Metaflies
In the fourth century BC, the cutting edge of science was wielded by Greek philosopher Aristotle. He was one of the earliest empiricists, abstaining (in part, at least) from making things up off the top of his head, relying instead on experimental evidence gleaned from the World around him.
Luckily for scathing modern scientists giving chronological talks on astronomy, for example, (almost all ‘general overview’-type talks on cosmology seem to start out with the Ancient Greeks) he believed that the Earth was at the centre of the Universe, and that the heavens comprised 55 perfect crystal spheres, in which the celestial bodies were embedded, executing a complicated dance overhead.
However, this approach doesn’t deserve too much scorn; the predictions did pretty much fit the low-quality data back then, and science often appealed to elegance; tens of crystal spheres is how it should be, right?
He also observed that meat left out for a while would, somehow, become covered in maggots. Thus, he surmised, meat generates maggots.
It was over two thousand years ago. Give him a break.
What is surprising is that it was not until the 17th century AD that he was proved wrong. An Italian chap called Francesco Redi tried the same experiment, but this time with two bits of meat, one covered with a fine cloth. Only one piece developed the familiar maggot infestation, and thus empirical science leapt forth another step; a few more experiments growing captured maggots and leaving meat with dead flies later, he realised that live flies, not hunks of beef, gave rise to the larvae.
This leads to the interesting idea that, at certain points in history, anyone proposing that flies laid eggs was in fact proposing a metaphysical concept: a concept which science did not have the tools to test. Sure, the idea that flies laid eggs might give some explanation of the phenomenon, but it’s not what’s really happening! It’s just an elegant predictive tool, right?
Physics has been doing this for centuries; when Copernicus made the first mathematical model of a heliocentric universe — one with the Sun at its centre — he proposed it as a purely predictive tool. It gave better results, but it was in no way intended to represent the manifestly geocentric reality; after all, that had been known for centuries, since the time of Aristotle!
It was only when Kepler came along with a new and improved solar-centred model that the results really knocked the spots off the Greeks’ 55 crystal spheres, and finally science accepted that the Earth really did go ’round the Sun.
A more recent example is atoms; back in the late 19th century, thermodynamics was at its peak: having developed the steam engines which powered the industrial revolution, it was still riding the wave. However, a rebel sect was demonstrating that the predictions of thermodynamics could all be made if we assumed that the World were comprised of little, indivisible atoms. This was seen by all the major scientists and philosophers of the time as crazy metaphysical speculation. It not what’s really happening: just a neat little theory, right?
In 1905, Einstein wrote a paper on Brownian motion — the complicated dance of tiny particles, like smoke particles you may have seen jiggling in a sunbeam or under a microscope — which allowed the theory of atoms to be tested after all. Every swerve taken by a particle is due to an impact with an air molecule, and the speed of recoil demonstrates precisely that atoms exist, just as predicted. Metaphysics turns to physics again.
The trend has continued right through the twentieth century, with subatomic particles, and then the quarks they are made up of being doubted and then proved in turn.
But now, we’re stuck. The latest fad in physical theories comprises those which attempt to encompass all of reality, and a special favourite at the moment is string theory. However, there are strings of different string theories, and a technical hitch; it may well never be possible to test any of them.
The smaller the things you wish to investigate, the bigger the microscope you need; in the case of particle physics, we need massive accelerators, tens of miles long, to lob subatomic particles at one-another at dizzying speed. We might need a particle accelerator bigger than the Earth to look at superstrings. That would make a manned mission to Mars look cheap.
So, if we do one day find a superstring theory, or some other ‘theory of everything’ as they are dubbed, and it works, will we be any better off than Aristotle and his meat? Our prediction about the underlying nature of reality could be as stupid as that meat spontaneously creates maggots, but if it gives us the results which work at the energies and speeds we can do experiments in, how would we know?
Won’t we look silly in a few hundred years when someone invents a fine cloth made of superstrings, pops it over a pile of quarks and tears our tidy mathematical Worldview to pieces?
February 27th, 2006 at 10:54
Well-written, but I’m pretty sure that the fallacy of hindsight is counting against us, here: I’m sure that while Copernicus was coming up with his crack-pot theories of heliocentrism (which, of course, later turned out to be a huge jump ahead of the thinking of people before him) there were simultaneously dozens of other equally implausible-sounding theories which turned out to be completely useless and as such were forgotten - lost in history. At any given point in time, there will be a lot more theories than the generation that follows will learn about, because only those which are demonstrated to be true (for varying values of true and of demonstrated) will be taught as scientific fact.
That we see a lot of theories appearing at the moment which try to unify the sum of our knowledge, which try to explain the expansion of the universe and why we have to put silly constants in to make it “work” (a-la “dark matter”, etc.), or which discuss the reasons behind the seemingly-random movement of subatomic particles just shows that it is these areas that currently hold humanity’s fascination. If we come up with some crack-pot theory that holds water and which is, in decades or centuries to come, proven “right”, it’ll be taught as being revolutionary and it’s author praised for being ahead of eir time (albeit, quite possibly, after eir death).
When “someone invents a fine cloth made of superstrings, pops it over a pile of quarks and tears our tidy mathematical Worldview to pieces”, people won’t be surprised - they’ll just say that there was this clever person, treated as a loonatic, in the 21st century who saw it coming. They’ll never have even heard of the crazy theories that didn’t make it.
February 27th, 2006 at 14:04
Firstly, on Copernicus and his ilk: though there is a tendency to simplify things with hindsight (and I certainly have done, compressing decades of philosophical, theological and occasionally even scientific argument about cosmological systems into a few paragraphs), it was genuinely pretty much a two-horse race. Either the Earth goes ’round the Sun, or the Sun goes ’round the Earth. What other possibilities could there actually be? Maybe there were people proposing that the Earth was flat and everything went around Jupiter, but history has brushed over them, and rightly so; their theories will have held no water at all by coming up with utterly unviable predictions about planetary movement!
Secondly, on the modern era: yes, we may well have a ‘visionary’ in our midst who will be hailed as such in centuries to come. Some people have already described superstring theory as “part of twenty-first century physics that fell by chance into the twentieth century”. The problem with it, now and apparently indefinitely, is that it makes no testable predictions. If we want to test it, we need apparatus larger than we could ever conceivably construct, and even if one day we do find a way, what about the intervening time?
My point was more philosophical worry than anything else: if we get a workable string theory and yet are unable for centuries to test it, in analogy with Aristotle’s theory that meat makes maggots, we will be making up an underlying mechanism to explain the Universe without any knowledge of why it works. There may even be several such theories, all of which work, but none of which we can test to tell them apart. Hence, this is what concerns me; if we lack the technology or even the physical possibility of turning metaphysics into physics, how are we better than Aristotle with his idiot meat hypothesis?
My worry isn’t that one day some lunatic’s theory will be proven right and we’ll look silly. It’s that there will never be a way to test it, and ‘truth’, whatever that may mean, may be impossible for humanity to ever reach.
February 28th, 2006 at 09:53
Aye, absolutely right.
And there are, of course, other possibilities regarding the Sun and the Earth, and under today’s physics, the one that is most correct is that they both orbit one another, relative to one another, or that they both orbit a point in space near to, but not quite at, the centre of the sun (nearer to the Earth than that), relative to the centre of gravity of the two objects.
February 28th, 2006 at 10:06
Yeah, but you’ve got to admit that’s something of a technicality; with the Sun weighing in excess of 330,000 Earths, there was no way Kepler, Copernicus or even Galileo with his seminal telescope was going to take any observations to demonstrate that!
The centre of mass of the system lies just under 300km from the Solar centre — 0.000201 Solar radii! To ignore it is one of the better approximations in physics…