As with SpaceX, then, Mr Musk is gambling Tesla’s future on AI, and his belief that he can harness his existing businesses to dominate the technology. Plenty of doubters have scoffed at his grand ambitions before. But never has Mr Musk put so much on the line. ■

Musk's memo announcing SpaceX and xAI's merger is full of space jargon. Here's your cheat sheet to bring the wonky language back down to Earth.