Over even longer periods of time, intelligent civilizations began thinking about problems that would appear far in the future.
They understood that the universe would continue changing for trillions of years. Stars would slowly disappear, galaxies would drift farther apart, and sources of energy would become more limited.
Because of this, scientists started studying how life and knowledge could survive in a universe with fewer stars.
One important idea was long-term energy management.
Civilizations carefully measured how much energy they used and how much they could store. Large systems were created to capture energy from stars while those stars were still active.
This energy was stored in many different forms so it could be used slowly over extremely long periods of time.
Habitats were also redesigned to operate with very low energy requirements.
