Understanding molecules, he's quick to point out, is a prerequisite for understanding just about anything else. "Look at the world," says Zewail. "Everything around us is chemical reactions. Everything--inside you and me, the atmosphere, everything we breathe, we touch. Everything is a chemical reaction. So we have to develop a unified theory of how chemistry takes place. We can't understand this unless we really have a coherent understanding of how atoms and molecules like or dislike each other. That's our ultimate goal."
The catch is that these intimate chemical acts occur on a time scale that is almost unimaginably short: they take place in femtoseconds, to be precise, which are the quadrillionth parts of a second. A quadrillionth equals a thousand-trillionth, or .000000000000001; for perspective, you might contemplate that a femtosecond is to a second as a second is to 32 million years. To capture such acts as they happen ...
