Best of PSE 2016 - Best self-answered post

Question

What was the best self-answered post in 2016?

Self-answered posts exist because the OP solved their own problem, or because they took the time to write up something useful/interesting for the benefit of the community.

Vote either by making a post linking to a self-answered question and giving a brief description of why that self-answered question should win, or by upvoting an existing submission, Voting lasts two weeks, i.e. until Jan 29 2017.

Unfortunately, self-answered questions are not that easy to search for on the direct site search, so here is a query for all of the 2016 ones, in case people find it useful (and which can then be refined by score / by tags / etc.).

This is part of the Best-of PSE 2016. If you are interested in providing a prize bounty for the winner (mostly highly upvoted answer of this meta post), please comment.

Answer 1

My proposal is John Rennie's What is the proper way to explain the twin paradox?, with his answer and appendix, as well as several other answers from different users. It's one of quite a few self-answered posts he's written, including a couple others in 2016.

I took an undergraduate special relativity course during the fall semester last year, and I was introduced to the twin paradox, among other freaky results of special relativity. I read several good explanations of how the paradox is resolved, which helped me quite well. John's self-answered questions-and-answer, however, went a step further by explaining how the Rindler metric fits into all this - an addition that seems to be rather rare in discussions of the twin paradox.

I'm recommending this question-and-answer pair because

1. It deals with a common problem that almost all beginners to special relativity face.
2. It is just as accessible as most treatments of the paradox, while still keeping all the gory details.
3. It combines equations with spacetime diagrams, the latter of which I've found to be extremely useful tools.

Answer 2

My proposal is John Rennie's answer What is time dilation really?.

I think the self answer is very comprehensive and informative.

Answer 3

I'll throw my own hat in here:

Consistent, complete, and generalized description of the quantum harmonic oscillator

The harmonic oscillator is studied so much not only because it models many physical systems, but also because it's a useful exactly solvable system illustrating important principles. This self-answered post concisely lays out a pretty thorough set of relations for the quantum harmonic oscillator using variables and notation that are much more clear than typical textbook treatments.