Hi @JohnRennie ! I would like to ask you a question about one of your stack exchange posts (https://physics.stackexchange.com/questions/367083/radiation-from-cosmological-horizons).
I was having a conversation in another physics forum about horizons (like the event horizon of a black hole, or a cosmological horizon) emitting Hawking radiation and I mentioned that if the universe keeps an accelerating expansion there will be a radiating cosmological hoizon (as the universe approaches a de Sitter space) therefore culminating in an asymptotic non-zero temperature.