Sep 4, 2018
If you want to open an actual door to the past, you’ll have to do it without a doorknob. The patent for the a knob that turns to move a latch inside the door wasn't filed until 1878. Lots of things, from CPR to timezones to sliced bread, that seem like they've been around forever are actually quite young.
Music by Kevin MacLeod.
Links to all the research resources are on the website.