Assuming that neither FTL travel nor communication are possible, and that other intelligent species have life times similar in length to ours (ok, maybe twice as long as ours), how does a society spanning dozens of light years work? It would take more than a generation for information, never mind things, to get from one end of the bubble to the other. How would culture work? How would the economy work? Is it really the same society at both ends of the bubble?