I heard the coolest thing the other day, so cool I had to sit down. 

Terry Gross was interviewing Charles Mann on NPR’s Fresh Air. Mann has just written a book called “1493” about the ecological aftermath of Columbus’ discovery. I’d learned a little about this in school: how Europeans introduced horses, how tomatoes come from the Americas. But I’d never heard that before Columbus, northern North America had no earthworms. They’d been wiped out there by the last Ice Age, says Mann. And so the leaves that fall here in New England would pile up into mats that trees would grow straight out of. Today earthworms turn those leaves into soil. If you spent any time in the woods as a kid, the thought of no earthworms and the ground under your feet having been totally different might have the same effect on you as it did on me. 

The story goes that the worms came in soil in the ballast of ships sent to bring tobacco back from Virginia to Europe (tobacco being another American original). In the centuries since, says Mann, a “worm front” has been spreading out from the eastern seaboard. Today it has reached as far as Minnesota, where the Minnesota Worm Watch is deputizing the locals to try to save the native forest. Needless to say I want to read this book. Very cool. 

The story got me thinking: what makes something cool? What is it about a book or story or research paper that makes you stop and say “wow” and want to tell people about it? And being practical, can one define a set of metrics or attributes that we can use to keep ourselves in a steady supply of cool? 

To be cool something has to be interesting, of course, but also new and unexpected. Connecting otherwise unrelated things—-electrodes and cooking hot dogs; the Santa Maria and a 5,000-mile inexorable front of earthworms—-seems also to be important. Mixing scales of measure—-the very big and very small, or the very quick and very slow—-also helps. But are all new, unexpected connections between unrelated things at different scales of measure cool? Do these things explain what makes this paper cool? 

What makes a paper cool to you?