"It's not a linear path. I did my PhD... in experimental explosion physics... I was interested in the , which was much harder then than it is now. This was before CCDs and CMOS sensors were built into things like high-speed cameras... [Y]ou had to do it the old-school way. ...[I]t was interesting and challenging and I liked building that kind of experiment. Looking at small things that were too quick... to see directly. But I never wanted to do [explosion physics]..."