# TP201: Introduction to General Relativity

## by *Zihan Yan*

##### Week 1-6, **Thursdays** and **Tuesdays** 2000-2200 (GMT+8), 24h in total

Newtonian mechanics is useful for our everyday life, the most common motions we see around us are low in velocity (compared with the speed of light) and occur in a rather weak and approximately uniform gravitational field. But, generally, is it good enough to give us the right physics picture and understanding? The answer is no. Problems arose everywhere: Maxwell’s equations suggests that the speed of light in vacuum is independent of observers, which is not compatible with Newtonian mechanics where velocity transformations for different observers are just simple addition/subtraction; Michelson-Morley experiment (1887) supported the above prediction, disproving Newtonian mechanics. This leads to the formulation of Special Relativity. But, when considering (Newtonian) gravity within the framework of SR, it failed since the gravitation in Newtonian picture is assumed as an instantaneous action at a distance which is not allowed in SR (no speed can exceed the speed of light). Also, Newtonian gravitation itself has flaws such as its failure in predict/explain the perihelion precession of Mercury and the bending of light. Thus, to incorporate SR and gravitation, General Relativity was born. I would say it is one of the greatest achievement of human mind and human civilisation obviously by its elegance and accuracy.

This course will be based on the *Introduction to General Relativity for Enthusiasts* course I taught at Centre for Mathematical Sciences, Cambridge during Michaelmas term 2019, and the course materials are far from original (mostly inspired by the *Relativity* course taught by Prof. A. Challinor at Cavendish Laboratory, University of Cambridge). For more information regarding this, please refer to the original page of the course.

The whole lecture series will be roughly 24 hours, in terms of 12 two-hour lectures. The exact timing can be flexible regarding the actual circumstances.

For more information, here is the Guide to Course.

## Lecture Notes

I keep updating the typed notes. Click on the links below to download the notes for each section.

## Lecture Recording

I keep uploading the lecture recording to Bilibili. Click on the links below to view.