Why do all size distributions look Weibull?


Where do Weibull or shifted/cut-off power functions come from?
Suggestion: Use Coalescence Theory
used to model size distributions of populations of
         physical objects that merge in nature 
applied to: formation of cloud droplets, bubbles, polymers, 
         stars, Universe...

Idea: Objects merge together, size = sum of both sizes
Rate of aggregation depends upon both objects' sizes
Special case: multiplicative coalescence, where
         probability of merging ~ product of sizes