I think he's referring less to the geometry of space(-time) and more to the structure of quantum mechanics. Classical probabilities are positive real numbers t

I think he's referring less to the geometry of space(-time) and more to the structure of quantum mechanics. Classical probabilities are positive real numbers that add up to 1. (The 1-norm of the vector of probabilities is 1.) Quantum ampltiudes are complex numbers whose squared absolute values add up to 1. (The 2-norm of the vector of amplitudes is 1.) A universe made by someone who preferred 1-norms would more likely be classical rather than quantum. For more on this from the author of the linked blogpost, see here: http://www.scottaaronson.com/democritus/lec9.html http://www.scottaaronson.com/democritus/lec9.html or the corresponding bit in his excellent book "Quantum computing since Democritus".