Let’s all take a moment, or a little while longer, to remember the mathematical physicist Freeman Dyson, who died on 28 February at age 96.
The New York Times has an obituary here.
But for the uninitiated, I’d suggest starting at the only TED talk I’ve ever liked, where Dyson gives a master class in physical reasoning to look for life on the jovian moons.
I went around looking for a good image of the Project Orion spaceship (the source of the featured image), and came across this document from 1964 on its theoretical basis: General Dynamics Corp. 1964. Nuclear pulse vehicle study Condensed Summary Report. January. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19760065935.pdf