The Biggest Identity Sandpiles and How to Compute Them

When I wrote Beautiful Abelian Sandpiles I wanted to show off some nice images of large identity sandpiles. But the simple algorithm I used was horrendously slow. Showing a sandpile identity that was larger than 100 by 100 took multiple seconds! That's not good enough! I became obsessed with trying to find a faster way, all in an effort to compute bigger and bigger sandpile identities, bigger than…