roger penrose

the large, the small and the human mind...
Just came back from the 9th Swiss Biennial in Lucerne on Science, Technics and Aesthetics.

Roger Penrose was a keynote speaker, next to many of his collaborators. Over a decade ago was the last time I saw one of his speeches. It is refreshing to see him in action again and in such good shape at the age of 80. And his old school overhead projector slides are just classic.

Simply scanning the table of contents of his 2004 over 1'000-page physics book, The Road to Reality, gives an idea of the impressive breadth of his expertise. Indeed, the contributions he has made have come from a very diverse array of topics:

• Penrose tilings.
• Penrose diagrams.
• Twistor theory, "according to [which], there is a fundamental underlying role for complex numbers in defining space time structures" (TRTR), linking the physics of the large to the physics of the small.
• Spin networks, used in Loop Quantum Gravity, an alternate unification formalism to String/M-Theory.
• An alternative interpretation of quantum mechanics, called Objective Reduction (OR), where the wave function is a real object and its collapse is triggered by gravitational energy. Moreover, quantum superpositions are related to space time curvature.
• Many contributions in cosmology.
• A couple of years ago, he introduced a novel cosmological model, called Conformal Cyclic Cosmology, in which the infinite expansion of a universe gives rise to a big bang of a new universe (see the picture above.). The theory builds on ideas like conformal (angle preserving) rescaling, the cosmological constant (or dark energy), dark matter, the Weyl curvature hypothesis, entropy, the notion of time (or the lack of, in a universe devoid of matter) and black holes. A prediction of this theory is the existence of concentric anomalies in the cosmic microwave background which are said to have been detected.

His most controversial research has been on the nature of consciousness. Based on his interpretation of quantum mechanics, and arguing with Gödel's theorems, Penrose asserts that the collapse of the wave function, i.e., the choice of state of the superposition, is neither random nor a computational or algorithmic property, but reflects a "transcendent" influence embedded in the fabric of space time at the Planck scale, he calls proto-consciousness.

Stuart Hameroff (anesthesiology, Univ. of Arizona, Tucson) proposed that the place this is happening in the brain is in microtubules. They teamed up and formulated the Orchestrated Objective Reduction (Orch-OR) theory, explaining consciousness as a phenomenon appearing at the threshold between the quantum and the classical world: topological quantum computations in the microtubules in neurons. These computations are proposed to be orchestrated by synaptic inputs and terminated by OR.

Microtubules are protein structures essential for mitosis and which form the cellular "skeleton" contained within the cytoplasm of cells, called cytoskeleton. Importantly, they can be understood as nano-grids with self-organizing and computational properties and underlie the activity in neurons. They have remarkable electronic properties and can be viewed as a new class of condensate. For instance, conductivity does not change with size. See the research of Anirban Bandyopadhyay and colleagues at the NIMS in Japan.

Microtubules have been excessively studied using computer modeling. This allows for the design of drugs that bind to microtubules and have the potential to target various diseases with minimal side-effects, from Alzheimer's to cancer. See the research of Jack Tuszynski (mathematical biology, oncology, Edmonton, Canada).

Penrose has received many awards and honors for his radical and diverse research. And when you see him lecture, one is simply captured by his humorous, passionate and expressive performance. His modesty and non-certainty (often saying things like "perhaps", "if true", "it appears as") make him a very likable great old scientist...