the art and science of dunking

One of the main problems that scientists have in sharing their picture of the world with a wider audience is the knowledge gap. One doesn't need to be a writer to read and understand a novel, or to know how to paint before being able to appreciate a picture, because both the painting and the novel reflect our common experience. Some knowledge of what science is about, though, is a prerequisite for both understanding and appreciation, because science is largely based on concepts whose detail is unfamiliar to most people.

That detail starts with the behavior of atoms and molecules. The notion that such things exist is pretty familiar these days, although that did not stop one of my companions at a dinner party from gushing, "Oh, you're a scientist! I don't know much about science, but I do know that atoms are made out of molecules!" That remark made me realize just how difficult it can be for people who do not spend their professional lives dealing with matter at the atomic or molecular level to visualize how individual atoms and molecules appear and behave in their miniaturized world.

Some of the first evidence about that behavior came from scientists who were trying to understand the forces that suck liquids into porous materials. One of the most common manifestations of this effect is when coffee is drawn into a dunked doughnut or tea or milk into a dunked cookie, so I was delighted when an English advertising firm asked me to help publicize the science of cookie dunking because it gave me an opportunity to explain some of the behavior of atoms and molecules in the context of a familiar environment, as well as an opportunity to show how scientists operate when they are confronted with a new problem.

I was less delighted when I was awarded the spoof IgNobel Prize for my efforts. Half of these are awarded each year for "science that cannot, or should not, be reproduced." The other half are awarded for projects that "spark public interest in science." The organizers have now changed these confusing descriptions for the simple "First they make you laugh; then they make you think."

It was a pleasure, though, to receive letters from schoolchildren who had been enthused by the publicity surrounding both the prize and the project. One American student sought my help to take the work further in his school science project, in which he studied how doughnuts differ from cookies. He subsequently reported with pride that he had received an "A" for his efforts.

This chapter tells the story of the dunking project and of the underlying science, which is used to tackle problems ranging from the extraction of oil from underground reservoirs to the way that water reaches the leaves in trees.

Doughnuts might have been designed for dunking. A doughnut, like bread, is held together by an elastic net of the protein gluten. The gluten might stretch, and eventually even break, when the doughnut is dunked in hot coffee, but it doesn't swell or dissolve as the liquid is drawn into the network of holes and channels that the gluten supports. This means that the doughnut dunker can take his or her time, pausing only to let the excess liquid drain back into the cup before raising the doughnut to the waiting mouth. The only problem that a doughnut dunker faces is the selection of the doughnut, a matter on which science has some surprising advice to offer, as I will show later in the chapter.

Cookie dunkers face much more of a challenge. If recent market research is to be believed, one cookie dunk in every five ends in disaster, with the dunker fishing around in the bottom of the cup for the soggy remains. The problem for serious cookie dunkers is that hot tea or coffee dissolves the sugar, melts the fat, and swells and softens the starch grains in the cookie. The wetted cookie eventually collapses under its own weight.

Can science do anything to bring the dedicated cookie dunker into parity with the dunker of doughnuts? Could science, which has added that extra edge to the achievements of athlete and astronaut alike, be used to enhance ultimate cookie dunking performance and save that fifth, vital dunk?

These questions were put to me by an advertising company wanting to promote "National Cookie-Dunking Week." As someone who uses the science underlying commonplace objects and activities to make science more publicly accessible, I was happy to give "The Physics of Cookie Dunking" a try. There was, it seemed, a fair chance of producing a light-hearted piece of research that would show how science actually works, as well as producing some media publicity on behalf of both science and the advertisers.

The advertisers clearly thought that there would be keen public interest. They little realized just how keen. The "cookie dunking" story that eventually broke in the British media rapidly spread worldwide, even reaching American breakfast television, where I participated in a learned discussion of the relative problems of doughnut and cookie dunkers. The extent of public interest in understandable science was strikingly revealed when I talked about the physics of cookie dunking on a call-in science show in Sydney, Australia. The switchboard of Triple-J, the rock radio station, received seven thousand calls in a quarter of an hour.

The advertisers had their own preconceptions about how science works. They wanted nothing less than a "discovery" that would attract newspaper headlines. Advertisers and journalists aren't the only people who see science in terms of "discoveries." Even some scientists do. Shortly after the Royal Society was founded in 1660, Robert Hooke was appointed as "curator of experiments" and charged with the job of making "three or four considerable experiments" (i.e., discoveries) each week and demonstrating them to the Fellows of the Society. Given this pressure, it is no wonder that Hooke is reported to have been of irritable disposition, with hair hanging in disheveled locks over his haggard countenance. He did in fact make many discoveries, originating much but perfecting little. I had to tell the advertisers in question that Hooke may have been able to do it, but I couldn't. Science doesn't usually work that way.

Scientists don't set out to make discoveries; they set out to uncover stories. The stories are about how things work. Sometimes the story might result in a totally new piece of knowledge, or a new way of viewing the nature of things. But not often.

I thought that, with the help of my friends and colleagues in physics and food science, there would be a good chance of uncovering a story about cookie dunking, but that it was hardly likely to result in a "discovery." To their credit,...