Biology and the second law of thermodynamics

At my recent conference, one of the speakers (Karl Friston) began by remarking on the curious relationship between biological systems and the second law of thermodynamics. What is curious about it, is that there doesn’t appear to be one.

As any physicist knows, the second law of thermodynamics is inescapable – things break, electronic equipment gives off heat, hot and cold gives warm, but never can warm be split into hot and cold (well, at least not without some external influence). So why is it that an organism manages to stay living for a hundred years with next to no change, or a termites nest stays a termites nest, or birds still migrate along the same route year after year? Where is the increase in disorder?


He talked about the way living things interact with the environment in terms of the physics of thermodynamics and statistical mechanics – a rather neat (if mathematically intensive) use of physics to a situation that might not readily spring to mind.  They key idea is that living things influence their environment to minimize something he called ‘surprise’ – that is, they do their best to create for themselves situations where they are most safe and comfortable. Fish might do it by shoaling, we might do it by building houses and equiping them with 40 inch plasma TV screens.

This action on the environment, in some way which I won’t pretend I properly followed, allows the organism to fend off the second law of thermodynamics and not degenerate into some blob lying on the footpath. So how come the law isn’t broken? Well, there is an increase in disorder, but it is within the external environment, not within the organism or group of organisms. Which kind of suggests to me that the more we want to be comfortable (minimise surprise), the more we have to stuff up our environment

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