It pays to stay humble before nature

At the 2011 sauropod gigantism symposium in Bonn, John Hutchinson gave a talk on biomechanics of large animals. At the end he showed a short video of a rhino running full-tilt, tripping, and literally flipping end over end. After the wipeout, the rhino got up and trotted off, apparently unhurt. I don’t remember John’s exact words, but they were something like, “We have no idea how this happens – all our models suggest that rhino should be a pile of broken bones.” His point was, there is a lot we don’t yet understand, and it pays to keep that in mind.

This morning Mike and I were discussing the Middlesborough meteorite, which fell to ground in front of some railway workers in 1881 and was reported be warm to the touch right after falling. Here’s a short, lightly-edited recap of our conversation.

Mike: If it had slowed to such a very mundane speed, due to atmospheric braking, how on earth was it only “new-milk warm” to the touch?

Me: You mean, since it was obviously melted to hell on its way in, how did it cool down so much? From what I’ve been able to find out so far, most small meteors that survive to hit the ground have finished aerobraking when they’re still about 50,000 feet up, and from there they experience a “dark fall” where they’re just a chunk of rock falling at terminal velocity. It’s pretty cold at 25,000 feet, much less 50,000 feet, so I assume a lot of the heat is pulled away by convection into cold air during the dark fall period. There are meteorites that have fallen onto lake or sea ice and not produced any apparent melting, so at least some of them do fall cold.

Mike: This makes sense. So we imagine that is was a lot hotter than that a short time before the impact, but that it cooled as it continued to fall.

This is an interesting example of how thoroughly physical intuition can mislead when you’re dealing with objects operating in unfamiliar realms: very big (e.g. the K/Pg impactor “splashing”), very small (e.g. insects “swimming” through air) or very fast (e.g. this meteorite’s temperature). Physics works over a huge range, and we only have developed intuition for a small sub-range.

Me: Your point about physics is well taken. The older I get, the more humility I have before nature, after seeing many, many things that I would have thought impossible.

The specific example I had in mind there was digging dinosaurs – if you’d asked me back when if any dinosaurs made burrows, I would have bet heavily against it. And yet, there they are.

Stay humble, folks. It’s weird out there.