Suppose we have a ~1 billion year old civilization a third of the way across the universe, occupying a 0.5 billion light year sphere. What fraction of the sky is that? Is there some fraction of the sky that happens to be especially difficult to see (e.g. because it’s on the other side of the milky way), and how much harder is it to see?
My guess would be that there is at most a negligible probability of this making it really hard for us to see a large alien civilization (if e.g. they had 3 beacons scattered randomly over their territory).
See zone of avoidance. At 7b ly, alien civilization would take up 4 degrees in the sky, and it seems that Milk Way makes more than that hard to see (not impossible though).
It seems that there are definitely some extragalactic objects known in the zone of avoidance, however I haven’t been able to find how far the farthest of them are, or how close to the center they appear. Radio waves pass through dust more easily than visible light, but I don’t think they are entirely unhindered. I have no idea, you might want to ask these questions somewhere like physics.stackexchange, where somebody knows something.
Would be interesting to know:
Suppose we have a ~1 billion year old civilization a third of the way across the universe, occupying a 0.5 billion light year sphere. What fraction of the sky is that? Is there some fraction of the sky that happens to be especially difficult to see (e.g. because it’s on the other side of the milky way), and how much harder is it to see?
My guess would be that there is at most a negligible probability of this making it really hard for us to see a large alien civilization (if e.g. they had 3 beacons scattered randomly over their territory).
See zone of avoidance. At 7b ly, alien civilization would take up 4 degrees in the sky, and it seems that Milk Way makes more than that hard to see (not impossible though).
My impression from wikipedia is that radio transmission is still fine, so radio loud quasars are still easy to detect. Does that sound right?
It seems that there are definitely some extragalactic objects known in the zone of avoidance, however I haven’t been able to find how far the farthest of them are, or how close to the center they appear. Radio waves pass through dust more easily than visible light, but I don’t think they are entirely unhindered. I have no idea, you might want to ask these questions somewhere like physics.stackexchange, where somebody knows something.