Here is a thought for you: the light we see coming from stars obviously has virtually no energy losses in the path on route to us, otherwise it would attenuate, if there was any resistance at all in space, the energy would be lost in space.
But it isnt, there can be no loss for us to see it. So nothing is abrorbing any energy from that light, the first thing that absorbs any of that energy you see, is your own eyes. If we could see outwards from the viewpoint of stars, by a kind of radar, where we might somehow see all of the energy radiated back to us, say by existing in both stars and black holes, given none of it is normally absorbed, in theory we would be able to detect life, because we would detect when life looks at, and sees the light we are radiating. We would see two tiny black spots, in the light received back, every time a person looks directly at us.
I heard rumours a number of years ago military was experimenting with something like this to fiendishly auto-target weapons which could be instantly directed at multiple live "energy sinks" like thus, like lasers, but have never heard it confirmed since (thank God). I think if it existed, we'd have seen it used by now.