New Delhi, Feb. 24 -- "I have to giggle," says Jim Chanos, asked if investors have become overly optimistic about artificial intelligence. "We've got to the 'data-centres-in-space' stage of the cycle." Firms from SpaceX and Blue Origin to Alphabet plan to shrug off earthly constraints on the computing clusters that power AI, and launch them into orbit. To Mr Chanos, who is perhaps Wall Street's most experienced short-seller, such pharaonic ambitions immediately ring alarm bells. Yet even he hesitates to say definitively that share prices are in a bubble: "That's something we'll only be able to tell with hindsight."

You might think that short-sellers like Mr Chanos, who bet on prices falling rather than rising, are looking forward to a bo...