Reality Is Not What It Seems: The Journey to Quantum Gravity by Carlo Rovelli
My rating: 3 of 5 stars

Making Space

Quantum Gravity is the closest thing in Physics to a coherent explanation of the origin and fate of the universe - how it began, how it works, how it evolves. Quantum Gravity also has a pretty fair shot to reconcile the apparent paradoxes and contradictions involved in and between the theories of General Relativity and Quantum Mechanics. Most recent scientific observations favour it over alternative theories as the way forward for Physics. But Quantum Gravity does fail to explain one important thing: meaning, including the meaning of the idea of Quantum Gravity.

According to the latest findings of empirical research in Quantum Mechanics, the fundamental constituents of the cosmos are fourteen or so 'quantum fields', the behaviour of which produces, more precisely constitutes, discrete particles of energy and matter. Despite the unintuitive character, and sometimes apparently paradoxical implications of Quantum Mechanics, every scientific test conceived and executed has confirmed its predictions. It is the biggest single scientific truth available at the moment.

Einstein's Theory of General Relativity states that Space and Time are not separate categories of existence but part of a composite Space-time. This may be tough to visualise but Quantum Mechanics makes the picture even less imaginable by portraying Space-time itself as a Quantum Field. Like other fields in Quantum Mechanics, it too is 'quantised', that is, composed of quanta, small indivisible bits. There is thus a smallest Space-time component which sets a definite lower limit not just on how small anything can be but also how densely compacted any material or energy can be. One implication, therefore, is that the mathematical horrors of General Relativity don't occur: the universe did not start as an infinitely dense 'point' at the Big Bang; nor do black holes consist of infinitely dense material.

At this point theoretical Physics starts to get properly spooky. Quantum Gravity considers Space, on its own, as a field. This field is theorised as composed of discrete 'threads', analogous to electromagnetic lines of force, which form 'nodes' when the threads intersect. The threads are conceived as 'loops' which then 'interweave' at the nodes. These nodes are the small, discrete bits of Quantum Space.

The most that can be said at this stage in scientific thought is that Space is somehow 'woven' by these discrete 'threads'. These are effectively, then, atoms of Space, upon which other quantum fields are somehow layered. Perhaps the most astounding aspect of the theory of Quantum Gravity is that Time disappears entirely as a basic component of the universe. Rather, Time is merely a manifestation of the underlying quantum gravitational field. Simple really!

In the world of Quantum Gravity, the principle of cause and effect no longer holds. Space, particles, quanta only exist when they interact. And they only interact probabilistically. Processes have starting points and end points. But a determinate connection between these points does not exist. Particles, quanta, fields interact but they do not cause 'future' states of particles, quanta, and fields because there is no determinate universal 'future'.

Therefore, there can be no sequence involving time. Time simply doesn't exist at the quantum level (happily perhaps because Special Relativity had already shown that time wasn't something anyone wanted to touch with a scientific barge pole). When the tortuously complex detail is put aside, it turns out the entire world is made of one 'Covariant Quantum Field', which includes Space as well as all the other fields of matter and energy layered onto it. Everything that happens in the universe emerges from this unified field.

Well not quite everything. The problem that Rovelli stays as far away from as he can is this: What the Covariant Quantum Field might not produce is Carlo Rovelli contemplating the Covariant Quantum Field. That is, nowhere in the theory is there an indication that anything like an idea, which is immaterial, can be produced. The only products of the field are material: space, energy or matter. None of these constitutes an idea. Nor do they collectively constitute the emotion that Rovelli clearly has about the Covariant Quantum Field. The issue is important to keep science from slipping into ideology, a pattern typical in modern science from Millsian economics to Darwinian biology to Nietzschean philosophy.

Rovelli implies that the Covariant Quantum Field does indeed generate ideas and emotions, at least indirectly, because it is the ultimate foundation of all that exists, including his brain and the readers'. There may be many rungs up the ladder from the field, to fundamental particle interactions, to non-quantum events, and ultimately to life, both human and otherwise. But the field, inevitably, is the ultimate source for all human behaviour, including human thought.

This argument would then include the thoughts of, say, Purpose and Success. Rovelli makes no attempt to explain the precise connections up the great chain of being from the 'sea foam' of the quantum fields to the grey matter of the human brain. But his implication is clear: We, our ideas, our actions, including the writing of a book about the Covariant Quantum Field are generated by the Covariant Quantum Field.

Although Rovelli's presentation is couched in terms of Quantum Gravity, it is precisely the same stand (and the same hubris) taken by generations of classical physicists who believed that the world ran exclusively on Newtonian laws - from atoms right up to professors of physics. It is called Reductionism: the claim that all of existence can be reduced to the laws, rules and observations of a single discipline. Judging by his incidental comments about the harmful effects of religion on science throughout the ages, it is immateriality that is his intended reductionist target. But this gets him into a bit of trouble. Ideas, in particular, don't fit easily into the theory. Any theory that claims universality ultimately has to deal with them.

Rovelli has his own intentions which are stated or implied in the book: to communicate facts and theories, to contribute to the prestige of his discipline, to express his poetic take on science, to establish science's superiority over other modes of inquiry. Finally, he is making a case that science is beneficial for the world; it is successful; it has value. None of these intentions are pure description. They are all ideas and they all involve what we commonly call purpose. And they all clearly have great emotional significance for Rovelli.

Where did these ideas, these purposes, and implicit criteria of success or value along with their emotional baggage come from? Who or what is responsible for them? How are they to be assimilated into political and social life? This book, according to the title, has a claim to defining reality. Any such claim needs more than mere disciplinary or even scientific justification. Physics cannot claim a privileged position. This is Scientism, the presumption the superiority of scientific authority in the description of the world.

One possibility is that Rovelli is being manipulated by Quantum Gravity to investigate itself, and the field is providing him the criteria for successful investigation at the same time. Unlikely as it is that the author would like such an interpretation, it's a logical possibility. Is there an alternative?

Could it be that purpose, intention, emotions are not a properties or implications of the field at all? Could it be that the Covariant Quantum Field has absolutely nothing to say about what is a criterion of better or worse, or of what constitutes success? To admit this possibility would mean that purpose and other ideas, like Quantum Gravity itself, are independent of the field. Such a possibility would require Rovelli's inclusion in the theory not merely as an observer who affects quantum results, but as an evaluator, a judge of the reasons for his inquiry in the first place, one who defines what a result is.

Purpose, for example, could well be what is called in Systems Theory an 'emergent property.' Such a property would not be a simple consequence of the behaviour of the field, neither logically nor physically. Emergent properties can't be predicted on the basis of the interactions in the field. Such an emergent property would fit with the random character of field interactions. But it would also 'transcend' these interactions. That is, some relations and interactions, like Purpose and Success, have the field as a necessary condition, but not as sufficient condition for their existence. Something else has to contribute.

Rovelli accepts the relativity involved in modern physics. But he doesn't like the relativity implied by differences in Purpose and Success, what might conveniently, if somewhat loosely, be called Politics, the process of the establishment of value. He considers particles but not people to be defined by their relationships. On the one hand he clearly detests religion for its dogmatic stance on truth and about what's important. On the other hand, he dislikes modern philosophy for its challenge to dogmatic claims to truth and about what's important. Only physical scientists, it seems for Rovelli, have the imaginative skill to understand the world and to express it adequately. This is not just a cosmology, it is a cosmological ideology.*

He is therefore ambiguous about what Quantum Gravity really means. He can only state rather tired cliches about the superiority of scientific method - science as exploring new ways of thinking; tireless scientific genius; religion, particularly monotheism, as an enemy to thought; philosophy as misleading nonsense. What he means by scientific method are the procedures and criteria he and his colleagues employ at the moment, whatever they are. But he doesn't want the philosophical arguments that justify his freedom applied generally. This he sees as 'relativism.' He wants the theory Quantum Gravity accepted by the public. But he doesn't want current theories to be taken literally, that is to be interpreted by non-scientists, as a description of the world. He wants us to rely on the experts to know what Quantum Gravity implies and to leave what it means alone.

In short, he wants power to realise his intentions. Ideologies are ideas that justify power. In this case, the power of physicists to establish the definition and boundaries of reality. Ideologies work by limiting the scope of what can be considered real and important, by prescribing what's valuable. The ideological import of the book is apparent in the title, and subtly confirmed in its content.

Is there space in Quantum Gravity for something else?

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* An important clue to Rovelli's ideological intent is his inclusion of Shannon's Theory of Information to support the conjectures of Quantum Gravity. Written in 1948, this theory is hardly state of the art. However it does have a compatibility with Rovelli's point of view. It 'reduces' all of reality to bits of digital information. It is this theory which inspired the Beam Me Up Scottie of Star Trek as well as Neal Stephenson's Cryptonomicon. It is also an idealised description of the totalitarian state in which all individuals are the information stored about them. Theories of this sort are not simply descriptions of the world. They transform easily and almost invisibly from method to ideology. Shannon's theory for example played a large part in the influence of Cybernetics in the 20 years following WWII. Cybernetics as an ideology deflected public and scientific attention away fro the discussion of ends, purpose, to the discussion of means, mainly the technology of industrial efficiency and war. See GR review of Kurt Vonnegut's novel Player Piano.

Contrast Shannon's reductionist's theory of information with that a semiotic theory of information. In Semiotics the unit of analysis is called a 'sign'. A sign is something that can be interpreted as having a meaning, which is something other than itself, and which is therefore able to communicate information to the one interpreting or decoding the sign. In Semiotics, words are signs, behaviour is a sign, anything with a potential meaning is a sign. So the Covariant Quantum Field is a sign. In fact a person is also a sign. Defined as a sign, a person is not 'decomposed' into bits, but taken as an entire human entity. This entity can, in fact insists upon, being interpreted and interpreting. It is not constituted by anything other than itself. Like quantum particles, a sign is always relative to other signs but not subordinate. Unlike quantum particles, the human sign can love. Perhaps Professor Rovelli might consider this sign as an alternative reality.

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