Monday, June 27, 2011

The Irrational Fear of Entropy Production

There have been a number scientists, engineers and philosophers who think that entropy production is evil. For example, Adrian Bejan stated his book Entropy Generation Minimization, "The task of improving the thermodynamic performance of an engineering system requires the proper identification of those features most guilty of entropy production." I'm not sure what he means by 'guilty,' but this post is dedicated to showing that entropy production is not an evil to be avoided, but rather entropy generation is a nature part of living.

In a previous post on the Thermodynamic Imperative, I noted that there has been a philosophical trend to see the production of entropy as something to be avoided at all costs. This is, to some extent, due to misconceptions about entropy. We equate entropy with disorder, but this is silly. Entropy has nothing to do with disorder. It has to due with the number of equivalent microstates...it has to do with permutation symmetries, not disorder.

But because people have associated entropy with disorder, some people have objected to the generation of entropy because they think that order is better than disorder. I'd like to quote D.S. Scott (an engineering professor) and his misconceptions about entropy because there are some environmentalists who use these misguided conceptions of entropy to suggest that we should be minimizing our impact on the environment. There is no physical foundations for such beliefs, so I'd like to quote some of the misguided statements and then discuss them below.


"In the belief that efficiency means we will use our natural resources as sparingly as possible, to provide the best possible services with the lease possible environmental intrusion, at the lowest possible cost. Stated this way, the objective is appropriate and important. Indeed, the pathway to this objective is the pathway to a brighter 21th Century."
"Tomorrow will continue bringing more service for less energy. There is no end in sight."
"Whenever appropriate, using fewer energy services can both clean the place up and enhance lifestyles."

"Biking reduces my call on civilization's energy services--but not my quality of life."

"We should enjoy life. And while enjoying life, we should continue seeking ways to use less energy while providing more services...A straight-up-the-middle attack will be to build better energy systems. To do that we must understand what better systems are, and it helps if we get things by their right names. Words do shape actions."

"Another of exergy's gifts is the ability to calculate sensible, meaningful efficiencies. To be useful, efficiencies must compare a technology's inputs and outputs in terms of exergy, not energy."

"Because it's structure we want--that living things and our energy structure take from energy flows."

And saving the most incorrect statement for last:  "High entropy is a symptom of disorder, low entropy a symptom of structure--or, if you like, organization."

Quotes: Above         Discussion:   Below
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All of D.S. Scott's conclusions, such as 'biking to work is good because it doesn't consume as much exergy as driving,' stem from his misunderstanding of entropy. Entropy is not disorder, and the lack of entropy does not mean organization. A system with less entropy than another system has less permutation symmetries. That's it. The universe is trying to increase the entropy at as fast a rate as possible given the constraints within the system. The universe is becoming more symmetric. This is not a bad thing. We shouldn't be trying to fight the universe from becoming more symmetric. There's nothing in the laws of physics that says we should be trying to maximize 'quality of life.'  What does 'happiness' have to do with the laws of nature? Also, there's nothing in the laws of physics that says we should be trying to minimize the consumption of 'exergy.' In fact, it appears to be just the opposite. The consumption of exergy is a good thing if the exergy is consumed in a way such that more exergy can be consumed in the future (via a return on work invested.) This is how life expands. Biking to work is only better than, let's say, driving to force is there is a larger rate of return on work invested. But let's stop thinking that biking to work is somehow morally better than driving to work because it uses less exergy. If you can save money by biking, then you can spend it on other things. Spending money always consumes exergy and generates entropy. The question is always: what is the rate of return on investment of the work (money) invested?

We need to stop thinking that there are a finite number of resources, and we need to stop thinking about how to 'conserve energy.' Wealth is for the creating. You create wealth from the purposeful consumption of exergy in such a way as to be able to consume more exergy in the future. This is the definition of growth, and we are no where near the limits of our growth because there are so many sources of exergy left for us to consume.

So, I would like to change how we talk about 'consuming resources.' We need to stop talking about how to minimize our impact on the environment and instead we need to talk about how we plan to grow society! (i.e. to how expand science, expand the arts, expand applied science, expand democracy, expand life on other planets, etc... so as to be able to consume more exergy in the future.) The purpose of our knowledge is not for the sake of knowledge. Instead, the purpose of knowledge is to be able to design 'dissipative structures' that are even better at consuming exergy in such a way that they have positive rates of return on work invested.

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