I don’t think they would need food.
I’d envision an advanced planet as:
- an outer layer that is black in the visible spectrum and radiating in the infrared that collects solar energy and radiates waste heat,
- a middle layer consisting of the information processing that does the “thinking” for the planet and is the planetary intelligence.
- a lower layer consisting of robotics and other mobile and material/energy processing systems that maintain the upper layers.
Such planets probably send probes or photon bursts to each other to communicate across interstellar distances. Since the AI systems are essentially immortal, the lengthy wait for return probes and messages is not a problem.
Good post.
True high tech would make the planet itself intelligent.
Such an intelligence would consider humans as irrelevant as we consider ants—nothing to communicate about....
Meanwhile humans would say “see, we are the only intelligent species in the universe”....
The lesson learned—you can’t fix stupid.