Astrophysics for Babies

\[\begin{align} \nabla\cdot\boldsymbol{D}&=\rho_0\nonumber \\ \nabla\times\boldsymbol{E}&=-\frac{\partial\boldsymbol{B}}{\partial t}\nonumber \\ \nabla\cdot\boldsymbol{B}&=0\nonumber \\ \nabla\times\boldsymbol{H}&=\boldsymbol{j}_0+\frac{\partial \boldsymbol{D}}{\partial t}\nonumber \end{align} \]

Welcome to my homepage!

This is a dumb undergraduate majoring in physics in an unknown university. I've studied some astronomy myself but haven't figured out anything T_T

But I really want to study astrophysics aaaaaaaaaaaaaaaa

I may post some study materials and daily thoughts here.

The first year I didn't feel anything, but the second year I realized that there were too many mad teachers at the university.🥵🥵🥵

This semester there are three courses: Optics, Theoretical Mechanics and Mathematical Methods for Physics. The only one that's normal is MMP (after all, it's the God of MMP, Guoquan Zhou). But the teachers of the remaining two classes are a bit crazy.

Theoretical Mechanics

The textbook is Landau, which is not suitable for beginners. This book is not suitable as a textbook for beginners, it has no mathematical details and the notation is different from other books. In the end, I chose to follow along with other books.

And I'm a sophomore, sophomore, sophomore, and I haven't finished the math and physics stuff yet, and even though you're in astrophysics and I'm interested in it, all of a sudden there's a lot of metrics and general relativity and abstract metrics and tensor analysis and it just makes me feel like I'm taking a very abstract class.

Conclusion: self-study.

Optics

A few days ago, I read the new book "Classical Mechanics" by Prof. Xian Gao from Sun Yat-sen University, and I have a preliminary understanding of the concept of "metric".

The key lies in the fact that Prof. Gao combines some of our existing concepts with some advanced mathematical tools, and introduces new concepts in a more concise and easy-to-understand language.

Generalization of the Pythagorean Theorem

We know that in flat Euclidian space, the distance between two points can be expressed by the Pythagorean theorem: \[ \begin{equation} \label{eq1} \mathrm{d}s^2=\mathrm{d}x^2+\mathrm{d}y^2, \end{equation} \] or in polar coordinates: \[ \begin{equation} \label{eq2} \mathrm{d}s^2=\mathrm{d}\rho^2+\rho^2\mathrm{d}\varphi^2. \end{equation} \]

As a newbie(T_T) who has only participated once in CNAO, I've organized some test questions from previous years in my free time before and after the olympiad. I'm going to put them up for future BR's reference (orz).

Final round problems of Chinese National Astronomy Olympiad(2002-2020)

Final round problems of Chinese National Astronomy Olympiad (2021-2022)

Video for Problem 3 in CNAO 2021-2022

It's not easy to organize, try not to spread it widely, but you can promote this site when you share it QAQ (

If there are any omissions or updates, please feel free to contact me.