Recently Published
Effective Field Theory, Starting From the Propagator You Just Learned
An effective field theory is what you get when you cannot afford the energy to make a heavy particle. This is EFT for someone a few weeks into a first QFT course: one line of algebra on the propagator you already know, one heavy scalar integrated out by hand, then Fermi's theory of beta decay, why non-renormalisable is not an insult, then how a theory predicts the energy at which it will stop working.
The Renormalisation Group: from Block Spins to Running Couplings
An eight-part beginner's course on the renormalisation group, in simple words with an everyday picture for every idea: loops and cutoffs from scratch, block spins and the Ising chain, fixed points and universality, Wilson's momentum shells, the Wilson-Fisher fixed point, running couplings in QED and QCD, then effective field theory. Every formula checked in Wolfram and FORM, with live simulations in the browser.
Tree Codes: Recreating Hernquist (1987)
Recreating Hernquist's 1987 paper on the performance of Barnes-Hut tree codes, from scratch in Julia: the Plummer model, the leapfrog integrator, the multipole expansion and every timing and error test in the paper.
Minkowski Functionals: Measuring the Shape of the Universe
A first-principles guide to Minkowski functionals: from 'what is shape?' through Hadwiger's theorem, curvature, the Steiner inflation formula, and the Hermite-ladder Gaussian predictions, to measuring non-Gaussianity in cosmology. Physical analogies (a flooding landscape), full derivations, symbolic checks in SymPy and WolframScript, numerical checks in Python and Julia, and an interactive 3D water-level widget.
Grassmann Algebra: Multiplying with Area and Orientation
A friendly, visual introduction to Grassmann (exterior) algebra: the wedge product, bivectors, orientation, multivector grades, and the tensor-algebra quotient definition — with runnable SageMath and SymPy code. The first part of a mini-series leading to Clifford algebras and spinors.
The Physics of Neutrinos: Chirality, Helicity, and Parity Violation
What chirality, helicity and parity violation actually mean, and where they come apart once the neutrino has mass: Weyl spinors and the gamma-5 projector, the (m/2E)^2 ~ 10^-17 gap between chirality and helicity, why the pion refuses to decay into an electron, V-A theory and the group structure behind it, and Dirac versus Majorana mass with the seesaw.