Compared with its rivals Facebook, Instagram and TikTok Twitter is a minnow. But the deal matters. One reason is that Twitter’s size belies its importance. As a haunt of politicians, pundits and wonks, it does much to set the political weather a digital “public square”, as Mr Musk put it. The world’s best-known engineer gives himself another grand problem to solve. How do you think that twitter public space should change for better?

