Olbers' paradoxon

classic cosmology question: Why is it dark at night? What are minimal assumptions for answering this, and how would you reply with the knowledge of a FLRW-cosmology? Are there other (astrophysical) explanations you can think of? could you construct an alternative whacky cosmology (i.e. non-FLRW) that would resolve the paradoxon?

bonus question: What’s \((\pi+20)^\mathrm{i}\) with \(\mathrm{i} = \sqrt{-1}\)? surprised?