Roger Penrose: Physics of Consciousness and the Infinite Universe | Lex Fridman Podcast #85

The podcast begins with an introduction to Roger Penrose, a renowned physicist, mathematician, and philosopher at the University of Oxford. His significant contributions span across various disciplines, including the mathematical physics of general relativity, cosmology, and the computational view of consciousness. The host expresses the honor of engaging in a conversation with Penrose, emphasizing the importance of embracing curiosity akin to that of a child, which is the underlying theme of the podcast. The recording took place before the pandemic, and the host sends support to those affected by the crisis.

The conversation delves into the portrayal of artificial intelligence in the movie '2001: A Space Odyssey' and its impact on Penrose's views. The discussion explores the concept of a machine, like HAL from the movie, potentially developing consciousness and the ethical implications of such a development. Penrose challenges the idea that consciousness arises solely from complex computation, drawing parallels with the unconscious yet computationally dense cerebellum. He suggests that understanding consciousness may require looking beyond computational models.

Penrose discusses the cerebellum's significant role in computation, highlighting its vast number of neurons and connections. He argues that the cerebellum's unconscious nature, despite its computational prowess, challenges the notion that computation alone gives rise to consciousness. The conversation touches on the unique structure and function of the cerebrum, suggesting that there may be aspects of consciousness that are not governed by computational rules.

Penrose recounts his experience with Godel's Incompleteness Theorems, which profoundly influenced his understanding of mathematics and computation. He explains how these theorems demonstrate the existence of true mathematical statements that cannot be proven within a formal system, challenging the idea of a universal Turing machine's ability to solve all computational problems. This revelation led Penrose to consider the nature of understanding and intelligence, which he believes transcend the rules of formal systems.

Penrose explores the concept of 'understanding,' suggesting that it is a quality beyond computational processes. He questions the idea of machines possessing creativity, highlighting the difficulty in defining creativity. Penrose also discusses the importance of understanding in the evolution of species, using examples from nature such as hunting dogs and elephants to illustrate non-human consciousness and its potential advantages in natural selection.

The discussion continues with Penrose contemplating the nature of consciousness and its potential roots in evolution. He considers whether consciousness is a product of biological evolution or if it might have arisen independently in different species. Penrose expresses hope that further research, particularly in the area of microtubules and their potential role in consciousness, will shed light on these mysteries.

Penrose discusses the potential intersection of quantum mechanics and consciousness, suggesting that the principles of quantum mechanics might need to be modified to account for the collapse of the wavefunction and the emergence of consciousness. He highlights the importance of considering the effects of gravity on quantum mechanics and the possibility of a new theory that goes beyond the conventional understanding of quantum mechanics.

The conversation turns to the experimental approach to understanding consciousness, particularly the work of Stuart Hameroff on microtubules and their potential role in consciousness. Penrose discusses the impact of general anesthetics on microtubules and the ongoing experiments aimed at demonstrating the need for a new understanding of quantum mechanics in the context of gravity and consciousness.

Penrose shares his thoughts on the Big Bang, the concept of an infinite universe, and the nature of time. He discusses the conformal cyclic cosmology theory, which posits a cyclic universe with each cycle beginning with a Big Bang and ending with infinite expansion. He also explores the idea of the universe becoming increasingly boring as it expands and black holes evaporate, leading to a cold, empty cosmos.

Penrose reflects on the beauty of complex analysis and the concept of infinity in mathematics. He discusses the introduction of imaginary numbers and their profound impact on solving equations, as well as the significance of complex numbers in quantum mechanics. He also touches on the philosophical question of the nature of mathematical entities, whether they are discovered or invented.

In the concluding part of the conversation, Penrose contemplates the meaning of life, suggesting that it is not a trivial question. He posits that the mysteries of consciousness and quantum mechanics may be interconnected and that understanding these mysteries could provide insights into the purpose and meaning of existence. He emphasizes the importance of maintaining the sense of wonder and curiosity that children possess when exploring the fundamental questions about the universe and our place within it.