Vaibhav Kalvakota

Vaibhav Kalvakota

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Aspects of the Generalized Second Law and the Covariant Entropy bound

Published:

In this talk, we will look at generalized entropy and the generalized second law in the perspective of singularities. We will review the GSL in a cosmological perspective, and find motivation towards the GSL and entropy based singularity theorems. We will see how the fine-grained GSL and the covariant entropy bound provide a physical tool for singularity theorems, replacing topological conditions such as the presence of a non-compact Cauchy surface with instead the quantum focusing conjecture. We will then discuss further aspects of the GSL such as quantum holographic screens in different cosmologies, and if time permits we will provide an outlook for the role of generalized entropy in the asymptotic nature of null hypersurfaces, which will formulate a quantum Penrose inequality for null hypersurfaces on the basis of the generalized entropy. Recording available at https://www.youtube.com/watch?v=dH2IhL_s3o8. Read more

Holographic Quantum Gravity and Horizon Instability

Published:

In this talk, we will look at the relation between the No Transmission principle and the Strong cosmic censorship (SCC), which we will highlight in the background of quantum gravity. We show that taking quantum gravity into account, one can provide a complete picture of the instability of the inner horizon and the principle that two independent CFTs, under the gauge-gravity duality, imply that the dual bulks must also be independent in that there must not exist a way to transmit a signal between the two spacetimes. We show that this can simply be interpreted as SCC, and that the inner horizon must be unstable (at either linear or nonlinear orders) to be in accordance with holographic quantum gravity. Read more

The Definition of Holography

Published:

In this talk, we will review the notion of holography in quantum gravity. We will discuss some subtleties around the definition of holography, and the implications of holography. In the first half, we will discuss some elementary aspects of (A)dS/CFT, some comparisons, and how certain technicalities complicate the general notion of holography as a bulk-(cutoff-)boundary duality. In the second half, we will discuss some aspects in more technical detail, especially in the direction of establishing holography mathematically. Read more

teaching

On the Poincare conjecture, Ricci flow and all that

Lecture notes, math.DG, 2023

This set of notes contains some things I found interesting about the Poincare conjecture. I must say that I am not an expert, due to which I am not sure when or if at all these notes will be complete. However, this is a very fascinating subject, and I have written these for the sake of capturing some results I found, that discuss some of the more nontrivial aspects of the then Poincare conjecture. Read more

Bulk Physics, Algebras and All That

Lecture notes, hep-th, 2023

This is a course on AdS/CFT in the direction of bulk physics, operator algebras, and other recent developments. Originally a three-part series, now an N-part series in the large N limit. :) Read more