The dream of clean hydrogen has tantalized energy experts for years, but producing it has been tough. Many start-ups think the answer could lie beneath our feet.

Recursive Superintelligence, founded by former Google, Meta and OpenAI researchers, is part of a growing effort to automate the creation of artificial intelligence.

Recursive Superintelligence, founded by former Google, Meta and OpenAI researchers, is part of a growing effort to automate the creation of artificial intelligence.

The start-up, which makes A.I.-backed weapons, was valued at $61 billion in the financing round, double what it was a year ago.

The start-up, which recently released a powerful A.I. model called Mythos and is separately battling with the Pentagon, was previously valued at $380 billion.