Research & Projects

My primary focus is on tackling conceptual and computational challenges in black holes, cosmology, and quantum gravity. Black holes and cosmology provide the perfect test-bed to delve into the nature of quantum gravity due to the interplay between quantum mechanics and general relativity.  I study string theory and holographic approaches to quantum gravity, enhancing our understanding of non-trivial gravitational solutions with a particular emphasis on accelerating solutions such as de Sitter (dS) spacetime that are less well understood in string theory.   I am interested in diverse intriguing aspects of dS: its isometry structure, which imposes unique constraints on the computation of observables within a well-defined mathematical framework. I want to understand the compatibility of quantum systems in satisfying the symmetries of classical dS space and the finite entropy linked to its cosmological event horizon, as well as comprehending the UV completion of accelerating solutions in quantum gravity, including both black hole and cosmological applications.

I employ a diverse range of techniques, ranging from top-down string compactifications  to quantum information and holography, to gain a deeper understanding of the unique geometry associated with horizons and singularities of accelerating spacetime. One theme of my research interest is based upon the principles of holography  and the universal property of gravity theories, while the other part of the research projects is based upon full string theory construction, where we can exploit the duality symmetries of string theory. Both approaches are independent and complementary, with the central goal of all our efforts being to address the challenges in accelerating spacetime. 

The black hole horizon is one of the most perplexing constructs in General Relativity: it is defined from a global perspective - the past of future infinity - yet our observations of black holes can only take place in a finite time frame. Further, our understanding of Quantum mechanics is rooted very much in a framework of time evolution. Understanding the tension between these perspectives is key to understanding the quantum nature of the horizon. The puzzle of horizon entropy and how this arises from microstates is at the core of this conundrum. A significant unresolved open problem is whether the entropy associated with any horizon in an accelerating spacetime is really an entropy.

If so, according to Boltzmann Statistical Mechanics, it should be counting a number of microstates, but what are these microstates? Significant progress in the context of black hole horizons has been made in String Theory; recent developments in holographic approaches show that non-perturbative gravitational corrections describe the correct characteristics of late-time correlators, consistent with finite entropy.However, these black holes are embedded in asymptotic Anti-de Sitter spacetime -- in contrast, the universe we live in is more like de Sitter space, with accelerated expansion at both early and late times.

Accelerated backgrounds are therefore of fundamental  importance: any observer in such a geometry is surrounded by their own cosmological event horizon which also has finite entropy. How to describe this from a Boltzmann perspective is far more mysterious and I am working towards comprehending this problem

The characteristics of gravity at all length scales are one of the fascinating challenges in theoretical physics. We want to probe the universe on the very largest scale (cosmology), yet also at the smallest scale (elementary particle physics). Gravity is attractive on mundane and astronomical length scales, but appears to be ’repulsive’ at large cosmological distances, leading to the universe expanding at an increasingly rapid rate. However, this poses an issue. The scale involved is extremely small rather than large, rendering quantum mechanics incompatible with cosmology. To comprehend the properties of late-time acceleration in cosmology, we need to comprehend how quantum mechanics can be developed to be compatible in expanding spacetime, i.e., we need a theory of quantum gravity.

Accelerating cosmologies in string theory are a fundamental challenge, given its status as the leading candidate for quantum gravity. String theory is embodied with supersymmetry, which connects the bosonic constituents of the theory to the fermionic ones. However, the symmetry of accelerating spacetime is not compatible with supersymmetry. Therefore, it is of fundamental significance to study supersymmetry breaking in string theory both from an observational as well as a theoretical perspective. The stability conditions due to supersymmetry breaking are crucial for understanding the relation between accelerating cosmology and the string theory landscape. I am also working to understand the properties of accelerating cosmology from String compactifications.