Summary for 2020 — Physics
For my first research project here at the University of Tokyo, the analysis was finished in early November and the first draft of the paper came out in middle December.…
Summary for my favorite 2020 TV shows and books
2020 is worse than expected for everybody due to COVID-19. The pandemic started in China in February, and quickly spread world-widely. It is extremely difficult to travel oversea and the…
Computational way of understanding physics
In one of my ongoing research topic, I need to use a novel technique called automatic differentiation to take derivatives. If you never heard of automatic differentiation before, it is…
Review of angular moment in quantum mechanics
I've gradually realized that spin is used everywhere in theoretical physics and also mathematics. Let alone in particle physics, where all the material particles are described by spin-1/2, even in…
CFT notes by David Simmons-Duffin
I went through the first four chapters in a CFT notes by David Simmons-Duffin prepared for his lecture in Caltech, Ph229ab during the last few weeks. What is Conformal Field…
Summer vacation
From late-July to mid-September is the summer vacation of our group. I moved to a dormitory of The University of Tokyo called Kashiwa-no-ha International Village (KIV) on 21st July. So…
Mill and Dirac
I started to watch the famous Harvard online course Justice by Professor Michael Sandel. It mainly discusses ethics and what is the criteria for the right thing. The course started…
Symmetry and Harmonic Motion (conti.)
About two months ago, I wrote a study notes named Symmetry and Harmonic Motion on how to exploit symmetry of a system doing harmonic motion. I use a baby problem:…
西方哲学史by张志伟(The History of Western Philosophy)
This notes will be written in Chinese, since the lecture videos I watched are in Chinese. It will be easier for me to keep track of various philosophy terminologies in…
Symmetry and Harmonic Motion
Table of contentsWhat is the Problem?Two Key TheoremsThe Baby Problem: Two Particles in 1DProjection Operator into desired Representation ModeExplicit Connection to the Old Way of Solving the Problem in Classical…