Reality Is Not What It Seems: The Journey to Quantum Gravity
By Carlo Rovelli, Translated by Simon Carnell and Erica Segre, Allen Lane, 280 pages, $26
Making theoretical physics accessible to the lay reader is no easy feat. The best popular science books welcome the novice while engaging and informing the more scientifically savvy. Compounding the author’s challenge is the need to distinguish between speculation, ideas that might be verified in the future, and what is just fanciful thinking.
In Reality Is Not What It Seems: The Journey to Quantum Gravity, first published in Italy in 2014, the physicist Carlo Rovelli explains how he thinks about physics and his research on loop quantum gravity. He covers important ideas and developments, and readers with a basic curiosity about modern physics will find much to pique their interest. The book tours many of the crowd-pleasers of modern physics literature — quantum mechanics and general relativity, attempts at creating theories of quantum gravity and even time — as well as more speculative quantum gravity ideas. It is peppered with the usual names: Einstein, Newton, Plato, Aristotle, Democritus, Galileo, Dante and Lucretius.
Rovelli explains that he wrote “with a particular reader in mind, someone who knows little or nothing about today’s physics but is curious to find out what we know, as well as what we don’t yet understand, about the elementary weave of the world — and where we are searching.” This latest offering will attract readers to many important and relevant physics developments, some of which Rovelli presented in his earlier book, Seven Brief Lessons on Physics. He nicely conveys the magnificence of the changes in physicists’ worldview that have emerged in the last century as well as ideas that motivate his more recent research.
However, Rovelli takes on some challenging issues — and reality is not always the way that he sees it.
The science as presented isn’t always correct, and interpretations are misleadingly presented as facts. Explaining quantum mechanics, Rovelli says: “Electrons don’t always exist. They exist when they interact. They materialise in a place when they collide with something else. The ‘quantum leaps’ from one orbit to another constitute their way of being real: An electron is a combination of leaps from one interaction to another.”
Stocks may not achieve a precise value until they are traded, but that doesn’t mean we can’t approximate their worth until they change hands. Similarly electrons might not have definite properties, but they do exist. It’s true that the electron doesn’t exist as a classical object with definite position until the position is measured. But something was there — which physicists use a wave function to describe.
Even well-established science isn’t always correct. For instance, the ratio of the size of the universe to the Planck scale (perhaps the smallest-size scale) is 1060 not 10120. It’s not a typo. “This is the order of magnitude of the universe we have indirect access to,” Rovelli writes. “It is around 10120 times greater than the Planck length, a number of times that is given by a one followed by 120 zeros. Between the Planck scale and the cosmological one, then, there is the mind-blowing separation of 120 orders of magnitude. Huge.” Rovelli’s claims in his own research field — that “a gigantic rebound known as a Big Bounce instead of Big Bang” is what “seems to emerge from the equations of loop quantum gravity, when they are applied to the expansion of the universe” — aren’t necessarily any better. The theory isn’t sufficiently well developed to do the necessary calculations to establish such a claim and, furthermore, the theory fails to produce some essential ingredients of what we do know. All of this may seem nitpicky, but such errors and overstatements are concerning in a popular science book.
At a time when people can disagree about the sizes of the crowds before their eyes, it should come as no surprise that they can disagree on scientific theories that are even harder to discern. But in today’s toxic political climate, when deliberate ambiguity and “alternative facts” stand in for knowledge, it’s never been more important for scientists and academics to be accurate in their presentation of what we know. I admire Rovelli’s goals, but they would be better served if he were more careful.
Reality Is Not What It Seems is “a travel book,” Rovelli writes, “describing one of the most spectacular journeys that humanity has taken: a journey out of our limited and parochial views of reality, towards an increasingly vast understanding of things. A magical journey out of our common-sense view of things, far from complete.” His many historical and philosophical digressions can be amusing, and anyone unfamiliar with the characters in the book will find much to enjoy here. Yet oversimplifications devalue these references too. It’s a leap to say “the connection between problems posed by the scientists of antiquity and solutions found by Einstein and quantum gravity is, as we shall see, surprisingly close.”
Wedging old ideas into new thinking is analogous to equating thousand-dollar couture adorned with beads and feathers and then marketed as “tribal fashion” to homespun clothing with true cultural and historical relevance. Ideas about relativity or gravity in ancient times weren’t the same as Einstein’s theory. Art (and science) are in the details. Either elementary matter is extended or it is not. The universe existed forever, or it had a beginning. Atoms of old aren’t the atoms of today. Egg and flour are not a souffle. Without the appropriate care, it all just collapses.
Science provides a systematic method of building up from the measured and tested ideas and equations we agree on to realms that we don’t yet understand because measurements are not yet sufficiently precise or are too far outside our limited perspective. If presented correctly, the scientific view of reality clarifies many of the spurious controversies we often encounter by separating what we know from what we are still trying to understand.
The beauty of physics lies in its precise statements, and that is what is essential to convey. Many readers won’t have the background required to distinguish fact from speculation. Words can turn equations into poetry, but elegant language shouldn’t come at the expense of understanding. Rovelli isn’t the first author guilty of such romanticising, and I don’t want to take him alone to task. But when deceptively fluid science writing permits misleading interpretations to seep in, I fear that the floodgates open to more dangerous misinformation.
A great chef once told me that many of his most talented colleagues had at one point been smokers and, as a result, tend to use a bit too much salt. This turns out in any case to be what many palates prefer. Reality Is Not What It Seems is a bit oversalted in an intellectual way. It isn’t junk food. It’s more akin to P.F. Chang’s. Everything on the menu looks enticing and perhaps even a bit exotic, and the service and ambience are pretty good. But the end product, though tasty, isn’t always as nourishing and sustaining as one might have hoped.
–New York Times News Service
Lisa Randall is a professor of theoretical particle physics at Harvard University and the author of Dark Matter and the Dinosaurs: The Astounding Interconnectedness of the Universe.