we should be able to notice this for galaxies orders of magnitude farther away than Andromeda.
If it happened long enough ago for the signal to reach us. Andromeda is close (2.5 millions light years), but for a galaxy two orders of magnitude farther away (250 millions light years away), this starts being significant : maybe there is a galaxy whose Dysonification started 250 millions of years ago, and was completed 200 millions of years ago, but we don’t see it because the signal didn’t reach us yet.
If it happened long enough ago for the signal to reach us. Andromeda is close (2.5 millions light years), but for a galaxy two orders of magnitude farther away (250 millions light years away), this starts being significant : maybe there is a galaxy whose Dysonification started 250 millions of years ago, and was completed 200 millions of years ago, but we don’t see it because the signal didn’t reach us yet.