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
Labels:

Comments

  1. Akshat26 February 2019 at 14:53

    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. GT27 July 2019 at 01:00

    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

The Laws of Thought - Tom Griffiths *****

In giving us a history of attempts to explain our thinking abilities, Tom Griffiths demonstrates an excellent ability to pitch information just right for the informed general reader.  We begin with Aristotelian logic and the way Boole and others transformed it into a kind of arithmetic before a first introduction of computing and theories of language. Griffiths covers a surprising amount of ground - we don't just get, for instance, the obvious figures of Turing, von Neumann and Shannon, but the interaction between the computing pioneers and those concerned with trying to understand the way we think - for example in the work of Jerome Bruner, of whom I confess I'd never heard.  This would prove to be the case with a whole host of people who have made interesting contributions to the understanding of human thought processes. Sometimes their theories were contradictory - this isn't an easy field to successfully observe - but always they were interesting. But for me, at least, ...
Post a Comment
Read more

The AI Paradox - Virginia Dignum ****

This is a really important book in the way that Virginia Dignum highlights various ways we can misunderstand AI and its abilities using a series of paradoxes. However, I need to say up front that I'm giving it four stars for the ideas: unfortunately the writing is not great. It reads more like a government report than anything vaguely readable - it really should have co-authored with a professional writer to make it accessible. Even so, I'm recommending it: like some government reports it's significant enough to make it necessary to wade through the bureaucrat speak. Why paradoxes? Dignum identifies two ways we can think about paradoxes (oddly I wrote about paradoxes recently , but with three definitions): a logical paradox such as 'this statement is false', or a paradoxical truth such as 'less is more' - the second of which seems a better to fit to the use here.  We are then presented with eight paradoxes, each of which gives some insights into aspects of t...
Post a Comment
Read more

Einstein's Fridge - Paul Sen ****

In Einstein's Fridge (interesting factoid: this is at least the third popular science book to be named after Einstein's not particularly exciting refrigerator), Paul Sen has taken on a scary challenge. As Jim Al-Khalili made clear in his excellent The World According to Physics , our physical understanding of reality rests on three pillars: relativity, quantum theory and thermodynamics. But there is no doubt that the third of these, the topic of Sen's book, is a hard sell. While it's true that these are the three pillars of physics, from the point of view of making interesting popular science, the first two might be considered pillars of gold and platinum, while the third is a pillar of salt. Relativity and quantum theory are very much of the twentieth century. They are exciting and sometimes downright weird and wonderful. Thermodynamics, by contrast, has a very Victorian feel and, well, is uninspiring. Luckily, though, thermodynamics is important enough, lying behind ...
Post a Comment
Read more