Humpty Dumpty's physics lesson

'When I use a word,' Humpty Dumpty said, in rather a scornful tone, 'it means just what I choose it to mean — neither more nor less.'

'The question is,' said Alice, 'whether you can make words mean so many different things.'

'The question is,' said Humpty Dumpty, 'which is to be master — that's all.'

(Lewis Carroll, Through the Looking Glass)

If you can get hold of the August issue of Scientific American, you really should take the time to read an extraordinary article by Meinard Kuhlmann, about sub-atomic physics.  (There's a link to a preview page here, but you have to subscribe to see the whole thing). Kuhlmann, who is clearly a Bear with a Very Large Brain, is a professor at the University of Bremen in Germany, and an expert in the philosophy of physics.  (Yeah, who knew, right?)

Kuhlmann effectively demonstrates that while the standard models of subatomic physics "work", nobody really understands them.  Indeed, even the sense in which they can be understood is difficult to grasp, because words are not used in the way we're used to.  For example, most laypeople's understanding of "particles" is,  Kuhlmann suggests, something like billiard balls caroming off each other.  But that's nothing like what the theorists now believe.  Equally, talking about "fields" makes most people think in terms of iron filings around a magnet, but the theory sees something quite different.  So when physicists talk about "particle fields", it's not at all clear what is meant, and it's certainly not what most laypeople assume.

If that's not enough for you, Kuhlmann then launches into a discussion of alternative ways of looking at reality.  At this point you may need a pot of strong coffee and a bottle of your favoured analgesic.  We learn about "primitive thisness", "state vectors" and "tropes", and we are told that although a vacuum contains an average of zero particles over time, at any given moment it's abuzz with activity.  We are also reminded that nobody ever sees particles -- they just observe their traces, and hope that those traces are where the model says they should be.  That casts a new light, at least for this ignoramus, on the recent "discovery" of the Higgs Boson.

Kuhlmann's underlying argument in all of this seems to be that as long as we don't understand our present theory, even if it "works", it's dangerous to press on into new fields such as string theory.  He wants the metaphysics, or the ontology, to catch up with the math.  And you can see his point -- as things stand, sub-atomic theory is almost as much a matter of faith as religion is. We may know much more than we used to, but we understand less.

I've written a few posts lately about physics, a subject of which I am largely ignorant, and I've started to wonder what it is that keeps getting me interested.  I think it comes back to this.  Decades ago a Cambridge economist, John Eatwell if memory serves, said something to the effect that "if the real world does not correspond with the economic models, so much the worse for the real world".  It was probably said tongue in cheek, but he was castigated for it anyway.  In modern physics, however, whether we're talking dark energy or primitive thisness, Eatwell would be a mainstream thinker.