How to Invent Everything: A Survival Guide for the Stranded Time Traveler
by Ryan North
Riverhead Books
(c) 2018 by the author

It’s a fun conceit. Your rental time travel machine broke down, leaving you stranded in the distant past. And your FC3000(tm) personal time machine has no user serviceable parts. What do you need to know in order to not just survive or thrive, but start things moving towards an advanced technological civilization?

The book assumes you can manage to make a fire and build some sort of shelter (if your time machine has been damaged to the point where it won’t serve in that capacity, that is). As far as food goes, it gives the standard technique for safely determining if a plant is inedible or poisonous, and the helpful information that virtually all mammals and birds are safe to eat once cooked.

But then what?

It’s not really a science fiction work, although there are occasional winking asides to time travel and how the manufacturer cannot be legally held liable for your device’s failure. The idea is to show just how easy it is to get modern technology from scratch when you know what you are doing, and what you want to get. Turning wolves into dogs? A group of scientists in Russia started with a wild fox population in the late 1950s, and through selective breeding created genetically distinct animals that can be – and are – sold as pets today.

It’s presented as a set of simple overviews, but the reader can easily tie it all together. Knowing how to make charcoal at a large scale and a basic kiln out of clay bricks means you can make a furnace that gets hot enough to smelt ores and make glass – which you can then use to make a simple microscope with which you can show people microorganisms, thereby getting them to accept your Germ Theory of Disease, and therefore convince them that they need to use soap, which you have also invented. Advance knowledge also lets you save time by skipping over intermediate technologies. If your world is at the point where ocean travel is common enough to make worrying about the determination of longitude at sea a major concern, you can probably just skip over the special mechanical clocks and give every ship in the fleet a simple crystal radio receiver….

North mentions in footnotes and asides that there have been occasions where greed and stupidity kept useful technologies from developing and spreading. Flight technology was kept back in the US because the Wright Brothers spent more time suing their rivals (pretty much everybody trying to work on airplanes) than improving their Flyer. People were attaching beads of all sizes and shapes to clothing for thousands of years before someone got the idea to use them as fasteners and invent the button.

Things are given in terms of basic principles and not recipes or formulae. Fair enough; when you’re stuck in the past, coming up with a standard set of units of measurement is likely to be low on your To Do list. The book includes a ten-centimeter ruler on the dust jacket, just in case.

It’s a fun, lighthearted read; with many hints that you can name things after yourself, and how awesome you are because you came up with things in one paragraph that took ordinary humans centuries to figure out. I haven’t found many errors in this well-researched book (yes, there’s a bibliography if you want more information on the details); my complaints are more a matter of disagreements with what was included.

The section on music is nice, I suppose. And it will be fun to take credit for the “Ode to Joy” (which is helpfully included). But I would have trimmed it down to make room for a section on mathematical notation. North does have “Non-Sucky Numbers” (i.e. positional notation with a symbol for zero) as one of his key technologies, but he neglects to mention that without a set of standard symbols to cover the various arithmetical operations and algebraic notation (+, -, =, x, y, z, etc.) you’re stuck doing ALL of your math as word problems. In our timeline, these symbols hadn’t come into common usage until the Renaissance….

There’s also a large section on computers and how logic gates work. I’d scrap this entirely. Even if you can make a functioning computer using water (and pipes and pumps and buckets….) or even dominoes, you’re not going be able to build a practical computer until you get electronics. And by that point in technological development, you’re going to be pretty comfortable anyway, and your scientists can figure it out on their own. I would have replaced it with something on mechanical calculators like the slide rule. Which is rather easy to make, once you know the principle behind logarithms (North includes a table of sines and cosines in his Appendix on trigonometry; how about a table of logarithms? Heck, he could have included a “Cut Out and Fold” paper slide rule in the book itself!) and requires no external source of power to operate.

If you’re lucky, you’ll also be able to pick up the “bandana” version of the book, which distills (distillation is another key technology, by the way) the entire book down to what can fit on a piece of cloth. The cloth, by the way, can also be used to make a sling, cold compress, hot compress, water filter, bandage, and tourniquet….