Author Archives: Raghu Mahajan

Let when , and when . The following statements are all correct:

With Edgar Shaghoulian, we wrote a brief pedagogical note explaining some confusing points about the application of the island formula to closed universes.

Here is a list of books that have influenced me the most, and almost define who I am and what my outlook on life is: String Theory Vol. 1 and Vol. 2, by Joseph Polchinski The poem Sab Ton Khatarnaak, … Continue reading →

Here is a nice way to get the volume of a sphere. The idea is to consider the dimensional integral . In Cartesian coordinates, this is just a product of Gaussians, and thus is equal to . The other way … Continue reading →

The attached pages from the QFT textbook by Itzykson and Zuber show the technique of the Borel transform applied to the integral of a gaussian with a quartic term. In this example one can explicitly compute the Borel transform, see … Continue reading →

Consistent interpretations of quantum mechanics, Roland Omnes, Rev Mod Phys (1992) 64 339 The introduction to this paper expresses echoes many of my thoughts on the Copenhagen interpretation of quantum mechanics. The actual content of the paper is a bit … Continue reading →

I like it when authors of academic papers present strong personal opinions on something. Eventually the authors might be wrong, but it gives the paper an interesting touch and I feel it makes the paper easier to read (since the … Continue reading →

I am putting up here for convenience a short Mathematica calculation using Matt Headrick’s diffgeo.m package (http://people.brandeis.edu/~headrick/Mathematica/). We will work in light-cone coordinates. There is a particle moving to the right, at the speed of light. It sources a stress … Continue reading →

A vortex field in two dimensions is a velocity field or a vector field that equals . If we take around a circle centered at the origin, we get a constant. Let us stay away from the origin to avoid … Continue reading →