you need to think about physics, engineering, thermodynamics and information processing
Like this guy did. Short short version: to get the most out of your star, you drain the energy of the emitted photons until they are (almost) at the temperature of the CMB. Infra-red is still harvestable.
Getting rid of all the stars in one part of space and replacing them with near CMB doesn’t seem to produce what we see: it would produce a raised CMB signal in one direction (would it be strong enough to pick out? How close, exactly, to CMB would it be?), a reduced star density in one region, and presumably a bunch of half-eaten galaxies on the boundary of the region.
The point that “it would be an amazing coincidence if alien engineering just happened to look exactly the same as pristine nature” seems reasonable convincing to me.
I think the idea is not all the stars in a region—it’s one star per civilization. The basic idea is to maximally exploit energy transfer between the star and interstellar space, so optimal efficiency makes the artifact appear from the outside to be as close to interstellar space as possible.
Like this guy did. Short short version: to get the most out of your star, you drain the energy of the emitted photons until they are (almost) at the temperature of the CMB. Infra-red is still harvestable.
Getting rid of all the stars in one part of space and replacing them with near CMB doesn’t seem to produce what we see: it would produce a raised CMB signal in one direction (would it be strong enough to pick out? How close, exactly, to CMB would it be?), a reduced star density in one region, and presumably a bunch of half-eaten galaxies on the boundary of the region.
The point that “it would be an amazing coincidence if alien engineering just happened to look exactly the same as pristine nature” seems reasonable convincing to me.
I think the idea is not all the stars in a region—it’s one star per civilization. The basic idea is to maximally exploit energy transfer between the star and interstellar space, so optimal efficiency makes the artifact appear from the outside to be as close to interstellar space as possible.