PRO TIP Block youtube.com at the DNS level — Pi-hole, NextDNS or your hosts file — but allow youtube-nocookie.com and i.ytimg.com. These tutorials keep playing; the rabbit hole does not.

Gravitational Waves (extra footage)

105.4K views on YouTube

Jan Kooter 185 tutorials here

Physics

Main video: https://youtu.be/hIgZG7A1fqc
Discussed by Ed Copeland and Mike Merrifield.
More on Black Holes from Sixty Symbols: http://bit.ly/Black_Hole_Videos
LIGO: https://www.ligo.caltech.edu