In our time epoch and location in space, it seems that even if we received signals of some extraterrestial civilization, or detect some extrasolar inhabitable planet, unless we would achieve some huge breakthroughs it would be impossible to ever visit each other. But can we conceive of other places where star density is much higher than in our vicinity, or perhaps much earlier epochs when the universe was much smaller so all stars were much closer to each other, where several inhabitable planets may have been close enough to each other so as to make space travel between them for any eventual advanced civilizations developing in them feasible? A related question, would life have been possible at those much earlier epochs when star systems were much more densely packed? As from which age of the universe would heavy elements be present in enough quantity so as to permit life to emerge in suitable planets? Or were cosmic cataclysms too frequent for any emerging life to survive for long enough?