Storm in a Teacup: The Physics of Everyday Life(22)

BEFORE YOU CAN worry about things that are too small to see, you have to know that they’re there. Humanity faced a catch-22 here—if you don’t know there’s anything there, why would you go looking for it? But all of that changed in 1665 with the publication of one book, the first scientific bestseller: Robert Hooke’s Micrographia.

Robert Hooke was the Curator of Experiments at the Royal Society, and so he was a generalist, free to roam among the scientific toys of the day. Micrographia was a showcase for the microscope, designed to impress the reader with the potential of this novel device. The timing was perfect. This was an era of great experimentation and rapid advances in scientific understanding. Lenses had been lurking around the edges of human civilization for a few centuries, mostly unappreciated and seen as novelties rather than serious tools for science. But with Micrographia, their moment had arrived.

The wonderful thing about this book is that although it wears the robes of respectability and authority, as befits a publication of the Royal Society, it’s unashamedly the product of a scientist at play. It’s full of detailed descriptions and beautiful illustrations, expensively produced and carefully presented. But underneath all that, Robert Hooke was basically doing what every child does when given a microscope for the first time. He just went around looking at everything. There are stunningly detailed pictures of razor blades and nettle stings, grains of sand and burnt vegetables, hair and sparks and fish and bookworms and silk. The level of detail revealed in this tiny world was shocking. Who knew that a fly’s eye was so beautiful? In spite of the careful observations, Hooke didn’t make any claims to in-depth study. In the section on “gravel in urine” (the crystals commonly observed on the insides of urinals), he speculates on a way of curing this painful affliction and then happily leaves the hard work of actually solving the problem to someone else:

It may therefore, perhaps, be worthy some Physicians enquiry, whether there may not be something mixt with the Urine in which the Gravel or Stone lies, which may again make it dissolve it, the first of which seems by it’s regular Figures to have been sometimes Crystalliz’d out of it. . . . But leaving these inquiries to Physicians or Chymists, to whom it does more properly belong, I shall proceed.


And proceed he does, dancing through mold and feathers and seaweed, the teeth of a snail and the sting of a bee. On the way, he coins the word “cell” as a description of the units that made up cork bark, marking the start of biology as a distinct discipline.

Hooke hadn’t just shown the way to the world of the small; he’d thrown open the doors and invited everyone in for a party. Micrographia inspired some of the most famous microscopists of the following centuries, and also whetted the scientific appetite of fashionable London. And the fascination came from the fact that this fabulous bounty had been there all along. The annoying black speck buzzing around rotting meat was now revealed as a minute monster with hairy legs, bulbous eyes, bristles, and shiny armor. It was a shocking discovery. By then, great voyages had crossed the world, new lands and new people had been discovered, and there was great excitement about what was to be found in faraway places. It hadn’t really occurred to anyone that navel-gazing might have been severely underrated, and that even belly-button fluff might have much to say about the world. And once you’d got over the shock of the flea’s hairy legs, you could see how they worked. The world down there was mechanical, it was comprehensible, and the microscope made sense of things that humans had noticed for years but hadn’t been able to explain.

But even that was just the start of the voyage into the world of the small. Over two centuries more would pass before the existence of atoms was confirmed, each one so tiny that you’d need 100,000 of them to make a line as long as a single one of the cork cells. As the famous physicist Richard Feynman was to point out many years later, there’s plenty of room at the bottom. We humans are just lumbering about in the middle of the size scales, oblivious to the minuscule structures that our world is built of and built on. But 350 years after the publication of Hooke’s Micrographia, things are changing. We can do more than just peer into that world like a child peering into a protective glass museum case, forbidden to touch. Now we’re learning to manipulate atoms and molecules on that scale; the glass is off the case, and we can join in. “Nano” is in fashion.

A major part of what makes the world of the tiny both fascinating and extremely useful is that things work differently at that level. Something that’s impossible for a human might be an essential life skill for a flea. All the same laws of physics apply; the flea exists in the same physical universe as you and me. But different forces take priority.? Up here in our world, there are two dominant influences. The first is gravity, pulling us all downward. The second is inertia; because we’re so big, it takes a lot of force to get us moving or to slow us down. But as you get smaller, gravitational pull and inertia also get smaller. And then they find themselves in competition with the other weaker forces that were there all along, but insignificant. There’s surface tension, the force shifting the coffee granules about as the coffee puddle dries. And then there’s viscosity. Viscosity in the world of the small is why we don’t get a nice layer of cream on top of the milk anymore.

It was always the gold-and silver-topped milk bottles they went for. If you were early enough, and careful when you opened the front door, you’d catch them at it. Bright-eyed perky little birds, perched on the top of the bottle, snatching hasty sips of cream from the hole they’d pecked in the thin aluminium bottle top while keeping a beady eye on the world around them. As soon as they knew they were caught, they were off, probably to try their luck at the neighbor’s doorstep. For about fifty years in this country, blue tits were masters at stealing cream. They learned from each other that right below the flimsy lid there was a rich fatty treasure, and that knowledge spread throughout the UK blue-tit population. Other bird species didn’t seem to cotton on to this trick, but the blue tits were waiting for the milkman every morning. And then the game came to an end quite suddenly, not just because of plastic milk bottles but because of something more fundamental. For as long as humans have been milking cows, the cream has risen to the top. But these days, it doesn’t.