Review: “The Greatest Ideas in the Universe” by Sean Carroll


There’s an old adage among science writers: “For every equation you put in your book, you lose half your audience.” For physicists like me who also moonlight as science writers, this truism is particularly vexing, because these are the equations we are so passionately in love with. Equations are poetry – the beautiful skeleton that bears the flesh of the world. What a loss that I cannot share this beauty and power with my readers.

But maybe, just maybe, that truism isn’t true. Perhaps intelligent readers with an interest in science but no mathematical inclination cannot be introduced to these equations and their most important meanings.

This is the bet that Sean Carroll makes in his new book, The greatest ideas in the universe. Carroll is a theoretical physicist and bestselling author who has written a number of beautiful books that operate in the normal “popular science” mode. (In other words, no equations.) But in his new work, Carroll wants to go further. As he puts it in the opening of the book:

“I want to live in a world where most people have informed and passionate opinions about modern physics. Where you hit it off after a hard day’s work, hit the pub with friends and chat about your favorite dark matter candidate or your competing interpretation of quantum mechanics.

But as Carroll rightly observes, even if physics addresses some of the biggest ideas in the Universe, the fact that it does so using sophisticated mathematical formulations blocks broader engagement with the field. In response, an entire ecosystem of physics awareness practitioners (13.8 inclusive) has emerged to translate the profound beauty and power of physics into everyday language. That these efforts find so many readers, listeners, and viewers speaks to people’s sincere desire to understand the world through science, even if they are not scientists. But it also means that something is lost. As Carroll says, “What you get are images and metaphors, rough translations of the underlying mathematical essence…”

What Carroll wants is to give readers something of the mathematical essence which, after all, is the way physics is done. To achieve this goal, he proposes a new approach. As he rightly notes, to become a practicing physicist a student must not only learn the equations and their meanings, but they must also spend countless hours solving the equations in specific circumstances. To give an example, it is not that difficult to learn the basic equations of Newtonian gravity. I guide my non-science freshmen through them. The really hard part is solving these equations for something like the motion of a comet around the Sun when perturbed by Jupiter’s gravitational pull. This part takes hours and hours of calculation. Learning how to solve equations is what the one-week graduate student homework is for.

A glimpse of real physics

But Carroll is betting that scientifically interested nonscientists don’t need to solve physics equations – they just need to know how to read them. For Carroll, understanding specifically what specific equations say and how they say it should be enough to go beyond the metaphors of most popular science narratives. That way, readers might get a truer, more visceral sense of why physics is so powerful.

It is the philosophy that drives The greatest ideas in the universe. Carroll takes readers on a remarkable journey through some of the most important ideas in the field and explains how these ideas manifest in mathematical form. It’s a bold move, and because of it, Carroll is able to take his readers on a much deeper exploration of fundamental notions like force, motion, and momentum than other books deal with.

But does it work? Will readers continue to follow their guide as it unfolds how calculus or differential geometry shape our ideas of motion, space and time? Since I already understand the mathematical physics that Carroll shares, I’m not in the best position to answer this question. What I can say is that even with my training, I always had insight into the book descriptions. That’s how good Carroll is at explaining physics. Equally important, The greatest ideas in the universe epitomizes Carroll’s approachable style. It’s full of humor, imagination and enthusiasm. If anyone can accomplish the task Carroll has set himself, it’s him.

So what I can also say is that if you are interested in physics, you should read this book. It can open a window through which your view of the Universe will be richer, more subtle, and far more awe-inspiring.


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