in my studies of nuclear science, i started seeing how devastating a nuclear attack would be. you would kill hundreds of thousands of people or more compared to the hundreds of people killed in the aircraft attacks. i realized how big the threat was that we had basically open borders to nuclear terrorists and nuclear proliferators. i started to realize i could do something about this. i discovered a couple applications for scanning things like cargo containers for nuclear weapons. they actually use water, and they're possibly more sensitive than the present detectors but they're much less the cost. everyone was excited about this. scientists and government officials. president obama invited me to the white house. >> i was so proud of him. >> pretty amazing.