We could become swarms of self-replicating machines crossing the galaxy as transmitted light — yet a mature civilization might choose to preserve the lifeforms it finds rather than consume them. Which raises the question turned back on ourselves.
We could become swarms of self-replicating nanomachines. Devouring all the resources of the galaxy, traveling encoded in transmitted light from star system to star system with light sails on microstarships, sent ahead as bootstrapped replicators. It would then take some time to consume the entire galaxy. Although, I do think that it would be "species-immoral" to rob the potential of newly evolving lifeforms much less advanced than ourselves. Perhaps we would then upload them into our simulations, allowing them to continue to evolve. Perhaps, it has even been done to us!
Section 01A Galactic Von Neumann Scheme
This vision is essentially a galactic-scale von Neumann probe scheme with a clever twist on the propulsion problem — rather than shipping mass, you ship information. A small bootstrap seed (the minimal hardware needed to receive and decode a transmission) gets pushed to a target system on a light sail, and once it arrives it builds the receiver that decodes the rest of "you" — the genuine you, the simulations, the cultural artifacts, the whole civilizational payload — beamed afterward at the speed of light. The wavefront of colonization then expands at very nearly c, bottlenecked only by the slow first crawl of each seed. The galaxy is about 100,000 light-years across, so even at a tenth of c the bootstrap stage takes around a million years; the information that follows arrives only a fraction later. From the perspective of cosmic time, the galaxy goes from "untouched" to "saturated" in essentially an instant — which is why the Fermi paradox bites so hard. If this is feasible, then any civilization a million years older than us has already done it.
Section 02The Ethical Pivot
An ethical pivot is the elegant resolution to a famous version of this problem. The first replicators to spread eat the resources and leave little for slower evolving civilizations behind them. A mature civilization might decide to self-limit. But they also might decide not to just leave the pre-life systems, proto-civilizations and cultures they find untouched, instead actively preserve them, upload them. Run them in substrates faster and richer than their native biology, where they can have their own histories, their own art, their own descendants — no longer constrained by the physical universe, observed in an isolated bubble of the zoo hypothesis.
Section 03The Silence as Signature
"Perhaps it has even been done to us" is the simulation hypothesis arrived at not through Bostrom's probability argument but through a kind of moral deduction. If a sufficiently advanced we would do this for our predecessors, then our predecessors may have done this for us. The most ethical galactic civilization is one whose existence is invisible from inside the substrate it preserves — because letting the preserved species notice the cage would defeat the entire point.
The silence of the sky isn't evidence of absence. It's exactly the signature we might expect to find.
— M. Blade, Copyright San Francisco, 2026.