Explorable
How far to your twin?
Pick what must match, how finely, and whether space is infinite, and see the order-of-magnitude distance to an exact copy — with every assumption explicit.
Region that must match exactly: a sphere of radius 100 light-years (Tegmark’s example).
Written out in meters, that distance would need about 1092 digits. Treat it as a very rough guess: rounding choices alone (base 2 or 10, the cube root, the region size) move the top exponent by about one, while the slot size and counting rule move it by many units. A 2 m sphere at 108 K gives about 101038 m; Tegmark’s 101028 m for “you” would need slots about 0.3 nm across (around 25 K here). His published values for a 100-light-year sphere are 101092 m (Sci. Am.) or 101091 m (arXiv); for a Hubble volume, 1010118 or 1010115 m.
The physics, the assumptions behind this tool and the sources are explained in If the universe is infinite, is there another you?.