Why eight (Transbellum)
From Alternative History
The 8 uchronies arise from the fact that only 3 spatial dimensions remained extended in our universe. All the other dimensions collapsed to Plank scale remnants. If we express the number of allowed string vibration states in a quantum-mechanical vacuum for each of the three extended dimensions as x, y and z the number n then turns out to be the vacuum energy for our universe: 
The eight divisors of n correspond to the eight possible three dimensional universes attached to the 10-brane that our universe is attached to: 
often called {Alpha, Beta, Gamma, Delta, Epsilon, Zeta, Eta, Theta}
