Disorder Rules: Sella on the Second Law

Order and Disorder, presented by Professor Jim Al-Kahlili, is part of the BBC Four Big Science Season. The first episode of this two-part exploration uncovers the laws that govern the organisation of energy and its all-encompassing role in our universe. University College London’s Professor Andrea Sella was also involved in the documentary. I took the opportunity to speak to him about participation, his views on its execution and the general state of thermodynamic understanding.

When I sat down with Professor Sella I wanted to get a clear idea of his reasons for getting involved with Order and Disorder and what he hoped the programme would achieve, particularly in its impact on a non-specialist audience.

“I proposed the idea five years ago; it’s been a long time in the making”, he revealed. “Everyone needs to have some understanding of thermodynamics because it rules and puts boundaries on all of our lives.” He explained that thermodynamics was vital in our approach to dealing with the energy available to us. “The people who perhaps who need it the most are politicians. Thermodynamics may be couched in the language of physics but it sets the the constraints, the boundaries of what we can do with gas, nuclear, wind, or solar power.”

In the episode Jim Al-Khalili states that the Second Law of Thermodynamics is one of the most important ideas in science. The Law states that in an isolated system, entropy (energy that isn’t available for use) will always increase. When left alone, any system will thus go from being ‘ordered’ to becoming ‘disordered’ as it loses the energy to keep it in an ordered state. Al-Kahlili argues that the Law applies to everything.

However, Professor Sella disagrees with this particular use of the term ‘disorder’. “It is a common simplification of the subtleties and a poor analogy.” He reveals. “[Entropy] is not about the messiness of the world. It is really about the quality of the energy you have – its usefulness.” Professor Sella prefers to discuss entropy in terms of dispersal: “I like to use the analogy of a briefcase filled with crisp bank notes. You have incredible purchasing power there. Like petrol in the tank. But what happens in life? You make transactions and the money trickles out and turns into small change. Instead of being all tied up, energy ends as useless, dispersed warm air.”

There is an ominous undercurrent spanning the episode which prophesises a future whereby a state of maximum entropy is reached. When I asked about the tenability of such a prediction, Professor Sella responded that we should not worry about this outcome: “Focused on decay, the Second Law is extraordinarily depressing, but on a timescale that we need not to worry about. There are bigger things, such as the sun turning into a red giant and swallowing Earth”, he teases. “Ironically it is precisely as entropy rises that you can get beautiful structures, ephemeral constructs that appear to violate the flow – life itself” he notes. However, this is only mentioned fleetingly in the episode.

Professor Sella closes our discussion with his personal thoughts regarding the effectiveness of the episode’s take- home messages.

“I would have replaced the last seven minutes with more of a manifesto; a call to arms”, he avows. “Thermodynamics can guide us with the tough choices we face, both globally and nationally in the next 50 years. In addition to climate change, we will need to feed nine billion people. At home, the UK faces a real energy crunch as both coal and nuclear power stations reach the end of their lives. How do we keep the lights on? We have choices and thermodynamics can give us answers to the best way of achieving Jeremy Bentham’s ideal of greatest good for the greatest number.”

The Big Science season continues on BBC Four for the next couple of weeks. The full two-part exploration of Order and Disorder with Jim Al-Khalili is available to watch on iPlayer, with part two focusing on information.



Posted on October 31, 2012, in Uncategorized. Bookmark the permalink. Leave a comment.

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