Not for the faint of art. |
Complex Numbers A complex number is expressed in the standard form a + bi, where a and b are real numbers and i is defined by i^2 = -1 (that is, i is the square root of -1). For example, 3 + 2i is a complex number. The bi term is often referred to as an imaginary number (though this may be misleading, as it is no more "imaginary" than the symbolic abstractions we know as the "real" numbers). Thus, every complex number has a real part, a, and an imaginary part, bi. Complex numbers are often represented on a graph known as the "complex plane," where the horizontal axis represents the infinity of real numbers, and the vertical axis represents the infinity of imaginary numbers. Thus, each complex number has a unique representation on the complex plane: some closer to real; others, more imaginary. If a = b, the number is equal parts real and imaginary. Very simple transformations applied to numbers in the complex plane can lead to fractal structures of enormous intricacy and astonishing beauty. |
Solstice tomorrow (around 4:20 am here), so this is my last entry of astronomical fall. Today's article, from BBC, has nothing to do with seasons, though, and it's a subject I really shouldn't be weighing in on—but of course, I'm going to do it anyway. What inspired me to jump in above my head here was the lede: Far from triumphantly breezing out of Africa, modern humans went extinct many times before going on to populate the world, new studies have revealed. Now, there's a poorly phrased sentence if I've ever seen one. It should be blindingly obvious to everyone who can read this that modern humans didn't go extinct. This is a fact on par with "Earth is roughly spherical" and "Space is mostly vacuum." Actually, wait, no, I'm even more sure that modern humans didn't go extinct than I am about those other things, because, last I checked, there were about 8 billion modern humans running around. Or sitting around. Whatever. You do you. Point is, we're not extinct yet. Likely, the author meant "sub-populations of modern humans went extinct many times," which, okay, I guess they have science to back them up on that, and I'm not going to argue about it. But I feel like the way it's phrased would be like if they said "humans went extinct in Pompeii in 79 C.E." The new DNA research has also shed new light on the role our Neanderthal cousins played in our success. This is, I think, the interesting bit here. But I'd like to emphasize the "cousins" metaphor there. Sapiens and neandertals (the spelling of the latter appears to have legitimate variants) shared a common ancestor. A certain ape population separated at some point, genetic drift and selection occurred differently in each population, until you got groups with clear physiological differences in the fossil record. But, apparently, the physiological differences weren't enough to prevent interbreeding. The definition of a species is, to my understanding, a bit of a slippery concept in biology. That is, it's not always obvious what constitutes a separate species. If it were as easy as "a population that can breed to produce fertile offspring," we wouldn't consider sapiens and neandertals separate species because, according to DNA evidence, they produced fertile offspring together. While these early European humans were long seen as a species which we successfully dominated after leaving Africa, new studies show that only humans who interbred with Neanderthals went on to thrive, while other bloodlines died out. Again, I feel like this is poorly phrased, and puts too much emphasis on Europe. Apparently, there are populations in sub-Saharan Africa today with no neandertal genes and, again, obviously they didn't die out. And they're the same species as the rest of us mostly-hairless bipeds. Apart from these nitpicks, I think the new findings are fascinating, delving into how, basically, hybridization led to greater hardiness. As with all science, it may be overturned or refined through later studies, but this article itself describes an overturning of previous hypotheses about early human ancestry. And it has helpful infographics and pictures. But unless we invent time travel (unlikely), all we can do is make hypotheses and test them. It's really a very human thing to do. |