Michael Hartl

I’m Michael Hartl—author, educator, and entrepreneur.

I’m a founder of Learn Enough, an education company dedicated to teaching tech literacy, including key technologies like the command line, text editors, version control, HTML, CSS & Layout, JavaScript, and Ruby. Since 2007, I’ve published over ten books on programming and related subjects.

Learn Enough is an outgrowth of the Ruby on Rails Tutorial, an introduction to web development that Wikipedia founder Jimmy Wales once called his “favorite book”. Since its launch in 2010, the Rails Tutorial has been the leading introduction to web development with Rails. Taken together, the various print editions of the Ruby on Rails Tutorial have garnered over 450 5-star reviews on Amazon.

I’m also (in)famous as the author of The Tau Manifesto, which is dedicated to the proposition that “pi is wrong”—the right number being $\tau\ \mathrm{(tau)} = C/r = 6.283185\ldots$ The Tau Manifesto’s introduction of $\tau$ as the “true circle constant” has had a significant impact on geek culture—for example, in 2012 MIT changed its admissions timing from “Pi Day” (3/14) to “Pi Day at Tau Time” (3/14 at 6:28 p.m.), and the official Google Calculator correctly evaluates tau/2 as $3.14159\ldots$ Meanwhile, its associated holiday, Tau Day, is celebrated annually on 6/28 by thousands of math nerds around the world.

My educational background is in physics, with a bachelor’s degree from Harvard and a Ph.D. from Caltech, where I studied black hole dynamics and was an award-winning instructor in theoretical and computational physics. I’m also an alumnus of Y Combinator, the entrepreneur program that has produced companies such as Reddit, Stripe, Dropbox, and Airbnb.