It started out with a Manifesto at ChangeThis about not buying more stuff than you need and a clothing company that is trying to create a society of abundance (not by making more stuff, but by getting people to be happy with less things), and it quickly wandered all over the place from there.
After taking in the story about Local Lucy and the Tale of Two Tomatos, I was soon marvelling at the massive engines and other parts at How Diesel Locomotives Work and all the cool switches the engineer gets to play with when he starts the engine. One of the many things I did not know about trains was that the diesel engines on a train are 2-cycle instead of 4-cycle, and as a consequence of that, they have to be turbo-charged or super-charged.
This led me into the land of supercharging stock car engines, where I learned that unlike modern turbochargers which are radial turbines; the best superchargers use positive displacement pumps, the most favored being the twin screw design. This is same style of compressor that is used on the first stage of high volume industrial air compressors which I had been studying previously, because compression (with cooling and subsequent expansion), is one way to cool air down enough that it liquifies and with care can be seperated into its various gasses (argon, nitrogen, oxygen).
But that's a story for another day.