Apologies for the hyperbole in the title, but if we are to believe this BBC article on National Tau Day, pi has provoked violent anger in people
“They feel like they’ve been lied to their whole lives, so it’s amazing how many people express their displeasure with pi in the strongest possible terms – often involving profanity.
“I don’t condone any actual violence…”
So I’m nailing my colours to the mast, with suitable hyperbole, but I’m sticking with pi. I think we should save it.
The tau-ists movement is purely a notational one, something its leader, Dr Michael Hartl, openly admits.
“When I say pi is wrong, it doesn’t have any flaws in its definition – it is what you think it is, a ratio of circumference to diameter. But circles are not about diameters, they’re about radii.”
I’m not just unimpressed by the fact this is purely a nit-pick with convention, however. My concern extends to the fact that this is a somewhat limited view of pi, and it ignores the fact that using pi produces far more elegant mathematical presentation.
Hartl seems to be deeply wedded to his circumference based definition of pi.
“What you’re really doing is defining it as the ratio of the circumference to twice the radius, and that factor of two haunts you throughout mathematics.”
Well, no. How about if you use pi to find the area of a circle. Slice your circle up into sectors and place them top to tail so they approximate a rectangle, the more sectors, the better the approximation. Taken to its limit, this rectangle will be a radius in width, and half the circumference in length. The length is pi*r, in fact. But with tau that would be tau*r/2. Eww.
The factor of 1/2 you do not want to be haunted by.
Worse is to come. Pi goes beyond just measuring circles. Euler’s identity combines so beautifully five fundamental constants:
Tau, haunted by that ugly factor 1/2, ruins it.
Don’t get fooled. Say no to tau, and save pi.