It is a binary question whether their expansion is detectable to us at distances of hundreds or thousands of light years. I actually like something about this i

It is a binary question whether their expansion is detectable to us at distances of hundreds or thousands of light years. I actually like something about this idea - arguably any species that can't learn to live in a sustainable and small footprint won't last long; so any civilization that does survive on astronomical scales had to pass through this filter and might therefore be undetectable to us.