Storm in a Teacup: The Physics of Everyday Life(54)

The difficulty was that as water freezes, the water molecules must take their places in their rigid lattice. If the temperature sinks low enough, they will stick. And if there isn’t enough room to sit in their proper place, they’ll push outward on everything nearby in order to make space. Any ship frozen into the ice suffered because growing ice took up more and more space, forcing itself outward. No known ship could resist that pressure, and no one knew how thick the ice would get in the middle of the Arctic. The Fram solved the problem in a brilliantly simple way. She was made to be chubby and round, only 128 feet long and 36 feet wide. She had a smooth curvy hull, almost no keel, and engines and rudder that could be lifted right out of the water. When the ice came, the Fram became a floating bowl. And if you squeeze a curved shape like a bowl or a cylinder from below, it will pop upward. If the squeeze from the ice got too much, the Fram would just be pushed upward to sit on top of it—or so went the theory. She was made from wood that was over 3 feet thick in places, and insulated to keep the crew warm. And in June 1893, she left Norway with tremendous public support and a crew of thirteen, rolling her way around the northern coast of Russia until she reached the place where the Jeanette had sunk. In September, she saw ice close to 78°N, and not long after that she was surrounded. As the ice first trapped her, she creaked and groaned, but as it expanded around her she rose, shifting upward exactly as expected. Frozen in, she was on her way.

For the next three years, the Fram floated with the sea ice, drifting northward at an agonizingly slow 1 mile a day. Sometimes she went backward or around in circles. The fickle freezing ice squeezed and released her, and she rose and fell in response. Nansen kept his crew occupied with scientific measurements, but got increasingly frustrated with the slow progress. When the Fram reached 84°N, it was apparent that she was not going to get to the pole, 410 nautical miles away. Nansen took a companion and left the ship, skiing over the ice in an attempt to go where his ship couldn’t. He set a new record for the farthest north anyone had been, but his best was still 4° short of the pole. He carried on across the Arctic toward Norway, meeting a fellow explorer on Franz Josef Land in 1896. The Fram and her remaining eleven crew stayed the course, carried by the ice to 85.5°N, only a few miles south of Nansen’s new record. On June 13, 1896, she popped out of the ice just north of Spitsbergen, exactly as originally planned.

Even though the Fram never reached the pole, the scientific measurements taken during her journey were invaluable. Now we knew for sure that the Arctic was an ocean and not a land, that the North Pole was hidden beneath ever-shifting sea ice, and that there really was a current that crossed the Arctic between Russia and Greenland. The Fram went on to carry men on two other great trips. The first was a four-year mapping expedition to the Canadian Arctic. And then in 1910 she carried Amundsen and his men to Antarctica, where they would beat Captain Scott to the South Pole. Today, she sits in her own museum in Oslo, lauded as the greatest symbol of Norwegian polar exploration. Instead of fighting the inexorable expansion of the ice, she had used it to ride across the top of the world.

The expansion of ice as it freezes is so familiar to us that we don’t really notice it. Put an ice cube in your drink and it floats—that’s just the way things work. But there’s an easy way to see that the frozen water really is the same stuff, just taking up more space. If you put some water in a transparent glass and add some largish lumps of ice, the ice floats so that most of it is below the surface but about 10 percent sticks up above the liquid level. You can mark the liquid level on the outside of the glass with a marker pen. The question is this: As the ice melts, will the water level go up or down? Once it’s melted, all those water molecules that are now sticking up above the water level will have to join the rest of the drink. Does this mean that the water level will rise? This is proper cocktail party physics, if you’re patient enough (or bored enough) at a party to spend time watching ice melt.

The answer is straightforward, and you should test it for yourself if you don’t believe me. The water level will stay in exactly the same place. Once the molecules in the ice become liquid again, they can fit together more closely. This means that they’ll fit perfectly in the hole that the submerged part of the ice was taking up. That bit of the ice cube that’s sticking up above the water line is exactly the size of the extra volume that the ice cube has because it expanded as it froze. You can’t see the atoms themselves in their lattice, but you can directly see the extra space they need when frozen.?

Water transforms from liquid to solid in a particular way—the atoms in the solid each have a fixed location in a lattice. This is called a crystal even when it isn’t the gleaming centerpiece of a tiara. A crystalline material is just one that has a fixed repeating structure when it’s solid, like salt or sugar. But there is another sort of solid, one without this strict positioning. These solids have a structure more like that of a liquid frozen on its way somewhere else. Even though the atomic positioning is all happening on a minuscule scale, and is far too small for us to see, we can still sometimes see the effect that it has on the object that we pick up. The most obvious example of this is glass.

I remember seeing glassblowers for the first time on a family trip to the Isle of Wight when I was about eight. I was spellbound by the smooth globules of molten glass, glowing and ballooning, constantly shifting from one beautifully bulbous shape to another. I had to be dragged away because I would happily have spent all day gazing at this wizardry, the magic of blobs flowing until they were vases. It was many years before I got around to what I’d really wanted to do: having a go at it myself. But one chilly morning this year, my cousin and I arrived at a small stone barn where they would apparently pull back the curtain and show us how the magic was done.