Skip to main content

The Demon in the Machine - Paul Davies *****

Physicists have a habit of dabbling in biology and, perhaps surprisingly, biologists tend to be quite tolerant of it. (I find it hard to believe the reverse would be true if biologists tried to do physics.) Perhaps one reason for that tolerance is Schrödinger’s lecture series and book What is Life?, which had a huge impact on molecular biology and with a reference to which, not surprisingly, Paul Davies begins his fascinating book. 

At the heart of the The Demon in the Machine (we'll come back to that demon in a moment) is the relationship between life and information. In essence, Davies points out that if we try to reduce life to its simple physical components it is like trying to work with a computer that has no software. The equivalent of software here is information, not just in the best publicised aspect of the information stored in the DNA, but on a far broader scale, operating in networks across the organism.

This information and its processing gives life its emergent complexity, which is why, Davies suggests, Dawkins-style reductionism to the gene level entirely misses the point. What's more, the biological setup provides a particularly sophisticated relationship between information and the physical aspects of the organism because the information can modify itself - it's as if a computer program could redesign itself as it went along.

The subtitle 'how hidden webs of information are solving the mystery of life' probably over-promises. As Davies makes clear, we still have no idea how life came into being in the first place. However, by bringing in this physical/information aspect we at least can get a better grip on the workings of the molecular machines inside organisms and how biology can do so much with so little. Here's where the demon in the title comes in. This is Maxwell's demon, the hypothetical miniature being dreamed up by the great nineteenth century Scottish physicist.

Maxwell's demon has the remarkable ability to tweak the second law of thermodynamics allowing, for example, heat to flow from a colder to a hotter body or, to put it another way, providing a mechanism for entropy (the measure of disorder in a system) to spontaneously decrease. Entropy has a strong (negative) relationship with information and Davies shows how miniature biological systems act in a demon-like fashion to effectively manage information.

There's lots to like here, from the best explanation I've seen of the relationship of information and entropy to fascinating coverage of how far we’ve gone beyond the selfish gene. This is not just about basic epigenetic processes (operating outside of genes, switching them on and off and so on) but how, for example, the electric field of a (biological) cell apparently has a role to play in ‘sculpting‘ the physical structure of an organism.

My only real complaint is that in part of the chapter Enter the Demon dealing with information engines and most of the chapter The Logic of Life, describing the relationship between living organisms and computation, Davies fails to put across clearly just what is going on. I read it, but didn't feel I gained as much information (ironically) as I needed from it. There was also one very odd statistic. We're told the information in a strand of DNA contains 'about 2 billion bits - more than the information contained in all the books in the Library of Congress.' There are about 32 million books in the Library of Congress, so that gives us on average 62.5 bits per book. Unless those are very short books, some information has gone astray.

Really interesting, then, from a transformed understanding of the importance of information in living organisms through to Davies' speculation on whether biological systems need new physical laws to describe them. But expect to come away feeling you need to read it again to be sure what it said.
Hardback 

Kindle 
Using these links earns us commission at no cost to you
Review by Brian Clegg

Comments

  1. Nick lane argues in his book The Vital Question that biological systems are not really working to decrease entropy they exist because they essentially dont violate the second law of thermodynamics . I wonder how that reconciles with the theory here

    ReplyDelete
  2. I find it difficult to follow some of this stuff. Not the fluffy conceptual models, but the simple aspergers stuff.

    eg p95, text describing Fig 11, says 'barred lines [indicate inhibition]'. Then seems to use a different term - 'loopy broken arrows' to denote self inhibition. Change of term is confusing but not fatal.

    But Fig 11 contains no broken or barred loopy arrows, only solid ones, thus indicating self activation, not self inhibition. Again, I guess, not fatal, if the reader is expected to be alert for errors or misprints.

    But table 2, P96 shows that in at least 2 cases, the loop is self suppression, so the loop should be broken or barred. Still not quite fatal.

    But then, following Table 2 and Fig 11 together, node G suddenly gets activated in step 8, although in Fig 11 there is no 'incoming [activation] arrow' pointing at it, except for it's own self activation loop, which can never be initiated.

    So what's going on? AFAIK just errors, which I'd hope not to have been included in this book.

    So, how do we read this book? Perhaps best just to gloss over all the clever diagrams & tables, say 'Gee, Whizz, that's all amazing!'

    OTOH if I'm really not understanding a perfectly valid exposition, I'd love to know.

    ReplyDelete

Post a Comment

Popular posts from this blog

We Are Eating the Earth - Michael Grunwald *****

If I'm honest, I assumed this would be another 'oh dear, we're horrible people who are terrible to the environment', worthily dull title - so I was surprised to be gripped from early on. The subject of the first chunk of the book is one man, Tim Searchinger's fight to take on the bizarrely unscientific assumption that held sway that making ethanol from corn, or burning wood chips instead of coal, was good for the environment. The problem with this fallacy, which seemed to have taken in the US governments, the EU, the UK and more was the assumption that (apart from carbon emitted in production) using these 'grown' fuels was carbon neutral, because the carbon came out of the air. The trouble is, this totally ignores that using land to grow fuel means either displacing land used to grow food, or displacing land that had trees, grass or other growing stuff on it. The outcome is that when we use 'E10' petrol (with 10% ethanol), or electricity produced by ...

Battle of the Big Bang - Niayesh Afshordi and Phil Harper *****

It's popular science Jim, but not as we know it. There have been plenty of popular science books about the big bang and the origins of the universe (including my own Before the Big Bang ) but this is unique. In part this is because it's bang up to date (so to speak), but more so because rather than present the theories in an approachable fashion, the book dives into the (sometimes extremely heated) disputed debates between theoreticians. It's still popular science as there's no maths, but it gives a real insight into the alternative viewpoints and depth of feeling. We begin with a rapid dash through the history of cosmological ideas, passing rapidly through the steady state/big bang debate (though not covering Hoyle's modified steady state that dealt with the 'early universe' issues), then slow down as we get into the various possibilities that would emerge once inflation arrived on the scene (including, of course, the theories that do away with inflation). ...

Why Nobody Understands Quantum Physics - Frank Verstraete and Céline Broeckaert **

It's with a heavy heart that I have to say that I could not get on with this book. The structure is all over the place, while the content veers from childish remarks to unexplained jargon. Frank Versraete is a highly regarded physicist and knows what he’s talking about - but unfortunately, physics professors are not always the best people to explain physics to a general audience and, possibly contributed to by this being a translation, I thought this book simply doesn’t work. A small issue is that there are few historical inaccuracies, but that’s often the case when scientists write history of science, and that’s not the main part of the book so I would have overlooked it. As an example, we are told that Newton's apple story originated with Voltaire. Yet Newton himself mentioned the apple story to William Stukeley in 1726. He may have made it up - but he certainly originated it, not Voltaire. We are also told that â€˜Galileo discovered the counterintuitive law behind a swinging o...