Noam Shazeer, a key author of the Transformer architecture, has left Google for OpenAI. Google had spent about $2.7 billion to bring him back in 2024 via a licensing deal. Shazeer, an IMO gold medalist, co-wrote Attention Is All You Need and is regarded as the main inventor of modern LLM core technologies. All eight original Transformer authors have now left Google, with two joining OpenAI.