Captain Plum was looking at a cooking pot when it occurred to him that he had no idea what it was made of.
This seemed a little rude. The pot had been helping him make supper for years.
It looked like stainless steel. It might also contain aluminum. So Plum fetched a magnet. It stuck to the bottom of one pot. On the big pot, it stuck to the sides as well.
Supper was now a science lesson. Nobody had consulted the spaghetti.
A magnet can tell you that there’s magnetic material close enough to pull on it. In the first pot, that material seemed to be concentrated at the base. In the big one, it reached up the sides. Either pot could still have a hidden layer of aluminum. Plum had learned something from a ten-second experiment, and he still had a question worth asking.
Why put two metals in one pot? Because they do different jobs. Aluminum spreads heat sideways from the burner, so the middle of the pot doesn’t get all the attention. Stainless steel gives the food a tough surface that can handle years of cooking and washing. The chromium in stainless steel helps form a protective film so thin you can’t see it. This is why a shiny pot can survive tomato sauce, dishwater and whatever happened to the porridge on Thursday. Health Canada’s guide to cookware materials.
Then Plum wondered where the metals came from.
Iron is found in rocks such as hematite, where it’s joined to oxygen. Aluminum often comes from an ore called bauxite. To get aluminum metal, people refine the ore and use electricity to separate aluminum from oxygen. Think about that the next time you lift a light saucepan. An enormous amount of human ingenuity went into making it feel like very little had happened. USGS on iron ore and the Aluminum Association on aluminum production.
And where did the iron come from before it was in the rock?
Now we need stars.
Earlier generations of stars made and scattered elements into space. Some of that material became Earth. In some exploding stars, iron took a particularly interesting route. The explosion made radioactive nickel, which changed into cobalt and then into stable iron. Each change happened in the nucleus of the atom. By the time there were rocks to dig up, those atoms had already had quite a career. NASA on where our elements came from and the evidence for nickel decaying into iron.
Plum couldn’t tell which star supplied his pot. The magnet was doing its best, but there are limits to what you can ask of a fridge souvenir.
He could, however, stand in his kitchen and follow a real chain of events. Stars made atoms. Earth gathered them into rock. People dug up the rock, separated the metals, and worked out how to make a vessel that would heat his supper evenly.
That’s what Plum likes about scientific wonder. The closer you look at something ordinary, the more there is to be curious about. And you can begin with whatever’s already in front of you.
In this case, the universe had done its part. The miners and metalworkers had done theirs.
Plum still had to stir.
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