Brian Greene, one of the world’s foremost string theorists, heads the Centre for Mathematical Physics at Columbia University, New York. He has previously written several compelling expositions of modern physics for the (highly intelligent!) lay reader. This latest book’s eleven chapters, though not formally divided, effectively fall into three groups. The first four chapters, close to the vein of the previous books, provide a pacey stride through both the physical and biological worlds as currently understood by physicists. The next four have a more relaxed pace, reflecting philosophically upon human life. The final three chapters return to physics, ever more wildly speculating upon the long-term fate of the universe.
To go into somewhat more detail, Chap. 1, The Lure of Eternity (one of the shortest chapters, despite the massive reach of its title), toys particularly with our sense of time, and therefore of eternity. Chap. 2, The Language of Time, stresses the importance to us of mass properties, rather than those of individual molecules, and thus approaches statistical laws, especially those of thermodynamics. Chap. 3, Origins and Entropy, refines the concept of entropy in considering the Big Bang, regions of order formed at the expense of increased disorder elsewhere, and the effects of gravity on large volumes of matter. And Chap. 4, the longest of this group, entitled Information and Vitality, and making frequent genuflexions to Schrödinger’s 1943 book What is Life?, manages to consider energy processes in both plant and animal cells, DNA, RNA, the origin of life, and Darwinian evolution both in living systems and in prebiotic ones. To quote from half-way through this account (p. 107), “Life is physics orchestrated”. As a physiologist, I was particularly drawn to this chapter.
We now come to the four chapters which I characterised above as less pacey, more philosophical. This is abundantly the case in Chap. 5, Particles and Consciousness. Though representing himself as an out-and-out reductionist, Greene nevertheless has recognised earlier (p. 72) that “Even the staunch reductionist realizes that, as fatuous as it would be to explain a baseball’s trajectory in terms of molecular motion, it would only be more so to invoke such a microscopic perspective in explaining what a batter was feeling as the pitcher went through his windup, the crowd roared, and the fastball approached. Instead, higher-level stories told in the language of human reflection provide far greater insight”. Gradually, in this new chapter, he approaches that goal. Referring (p. 125) to Nagel’s What is it like to be a Bat?, he recognises that “Even if we had a complete accounting of all the underlying fundamental physics, chemistry, and biology that make a bat a bat, our description would still seem unable to get at the bat’s subjective ‘first- person’ experience. However detailed our material understanding, the inner world of the bat seems beyond reach.” And of course “What’s true for the bat is true for each of us.” The ensuing pages cover a range of ideas, floated by other thinkers, including the suggestion that all the particles of the universe embody some degree of proto-consciousness. “If you’re wondering what proto-consciousness really is or how it’s infused into a particle.... your questions are beyond what anyone ... can answer. .... [But] if you asked me similar questions about mass or electric charge, you would likely go away just as unsatisfied. I don’t know what mass is. I don’t know what electric charge is. What I do know is that mass produces and responds to a gravitational force, and electric charge produces and responds to an electromagnetic force. So, while I can’t tell you what these features of particles are, I can tell you what these features do” (p. 133). Wonderfully tolerant! The discussion then moves to include the widely canvassed notion that quantum uncertainty underlies the puzzle of consciousness. But Brian Greene will have none of this: “Our choices are the result of our particles coursing one way or another through our brains” (p. 147). So are our movements, and our thoughts. This is absolute physicalism – “phooey” to freewill! But, with great respect, I take issue with that dismissal. What matters to me is that, unless I am under external constraints, what I decide to do, I do. The determinist’s picture, as usually painted, implies that physical law will make me do much that I don’t want to – that I shall act against my own will. Such a picture overlooks what “I” consist of. I consist of the sum total of all the influences which have acted on me, at whatever level they may be described – particles, cells, hormones, neurophysiology, genetics, upbringing, what I had for dinner. They all come together to comprise me, at a particular moment. That me, that “I”, decides to act in a certain way, and no external force opposes. Historical and external forces have indeed shaped the “I”, but it is that “I” which decides the action.
It is clear later that our humane and civilised determinist author really under- stands this: “At any given moment, I am my collection of particles; ‘I’ is nothing but a shorthand that signifies my specific particulate configuration” (p. 157). However, caught up in his own commitment to reductionism he falls just short of recognising the philosophical implications of this point. Yet doing so is surely VITAL?
In Chap. 6, theories of the origins of language and of story-telling are explored, though with the comment that there is less consensus on these topics than on the early stages of the universe. Chap. 7 looks sensitively at Brains and Belief. It pays considerable attention to the cognitive scientists of religion, such as Pascal Boyer and Jesse Bering, but ranges widely to draw upon pre-historical finds, the Vedas, the Old Testament (Greene’s upbringing was Jewish), a striking debate with the Dalai Llama, and his own response to the Jewish rituals at the time of his father’s death. He concludes, much like William James, that “if religious practice – or perhaps a better label here would be spiritual practice – is undertaken as an exploration of the mind’s inner world, an inward-directed journey through the inescapably subjective experience of reality, then questions of whether this or that doctrine reflects an objective truth become secondary” (p. 217). Chap. 8, Instinct and Creativity, places great weight on the wordless significance of music; this notably for Einstein, whose edifice of Relativity was based on no new facts but relied on “imagining a simple but fundamental rearrangement of the Lego pieces of reality” (p. 232). So ends what I regard as the middle section of the book.
The final one begins (Chap. 9: Duration and Impermanence) by starting us on an imaginary climb of the Empire State Building, with each floor representing a period of the earth’s history ten times longer than the floor below. We are currently a few steps above Floor 10, but the rate of change is exponential. Only one full floor higher, repulsive gravity and increasing dark energy could blow the whole universe apart in a “Big Rip”. But if dark energy does not increase, it will be worthwhile to climb several floors higher, where more restrained yet still accelerating expansion has taken most galaxies out of our sight, leaving the sky predominantly dark. If the earth has escaped being consumed by the sun’s expansion, by floor 15 its surface will be deadly cold, but life in oceanic thermal vents will be kept warm by deep-core nuclear fusions. On floor 23, however, having dissipated its kinetic energy in gravi- tational waves, the earth will sink into the cold, dark sun. The thought-trip continues many floors further, but the contact with the world we know be- comes exponentially more remote with every floor, so that in Chap. 10 (The Twilight of Time) Black Holes disintegrate, the Higgs Field changes value, and bodiless brains, first contemplated two generations ago by Freeman Dyson, can form. Finally, in Chap. 11, The Nobility of Being, our author reflects (p. 323) “how utterly wondrous it is that a small collection of the universe’s particles can ... examine themselves and the reality they inhabit, determine just how transitory they are, and [yet] with a flitting burst of activity create beauty, establish connection, and illuminate mystery. .... We are ephemeral. We are evanescent. Yet our moment is rare and extraordinary, a recognition that allows us to make life’s impermanence and the scarcity of self-reflective awareness the basis for value and a foundation for gratitude.” The tour de force has run its course, and ends by recognising human value, perhaps unique to the present epoch.
Not that the book strictly ends here, for there are nearly 60 expansive pages of notes, many of them exploring the basic ideas of the main text in more detailed, sophisticated, and sometimes mathematical ways. And final credit must go to a fine index, of more than 20 pages.
A book not to everyone’s taste, but beautifully written and exceptional within its genre.
University of Glasgow
Reprinted from ESSSAT News and Reviews, n. 30:3 (September 2020), pp. 17-20.