You know we come in two sorts. We are either attempting to comprehend the true nature of reality or we’re melting ice in a bucket. Some of us are poets. And some are merely prose stylists.
Now, I was taught Solar System Dynamics* by Carl Murray at QMC and Professor Murray is a “Physics for poets” type. You may have seen him. Queen Mary is a very media savvy college and the likes of the BBC drag out Carl to give brief comments on NASA probes to the outer planets.
I actually have an early draft of his book**, scrawled upon and tea-ringed by my twenty two year old self… Let’s have a look shall we…
OK, so that’s the poetry. Now let’s turn to the back and have a butcher’s at the Physics. Those of you of a nervous disposition when it comes to math might want to look away now because in Appendix 2, lurking Smaug-like is The Disturbing Function. It is only expanded to fourth order in both direct and indirect parts, possibly both canonical and secular if not also real and imaginary***
Now you wanna know the best bit? That’s pages one and two. I left out the next 34. Also that is written in a very condensed form and, as I said, only to fourth order. Disturbing function. It disturbed me alright. And I had just graduated with a top-notch degree from a top-notch University and I was young and funded and in London and it was the age of Britpop and life was cool and we used to hang in the same clubs as Jarvis Cocker and a friend of a friend shagged Sophie Ellis Bextor (before she was famous, or even sixteen) round the back of a kebab shop on Fleet Street but I digress… Though you get the general idea of invincibility. Because the scamps that we were we got up to some capers I can tell you…
But what, you are no doubt wondering does that have to do with the disturbing function? And what indeed is the disturbing function for? Well, it’s a partial solution to the vexed three body problem. You see you can’t get a closed form (neat) solution to the mutual gravitational interaction of three bodies. Even treating them as point masses. It just don’t integrate. So we have the disturbing function. And I’m sure you’ll agree it’s a bit of a ‘mare ain’t it?
Two bodies – fine. Keplerian Orbits and all that jazz and they’re easy but bring in a third body and it gets messy. So why am I boring you with all this astrophysical dullness? Simple. The disturbing function has to be worked out on computers. The principle of it goes way back but nobody got it right. It was not until computers were used that the expansion was possible with any degree of accuracy. You might think it looks evil but just imagine trying to work it out, sat at a ledger, by candlelight. Science has wrestled with few demons worse than that.
But surely the three-body problem is simple? It should be down? It should be on the canvas and it’s second thrown the towel into the ring by now? No. It’s alive and kicking. It may just be three point masses interacting by a 1/r2 field but it’s nightmarishly difficult. We have cludges like the disturbing function not because we aren’t smart enough but because the problem cannot be solved. Not because it’s too complicated but because it can’t be solved in principle.
And that’s particle mechanics. And as any fule knows particle mechanics is much easier than dealing with a continuum such as a fluid. Like the atmosphere for example. The atmosphere also interacts with the oceans. Both interact with the biosphere which is of course an adaptive system. All interact with our tame G2 yellow dwarf (aka Sol) which quite frankly we don’t really understand that well at all.
I have mentioned Solar System Dynamics but that wasn’t really my field. My field was fluids. And if any bugger tells you the “science is settled” on global warming then I advise you to laugh yourself hoarse and remember the disturbing function. Because anyone who claims that the “science is settled” is claiming that a scientific problem several orders of magnitude more complex**** than anything ever solved before is indeed down.
And then remember the disturbing function and our limits. Maybe even remember the ultimate “Physics for Poets” physicist, Richard Feynman. Whilst designing the “gadget” at Los Alamos in the forties his wife, Arline, was dying of TB, a bacterial infection. We have never known it all and complexity is the eternal stumbling block. You want an atom bomb designing? You want a laser? You want a moon-shot? Ask a physicist. You want complexity? Ask someone else. Because we are poets and we just don’t know.
*It used to be called “Celestial Mechanics” but I think we can all agree that that sounds needlessly messianic.
**I say book but it was a really a spiral-bound draft back then typeset in Latex and photocopied.
***There are imaginary numbers. They are multiples of the square root of -1.
**** Science, especially physics is exceptionally good at tackling the difficult. It is remarkably poor at tackling the complex. In principle all biology reduces to chemistry and all chemistry to physics. Except that ain’t how it is in practice. There is still a place for the bug-collectors and the smell-merchants and that is for a good reason. You can write out the Schroedinger equation for a dog but it won’t get you anywhere. If you wanna know dogs then you’ll get much further going to the park and throwing a stick.