Edited:   November 28, 2019


My name is Yingkai Liu (Google Scholar). I am currently a graduate student at Yeshiva University, US. I major in Physics.

With more understanding of physics, I found the theory used to describe a phenomenon is more and more elegant but in the same time complicated. I was happy about the differential equations, impressed by linear algebra, struck by group theory and now mesmerized by topology and differential geometry. I am aware that physics requires much more than just mathematics. In the same time I believe that with more mathematics there will be deeper physics.

As for my current interest, on my CV I wrote:

Learning Mathematical tools that explain the topological aspects of materials. Understanding the phenomenon of integer discreetness arising from continuous symmetry. Describing and discovering topological quantum systems. Learning through examples and models, especially coding and seeing the numerical result.

Here is my CV (last update: 2019-11-28).

This Site

When I started writing on this website, I wanted to share notes on what I have learned. I benefited a lot from many insightful blogs and now I have something to give back. Watching my notes published on websites also gives me motivation and a strange consolation.

I also realized that this website can be used as a billboard of my professional backgrounds. This is a great proof for what I have learned.


The posts are at different status.

Status Meaning
Completed This post is considered completed, but I might edit it when I came up with something new.
Writing This post is being actively edited.
Paused This post is considered of low priority. I will come back to this post later.
Archived This post is outdated and probably won’t receive any update.


This website (source code here) uses these sources:

Module Mainly used in License/ TOS
Particle.js Homepage MIT
Visitor map Homepage, footer TOS
Homepage and color scheme Layout @ homepage, color scheme @ all pages MIT
List of recent post Homepage, Post index MIT
Search Post index, Tags index MIT
Side bar Post, all pages with these elements MIT
Table of content Post BSD-3 or MIT
Markdown vue theme and color scheme Markdown theme @ Post, color scheme @ all pages Apache-2.0
Tags, Tag cloud, Tag page Post, Post index, Tags index MIT, repo here. Tag page inspired by haixing-hu
Font size adjustment Post MIT
comment Post APGL-3.0
404 T-rex game 404 page from Chromium source code, license
Encryption Secret Pages MIT

Additional licensing information can be found here.

I mainly use Typora to write my post.

The Name

I named this website “A Finger Pointing to the Moon”, as in the Buddhism story:




Which has been beautifully put by Bruce Lee:

It’s like a finger pointing away to the moon. Don’t concentrate on the finger or you will all that heavenly glory.


The best way to reach me is via email: $water$ @ $mail.nankai.edu.cn$