(Short intro in Dutch, the post itself is in English.)
De losgebarste discussie over het geknip in David Attenborough door de EO (mijn standpunt: het is -ook van de BBC die kennelijk toestemming gaf- niet erg netjes tegenover Attenborough, én de EO had op z’n minst aan het publiek duidelijk moeten aangeven wat ze gedaan hadden: “delen van deze documentaire zijn door ons gewijzigd of verwijderd”), die discussie deed mij denken aan twee oude postjes van mij over Intelligent Design en Quantummechanica.
Want het is nog niet ingewikkeld genoeg. :-)
(First posted on Friday 27th januari 2006 – 11:09:36 AM)
Last week I was talking about Intelligent Design (with, by the way, the founding father of the now sadly closed down UVvN) when an analogy with quantum mechanics occurred to me. Or maybe even two analogies. Today, I bring you the first one.
Both theories have a problem with evolution.
Of course, it’s not the same evolution. In the case of ID, it’s the famous Darwinian evolution of random mutations and natural selection, that is the mechanism for change in large groups of organisms, over (usually) large stretches of time. For QM, the evolution at stake is the way the Schrödinger equations tells the wavefunction of a system, say: the physical state it is in, to change over time. The wavefunction is said to evolve according to the Schrödinger equation.
So how is there a problem with evolution? Well, it’s not the whole story. In QM (at least in the orthodox interpretation) there are exceptions to the rule that the wavefunction simply evolves. These exceptions are called measurements. In the usual course of nature, the wavefunction obeys the Schrödinger equation, but when a measurement is done, it is said to collapse instantly into something else. (It does not matter so much now into what exactly.) In ID, on the other hand, there are exceptions to the usual course of the Darwinian evolution. These exceptions happen when the change is too great, when something truly new and different emerges. In that case, there is said to be design.
So in both cases there are two competing mechanisms to describe change. Either it is evolution, or it is a “jump” (either collapse or design). Now, having two mechanisms wouldn’t be too bad, if not too pretty either, if you knew exactly when to apply which. This is where the real problems are: when does a “jump” occur? For ID, this amounts to asking: what steps are too great? This question is answered with things like (I’m not sure if this are all the cases) there is a change from one species to another, and/or when something with irreducible complexity is formed.
But: what is irreducibly complex? when are two individuals members of different species? Is this always well-defined? Likewise, in QM, the difficult question is: what is a measurement? And how is it different from any other physical interaction? There have been many attempts to dodge this question, for instance by saying that collapse occurs when a system becomes macroscopic. But that hardly helps: where, exactly, is the line between microscopic and macroscopic?
And when we think we have answered these question, what if we find, say, animals with intermediate stages of formerly thought irreducibly complex features? Or when we see quantum behaviour of buckyballs or still larger molecules? Do we move the line and try not to think about it?
It seems to boil down to this: is there a qualitative difference between situations in which ‘normal’ evolution is at work and situations with jumps? And in both cases, it proves very hard to find such a difference.
I don’t mean to argue that ID and QM are completely similar. Just to be clear, I’ll add an important difference. QM is a widely accepted, very thoroughly tested and hugely successful theory, and although there is a thing called the ‘measurement problem’, QM is very clear on its predictions (and very right as well). ID, on the other hand, is at best an alternative for the otherwise widely accepted biological evolution theory, and does not (or even can not) provide predictions that distinguish it from ‘normal’ evolution theory.
Moreover, while many physicists do not worry much about these things (as QM works so well), some of them and lots of philosophers of physics do, but it seems that the only people worrying about the evolution vs jumps problem in ID are its opponents. Related to this is the final point that while it is very hard, or maybe impossible, to get rid of the jumps in QM (there are attempts made, Bohm is probably the best known example), in ID the jumps are rather an add-on to the evolution, something deliberately put into the theory, next to evolution.
More in Part 2, to appear soon.