---
layout: post
title: "Space-Time"
date: 1961-11-28
categories: "Lecture Notes"
---

## Lorentz transformation

$$
\begin{equation}\label{lorentz}
\begin{aligned}
x' &= \frac{x-ut/c^2}{\sqrt{1-u^2/c^2}} \\
t' &= \frac{t-ux/c^2}{\sqrt{1-u^2/c^2}}\\
y' &= y \\
z' &= z
\end{aligned}
\end{equation}
$$

## Rotation

$$
\begin{equation}\label{rotation}
\begin{aligned}
x' &= x\cos(\theta) + y\sin(\theta) \\
y' &= y\cos(\theta) - x\sin(\theta) \\
z' &= z \\
t' &= t
\end{aligned}
\end{equation}
$$

Equation \eqref{lorentz} is beautiful. So is equation \eqref{rotation}.

## References

- [The Feynman Lectures on Physics First Year Photos (1961‑62) Lecture 17](https://www.feynmanlectures.caltech.edu/flpphotos.html#17)
- [Lorentz transformation on Wikipedia](https://en.wikipedia.org/wiki/Lorentz_transformation)
