Machines were designed to work for extremely long periods before needing repair. Materials were chosen for durability so that structures could last millions or even billions of years.
When parts eventually wore out, they were recycled and used again.
Nothing was thrown away unless it had completely lost its usefulness.
Energy systems also became more advanced.
Instead of producing large amounts of power quickly, most systems focused on producing small but steady amounts of energy over long periods.
Black holes became one of the most valuable energy sources.
Some civilizations built large structures around slowly rotating black holes to collect the energy released by matter falling into them.
These systems could provide power for extremely long periods.
Another source of energy came from the slow decay of particles and the faint radiation that still existed throughout the universe.
