Observational Signals of Self-Destructive Civilisations

[Matterplay1]

http://arxiv.org/abs/1507.08530

I note that grey goo (thought to be intentional and aggressive in these scenarios, rather like an all-out nuclear war, rather than purely accidental) is considered as a possibility. Our use of the word 'goo' is not as old-fashioned or as silly as some of us fear, I think, if it makes it into a paper like this one.