Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: Exercise: Solve "Thinking Physics", published by Raemon on August 1, 2023 on LessWrong.

Note: please write any answers to this prompt in spoiler-tags.

Recently I set out to deliberate practice at "reasoning about confusing intellectual problems."

Eliezer's Class Project has a fictional group of rationality students try to find the true theory of quantum gravity in one month. This always seemed like a cool goal and test for rationality training to aspire to. If you're not solving difficult open problems faster than science, your Art of Rationality probably isn't complete.

Of course, our Art of Rationality isn't complete yet. But, I think there is something promising in this area, as a way to ground out "rationality training" in something concrete. It seems like good practice to take a given physics question you don't understand the theory behind, and try to invent the theory yourself.

I don't think we're anywhere close to the "definitively impressive" version of rationality practice/training. But, I think a good next step is "Solve Thinking Physics™"

Thinking Physics is a textbook teaching physics "question-first" - it presents a physics-y situation, and asks you to figure out what happens next. The questions are multiple choice, but often fairly tricky nonetheless.

I think a good rationalist-training goal is aim for a goal of "be (correctly) 95% confident in the answer", as a rough proxy for "there were no major lingering confusions about the problem except for generic 'maybe I missed something?'". And, failing that, have the subgoal of at least being calibrated about how confused you. Every time you look at an answer, first log your probabilities for each of the multiple-choices in Fatebook.io (or prediction-tracking tool of your choice).

The problems are set up in a way that you can probably reason about them from some basic background knowledge, without much math background. They're ideal for people who don't have much physics background (since the whole point of the book is to teach you physics), although I know people with got a physics degree 10 years ago who still find it fairly hard.

I spent two weeks working on Thinking Physics problems, and hosting meetups/workshops where other people could join me. With each question, I focused on learning as much as I could about how-to-think.

My original hypothesis was that I could get significantly better at it in 6-8 weeks. I only spent two, and the result so far is I think I'm significantly better although didn't yet hit my goal of 95% accuracy. (In my final test-set, I got 1 out of 5 questions wrong, when I was aiming for zero. I do think I have a pretty clear sense of why I got that 1 question wrong, and what I should have done differently)

After workshopping some ideas for "the Thinking Physics rationality challenge", I now present you with three tiers of challenge.

Challenge I: Solve three problems (and learn from them)

Step 1: Do an exercise.

Spend some time trying to solve three Thinking Physics question. Aim for 95% accuracy, fully deconfusing yourself about each exercise.

Write down your probabilities for each answer.

It's important to actually write down the probability for each answer - otherwise, you may get a vague sense of "yeah that's probably right", that doesn't allow me to cleanly say "I got this one wrong." And doing it for all the answers, not just your favorite one, gives you additional bits about whether your models made any sense. (i.e. having clearly stated "I think answer A is most likely and B is second most likely" gives you a harder update if it turns out that A and B were both wrong)

Step 2: Learn from it

Then, think about how you could have solved the problem better.

Your primary goal is to learn as much as possible from each question.

Babble as many new insights as you can about how to th...