Physicists are well-known for wading into other fields assuming that they're essentially simple, and studied only by people too stupid (in other words: not by physicists) to realise that, often completely missing all the subtleties which mean that, in fact, they are not simple at all. This is particularly true for fields where there is a lot of inherent complexity. Physicists tend to be very good at approximating complex systems by much simpler ones1: sometimes this works brilliantly, quite often it fails miserably2.
Well, a lot of people now are suddenly experts in epidemiology, because well, what could be hard about it? It turns out that quite a lot could be: who knew? At least, since no-one is reading this, I haven't caused any harm by my idiocy. But people who don't just write things for their own interest, but whose writing is read, are writing, often, a lot of confused junk3. Perhaps we should all leave it to people who actually know what they are talking about.
Cartoon from xkcd.
Spherical cows is the canonical example: I don't know if it was ever something real. ↩
'The greenhouse effect? Easy, here, I did some maths for you, and you can see you're overestimating it hugely as the atmosphere is already opaque in the infrared ... oh, yes, I should take that into account ... oh, you mean I can't model the atmosphere as a single layer ... oh, you mean you've actually thought about this?' Except, usually, they stop at the first stage. ↩
Of course they are hugely outnumbered by the people who intentionally set out to mislead – almost all politicians – or who have no idea what truth is at all. But that cause is lost. ↩