re: Dark Matter Whimsy
Very nicely done. Almost started looking up info on Dr. Allen.
So if we can see a galaxy, that means there are no seriously advanced technological life forms in it (yet). Of course they could contain a whole
bunch of Kardashev 2s on their way to becoming a KTC 3. And we have
to keep in mind that just about every galaxy we can see is as it was
millions of years ago - so things may have changed by now.
We should keep watch for dimming galaxies and stars in our galaxy.