Lex Fridman interviewed Penrose on this topic recently (2020) and Penrose delivered a very accessible walkthrough of his historical and current thoughts on the

Lex Fridman interviewed Penrose on this topic recently (2020) and Penrose delivered a very accessible walkthrough of his historical and current thoughts on the topic. https://youtu.be/orMtwOz6Db0?t=2654 https://youtu.be/orMtwOz6Db0?t=2654 (Deep-link half-way through to his discussion on microtubules)