The Feynman point is actually one 9 longer in tau.

I think that settles the matter.

But is my "i" is the same as your "i" or your "-i"? The physical facts about us cannot settle this question either way. Therefore physicalism is wrong!

I agree that the long manifesto on how "pi is wong" is overdoing it. After all, pi works for all intents and purposes (with one disagreement, and it's not even about the math).

On the other hand, tau, while only being 2pi, does make a number of equations look nicer (or fit how others look, in the example about quadratics), and makes understanding angles in radians more intuitive.

I can't find a good reason to keep pi around for any more than historical purpose, and I was curious if anyone had some. My main reason for not changing to tau is a mix of habit and to avoid confusion for my math professors :)

I claim that -i is the true square root of -1.

Both i and -i are square roots of -1. For any non-zero complex number c there exist n n-th roots, corresponding to a rotationally symmetric partition of a circle centered on the origin into n "wedges" such that one boundary falls along the line joining the origin and c.

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However, on behalf of my left-handed friends, I claim that -i is the true square root of -1.

The map x+iy -> x-iy is an isomorphism. So i and -i are mathematically indistinguishable.