I think first we have to agree that a) aliens and humans are similar enough to even recognize the other as both life and intelligence and b) the alien must have some existence that experiences the physical universe in a way that is consistent with how humans do.
I think given these two (very general) requirements the clear way for that alien civilization to get our notice would be to modulate the emissions from their galaxy in a way that cannot be due to a natural state or natural process.
I think it would be necessary that the two civilizations have some shared understanding of how the universe really works (I don’t really think we do yet). If not then all the signally will simply be seen as unusual natural phenomena that needs to be explained. This of course has me wondering just how much of our current cosmology is the equivalent of the alien civilization trying to figure our what natural process produces the radios signals they see which were actually just the broadcast of Two and a Half Men or Married with Children.
modulate the emissions from their galaxy in a way that cannot be due to a natural state or natural process.
OK, what is the modulation, and when would we have seen it?
Would we notice if a galaxy had an unusual spectrum?
(I think you can’t make a galaxy flicker or anything like that because it is too big. Though seems fine to concentrate the power and then have it flicker.)
I think first we have to agree that a) aliens and humans are similar enough to even recognize the other as both life and intelligence and b) the alien must have some existence that experiences the physical universe in a way that is consistent with how humans do.
I think given these two (very general) requirements the clear way for that alien civilization to get our notice would be to modulate the emissions from their galaxy in a way that cannot be due to a natural state or natural process.
I think it would be necessary that the two civilizations have some shared understanding of how the universe really works (I don’t really think we do yet). If not then all the signally will simply be seen as unusual natural phenomena that needs to be explained. This of course has me wondering just how much of our current cosmology is the equivalent of the alien civilization trying to figure our what natural process produces the radios signals they see which were actually just the broadcast of Two and a Half Men or Married with Children.
OK, what is the modulation, and when would we have seen it?
Would we notice if a galaxy had an unusual spectrum?
(I think you can’t make a galaxy flicker or anything like that because it is too big. Though seems fine to concentrate the power and then have it flicker.)