Population ethics in an infinite universe

Population ethics studies the tradeoff between the total number of people who will ever live, and their quality of life. But widely accepted theories in modern cosmology say that spacetime is probably infinite. In this case, its population is also probably infinite, so the quantity/quality tradeoff of population ethics is no longer meaningful. Instead, we face the problem of how to ethically evaluate an infinite population of people dispersed throughout time and space. I propose spatiotemporal Cesàro average utility as a way to make this evaluation, and axiomatically characterize it.