A Cute Little Wave Estimate
Let us consider first the linear wave equation \[ \Box u = 0\] on (1+d)-dimensional Minkowski space. A well known property of the wave …
Where Does The π Go
It is fairly well known that experts in partial differential equations and experts in harmonic analysis prefer to define the Fourier …
How to ballast your ship or why my kitchen sink is always dirty
Recently I've been reading a bit of fluid dynamics, and came across the classical problem of free and forced vortices. In this post I …
Skyrmions are narcissistic
Paper announcement and exposition.
Symmetry and Uniformization
A bit of trivia (can't think of any use of it now)
Theorem Let $(M,g)$ be a two-dimensional compact Riemannian manifold with …
The Kodama vector field and the gravitational red-shift
We introduce the Kodama vector field for rotationally symmetric space-times and its relation to gravitational red-shift.
A Little Hilbert Space Problem
First let us consider the following question on a finite dimensional vector space.
Let $(V, \langle\cdot\rangle)$ be a $k$-dimensional …
Cartan's Spiral Staircase
I've just spent much too long puzzling over the geometric formalism of a paper of Lazar and Hehl, so I figure I'll write a little …
Irrationality of a common constant
We give a proof of the irrationality of π.
Conformal compactification of spacetime
We explain how to conformally compactify Lorentzian manifolds.