If we are inside the colonisation volume, its change will be isotropic and will not look strange for us. For example, if aliens completely eliminated stars of X class as they are the best source of energy, we will not observe it, as there will be no X stars in any direction.
Not a cosmologist but I’d guess that there are enough weird unexplained phenomena in cosmology for it to be possible for aliens to hide in them, or, for us to have just rationalized them away as natural phenomena with fake cosmological theories.
If we are inside the colonisation volume, its change will be isotropic and will not look strange for us. For example, if aliens completely eliminated stars of X class as they are the best source of energy, we will not observe it, as there will be no X stars in any direction.
Not a cosmologist but I’d guess that there are enough weird unexplained phenomena in cosmology for it to be possible for aliens to hide in them, or, for us to have just rationalized them away as natural phenomena with fake cosmological theories.