I guess everything gets stressful at times. Atoms are tough little blighters, and if you work in anything where you use very small numbers of them then you are always being messed around by the world. I work with nanomoles of materials – I’m not sure if you know what it means, but it is like when people say ‘parts per million’. I work with a billionth of a part per million of stuff, and a single stray dust particle or sniffle can mess up a whole days work. That can be frustrating.