How to Make an Apple Pie from Scratch: In Search of the Recipe for Our Universe

How to Make an Apple Pie from Scratch: In Search of the Recipe for Our Universe by Harry Cliff

Harry Cliff takes the title for his wonderful non-fiction work, How to Make an Apple Pie from Scratch (2021), from the TV series Cosmos, the original one narrated by Carl Sagan, not the most recent Neil DeGrasse Tyson version (you should watch both, btw). Early on in his book, Cliff recounts how in one of the episodes Sagan “turns to the camera and with a twinkle in his eye says, ‘If you wish to make an apple pie from scratch, you must first invent the universe.’” Well, in the 40 years since Cosmos, humans have managed to figure out a few more ingredients and a few more steps in the recipe, and Cliff is here — with his own stylistic twinkle — to explain it to those of us who aren’t astrophysicists, particle physicists, theoretical phys-, well, let’s just say those of us who remember rolling a ball down an incline in high school but don’t recall why we did that (also for those of us who remember setting our lab tables aflame and do recall why we did that … )

Cliff calls the search for the recipe of the universe, “humankind’s most ambitious intellectual journey: the centuries long quest to uncover nature’s most basic ingredients.” And while it’s in part a personal story, delving into Cliff’s own work at the CERN collider complex, it’s mostly “the story of how thousands of people working over hundreds of years gradually discovered the fundamental ingredients of nature and traced their origins out into the cosmos, through the hearts of dying stars, and back to the first furious moments of the big bang.” That’s a heck of a tour, and Cliff makes for the best kind of tour guide: knowledgeable but not condescending or arrogant, funny but knowing when to pull out the jokes and when not to, eloquent but aware of when to let the awe of the spectacle itself do the work, relatable and charming but not smarmily gladhanding, and contagiously enthusiastic. All of which creates a work of top-notch popular science.

The universe is a pretty big topic, and so it’s no surprise that Cliff wends his way pretty widely across time and space. The book is generally structured by moving from the “big” building blocks — elements — and then showing how once we had those in place, we began to break down the “unbreakable” into atoms, protons, quarks, and so forth. Thanks to the structure, the book moves broadly chronologically — the Higgs Particle is a more recent discovery than quarks, themselves more recent than protons — but not strictly chronologically, as in each section we wind our way back in time to the beginning suspicions of something new, then move forward to tracking down the quarry, finding it, figuring out what it all means, then moving on to the next layer and again, going back to when we first realized there might another layer, etc. Which sounds perhaps more confusing than it actually reads. Despite all the movement in time and space as we follow various scientists and experiments, we are always clear on where and when we are: 18^th Century France, 19^th Century England, early 20^th Century Germany, late 20^th Century Switzerland, 21^st Century Italy (one of the strengths of Cliff’s work is how up to date it is).

In fact, almost nothing in How to Make an Apple Pie from Scratch is confusing. I’m going to repeat that, because in a work of popular science, this is all-important, and in a work discussing particle physics/quantum theory, it’s nigh on astonishing: almost nothing in How to Make an Apple Pie from Scratch is confusing. Cliff is consistently, always methodical, lucid, precise, and patient. He takes exactly as much time as is needed to explain an experiment, a theory, how an experiment proves or disproves a theory. And he has a true gift, as any popularizer of science must, of creating analogies to make the esoteric more mundane and thus more comprehensible. As when he compares the nucleus’ repulsive electric field to “the steeply rising ramparts of a heavily fortified castle,” explaining how “to storm the keep, a proton needs to be moving fast enough so it can ‘jump’ to the top of the walls.” An analogy which he returns to several times for other concepts, allowing the reader to focus on the idea at the heart rather than trying to track another metaphor. Cliff offers up multiple examples of clarifying analogies; his explanations of quantum fields versus regular fields and of the difference between global and local symmetries are perhaps the best I’ve read, as in, the easiest to follow.

He also makes use of illustrations — charts and graphs and tables — when they will be helpful (as with a listing of the relationships between particles and forces) but doesn’t overload the reader with them. Nor does he overwhelm the reader by being overly dense. Instead, he wonderfully balances the scientific explanations with less esoteric segments: sketches of the significant figures such as Einstein or Dirac or Rutherford, personal anecdotes of his own experiences as a grad student or working at CERN, personal interviews with other scientists, descriptions of the fantastic machines being employed, and others. Meanwhile, math makes almost no appearance here at all. One time it does, Cliff confesses he is “going to commit a cardinal sin of popular science writing and show you the equation I am babbling on about” and then offers up (iγμ∂μ − m) ψ = 0. And no, I have no idea what that says; it took me 20 minutes just to figure out how to type it. But you forgive Cliff’s “cardinal sin” thanks to his enthusiasm, which just leaps off the page:

[Dirac] had discovered an equation of near incomparable beauty … like you might recognize beauty in the smooth clean lines of a sailing ship. Dirac’s equation had a piercing simplicity … a razor-sharp blade cutting through a dense tangle of undergrowth … So simple, so elegant, and yet so powerful … Isn’t it a gorgeous thing?

I don’t know if I see its beauty, but I can feel how Cliff does and even understand why he does, and that’s enough for me. Just as important, I don’t feel ignorant for not seeing its beauty. Cliff never makes the reader feel dumb. And in fact, he cops to his own lack of knowledge in several areas, more than once admitting he had a hard time following or recalling in detail what one of his interview subjects was explaining. Even if I’m sure at least some of that was exaggerated self-deprecation, I appreciated it. Just as I appreciated the humor that runs throughout, which never (or rarely) felt forced and never felt like it was trying to draw attention to the author as opposed to the topic.

One of my tests for how good a non-fiction work is how much highlighting I’ve done. And I did a lot here. But the way I can tell How to Make an Apple Pie from Scratch is not just good, but superlative, is that I highlighted material I already knew because I so liked the way Cliff put it. By now I’ve read a lot of popular science books, and a lot of those have been on the topics of particle physics, quantum mechanics, cosmology, but off the top of my head, and even stopping to think about it for a minute or two, I can’t think of one, at least not that I’ve read in the past few years, that was so consistently clear, accessible, engaging, exciting, and witty. It’ll certainly be on my top ten (almost assuredly top five) list of popular science books for 2021. I hope that in a few years’ time some of the future experiments Cliff discusses bear fruit, and that Cliff has the time and desire to pen another book on what we’ve learned. Like the vanilla ice cream on top of that apple pie.