Most of those "billions of planets" cannot support life (the exact number of which can is currently unknown). And who says no life evolved "capable of spreading

Most of those "billions of planets" cannot support life (the exact number of which can is currently unknown). And who says no life evolved "capable of spreading out of its gravity well"? > As for Dyson spheres, don't take the remark so literally. Of course it should be taken literally, because all of this is all about what the laws of nature do and don't allow and the practicalities surrounding that. This isn't an class or discussion about what does and doesn't make a good sci-fi story. And what is a "galaxy-spanning slime mould" even? > Life on a ship is depressing? You may as well argue that life in hydrothermal vents would be boring. Yes, it would be. There is no intelligent life living near thermal vents. What an odd thing to say.