Nehaveigur

Short version: Paul J. Steinhardt’s The Second Kind of Impossible is the best science book I’ve read in a long time.

Long version: Crystals are formed by identical, neatly arranged building blocks. One example are the stacked water molecules that make up ice crystals. Quasicrystals are different and Penrose tiling is a good way to illustrate this in two dimensions: The Penrose tiling pattern is composed of multiple kinds of tiles and, unlike a typical crystal, is aperiodic. You can probably tell that if you cut the pattern below along the tiles and rearranged the two parts, they wouldn’t easily fit together. That’s the definition of aperiodicity. Quasicrystals are like that, but in three dimensions.

Penrose tiling is an amusing subject, and that could be the end of it. Fortunately, there are scientists like Steinhardt who strive to make the connection between theoretical physics and real life. In The Second Kind of Impossible, he describes his discovery that quasicrystals, rather than just being a mathematical amusement, exist in nature. He and others pursued this idea even though Richard Feynman, when hearing about the idea, was skeptical and Linus Pauling was outright hostile, saying: “There is no such thing as quasicrystals, only quasi-scientists.” They were wrong, and in 2011 Steinhardt’s colleague Dan Schechtman was awarded the Chemistry Nobel price for his work on quasicrystals. 

I’m not giving away too much by mentioning that the story involves international mineral smugglers and an expedition to Siberia. I wish that more scientists wrote books like this. But even more, I wish that more scientists took risks in what research topics they pursue the way Steinhardt did. It might make for better science and it definitely makes for better science writing.

Aside: While reading Steinhardt’s description of quasicrystals, I remembered that in his 1944 book What is Life?, Erwin Schrödinger described the molecule carrying genetic information as an aperiodic crystal. This was before the discovery of structure of DNA in 1953. While DNA is aperiodic – otherwise, it wouldn’t encode information – in its native state it is not a crystal. Just in case you were wondering, there’s therefore no meaningful connection between DNA and quasicrystals.