I would like, if I may, to take you on a strange journey, into archaic pre-Cambrian life and cosmology.
But first, note that the first season of The Kids in the Hall is coming out on DVD.
Have you noted? Oh good. Let's carry on.
Consider this paper, which also appeared in Nature. It's motivated by studies of the temperature fluctuations in the cosmic microwave background. Like pretty much everything else in life, these fluctuations can be viewed as a sum of harmonics. It's precisely analogous to the way a sound wave can be decomposed into simpler, pure sine waves. In mathspeak, one finds a convenient orthonormal basis for the Hilbert space of functions one is studying. In this case, cosmologists are mapping microwave temperatures on the surface of a sphere, since that's all we can observe. The natural basis for functions on a sphere are the famed spherical harmonics, which are combinations of cosines and complex exponentials, and very pretty. You can plot them online here. They also inspired the science fiction novel Spherical Harmonic by Catherine Asaro, which I've been meaning to read.
Anyhow. One can break up the microwave temperature fluctuations into spherical harmonics, and use this data to evaluate cosmological models, since the temperature fluctuations stem from primordial cosmic evolution. As it transpires, the usual picture of an infinite universe runs into some trouble here. It matches very well indeed with all the higher harmonics, but diverges wildly from what's actually observed in the quadrupole, the lowest observable term. This corresponds to an absence of very long-wavelength density fluctuations in the early universe, since density fluctuations are the primary source of temperature fluctuations. In an infinite universe, this shouldn't be so; there should be no preferred length scale. The authors of the paper try to get around this by positing that space might not be infinite at all; perhaps, they say, topologically at least, the universe is the Poincare dodecahedral space.
You can imagine this as a dodecahedron, with opposite faces glued together (with a p/5 twist): if you or someone you loved happened to run into a face on the boundary of the dodecahedron, you'd find yourself coming back into the dodecahedron from the opposite face, yacked around a bit. So it's a finite space, but unbounded, like the surface of a sphere. Only weirder. Obviously, a finite space couldn't support any waves bigger than the space itself, so a finite universe like this dodecahedral space would naturally lead to the low quadrupole.
Now isn't that neat?
For some bizarre reason, last night I suddenly started to remember an article I'd read early in high school in a pop-science magazine, about bizarre, extremely primitive forms of life pre-dating the Cambrian. I couldn't for the life of me remember what they were collectively called, though. Fortunately, a little Googling saved me a lot of brain-wracking. The critters I was thinking of were the Ediacarans, from the Vendian Period. The Vendian stretched from about 605 million to 543 million years ago, an epoch practically Lovecraftian in its antiquity. For the last twenty million or so of these years, the soft-bodied beasties called Ediacarans (named after the Ediacara Hills in Australia, where a large deposit of their fossils was found) collectively thrived. Even now, no-one is entirely sure what these creatures were, since they have pronounced differences from any more familiar forms of life. They were generally floppy, blobby sorts of things, like fried eggs, modellable by a substance not unlike Jell-O. (Lovecraftian, indeed; protoplasmic, prehistoric proto-Shoggoths. Only tiny and harmless.) And then there are oddments like my personal favourite, the Tribrachidium, exhibiting a really beautiful threefold rotational symmetry, which you can see again here. What the heck were the Ediacarans? Were they jellyfish? Worms? Corals? Were they a weird dead end that died off completely in the Cambrian? Were they animals at all? A lot of them seem to have had a sort of 'quilted' surface; perhaps, one theory goes, they were composed of flattened, fluid-filled balloons, possibly filled with symbiotic algae (though probably not). It's not really clear how such soft-bodied creatures managed to leave so many fossil traces at all.
Here's an article quoting a Dr McMenamin who seems to be verging on crackpottery and bad science. Fun though blobby balloon-beasts are, how the heck could he conclude they were on the way to intelligence? They're blobs. That's pretty much all we know. Also, people disliked his book.
There are more photos here.
And more here.
Whatever they were, they were jolly strange. And that is why I like them. It's almost enough to make me take up biology...I love a mystery.
So long as it isn't a mystery like 'Where did my underpants go?' or 'Why haven't I been paid in a month and a half?'
Posted by aloysius at October 14, 2003 02:17 PM | TrackBack |