This is a Science Sunday post, and a follow up to last week’s. But, after thinking awhile about how to talk about what I wanted to talk about, I decided a somewhat different approach than I’d normally use for writing about science. Here it goes.

Been nearly a year since I’ve taken any chemistry class. Last one was organic chemistry lab, taken over the summer because I thought it would be easier. Now, taking it in the school year may have been worse, but even so, how I hated that class. TAs who didn’t know how to give useful advice, but did know how to be anal about grading lab reports. Products that never weighted quite as much as they should have, except when they weighed more, which felt even weirder, because while it’s one thing to loose chemicals, its another thing to have it materialize out of the ether (in reality, I suppose it was insufficient drying–which in some cases, could literally mean ether, since we used that as a solvent.) And then there were the rare instances of things not turning the color they were supposed to, and universally unitelligibel NMR graphs. Yeah.

There was one part of the class I only almost hated though: when we went out of the real lab into the computer lab. I almost hated it out of boredom, but didn’t hate it because it was one of the easier parts of the class. Follow the instructions, get the numbers, no reality to get in your way, no real thinking necessarily involved. The exercises usually involved building molecules with a highly user-friendly interface and telling the computer to tell you things about them. The worst that could happen is that the computer, when trying to tweak your arrangement of the atoms, would sometimes wildly skew them. But all you had to do was undo that, tweak the starting location of the atoms in your molecule, and you were good to go.

But here’s something I sort of knew at the time, but didn’t put together right away: quantum mechanics is hard. Indeed, involves differential equations that may not be fully solvable. This is a major problem in science–it makes it harder to understand what’s going on, and left room for some doubts if our general approach was really right. Apparently in 1929, just two years after we got the quantum explanation of molecular hydrogen, physicist Paul Dirac was already declaring that quantum mechanics was the road to understanding everything. But that wasn’t totally clear at the time–the math necessary to prove that would be too hard.

Two things have helped change that situation. First, is computers, which work far faster and with fewer errors than human mathematicians. Second, however, is approximation techniques. For example, it does wonders for simplifying your calculations if you assume atomic nuclei are immobile, and given their great size relative to electrons, this works reasonably well. That’s the Born-Oppenheimer approximation, learned very early on in learning what little I know of quantum chemistry. But approximation techniques go far beyond such simple tricks, and was judged Nobel prize worthy material in 1998, when the Nobel prize in chemistry went to two guys who had worked on physical chemistry, Walter Kohn and John Pople.

I’ve looked up some of the news coverage on that Nobel prize, and it’s kind of vague. Talks about “quantum chemistry for everyone,” and similar such phrases. But what does that mean? From conversations with professors, I gather that that doesn’t mean quantum chemistry for electrophysiologists studying the brain–too much computing power would be needed. The limit is in the dozens of atoms, not hundreds or thousands.

But here’s what “quantum chemistry for everyone” does mean–first and second year undergrads walking into a computer lab, clicking “semi-empirical,” and getting some decent information on a modeled molecule. But semi-empirical, turns out, is a phrase from Pople. We were using his high-powered techniques at the drop of a hat. And we were doing it on desktops. Now that’s scientific advancement.