How to Invent Everything: A Survival Guide for the Stranded Time Traveler

by Ryan North

You can expect a day that’s about 17.8 seconds shorter for every million years you go back in time.

Polar ice caps can famously grow and shrink, which raises and lowers sea levels and thereby exposes or covers land, but even fully melted, polar ice can change sea levels only so much: 70m when fully melted, to be precise, which results in only about 3 percent less land.

London’s dramatic and hugely expensive sewer system—still in use today—was constructed for entirely the wrong reasons and only happened to improve public health by accident.

But what you really want is an analytical engine: some sort of machine with a crank we can turn (or get another machine to turn for us) that re-creates the steps humans take when reasoning, thereby transforming physical labor into mental processing.