area $S_{BH} = A/4$ of the surface, rather than the volume $V$. While I am aware that most ...
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Research progress in the symmetries of flat space holography
I was studying the papers
[$1$] Arjun Bagchi. The BMS/GCA correspondence
[$2$] Duval, C., Gibbons, G. W., & Horvathy, P. A. (2014). Conformal carroll groups. Journal of Physics A: Mathematical ...
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Jackiw-Teitelboim (JT) gravity as a matrix integral
I am reading https://arxiv.org/abs/1903.11115 by Saad, Shenker and Stanford. They relate an (averaged) $n$-point function in a random double-scaled matrix model to a path integral genus expansion in ...
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In the context of the holographic principle, is the bulk-boundary correspondence due to entanglement?
According to the holographic principle, a "bulk" region of D dimensions corresponds to a "boundary" region of D-1 dimensions. In this context, the laws of physics of the bulk can ...
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Does the holographic principle allow realistically-sized universe simulation?
I was reading about the holographic principle and a question came up to my mind which I can't find an answer to. My understanding is that the holographic principle states that the description volume ...
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What is the fundamental reason why information is on the event horizon of a black hole?
I don't know the mathematics behind black holes and information theory but is there a simple explanation of why information is on the event horizon. Why can't it be elsewhere?
user355436
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Why are physicists surprised that the information of a black hole is proportional to its boundary?
I don't understand why physicists are surprised that the information of a black hole is proportional to its boundary.
From a pure GR perspective, in my understanding, an observer outside a black hole ...
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In AdS/CFT, do we have Weyl-invariance or only conformal invariance?
The asymptotic symmetry group of $AdS_{d+1}$ is $SO(d,2)$, which just so happens to be the conformal group of $d$-dimensional Minkowski spacetime. Therefore the boundary dual, if it exists, has ...
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Solving equations of motion with a background ansatz
Consider the effective 4d gravitational bulk action article, dual to $QFT_3$ on $\mathbb{R}^{2,1}$,
$ S_{QFT_3}=S_{CFT_3}+S_r +S_i=\frac{1}{2\kappa^2}\int dx^4\sqrt{-\gamma}(R+6-\frac{1}{2}(\nabla\phi)...
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Motivation of Holographic Exact Renormalisation Equation
I've recently been studying exact renormalisation alongside holographic renormalisation, and came across the following paper on the arXiv: https://arxiv.org/abs/hep-th/0001193.
I'm trying to ...
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What does the discovery of pressure of black holes imply for spacetime thermodynamics?
As far as I know AdS/CFT and spacetime thermodynamics was motivated by the Bekenstein-Hawking Entropy formula of black holes.
Recently however it was discovered that black holes have a pressure as ...
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Reading list for JT/SYK correspondence
I have been studying Gábor Sárosi's review of holographic duality between Jackiw-Teitelboim gravity and the Sachdev-Ye-Kitaev models for the last few days. This field has grown since the review came ...
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How many apparent horizons could the universe have?
I was reading a paper written by Nobel laureate George Smoot, Go with the Flow, Average Holographic Universe, which assumes the holographic principle as true and conjectures that our universe would be ...
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Local conformal group of the Euclidean plane and the (local) diffeomorphism group of locally Lorentzian 4-manifolds
Maybe this question is rather too general to mention, but I hope the community can help to make it more precise in case it's needed.
The question is: if there's any link between the local conformal ...
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Conceptually, why is the entropy of black hole related to Planck length?
I was watching a lecture on the holographic principle, and it presented the equation for the entropy of a black hole as $$S_{BH} = \frac{A}{4l_p^2}$$ My question is why, conceptually, the entropy of a ...
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What is the relation between the free energy and the action? More generally, what is the relation between Thermodynamics and Lagrangian Mechanics?
My question stems from the sentence said by my professor "The action is the free energy" which I don't understand. Thinking that probably I'm missing some key concepts, I'd like to know: ...
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How is the Virasoro symmetry realised on $AdS_3$?
In the context of the Holographic correspondence, $AdS_{n}/CFT_{n-1}$, it is often cited as a "confirmation" that the two symmetry groups of the theories correspond. Indeed, in dimensions $n&...
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Can the holographic surface of our universe be located at the cosmic horizon?
I just listened to a Susskind's talk at Stanford, where, as an answer to a question, he said that may be the surface that contains the information to describe our 3D universe might be located at the ...
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Does the holographic principle imply a finite universe?
Please correct me if I am wrong here, but it seems that the holographic principle sets an upper entropy bound that scales quadratically with the radius of the sphere under consideration, while the ...
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Boundary condition from extremization
I have an AdS Schwarzschild blackhole spacetime where the metric is given by,
$$ds^2 = \frac{1}{z^2} \left( -f(z) dt^2 + \frac{dz^2}{f(z)} + dx^2 \right) \tag{1}\label{1}$$
There is a plane embedded ...
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Is the Quantum Gravity mystery already solved by Susskind? [closed]
Very recently, Leonard Susskind presented a lecture presenting his proposal of Quantum Mechanics = Gravity (equality means duality).
Quantum Origins of Gravity
Is this really the end of Quantum ...
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Relation between the condensation gap and the critical temperature in superconductors/holographic superconductors
In some articles about holographic superconductors, it is written that when the condensation gap increases, the critical temperature decreases. For example, here: https://link.springer.com/article/10....
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On the properties of a projection map from points in the bulk to qubits on the boundary
Note: I have completely re-edited my post, so as to make it much clearer. I apologize for the previous version of this post, which I had written rather fast.
Let $H^3$ denote hyperbolic $3$-space and ...
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AdS-CFT correspondance from 1D to 4D
From what I understand the AdS-CFT correspondence states that the bulk dynamics of a $n$-dimensional gravitational theory are encoded in the degrees of freedom of its dual CFT in the $(n-1)$ ...
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Computing the DBI action on $S^5$
I've been looking at this paper (arXiv: 1103.4079). On page 7, from the metric of the giant gravtiton on $AdS_5 \times S^5$,
$$ds^2 = -\cosh^2\rho \, dt^2 + d\rho^2 + \sinh^2 \rho \, d\tilde \Omega_3^...
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How can holographic duals (eg. AdS/CFT) be used to study magnetic monopoles? [closed]
What useful things are possible to find out about magnetic monopoles through the use of dual theories? I'm thinking of characteristics such as stability (or chaoticness), expectation values, central ...
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Transition amplitudes in AdS/CFT
Consider $AdS_{d+1}/ CFT_d$ duality. Suppose the bulk metric in Poincare coordinates is $$ds^2=\frac{l^2}{z^2}\left(dz^2+h_{ij}(x)dx^idx^j\right)$$ near the boundary, i.e. as $z\to 0$. Let $\sigma_1,\...
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Holography vs edge modes in Chern-Simons theories
There are two facts I have heard about Chern-Simons theories
They are dual to a WZW theory on the boundary (e.g. Relation between CS/WZW and AdS/CFT).
They require a chiral theory on the boundary due ...
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Riemann tensor of $R\times \mathbb{S}_{d-1}$ metric
I would like to give a general expression to the Riemann tensor of a metric
\begin{equation}\text{d}s^2=r^2(-\text{d}t^2+\text{d}\Omega^2_{d-1}).\end{equation}
This metric is actually decomposed in $R\...
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Boundary conditions and holographic principle
The statement of the holographic principle seems very similar to specification of boundary conditions. A differential equation can be uniquely solved if one specifies the boundary conditions. Put ...
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Holographic Degrees of Freedom
What does it mean when one says "holographic degrees of freedom" in dS space? As Susskind does in his recent papers, the latest here (page 18).
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$AdS_2/CFT_1$ toy model of a magnetic monopole
Is it possible to create a holographic $AdS_2/CFT_1$ (2D/1D) toy model, which contains a magnetic monopole solution in the bulk?
I would like to study certain behaviours on the boundary of a toy model ...
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Resources to start research on the SYK model, with AdS/CFT in mind
What are the main resources to learn the SYK model, focusing more on the AdS/CFT side rather than pure condensed matter theory, assuming a comfortable background in QFT, GR, and a bit of bosonic ...
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Understanding scalar bulk field in $\rm AdS$
I don't really understand the standard result in Holography and AdS/CFT that a source field can be expressed at
\begin{equation}
\phi_0 = \lim_{z \rightarrow 0} z^{\Delta -d} \phi(z,x)
\end{equation}
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Is entropy of planets and others bodies proportional to the area?
Is entropy of planets and others bodies proportional to the area? If yes, how do I prove that? I know it works for a black hole but, and for others? If no, then the entropy is really proportional to ...
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What information is retained on the boundary of a black hole?
If an object were to be pulled into a black hole, I’ve been told its information would be retained on the boundary.
But will that be just the information of the actual state it was in at the time? Or ...
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Simple question about the the holographic principle and the uncertainty principle
Given: The holographic principle as proposed by Susskind that states that the maximum amount of information stored in a 3D volume can be dictated by its surface area.
Would not: The simple square-...
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Conservation of information [closed]
Given: The holographic principle as proposed by Susskind that states that the maximum amount of information stored in a 3D volume can be dictated by its surface area.
Would not: The simple square-...
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