Jeff Bezos has raised yet another figure that's hard to say out loud with an average salary in mind. His physical artificial intelligence startup, Prometheus, has attracted $12 billion (around 11 billion euros) in a new funding round, at a valuation of $41 billion. And that just a year after the same company raised 6.2 billion in its first round.

Behind the money stand names that rarely miss when they sniff out a profit: besides Bezos himself, JPMorgan Chase, Goldman Sachs and BlackRock joined the stake. In other words, the biggest banks on the planet are putting money on an idea that still has no product on the market, just a promise.

And the promise sounds ambitious even by Silicon Valley standards. Prometheus, co-founded by Bezos and Vik Bajaj (a former co-founder of Verily, Google's biotech arm), is building software they call an "artificial general engineer" - a system that would supposedly design and produce complex physical systems on its own, from jet engines to medicines. For now, 150 people are working on it in offices in San Francisco, London and Zurich.

"Significant productivity in the economy will raise the standard of living," says Bezos - a sentence every billionaire says before automating someone's job. The question not asked at announcements like this is who exactly gets that raised standard, and who is left off the bill.

A figure of 41 billion for a company with no finished product says more about the state of the market than about the technology itself. When money is looking for somewhere to invest, a promise of a "general engineer" is more attractive than any real business with real costs. Whether Prometheus will build a jet engine - or just one more presentation for the next funding round - we are yet to see.