And in case it wasn't already obvious, that URL indicates Doug was at the University for a long time. The University stopped letting even its staff pick a username years ago, maybe even decades ago and the default assigned usernames are... a bit dull.
Your colleague i presume?
He also wrote another similar popular article on Relativity, I DO Understand Relativity - https://news.ycombinator.com/item?id=50220891
With article titles like these, i just had to share it on HN!
Somebody should work on the above two webpages to make them more readable with html+pdf formats. That would make these more accessible to the "interested layman".