It's sad how a fall so quickly leads to death in the elderly. I've seen this happen before -- it really comes out of the blue.
Ironically (in the Alanis Morissette sense), I just emailed Dyson about a month ago with a question for something I'm working on, and he gave me a nice reply, and then another after I followed up on that one.
I think by far his greatest work was showing that the different mathematical formulations of QED (quantum electrodynamics) of Feynman, Schwinger and Tomonaga were all equivalent. Dyson was in his 20s then (26 in 1949) when he did this, which is extremely impressive. His paper is a real tour de force. From what I remember reading about this, he did this after daily summer classes at a course in Michigan, to where Feynman drove him, in a road trip that almost seems like something out of Hunter Thompson. Dyson would go back to his upstairs dorm room each day to continue working on the QED problem. I learned about this as an undergraduate and still have a very romantic image of this in my mind, of Dyson hunched under the eaves up there, hot and sweaty, dealing with the difficult levels of perturbation theory for each formulation of QED. But this is just my image, the image you create when you read a book, without ever seeing the movie. It surely didn't happen exactly like that, but I cherish my images of it nonetheless.
Plus I remember reading about him, earlier I guess, working as a mathematician for the British war effort, figuring how the right size of hole for pilots and gunners to jump through after their planes had been shot up. From what I remember the hole was too small in the beginning, which cost lives, but making it too big cost lives too, from flak going upward. All while he was a very young man, being forged by the world war all around him.
Interestingly, his NY Times obituary says his famous idea of a Dyson sphere actually came from a science fiction writer.
When I was in graduate school and needed to take a few months off for back surgery, my advisor sent me off with a copy of Dyson's book Disturbing the Universe.
I realize I'm focusing on how Dyson affected me, even though I never met him or had any real interaction. I think people try to find a way to connect to a major event if they can, whatever it is. In my case it certainly wasn't much, but it was this.
We here know Dyson for his skepticism of manmade climate change. I was surprised to read how staunchly he put forth his position in this GWPF document. Sadly, to me it reads like the thoughts of a very old scientist who could only think that CO2 is good for plants! without thinking deeper, while complaining about the young guns had dared to come to a different conclusion than he did. Of course, Dyson himself was once a young gun, and we know that it's the young guns who are right -- they always are -- and it's kind of sad that Dyson didn't have enough wisdom to understand that.
As they say science advances one funeral at a time, and that seems especially true here. Not that Dyson was ever a significant player in climate science. I remember him saying this a decade ago:
“[m]y objections to the global warming propaganda are not so much over the technical facts, about which I do not know much, but it’s rather against the way those people behave and the kind of intolerance to criticism that a lot of them have.”
- Freeman Dyson, Yale Environment 360, June 4, 2009