The relativistic reason for quantum probability amplitudes
The paper derives quantum mechanics' probability distribution by imposing three natural conditions on a relativistically invariant probability function describing particle motion: pairwise Kolmogorov additivity, time symmetry, and Bayes' rule. These constraints uniquely lead to the Feynman path-integral formulation, showing that adding complex amplitudes before squaring is a mathematical necessity arising from relativistic invariance and minimal probabilistic rules.