Unless you are a fan of theoretical physics and physicists then Dyson will not have appeared on your radar. But if you are keen on science fiction and space travel then you might have come across the Dyson Sphere or possibly the Orion Project for nuclear propulsion.
The New York Times has a wonderful profile of him with this story about just how off-the-charts smart this gentleman is:
At Jason, taking problems to Dyson is something of a parlor trick. A group of scientists will be sitting around the cafeteria, and one will idly wonder if there is an integer where, if you take its last digit and move it to the front, turning, say, 112 to 211, it’s possible to exactly double the value. Dyson will immediately say, “Oh, that’s not difficult,” allow two short beats to pass and then add, “but of course the smallest such number is 18 digits long.” When this happened one day at lunch, William Press remembers, “the table fell silent; nobody had the slightest idea how Freeman could have known such a fact or, even more terrifying, could have derived it in his head in about two seconds.” The meal then ended with men who tend to be described with words like “brilliant,” “Nobel” and “MacArthur” quietly retreating to their offices to work out what Dyson just knew.The point of this profile, besides inherent interest in a remarkable man, is to delve into his sharp criticisms of global warming advocates. I've not put much thought into the details of the ins and outs of global warming but Dyson has. His thoughts are worth reviewing, not to debunk global warming, but to see the workings and priorities of an independent mind.