Posts from 2009-08

Sheldrake's New Science of Life

One of the books I read during my summer vacation is the recently published second edition of Rupert Sheldrake's "A New Science of Life". It is one of the most controversial books in science, having been both praised and condemned; a review of the first edition in the renowned science journal Nature concluded that this book should be burnt!

The question that Sheldrake addresses in this book is where form comes from. What defines the arrangements of atoms in a molecule? Or in a crystal? Why do proteins fold into their characteristic structures? How do biological molecules assemble into cells? And how to cells divide and specialize to form an embryo?

The standard reply to these questions you can find in science textbooks is that all these forms come from the fundamental interactions of physics. Molecules are simply energetically favorable arrangements of atoms. Proteins fold in such a way that free energy is minimized. Cells assemble as a result of complex attractive interactions between its constituents, which ultimately can be reduced to fundamental physics. Embryos develop according to a "genetic program" stored in the fecundated egg's DNA.

As Sheldrake rightly emphasizes, even though it may come as a surprise to most non-experts, these affirmations cannot be verified. They express a common belief among practicing scientists, and they are compatible with everything we know about nature, but they may well be wrong. We simply cannot verify them because the fundamental equations of physics can be solved only for very simple systems. Even for one of the simplest molecules, water, we cannot predict the arrangement of its atoms directly from the basic principles of physics. What we use in practice are approximations, but these approximations have been selected because they permit to predict the known molecular structures. We cannot use such approximations to verify more fundamental problems.

Sheldrake proposes an alternative theory, based on what he calls "morphogenetic fields". From my point of view as a physicist, the name is not very well chosen because these entities do not correspond to what a physicist would call a field, but of course this term may be perfectly clear to biologists. It's a minor point because Sheldrake explains this concept very clearly in his book. In summary, his theory says that forms exist because they have existed before; atoms, molecules, and cells arrange themselves into patterns that they "remember" from the past. His morphogenetic fields are a giant database of forms that the universe keeps around forever.

The main "problem" with this theory is that if it is right, even just approximately, then standard science, from physics to biology, is very much wrong. It is probably for this reason that his book has attracted so much criticism from the science establishment. Otherwise, there is little one could criticize: Sheldrake explains his theory and its consequences for chemistry and biology, and he proposes a large number of experimental verifications that would permit to test it. This is science at its best. Of course his theory may turn out to require modifications, or even be completely wrong, but that is true of any scientific theory when it is first formulated.

In fact, I recommend this book to anyone interested in the scientific process because of its detailed discussion of how scientific discovery works. I haven't seen many books accessible to non-specialists that explain the limits of verifiability of a scientific theory, for example. Nor have I seen any other book that makes the distinction between verified theories and widely accepted but untested beliefs so clear as Sheldrake does. Even if you don't care about his theory, you can gain a lot from reading this book.

Tags: computational science, computer-aided research, emacs, mmtk, mobile computing, programming, proteins, python, rants, reproducible research, science, scientific computing, scientific software, social networks, software, source code repositories, sustainable software

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