Reality Is Not What It Seems: The Journey to Quantum Gravity

  • By Carlo Rovelli
  • Riverhead Books
  • 288 pp.

Making science understandable to the rest of us.

Most people would rather go to the dentist than read about physics.

Still, this didn’t stop Stephen Hawking’s A Brief History of Time from selling 10 million copies worldwide. It did, however, catapult the book to becoming one of the best-known instances of “bought but not read.” The issue became so acute that Hawking published an abridged version, A Briefer History of Time, which is surely a scientific and literary sad trombone.

Presenting a coherent picture without losing your readers is a dilemma that scientists, especially those working in math-heavy fields, face when they write books for the general public. Italian astrophysicist Carlo Rovelli’s bestselling Seven Brief Lessons on Physics used a different strategy than Hawking’s book: totaling fewer than 100 pages, it comprised short essays, each exploring a single concept using concise yet poetic language.

His new book, Reality Is Not What It Seems, is billed as a fuller treatment of the material in Seven Brief Lessons, with a special emphasis on Rovelli’s own field, quantum gravity.

Rovelli starts at the beginning…not the Big Bang, but ancient Greece. The first half of the book traces the evolution of thinking about the nature of reality, from Democritus to Newton to Einstein. It’s a well-done introduction to these ideas, but there’s nothing novel about it.

Indeed, it’s a traditional approach that would, save for Rovelli’s compelling prose, veer toward textbook. His strange choice to title some subchapters with the first names of the physicists whose work he’s discussing (“Matvei”; “Niels, Werner, and Paul”) does nothing to humanize these folks. I’m no more likely to think of Einstein as “Albert” now than I was before reading.

Rovelli’s discussion does drive home the way which great new theories in physics tend to integrate previously disparate ideas. Quantum gravity does this in a profound manner, and as Rovelli moves into the meat of this theory, things get more interesting and more than a little mind-blowing. Quantum gravity proposes a great unity to the universe. Space and time, waves and particles, energy and matter: All are the same. Continuity does not exist, and thus, neither does infinity.

Two different types of questions arose as I read. The first type was around ticky-tack details: Rovelli sometimes doesn’t realize what laypeople don’t know, and in the quest for brevity, explanations are skipped.

Take, for instance, the second sentence of the section introducing quantum mechanics: “In 1900, the German physicist Max Planck tries to compute the amount of electromagnetic waves in equilibrium in a hot box.”

At this point, the reader has been introduced to electromagnetic waves, but what in the world is a hot box? What does it mean for electromagnetic waves to be in equilibrium? How did Planck try to measure this? Why did he care? A bigger problem is it’s not clear from the text or brief endnotes and bibliography where an interested reader should go to find out more about this or anything else.

The second kind of question was more profound. Quantum gravity seems to nullify the relevance of standard late-night dorm room questions like: How can there be a beginning or end to time? And: How could the whole universe have been squeezed into a singularity before the Big Bang? But its implications also raise questions. Why, for instance, has our neural circuitry evolved so that we perceive the universe in a way that’s so different from its true nature?

Part of the answer seems to be scale. Living things exist on scales intermediate between the very small and very large scales where quantum gravity reigns. This is why Newtonian physics worked perfectly well for several centuries: Nothing in human experience fell outside of it. This is also why the detection of gravitational waves last year required such an incredibly large and complex setup.

Rovelli clearly prizes the opportunity to communicate with the public. He wants to convey his enthusiasm not just for his field but for all science, scientific thinking, and the scientific method. He wants to show how science connects with philosophy and the arts.

He even wants to make physics less like the dentist, and emphasizes how Einstein himself, though a great conceptual thinker, was not a great mathematician (of course, saying Einstein wasn’t much of a mathematician is like saying Michael Jordan wasn’t much of a baseball player). And while all this is more than he can truly accomplish, it’s hard not to be carried along, and impossible not to admire the effort.

One other thing that sets this book apart is Rovelli’s willingness to leave the reader with more questions than answers. This is disarming, but also refreshing. More questions than answers, it seems, may reflect the true nature of reality.

Josh Trapani is a writer who contributes regularly to the Washington Independent Review of Books.

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