CHAPTER 10: THE EMPEROR'S NEW MIND

We discussed in Chapter 2 the path of twentieth-century physics, and the rankings of centuries of scientific thought that Roger Penrose presents in his 1989 book, The Emperor’s New Mind: Concerning Computers, Minds, and the Laws of Physics. Penrose is a prominent University of Oxford mathematician who has made major contributions to modern physics. His 1989 book—aimed at the popular market although with significant scientific substance—speculated on the nature of consciousness.

Penrose mentions that he’s been asked how he would rank a theory of physics—twistor theory—that he himself has been developing over the years as a proposed reconciliation of quantum physics with general relativity. Penrose answers that twistor theory can be placed no higher than “tentative.” It certainly can’t be any higher up on the scale that Penrose would rate his speculations on consciousness, with which he closes The Emperor’s New Mind.

Penrose is clearly of the school that consciousness goes beyond the simple accumulation of more and more complex algorithmic capabilities. Therefore, Penrose is not within the Strong A. I. school of artificial intelligence that advocates that computers either now have a mind, or at least will soon have a mind once we have exceeded a critical mass of computational capacity and speed.

Penrose supports his argument against the Strong A. I. philosophy by invoking the Gödel incompleteness theorem, by which the early-twentieth-century logician and mathematician Kurt Gödel proved that no mathematical system—no formal system of logic of any type—can ever be truly complete, in the sense of proving everything within its scope. This, in Penrose’s argument, contradicts any claim that a mechanical computational system will ever replicate the complexity of the mind and human intelligence.

Penrose speculates that consciousness involves access to the universe’s idealized concepts; these are the Platonic ideals of centuries-old philosophy. In Plato’s formulation, it is not our typically understood physical world that is real; what’s truly real are forms and ideas. The physical world is a mere shadow of the real world of forms and ideas.

When the mind perceives one of the mathematical concepts of Plato’s worldview, the mind is making contact with this world. Our experience of grasping a concept is a holistic experiences of seeing at once, as a whole, the solution to a problem. Or, as Penrose cites, it’s Mozart discussing how he seizes at a glance an entire musical composition: “It does not come to me successively . . . but in its entirety that my imagination lets me hear it.”

Before our mind reaches these kernels of understanding, Penrose proposes, a physiological process within the brain allows the brain to form these ideas. The process involves physical brain activity—rapid trials of combinations of growing and contracting dendritic spines, which stretch out to the synapses that separate a nerve cell from its neighbor.

These trials take place under the radar screen. They must be short-lived, because the nonvalid trials would otherwise be detected through the electromagnetic fields that they would produce. And the trials must take place below the one-graviton level.

Now . . . the one-graviton level . . . this is exciting stuff! Remember: the graviton is the particle that, according to quantum physics, transmits the force of gravity. The graviton is indivisible—it’s an elementary particle, and therefore it gives us the lower limit for the size of a granule of gravity. The smallest granule of gravity would be that transmitted by one graviton. And since gravity reshapes space, another way of saying the same thing is: the smallest disturbance of the shape of space that can be produced is that produced by one graviton. Above this level, we are operating in the world of measurable certainty. At this level and below, we are operating in quantum physics’ world of uncertainty, a world where things don’t exist with single-point definiteness, but instead have various probabilities as to the form in which they can precisely exist.

How small is this? Penrose makes a rough estimate that, measured in terms of mass, the one-graviton level is one ten-millionth of a gram, 10^-7 grams, which for the quantum world is very big. A hydrogen atom has mass one hundred million billion times smaller (that is, mass of 10^-24 grams).

Gravity is such a weak force that it requires mass enormously larger than an atom before gravity’s elementary particle can transmit or sense gravity. But we’ll sense a hydrogen atom electromagnetically long before we’ll sense it gravitationally. Penrose is proposing a quantum gravitational window, without detection aided by other forces, and he’s relying on the additional constraint of a short time duration to avoid electromagnetic detection.

So our brain has a window of opportunity within which to toy with possibilities for dendritic spine construction. How does the brain settle on its ultimate choice?

Penrose goes on. In part, the construction is influenced by the physiology and chemistry of its environment. So the construction depends in part on our emotional state and on the preexisting state of our brain and its connections.

But what provides the core decision-making criterion? How is a final dendrite construction settled on when our mind grasps a concept or glimpses a new symphonic work?

Here, Penrose takes this even further. His answer is quantum gravity, which is also the (still not found) answer to the question of how general relativity is to be reconciled with quantum physics.

Penrose has frequently collaborated with Stuart Hameroff, who has extensively studied microtubules, which give shape to our neurons and through which neuronal chemicals pass. Hameroff, tracing the evolution of life, marks the incorporation of microtubules into the modern cell as taking place about 1.5 billion years ago, as part of a general symbiotic merger of previously independent organelles (cell parts). A billion years later, during the Cambrian period which began 540 million years ago, there was a vast and abrupt emergence of varied lifeforms—the Cambrian explosion—which Hameroff attributes directly to the early precedents of consciousness that microtubules permit.

Penrose and Hameroff propose these microtubules as our brain’s link—through orchestrated reduction—to the collapse (reduction) of the quantum wave function: many neuronal microtubules, acting in concert (orchestrated), create an act of consciousness linked to the quantum physical world.

Penrose is not presenting the full story; he is looking first for the correct understanding of quantum gravity to be developed. It is Penrose’s belief that, through this understanding, the phenomenon of consciousness may be elucidated.

Penrose emphasizes the noncomputable nature of consciousness, and he expects to find an analogous noncomputability in our ultimate understanding of quantum gravity. But he warns: consciousness “will fit only very uncomfortably into our present conventional space-time descriptions.”

Reactions to The Emperor’s New Mind

In 1990, the year after the publication of The Emperor’s New Mind, the journal Behavioral and Brain Sciences published a summary by Penrose of The Emperor’s New Mind, as well as peer commentary on the book. Commentary from thirty-seven scientists was published, with most of this commentary raising questions about various aspects of Penrose’s conclusions. The journal also included Penrose’s response to the peer comments.

The criticisms concerned many aspects of Penrose’s mathematical, philosophical, and biological arguments, as well as his applications of physics to the realm of consciousness. Penrose has not backed away from his arguments, either in his Behavioral and Brain Sciences response, or in his expansion of his theories in his subsequent book, Shadows of the Mind: A Search for the Missing Science of Consciousness, and elsewhere.

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NEW PHYSICS AND THE MIND, although aimed at the general reading public, is intensively researched and sourced. See NEW PHYSICS AND THE MIND for the endnotes associated with this excerpt, as well as for a complete bibliography of the works referenced throughout NEW PHYSICS AND THE MIND.