Most of us have a fickle relationship with friction. We panic when we suddenly lose it, take it for granted when it’s working in our favor, and curse it when it becomes a drag. Whatever our momentary feelings towards this omnipresent force may be, though, one thing we can’t do is ignore it, tribologist Jennifer Vail argues in her ambitious new book, “Friction: A Biography.”
Coming from someone who literally rubs things together for a living — tribologists study friction, wear, and lubrication — this is perhaps not the most surprising opinion. But as Vail aptly demonstrates throughout her book, humans have been practicing tribology for hundreds of thousands of years, if not longer. “Once we discover it, we realize that it’s fundamental to who we are,” she writes.
BOOK REVIEW — “Friction: A Biography,” by Jennifer R. Vail (Belknap Press, 248 pages).
The story of friction goes back to one of our most consequential discoveries: the mastery of fire. To control this element, early humans first needed to understand friction’s role in producing heat, one of three key ingredients required to make fire, along with oxygen and fuel. The act of rubbing objects together produces mechanical energy, Vail explains, which friction can then convert into thermal energy. Once enough of the latter is produced, atoms in our fuel of choice (wood, straw, etc.) combust, and when combined with oxygen, produce a truly transformative tool.
“Our mastery of fire enabled permanent settlements and ignited (pardon the pun) a remarkable number of technological innovations, from cooking to pottery to metalworking,” Vail writes. “Fire also shaped our evolution. Cooked food, easier to chew and digest, allowed for more efficient extraction of nutrients, and as a result, our digestive tracts shrank, and our brains grew larger.”
While important, this is well-trod territory, and thankfully Vail quickly moves on to other tribological tricks of history, including Paleolithic cave painters who mixed oxides of iron and manganese with fats and plant matter to make their red and black pigments better stick to the walls; Egyptians who strategically poured small amounts of water over sand to make hauling massive stones a little less grueling; and Romans who smeared their chariot axels in olive oil sediment and lard for a smoother ride.
Vail sticks to a loosely chronological structure in “Friction,” highlighting a steady stream of important discoveries, along with the important figures who made them. But if there’s a core organizing principle, it’s probably more accurate to describe her approach as conceptual rather than chronological.
Similar to the way textbooks often use foundational concepts as scaffolding for more advanced ideas, Vail starts with the basics of this complex and multi-faceted force and then whisks readers off on a tribological tour that includes stops in contact mechanics, the history of solid and liquid lubricants, friction’s role in energy efficiency and waste, and finally, the ways in which it is helping to solve some of the universe’s biggest mysteries.
Humans have been practicing tribology for hundreds of thousands of years, if not longer.
Along the way, we get plenty of fascinating tidbits — including the physics behind the friction-friendly feet of anoles and geckos, how synovial fluid in our bodies lubricates our joint cartilage, and the reason WD-40 is called WD-40 (It’s short for “Water Displacement, 40th formula” and was the fortieth attempt to create a water dispersant.)
We also learn, or re-learn, that there are a lot of kinds of friction: static friction, dynamic friction, rolling friction, fluid friction, possibly even quantum friction. Each is governed by its own set of rules that have their own exceptions, which Vail cheerfully goes into way too much detail on.
Indeed, while Vail’s enthusiasm for friction can be contagious, it doesn’t always translate into a smooth reading experience. The flipside of her tribological passion is that it frequently, and sometimes abruptly, leads readers into some pretty dense mathematical and scientific terrain. As a result, “Friction” can at times read less like general interest non-fiction than academic tome.
“When we work through the Fun Friction equation, expressing F in terms of load, the coefficient of friction becomes inversely proportional to the load raised to the one-third power, and hence, less force is required for movement,” she writes in a section about the various ways tribologists try to break the laws of friction.
All that technical specificity stands in stark contrast to some of her characterizations of tribological innovations, which feel either vague or sanitized. Take Vail’s brief recounting of the discovery of Teflon, the controversial super-slick solid lubricant most of us now associate with nonstick pans.
Teflon, also known as polytetrafluoroethylene, or PTFE, was accidentally discovered in 1938 by DuPont scientist Roy Plunkett and his assistant Jack Rebok while trying to come up with a less toxic refrigerant. To manufacture this popular commercial polymer, the company relied on a specific “forever chemical” known as PFOA, or perfluorooctanoic acid, which it then dumped into the Ohio River Valley for years, exposing communities in West Virginia and southern Ohio, among other states, to toxins linked to serious health issues, including cancer.
While Vail mentions this — including the more than $1 billion settlement to the resulting class-action lawsuit filed against DuPont and other companies — her account leaves out a pretty significant detail: that the companies that manufactured or used PFAS knew, or at least strongly suspected, they were harmful to living organisms as early as the 1960s and to the environment by the 1970s, and kept this fact hidden from the public for decades.
In that sense her conclusion, that the concerns about PFAS “arose nearly eighty years after Plunkett discovered PTFE,” and that “until then, PTFE was a highly regarded material with intrinsically low friction,” doesn’t quite capture the full story.
Similar omissions occur around her discussion of tire innovation. As Vail convincingly shows, tribologists and engineers have made tremendous progress optimizing tire treads and tweaking compounds to achieve better rolling efficiency and handling in all kinds of inclement weather conditions. The part she leaves out? Tires — specifically, tire wear particles — now account for upwards of 45 percent of all microplastics in the ocean.
These absences wouldn’t be as noteworthy were it not for Vail’s repeated assertion that tribology might help us solve the energy and climate crisis. At what cost, readers might wonder? At the very least, it seems like a question tribologists need to engage with.
Ultimately, though, the book is less interested in the controversies related to the study and manipulation of friction, and more focused on giving us a better understanding of, and appreciation for, a force we only seem to think about when it annoys us. On that account, it’s an unmitigated success. Indeed, Vail makes a convincing case that friction continues to get a bad rap, partly due to its oppositional nature, and partly because engineers and scientists see it problem to be solved, rather than a useful tool.
Vail argues that friction gets a bad rap, partly due to its oppositional nature, and partly because engineers and scientists see it problem to be solved, rather than a useful tool.
For proof one need look no further than Silicon Valley, which has spent the better part of two decades trying to excise “friction” — synonymous with difficultly, effort, and inconvenience — from our lives. It’s been remarkably successful, too. “Frictionless” algorithmically-powered apps with “seamless” user interfaces have made everything from renting a house to expressing the thought that just popped into your head as easy as a few taps on a screen or keyboard. And now, if we’re to believe certain tech companies, generative AI is poised to remove even more friction from our lives, automating away inconvenience, effort, and anything else that rubs us the wrong way.
We needn’t be tribologists for this to give us pause. As Vail reminds us time and again, some of our greatest successes as a species have come not from trying to avoid or erase friction, but from leaning into it, recognizing how and when it can be useful, and then using it to our advantage.
Reading “Friction” may not be a frictionless experience. But as the book persuasively demonstrates, encountering a little resistance can yield big rewards.
Bryan Gardiner is a writer based in Oakland, California.