As Clear As Glass

This is another sciencey post. If you want something more trivial, read Channel Flip, although lately I have been mostly discussing science there as well. I’ll try to blog about something trivial later on. If not, then hey, it’ll be September soon and I’ll need a new Religious Crackpot…

In the meantime, here’s a Clever Analogy. There are people, or at least Creationists, who are, apparently, quite prepared to accept “microevolution”, the idea that small changes within a species can be explained by natural selection, but not “macroevolution”, the idea that cumulative small changes can eventually cause large changes and speciation. This is foolish, andI have a Clever Analogy to explain why.

Also, many people think glass is a liquid. This is also wrong. They usually have some spurious evidence for the claim, but it’s still wrong. Glass is a glass. Rubber, on the other hand, is a rubber. According to molecular physics, there is no structural difference between a rubber and a glass. Both take the form of a tightly packed mess of long polymer molecules, which are much like the cables behind your computer, unless you use a Mac in which case I’d like to know why you lot insist on that ridiculous one button mouse. Except that the molecules in rubbers and glasses are interlinked, so the object keeps its shape. Hence, a good rubber band could be all one molecule, theoretically.

The difference between a glass and a rubber is in temperature. A glass is cold, and as such the molecules can’t move around much, so when you hit it, it can’t distort so it fractures. A rubber, on the other hand, is warmer, and can simply bend out of your way as the molecules flow over each other. The reason some things are glassy and some are rubbery is that different materials have a different glass transition temperature. If that’s above room temperature, it’s a glass, otherwise a rubber. If you dunk rubber in liquid nitrogen, it turns to a glass and shatters on impact. You’ve probably seen it done, which is good because anagloising an obscure process we can’t observe to another obscure process we can’t observe is a bit pointless.

But here’s the thing: it’s all about molecule speeds, so instead of making the molecules faster, you could just make the impact slower. If you hit a glass very slowly, you could get it to move like a rubber. Or, if you have a very slow metabolism then you might see things we think of as glasses acting as rubbers. Equally, if you hit rubber fast enough, you can make it shatter. In theory.

“Micro-“ and “Macro-evolution” seem very different. They have very different results, although the underlying process is the same. But my point here is that a single process can produce dramatically different effects when viewed over different timescales. There’s absolutely no reason why that shouldn’t be the case.

It’s a common Creationist argument, but more than that I think it’s an important part of how evolution works that’s rarely explicitly addressed. If I can remove a mental block to understanding something as brilliant as the theory of evolution, I’d like to do that.