• At least we were consistent in being off by 1000: the solar system travels at 200,000 metres per second around the galactic centre; the Earth at 29,800 metres per second around the sun; and the International Space Station at 7700 metres per second around the Earth (27 June, p 28). We must speed up checking.
• At Igor Pikovski’s request, we make it clear that he is probing the interplay of quantum mechanics and gravity, not quantum gravity (20 June, p 8).
• We should have said that the calculated lifetime of neutrinos produced in the decay of superheavy dark matter is 1011 times the age of the universe (20 June, p 32).
