Style

Most of the style choices I made for the Clear Physics series are driven by two things:

• To make learning easier. Human lifespans are limited, so human understanding will continue to progress only if students can learn faster than their teachers did. Focusing on key insights is one of the most important ways to achieve that goal, but style can help a little, too.
• Ease of maintenance. My own lifespan is limited, so I don't want to spend any more time than necessary on mundane maintenance.

Here are some of my style choices and the specific reasons for them:

• Downloadable PDFs instead of online-only HTML. Physics uses lots of math, both for conveying concepts and for doing calculations. Writing mathy material in LaTeX syntax and posting the result as a standalone PDF file has several advantages, including ease of creation and reliable control over the appearance. Another reason is that compared to web pages, downloadable PDF files can be handled more like hardcopies. Downloaded files can be read without being connected to the internet. PDF files can be edited to save highlights and notes, like writing on a hardcopy. Decent PDF-viewing software should let you quickly flip back-and-forth across different pages using the left/right arrow keys on the keyboard (which is quicker and less distracting than using a mouse), like you can quickly flip through a hardcopy.
• Articles instead of books. Articles are more modular, which simplifies the task of polishing and posting the material for public consumption. Writing a book would have required more long-term planning — choosing the scope, choosing a sequence, choosing a globally-optimized notation, and so on. Trying to write a book would have prevented me from posting anything until I was ready to post everything. I didn't want to wait that long.
• Large font and short sections. The articles use large (14-point) font, and most sections are less than two pages long. Using short sections is meant to make the presentation more inviting and to help the reader focus on taking one small step at a time. The large font enhances those effects, and it also makes the articles easier to read on a computer screen, especially on a phone.
• Each section starts at the top of a page. This little detail is meant to facilitate quickly flipping back and forth between two or more sections, like I mentioned above.
• Non-sequential ID numbers. Each article has a unique ID number, which is important for behind-the-scenes reasons (I use scripts to automate several bookkeeping tasks) in addition to the more obvious reasons. The ID numbers are chosen to be unique, concise, and permanent. That's all. They don't say anything about the sequence in which the articles should be read. Cross-references are much better for that, because the learning process — and also the writing process — is more like a dynamic network than a static sequence.