#holographic QFT

[teledyn]

The Tao of Elmo

This short scene, for me, encapsulates the genius of Elmo. Of COURSE Elmo wouldn't know!

[teledyn]

We are Explorers | Theoretical physics will define our future

[teledyn]

Pretending? Or 'exploring and extending'…

Everything you think you “are” is borrowed. #spirituality #yoga #buddhism #consciousness #zen #awareness #meditation #mindfulness https://www.instagram.com/p/B3AAvJenlzD/?igshid=1twop5tmdo0mo

[teledyn]

“In the long run it is far more dangerous to adhere to illusion than to face what the actual fact is.”

— David Bohm

[teledyn]

"The politics of those whose goal is beyond time are always pacific; it is the idolaters of past and future, of reactionary memory and Utopian dream, who do the persecuting and make the wars.

-- Aldous Huxley, The Perennial Philosophy (P.S.)

"Behold but One in all things; it is the second that leads you astray."

- Kabir

[teledyn]

"The world she is a round a like a my head" - Christopher Columbus

[teledyn]

And to think, we arrived at it by accident!

thank you time

wow what incredible news that TIME exists. change is VERY neat and would be pretty dang difficult without time. i say thank you to time, i have so much gratitude for you. cant believe i am lucky enough to be a part of your beautiful river it is an honor to swim for a bit

[teledyn]

What's a QFT? re: Holographic QFT Google didn't come up with a applicable explanation. Thx.

Holographic quantum field theory is the subject of Thomas Hertog's On the Origin of Time, based on his work with Stephen Hawking. This can be compared to the work of Karl Pribam on the #holographicprinciple as applied to memory and cognition.

[teledyn]

Thomas Hartog cites this one:

You and I are out at the edge, the Origin of Time at the centre. For me, Prelkia adds the "what it's like to be there" 😅

Geometry of the Universe by Prelkia, Jean-Marc

[teledyn]

Also, there is no Archimedian Point, there is no "standing outside in a lab coat looking in", no God's Eye View. All we have are perspectives, each a Worm's Eye point of view and it behoves us to collect up all we can to get even the barest sense of what is happening.

Oh, causality has to be tossed too. Sorry. I know how much y'all like to lay blame. Ain't my fault, honest, blame Physics! Oh, sorry, we can't, physics is as much a victim of happenstance as the rest of us. Dang.

“It is a narrow mind which cannot look at a subject from various points of view.”

— George Eliot, Middlemarch

[arxt1]

Emergent gravity from hidden sectors and TT deformations. (arXiv:2010.04729v1 [hep-th])

We investigate emergent gravity extending the paradigm of the AdS/CFT correspondence. The emergent graviton is associated to the (dynamical) expectation value of the energy-momentum tensor. We derive the general effective description of such dynamics, and apply it to the case where a hidden theory generates gravity that is coupled to the Standard Model. In the linearized description, generically, such gravity is massive with the presence of an extra scalar degree of freedom. The propagators of both the spin-two and spin-zero modes are positive and well defined. The associated emergent gravitational theory is a bi-gravity theory, as is (secretly) the case in holography. The background metric on which the QFTs are defined, plays the role of dark energy and the emergent theory has always as a solution the original background metric. In the case where the hidden theory is holographic, the overall description yields a higher-dimensional bulk theory coupled to a brane. The effective graviton on the brane has four-dimensional characteristics both in the UV and IR and is always massive.

from gr-qc updates on arXiv.org https://ift.tt/312pYtb

[arxt1]

R\'enyi entropies and area operator from gravity with Hayward term. (arXiv:2005.11338v1 [hep-th])

In the context of the holographic duality, the entanglement entropy of ordinary QFT in a subregion in the boundary is given by a quarter of the area of an minimal surface embedded in the bulk spacetime. This rule has been also extended to a suitable one-parameter generalization of the von-Neuman entropy $\hat{S}_n$ that is related to the R\'enyi entropies $S_n$, as given by the area of a \emph{cosmic brane} minimally coupled with gravity, with a tension related to $n$ that vanishes as $n\to1$, and moreover, this parameter can be analytically extended to arbitrary real values. However, the brane action plays no role in the duality and cannot be considered a part of the theory of gravity, thus it is used as an auxiliary tool to find the correct background geometry.

In this work we study the construction of the gravitational (reduced) density matrix from holographic states, whose wave-functionals are described as euclidean path integrals with arbitrary conditions on the asymptotic boundaries, and argue that in general, a non-trivial Hayward term must be haven into account. So we propose that the gravity model with a coupled Nambu-Goto action is not an artificial tool to account for the R\'enyi entropies, but it is present in the own gravity action through a Hayward term. As a result we show that the computations using replicas simplify considerably and we recover the holographic prescriptions for the measures of entanglement entropy; in particular, derive an area law for the original R\'enyi entropies ($S_n$) related to a minimal surface in the $n$ replicated spacetime. Moreover, we show that the gravitational modular flow contains the area operator and can explain the Jafferis-Lewkowycz-Maldacena-Suh proposal.

from gr-qc updates on arXiv.org https://ift.tt/2WZRfe7

[arxt1]

$T \bar T$ Deformations, Massive Gravity and Non-Critical Strings. (arXiv:1911.06142v4 [hep-th] UPDATED)

The $T \bar T$ deformation of a 2 dimensional field theory living on a curved spacetime is equivalent to coupling the undeformed field theory to 2 dimensional `ghost-free' massive gravity. We derive the equivalence classically, and using a path integral formulation of the random geometries proposal, which mirrors the holographic bulk cutoff picture. We emphasize the role of the massive gravity \stu fields which describe the diffeomorphism between the two metrics. For a general field theory, the dynamics of the \stu fields is non-trivial, however for a CFT it trivializes and becomes equivalent to an additional pair of target space dimensions with associated curved target space geometry and dynamical worldsheet metric. That is, the $T \bar T$ deformation of a CFT on curved spacetime is equivalent to a non-critical string theory in Polyakov form, with a non-zero $B$-field. We give a direct proof of the equivalence classically without relying on gauge fixing, and determine the explicit form for the classical Hamiltonian of the $T\bar T$ deformation of an arbitrary CFT on a curved spacetime. When the QFT action is a sum of a CFT plus an operator of fixed scaling dimension, as for example in the sine-Gordon model, the equivalence to a non-critical theory string holds with a modified target space metric and modified $B$-field. Finally we give a stochastic path integral formulation for the general $T \bar T+J \bar T+T \bar J$ deformation of a general QFT, and show that it reproduces a recent path integral proposal in the literature.

from gr-qc updates on arXiv.org https://ift.tt/2D4fg8W

[teledyn]

If history teaches anything, compelling evidence is no guarantee either, Carl.

Believing when there is no compelling evidence is a mistake.

CARL SAGAN

[arxt1]

Back-reaction in massless de Sitter QFTs: holography, gravitational DBI action and f(R) gravity. (arXiv:2003.09435v1 [hep-th])

We employ gauge-gravity duality to study the backreaction effect of 4-dimensional large-$N$ quantum field theories on constant-curvature backgrounds, and in particular de Sitter space-time. The field theories considered are holographic QFTs, dual to RG flows between UV and IR CFTs. We compute the holographic QFT contribution to the gravitational effective action for 4d Einstein manifold backgrounds. We find that for a given value of the cosmological constant $\lambda$, there generically exist two backreacted constant-curvature solutions, as long as $\lambda < \lambda_{\textrm{max}} \sim M_p^2 / N^2$, otherwise no such solutions exist. Moreover, the backreaction effect interpolates between that of the UV and IR CFTs. We also find that, at finite cutoff, a holographic theory always reduces the bare cosmological constant, and this is the consequence of thermodynamic properties of the partition function of holographic QFTs on de Sitter.

from gr-qc updates on arXiv.org https://ift.tt/2WFEFAL

[arxt1]

Holographic Space-time and Quantum Information. (arXiv:2001.08205v2 [hep-th] UPDATED)

The formalism of Holographic Space-time (HST) is a translation of the principles of Lorentzian geometry into the language of quantum information. Intervals along time-like trajectories, and their associated causal diamonds, completely characterize a Lorentzian geometry. The Bekenstein-Hawking-Gibbons-'t Hooft-Jacobson-Fischler-Susskind-Bousso Covariant Entropy Principle, equates the logarithm of the dimension of the Hilbert space associated with a diamond to one quarter of the area of the diamond's holographic screen, measured in Planck units. The most convincing argument for this principle is Jacobson's derivation of Einstein's equations as the hydrodynamic expression of this entropy law. In that context, the null energy condition (NEC) is seen to be the analog of the local law of entropy increase. The quantum version of Einstein's relativity principle is a set of constraints on the mutual quantum information shared by causal diamonds along different time-like trajectories. The implementation of this constraint for trajectories in relative motion is the greatest unsolved problem in HST. The other key feature of HST is its claim that, for non-negative cosmological constant or causal diamonds much smaller than the asymptotic radius of curvature for negative c.c., the degrees of freedom localized in the bulk of a diamond are constrained states of variables defined on the holographic screen. This principle gives a simple explanation of otherwise puzzling features of BH entropy formulae, and resolves the firewall problem for black holes in Minkowski space. It motivates a covariant version of the CKN\cite{ckn} bound on the regime of validity of quantum field theory (QFT) and a detailed picture of the way in which QFT emerges as an approximation to the exact theory.

from gr-qc updates on arXiv.org https://ift.tt/2NOIWwQ