This book is about linking the little things we see every day with the big world we live in. It’s a romp through the physical world, showing how playing with things like popcorn, coffee stains, and refrigerator magnets can shed light on Scott’s expeditions, medical tests, and solving our future energy needs. Science is not about “them,” it’s about “us,” and we can all go on this adventure in our own way. Each chapter begins with something small in the everyday world, something that we will have seen many times but may never have thought about. By the end of each chapter, we’ll see the same patterns explaining some of the most important science and technology of our time. Each mini-quest is rewarding in itself, but the real payoff comes when the pieces are put together.
There’s another benefit to knowing about how the world works, and it’s one that scientists don’t talk about often enough. Seeing what makes the world tick changes your perspective. The world is a mosaic of physical patterns, and once you’re familiar with the basics, you start to see how those patterns fit together. I hope that as you read this book, the scientific hatchlings from the chapters along the way will grow into a different way of seeing the world. The final chapter of this book is an exploration of how the patterns interlock to form our three life-support systems—the human body, our planet, and our civilization. But you don’t have to agree with my perspective. The essence of science is experimenting with the principles for yourself, considering all the evidence available, and then reaching your own conclusions.
The teacup is only the start.
CHAPTER 1
Popcorn and Rockets
EXPLOSIONS IN THE kitchen are generally considered a bad idea. But just occasionally, a small one can produce something delicious. A dried corn kernel contains lots of nice food-like components—carbohydrates, proteins, iron, and potassium—but they’re very densely packed and there’s a tough armored shell in the way. The potential is tantalizing, but to make it edible you need some extreme reorganization. An explosion is just the ticket, and very conveniently, this seed carries the seeds of its own destruction within it. Last night, I did a bit of ballistic cooking and made popcorn. It’s always a relief to discover that a tough, unwelcoming exterior can conceal a softer inside—but why does this one make fluff instead of blowing itself to bits?
Once the oil in the pan was hot, I added a spoonful of kernels, put the lid on, and left it while I put the kettle on to make tea. Outside, a huge storm was raging, and chunky raindrops were hammering against the window. The corn sat in the oil and hissed gently. It looked to me as though nothing was happening, but inside the pan, the show had already started. Each corn kernel contains a germ, which is the start of a new plant, and the endosperm, which is there as food for the new plant. The endosperm is made up of starch packaged into granules, and it contains about 14 percent water. As the kernels sat in the hot oil, that water was starting to evaporate, turning into steam. Hotter molecules move faster, so that as each kernel heated up, there were more and more water molecules whooshing around inside it as steam. The evolutionary purpose of a corn kernel’s shell is to withstand assault from outside, but it now had to contain an internal rebellion—and it was acting like a mini pressure cooker. The water molecules that had turned to steam were trapped with nowhere to go, so the pressure inside was building up. Molecules of gas are continually bumping into each other and into the walls of the container, and as the number of gas molecules increased and they moved faster, they were hammering harder and harder on the inside of the shell.
Pressure cookers work because hot steam cooks things very effectively, and it’s no different inside popcorn. As I searched for teabags, the starch granules were being cooked into a pressurized gelatinous goo, and the pressure kept going up. The outer shell of a popcorn kernel can withstand this stress, but only up to a point. When the temperature inside approaches 360°F and the pressure gets up to nearly ten times the normal pressure of the air around us, the goo is on the edge of victory.
I gave the pan a little shake and heard the first dull pop echoing around the inside. After a couple of seconds, it sounded as though a mini machine gun was being fired in there, and I could see the lid lifting as it got hit from underneath. Each individual pop also came with a fairly impressive puff of steam from the edge of the pan lid. I left it for a moment to pour a cup of tea, and in those few seconds, the barrage from underneath shifted the lid and fluff started taking flight.
At the moment of catastrophe, the rules change. Until that point, a fixed amount of water vapor is confined, and the pressure it exerts on the inside of the shell increases as the temperature increases. But when the hard shell finally succumbs, the insides are exposed to the atmospheric pressure in the rest of the pan and there is no volume limit anymore. The starchy goo is still full of hot hammering molecules but nothing is pushing back from the other side. So it expands explosively, until the pressure inside matches the pressure outside. Compact white goo becomes expansive white fluffy foam, turning the entire kernel inside-out; and as it cools, it solidifies. The transformation is complete.
Tipping the popped corn out revealed a few casualties left behind. Dark burnt unpopped corn rattled sadly around the bottom of the pan. If the outer shell is damaged, water vapor escapes as it is heated, and the pressure never builds up. The reason that popcorn pops and other grains don’t is that all the others have porous shells. If a kernel is too dry, perhaps because it was harvested at the wrong time, there isn’t enough water inside it to build up the pressure needed to burst the shell. Without the violence of an explosion, inedible corn remains inedible.
I took the bowl of perfectly cooked fluff and the tea over to the window and stood watching the storm. Destruction doesn’t always have to be a bad thing.