Penguin waves

EmperorPenguin 2005 2592Over the weekend I was at workshop in Cornwall. It was mainly people from the Universities of Bristol and Bath, but they were a few people like me from further afield. It was in a very pretty village in Cornwall. During the Saturday lunch break we went for a stroll along a wooded river bank. It is the time of year that blue bells flower, and the fields of blue bells in the wood were beautiful.

The workshop was very informal. Two of the participants brought their two-and-a-half-year-old daughter, who wandered in and around the sessions. She stayed for her mother’s talk, but wandered off halfway through her father’s. Perhaps her father should have made more interesting slides. I enjoyed this very informal style. In a relaxed atmosphere everyone feels like they can ask questions if they don’t understand, and people can just chat with speakers over coffee.

Most of the talks were on more conventional physics, but one of the speakers mentioned some intriguing work on penguins. Male Emperor penguins incubating their eggs to be precise. The video he showed is here. This is from a paper by Zitterbart et al. on how the penguins deal with a pretty tough problem. Basically, the problem Emperor penguins have is that is really really cold, -40 C or below, while the male penguins are incubating their eggs. So as you can see in the video they huddle together for warmth. And to be as warm as possible, they need to pack together as tightly as possible.

So now the penguins in the middle of the huddele are warm and toasty, but of course the outer ones are still exposed to -40 C plus windchill. Periodically the huddle needs to reorganise to allow the outer ones to move to the middle, and for some of the ones in the middle to move to the outside to take their turn on the outside. But this is tricky as the penguins are packed in like sardines.

Zitterbart et al. reckon that the penguins solve this problem of moving while being packed in by moving collectively, there are kind-of waves of penguin motion in a huddle. It’s an interesting idea. It is known that many things tend to move in waves or groups when they are tightly packed. This can happen to pebbles when they are jammed together, and when glass is heated up so it can a flow a little bit, the molecules mostly move in waves. Both these situations have been studied a lot by physicists so maybe we can apply some ideas developed there to better understand how Emperor penguins have evolved to stay as warm as possible in crazily cold conditions, and to share the burden of being at the edge fairly.

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