Civilisation started with a good hard rub

In the 1960s, Prof Peter Jost ran a study for the British govt that showed better engine lubricants could save over £500mn each year by cutting friction losses. That’s £8.5bn in today’s money. By the early 2000s, engine design, vehicle aerodynamics and, of course, lube formulation had advanced significantly, yet a 2009 study found cars consumed 360mn tonnes of fuel – petrol and diesel combined – every year just to overcome friction. Even today, roughly 28% of fuel in a combustion engine car is lost to friction, with braking pushing the figure higher.

Imagine the savings that would result from cutting this loss. Less friction would mean engine parts last longer, so fewer need to be made. Think about the reduced greenhouse gas emissions... As a tribologist – an expert on friction – Jennifer R Vail spends a good deal of time on such challenges and finding solutions. But to her, friction is a double-edged sword. You can blame it for worn out shoes and tyres, and blunt shaving blades, but it’s also what keeps contact lenses in place, and makes cars turn and stop when you want them to. She’s written a whole book, Friction: A Biography , celebrating this resistive force – “Our ability to manipulate friction is at the heart of civilisation,” she writes in it.

If that sounds over-the-top, consider Vail’s reasons for this praise. One, we couldn’t have had fire without friction. Today, you can start a fire with an electric spark, but for 99% of history, we’ve lit fires by striking flints, matches, etc. Our first great invention, the wheel, would have been useless without friction as well. And pretty soon, we learnt to make friction our friend. We sharpened scythes and sickles with it. We used it to bind harvests with knots. But we also learnt to abate it. So, 4,500 years ago, ancient Egyptians were moving 6-ton blocks of stone for the Pyramid of Giza by splashing water before sledges, to ease their movement over sand.

The Romans went further and learnt to lubricate their chariot wheels with lard. Those ancient chariots – the kind seen in Gladiator – could hit speeds of 50kmph, and if the friction got out of hand, the heat made the wheels glow, and sometimes set them ablaze.
“Our relationship with friction depends on what we are trying to accomplish,” writes Vail. As a child ballerina, she applied rosin on her shoes to avoid slipping. Now, she uses it “to create friction between my bow and the strings of my viola”. And tribologists like her are always looking at ways to increase or decrease friction under specific circumstances. For instance, those working on cookware will try to find better ways to keep food from sticking to pans. Some are trying to create pet food that removes plaque from animal teeth – “What if we could develop food and treats that removed plaque just by rubbing against our pets’ teeth?” – others are working on syringes in which the plunger moves with almost no resistance. Yet others are tasked with making slippery rocket heat shields that glide through the atmosphere without heating.

Managing friction is also key to good user experience – creaky hinges and stiff knobs can put off buyers. That’s why, in whatever we do, it’s crucial not to rub the wrong way.