A highly accomplished physicist and out-of-the-box thinker. Rare intellect, by all reports kind to all he met, and a bit nutty on the side. Trifecta.
He found Project Orion to be the most stimulating thing he was ever involved with. For a long read on that: Project Orion: Its Life, Death, and Possible Rebirth
Dr. D had 'unconventional' views on climate change. Anyone who asserts that diminished his earthly arc will have to come through me!