Eternal Inflation, Black Holes, and the Future of Civilizations

We discuss the large-scale structure of the universe in inflationary cosmologyand the implications that it may have for the long-term future of civilizations.Although each civilization is doomed to perish, it may be possible to transmitits accumulated knowledge to future civilizations. We consider several scenariosof this sort. If the cosmological constant is positive, it eventually dominates theuniverse and bubbles of inflationary phase begin to nucleate at a constant rate.Thermalized regions inside these inflating bubbles will give rise to new galaxiesand civilizations. It is possible in principle to send a message to one of them. Itmight even be possible to send a device whose purpose is to recreate anapproximation of the original civilization in the new region. However, the messageor device will almost certainly be intercepted by black holes, which nucleate ata much higher rate than inflating bubbles. Formation of new inflating regionscan also be triggered by gravitational collapse, but again the probability is low,and the number of attempts required for a positive outcome is enormous. Theprobability can be higher if the energy scale of inflation is closer to the Planckscale, but a high energy scale produces a tight bound on the amount of informationthat can be transmitted. One can try to avoid quantum tunneling altogether, butthis requires a violation of quantum inequalities which constrain the magnitudeof negative energy densities. However, the limits of validity of quantuminequalities are not clear, and future research may show that the required violationis in fact possible. Therein lies the hope for the future of civilizations.