We analyze (2+1)-dimensional gravity with a Chern--Simons term and a negativecosmological constant, primarily at the weak field level. The full theory isexpressible as the sum of two higher derivative SL(2,R) "vector" Chern-Simonsterms, while the physical bulk degrees of freedom correspond

The most striking observable feature of our indeterministic quantum universeis the wide range of time, place, and scale on which the deterministic laws ofclassical physics hold to an excellent approximation. This essay describes howthis domain of classical predictability of every

Many models of high energy physics possess metastable vacua. It isconceivable that the universe can get trapped in such a false vacuum,irrespective of its origin and prior history, at an earlier stage during itsevolution. The ensuing false vacuum inflation results

Any hint of non-gaussianity in the cosmological initial conditions willprovide us with a unique window into the physics of early universe. We showthat the impact of a small local primordial non-gaussianity (generated onsuper-horizon scales) on the statistics of collapsed objects

Massive black hole binary systems, with masses in the range ~10^4-10^10\msun, are among the primary sources of gravitational waves in the frequencywindow ~10^-9 Hz - 0.1 Hz. Pulsar Timing Arrays (PTAs) and the LaserInterferometer Space Antenna (LISA) are the observational

We argue that CP violation has rather dramatic impact on the "gravity as theweakest force" conjecture. Namely we find that new ultraviolet scale must be$\Lambda \lesssim \theta g^3 M_P$, where $\theta$ is an effective parameterdescribing CP violation and $g$ is

Most of the properties of black holes can be mimicked by horizonless compactobjects such as gravastars and boson stars. We show that these ultra-compactobjects develop a strong ergoregion instability when rapidly spinning.Instability timescales can be of the order of 0.1

The purely affine, metric-affine and purely metric formulation of generalrelativity are dynamically equivalent and the relation between them isanalogous to the Legendre relation between the Lagrangian and Hamiltoniandynamics. We show that one cannot construct a dynamically equivalent, purelyaffine Lagrangian from

We investigate the spacetime of a slowly rotating black hole in theChern-Simons modified gravity. The long range feature of frame-dragging effectunder the Chern-Simon gravity well explains the flat rotation curves ofgalaxies which is a central evidence of dark matter. Our

In this paper we investigate gravitational waves production during the BigBounce phase inspired by the Loop Quantum Cosmology. We consider the influenceof the holonomy corrections to the equation for tensor modes. We show that theyact like additional effective graviton mass,

We consider symplectic time integrators in numerical General Relativity anddiscuss both free and constrained evolution schemes. For free evolution ofADM-like equations we propose the use of the Stoermer-Verlet method, a standardsymplectic integrator which here is explicit in the computationally expensivecurvature

We present the tensor computer algebra package xPert for fast constructionand manipulation of the equations of metric perturbation theory, aroundarbitrary backgrounds. It is based on the combination of explicit combinatorialformulas for the n-th order perturbation of curvature tensors and their

In this geometrical approach to gravitational lensing theory, we apply theGauss-Bonnet theorem to the optical metric of a lens, modelled as a static,spherically symmetric, perfect non-relativistic fluid, in the weak deflectionlimit. We find that the focusing of the light rays

A GHz maser beam with Gaussian-type distribution passing through a homogenousstatic magnetic field can be used to detect gravitational waves (GWs) with thesame frequency. The presence of GWs will perturb the electromagnetic (EM)fields, giving rise to perturbed photon fluxes (PPFs).

We are studying the dynamics of a one-dimensional field in a non-commutativeEuclidean space. The non-commutative space we consider is the one that emergesin the context of three dimensional Euclidean quantum gravity: it is adeformation of the classical Euclidean space and

The paper has euristic character. It exploits basic concepts of quantumphysics to infer on a self-consistent basis the properties of the gravitationalfield. The only assumption of the theoretical model is the quantum uncertainty:the physical properties of quantum systems depends on

In this paper it has been shown that a simple functional form of$\omega(\phi)$ in a generalised scalar tensor theory can drive the presentcosmic acceleration without any quintessence field or the cosmological constant$\Lambda$. Furthermore, it ensures a smooth transition from a

Raychaudhuri equation is generalized in the parameterized absoluteparallelism geometry. This version of absolute parallelism is more general thanthe conventional one. The generalization takes into account the suggestedinteraction between the quantum spin of the moving elementary particle and thetorsion of the

This paper is the first of a series of three which construct coherent statesfor spin networks with planar symmetry. Constructing such states is notstraightforward. After gauge-fixing, the full SU(2) symmetry is broken to U(1),but one cannot simply use the U(1)

This paper explores the properties of the Pauli-Lubanski spin vector for thegeneral motion of spin-1/2 particles in curved space-time. Building uponpreviously determined results in flat space-time, it is shown that theassociated Casimir scalar for spin possesses both gravitational contributionsand frame-dependent