No, really, pi is wrong: The Tau Manifesto (Tau Day, 2010)

Agreed, mainly because it's already used so widely in so many very standardized ways (including many constants). Of course, most of the Greek alphabet has been used by convention for one thing or another, and people would find it all but impossible to change those habits.

If the people who support double pi as the true symbol they should be writing papers with a definition of double pi and truly proving to the mathematical community that pi is the wrong definition. I personally think piD is a perfectly sane way to describe pi and that thinking in 180 degrees is just as easy as in 360 degrees.*

I don't think many people would dispute that 2pi is a much more natural angular constant than pi, the haters are absolutely right, we're stuck with all sorts of extraneous and unnatural factors that are simple powers of 2 because of that "mistake".

But long standing convention is hard to break. Every formula list in existence uses pi, as does every textbook, lecture, and problem set. Every formula that people have memorized is in terms of pi, and that's not something you can alter by fiat.

I fear that however well-intended, this may be a losing battle. It reminds me a bit of people complaining about the negative charge on the electron - yeah, you might be "right", and there are certainly some annoyances that we put up with as a result of the "mistake", but it's over a hundred years too late for that to matter, you're never going to get a critical mass of people to change.

Though I will say, at least if a new symbol is used for 2pi, it's possible to get a few people to change over, since using that notation is not mutually exclusive with using pi (whereas the charge of the electron is a choice that has to be made, and if you make a different one from your peers, there's going to be a lot of friction).