Robert Cunningham's Blog

Solar prices are falling exponentially, and humanity will soon require huge batteries to store power generated during the day for use at night. The default plan is to use large lithium-based batteries, like the ones in your computer or electric car. But could we do something cheaper for utility-scale energy

I have a solid understanding of microeconomics, but I don't know much about macroeconomics. Last month I read 24 of the 38 chapters in Tabarrok and Cowen's Modern Principles of Economics to remedy this. Here's the most important stuff I learned. GDPYou compute GDP by adding up a nation's final

Solar cost is down linear on a log chart. Solar cost is down linear on a log chart. Solar cost is down linear on a log chart. Solar panel cost is down linear on a log chart.And by the way, world solar adoption is up linear-ish on a log

Reading, writing, and talking all implement the same interface: they act as a valve through which information can enter and exit your brain. But they're not the same. They're great at very different things. Writing is great because you get time and space to think carefully about how to present

Here's a surprising result. Any program that transforms source code must have an input that behaves the same before and after being transformed. In other words, for this input, called a fixed point, the input and output programs behave exactly the same way. Sometimes fixed points are easy to find.

Margaret I broke up with Dustin three months ago. We were watching Breaking Bad, and my phone buzzes, right? So I look over, and it’s a text from Dustin–a long response consoling me about this thing yesterday. But when I look over, he’s glued to the TV!

Before we get into the definition of primitive recursive functions, let me tell you the two surprising things about them. Primitive recursive functions are more powerful than you'd expect from their definition. They can simulate almost all the functions you care about, including addition, multiplication, isPrime, nthPrime, and more.Primitive

Julia's CUDA.jl is famous for letting you run pure Julia on GPUs. This seems impossible, because Julia feels like a scripting language, but it works as advertised: fast and simple with no DSLs or C++ required [0]. Here's an example where we write and execute a CUDA kernel that

Every day, you attend a horse race between three horses. The bookie is giving fair 50%/30%/20% odds (i.e., if the third horse wins they return 1/20% = 5x), but you have inside information and know that the real chances are 70%/20%/10%. You have \$1000 total

This semester I took 18.404 ("Theory of Computation"). It's widely known as being among the best classes at MIT. 18.404 vis-a-vis 1100 other classesProf. Sipser teaches 18.404 in the standard format, with eighty minute lectures on Tuesdays and Thursdays. Perhaps it's because the format is standard that

I tie my raincoat around my waist shortly after we leave. With hard enough rain you get wet, raincoat or not. Might as well feel the rain on your skin. I let the rain soak through my hair, which hangs down in front of my eyes. I can sweep it

Hey! The purpose of this series is to teach you how to design, manufacture, and program a circuit board. Afterwards, you'll be well positioned to work on a simple circuit board that drives something like bluetooth headphones, a quadcopter, or an electric skateboard. My first circuit board <3 (and

What's a rock like granite really made of? It turns out that granite is a mix of two minerals, quartz and feldspar. You can see the individual specs of each if you look closely. The whitest speckles are quartz. The beige speckles are feldspar. The black specs are something else,

I've been deploying a bunch of web apps recently, and it turns out there's one pattern that's so common it might even be called classic. Basically: Each subdomain should get routed to its own docker container. blog.example.com should hit a blogging container, app.example.com should hit a

This post explains call/cc, which is a control flow operator that works like a time machine. Although call/cc is native to the Scheme family of languages, I explain it here with the more widely-accessible TypeScript syntax. call/cc is particularly unusual because you can use it to implement

Disclaimer: this is definitely not legal advice and I am neither a lawyer nor your lawyer. I dreaded cancelling my first LLC for an entire year. In the end, it wasn't nearly as complicated as I had imagined. This post outlines the steps you should follow to shut down your

My fourth semester at MIT is ending, which means it's time for me to take a moment to think about the classes that I took. I'll say a few words about what each class is, why I took it, what I got out of it, and what I thought of

Imagine you're a trader in medieval Europe, looking for a way to defend yourself. You can choose among three weapons. First, there's the dagger. You stick it in your pocket, and when you see someone dangerous on the street, you whip it out, stab them, and run away. Maybe you

Here's something I realized last year: it's OK to be vegetarian because you don't like the idea of killing animals. For much of my life I've had two reasons for being vegetarian: a real one and a fake one. Here's the real reason: there was a moment when I realized

Today I cleaned out my childhood dresser. There were 79 t-shirts in there, from every activity I've ever done. Almost all of them reflected my desire for status. Shirts from schools that admitted me. Shirts from events I won. Shirts from groups that I wanted to feel included in. Shirts

Imagine a foreign planet with three legged chickens, two suns in the sky, exotic megafauna, and pink trees everywhere. Crazy, right? But wait, we have pink trees on earth. You just have to stop and notice them.

I realized over the summer that I still didn't have a clear picture of who I wanted to be. Here's a procedure I used to help uncover the answer. Make a list of a hundred or so people that seem interesting. Lean towards over-including. My list has parents, presidents, teachers,

Here's a realization I had the other day. Nobody's job title is to "make cool stuff happen." When cool stuff happens, it's because someone just like you and me made it happen. And if you want to continue the cycle, you need to make stuff happen. There's a scene in

The Enneagram is a way of dividing personalities into 9 types, sort of like the MBTI. It's totally unscientific, but very much worth learning if you care about understanding people. The Enneagram feels a bit like the color wheel of personality. Knowing the color wheel gives structure to your observations

I noticed yesterday that suppressing emotion has a bodily sensation. It shows up in my sternum when something sad or frustrating happens. My chest muscles tighten, squeezing in a breath, and yet my throat feels open and wide. There's a straining sensation in the top of my throat: my body