My Christmas gift: telling you about PurpleMind, which brings CS theory to the YouTube masses
Merry Christmas, everyone! Ho3!
Here’s my beloved daughter baking chocolate chip cookies, which she’ll deliver tomorrow morning with our synagogue to firemen, EMTs, and others who need to work on Christmas Day. My role was limited to taste-testing.
While (I hope you’re sitting down for this) the Aaronson-Moshkovitzes are more of a latke/dreidel family, I grew up surrounded by Christmas and am a lifelong enjoyer of the decorations, the songs and movies (well, some of them), the message of universal goodwill, and even gingerbread and fruitcake.
Therefore, as a Christmas gift to my readers, I hereby present what I now regard as one of the great serendipitous “discoveries” in my career, alongside students like Paul Christiano and Ewin Tang who later became superstars.
Ever since I was a pimply teen, I dreamed of becoming the prophet who’d finally bring the glories of theoretical computer science to the masses—who’d do for that systematically under-sung field what Martin Gardner did for math, Carl Sagan for astronomy, Richard Dawkins for evolutionary biology, Douglas Hofstadter for consciousness and Gödel. Now, with my life half over, I’ve done … well, some in that direction, but vastly less than I’d dreamed.
A month ago, I learned that maybe I can rest easier. For a young man named Aaron Gostein is doing the work I wish I’d done—and he’s doing it using tools I don’t have, and so brilliantly that I could barely improve a pixel.
Aaron recently graduated from Carnegie Mellon, majoring in CS. He’s now moved back to Austin, TX, where he grew up, and where of course I now live as well. (Before anyone confuses our names: mine is Scott Aaronson, even though I’ve gotten hundreds of emails over the years calling me “Aaron.”)
Anyway, here in Austin, Aaron is producing a YouTube channel called PurpleMind. In starting this channel, Aaron was directly inspired by Grant Sanderson’s 3Blue1Brown—a math YouTube channel that I’ve also praised to the skies on this blog—but Aaron has chosen to focus on theoretical computer science.
I first encountered Aaron a month ago, when he emailed asking to interview me about … which topic will it be this time, quantum computing and Bitcoin? quantum computing and AI? AI and watermarking? no, diagonalization as a unifying idea in mathematical logic. That got my attention.
So Aaron came to my office and we talked for 45 minutes. I didn’t expect much to come of it, but then Aaron quickly put out this video, in which I have a few unimportant cameos:
After I watched this, I brought Dana and the kids and even my parents to watch it too. The kids, whose attention spans normally leave much to be desired, were sufficiently engaged that they made me pause every 15 seconds to ask questions (“what would go wrong if you diagonalized a list of all whole numbers, where we know there are only ℵ0 of them?” “aren’t there other strategies that would work just as well as going down the diagonal?”).
Seeing this, I sat the kids down to watch more PurpleMind. Here’s the video on the P versus NP problem:
Here’s one on the famous Karatsuba algorithm, which reduced the number of steps needed to multiply two n-digit numbers from ~n2 to only ~n1.585, and thereby helped inaugurate the entire field of algorithms:
Here’s one on RSA encryption:
Here’s one on how computers quickly generate the huge random prime numbers that RSA and other modern encryption methods need:
These are the only ones we’ve watched so far. Each one strikes me as close to perfection. There are many others (for example, on Diffie-Hellman encryption, the Bernstein-Vazirani quantum algorithm, and calculating pi) that I’m guessing will be equally superb.
In my view, what makes these videos so good is their concreteness, achieved without loss of correctness. When, for example, Aaron talks about Gödel mailing a letter to the dying von Neumann posing what we now know as P vs. NP, or any other historical event, he always shows you an animated reconstruction. When he talks about an algorithm, he always shows you his own Python code, and what happened when he ran the code, and then he invites you to experiment with it too.
I might even say that the results singlehandedly justify the existence of YouTube, as the ten righteous men would’ve saved Sodom—with every crystal-clear animation of a CS concept canceling out a thousand unboxing videos or screamingly-narrated Minecraft play-throughs in the eyes of God.
Strangely, the comments below Aaron’s YouTube videos attack him relentlessly for his use of AI to help generate the animations. To me, it seems clear that AI is the only thing that could let one person, with no production budget to speak of, create animations of this quality and quantity. If people want so badly for the artwork to be 100% human-generated, let them volunteer to create it themselves.
Even as I admire the PurpleMind videos, or the 3Blue1Brown videos before them, a small part of me feels melancholic. From now until death, I expect that I’ll have only the same pedagogical tools that I acquired as a young’un: talking; waving my arms around; quizzing the audience; opening the floor to Q&A; cracking jokes; drawing crude diagrams on a blackboard or whiteboard until the chalk or the markers give out; typing English or LaTeX; the occasional PowerPoint graphic that might (if I’m feeling ambitious) fade in and out or fly across the screen.
Today there are vastly better tools, both human and AI, that make it feasible to create spectacular animations for each and every mathematical concept, as if transferring the imagery directly from mind to mind. In the hands of a master explainer like Grant Sanderson or Aaron Gostein, these tools are tractors to my ox-drawn plow. I’ll be unable to compete in the long term.
But then I reflect that at least I can help this new generation of math and CS popularizers, by continuing to feed them raw material. I can do cameos in their YouTube productions. Or if nothing else, I can bring their jewels to my community’s attention, as I’m doing right now.
Peace on Earth, and to all a good night.