In this talk, will explain the reason for the excitement related to the recent detection of
a binary neutron star merger by LIGO and Virgo detectors and the consequent follow up
using several conventional telescopes. This joint set of observations led to many groundbreaking results in astrophysics, fundamental physics and cosmology, which I will explain (at an undergrad level).

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the lecture describes the story of how Stern and Gerlach tried to detect "space quantization" of Bohr orbits and ended up discovering the spin of the electron; and how it took five years to disentangle the muddle. I will also discuss briefly the vexing story of a possible Stern-Gerlach experiment for free electrons. I will note in passing the remarkably creative career of Otto Stern, sometimes (justifiably) called the founding father of Experimental Atomic Physics.

The classical dynamics of space times with event horizons is often of great interest - but in general is very complicated. We will demonstrate that event horizon dynamics simplifies in the limit of a large number of dimensions. In this limit event horizon dynamics is governed by the equations of a dynamical membrane that hosts a velocity and charge density field. At leading order in the large D expansion we determine the effective equations of membrane dynamics. We discuss possible applications of our construction.

I will explain what a quantum theory of gravity is and why we need one. I then proceed to describe the satisfactory construction of one specially symmetric quantum theory of gravity. The quantization I describe is simply the gauge gravity (or AdS/CFT) correspondence of string theory.