Reply to post: Re: Belief has nothing to do with it: The fundamental difference between religion and science

Climate-change skeptic lined up to run NASA in this Trump timeline


Re: Belief has nothing to do with it: The fundamental difference between religion and science

The problem is that the models are continually getting it wrong.

"All models are wrong, but some are useful" - George Box

"The best material model for a cat is another cat, or preferably the same cat" - Arturo Rosenblueth

Non-scientists routinely misunderstand the purpose and utility of models in science. Here's a famous example of an exceptionally useful - but completely "wrong" - model: it's the Ising model for ferromagnetism. When a ferromagnet is heated up to a specific temperature (the Curie point), it abruptly de-magnetises. This is a classical phase transition (like the boiling of water, etc.). The Ising model was proposed in 1924 by Ernst Ising, in an attempt to understand the ferromagnetic phase transition (phase transitions were poorly understood at the time). It is elegant, abstract, and - as a model for ferromagnetism - completely wrong. It's absolute rubbish. It's childishly simplistic. Real ferromagnets are, in reality, nothing like the Ising model - they're way more complex in structure and (quantum) electrodynamics. But here's the strange thing... the Ising model completely nails the ferromagnetic phase transition. It describes the behaviour of the relevant physical quantities near the Curie point astoundingly well. The Ising model (which was finally solved analytically in the 1940s by Lars Onsager) subsequently became the "fruit fly" of the physics of phase transitions. It's probably not far off the mark to say that almost everything we know about phase transitions (and we now know a lot) is rooted in studying the Ising model. It is one of the most elegant, successful and influential models in the history of science.

It's instructive to consider just why the Ising model is in fact so successful. It turns out that, in general, phase transitions fall into distinct "universality classes": that is, many apparently completely different physical phenomena which demonstrate phase transitions turn out to behave in identical, stereotyped ways near their critical point - they may be described, not just qualitatively but quantitatively, by the same mathematics. (This is a rather deep discovery, which stems from studying - you guessed it - the Ising model.)

So the Ising model didn't have to be "correct", or even "accurate" (it's not). It just had to nail the one phenomenon it was intended to model. It abstracts the problem. That is what useful models do - that's what they're for.

In climate science, as in any other science, that is how we should view models: not as "right" or "wrong" ("another cat"), but as useful in abstracting and pinpointing the crucial aspects of the phenomenon we wish to understand.

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