Freeman Dyson in Princeton, 2012.

Consider the set of brilliant twentieth century physicists. That's an impressively large set. Now consider the set of brilliant physicists who contributed important ideas to several diverse fields. The set shrinks. Now further include only those thinkers who not only satisfied these criteria but who could write like poets and historians. And now finally zero in on those thinkers who also demonstrated a sensitivity to human problems that is unusual among professional scientists. That's a set that occupies a dot compared to the vast universe we started out with.

As far as I am concerned, only two people inhabit this vanishingly small intersection of talents: Freeman Dyson and E. O. Wilson. There are of course others - Stephen Jay Gould, Peter Medawar, Carl Sagan, Oliver Sacks - but nobody does it as well in my opinion as Dyson and Wilson.

On Friday and Saturday I will be at the Institute for Advanced Study in Princeton attending mathematician and physicist Freeman Dyson's 90th birthday celebration. By any definition Dyson is one of the great thinkers and polymaths of the twentieth century. He was a founding father of quantum electrodynamics, was elected to the Royal Society at age 30, made important contributions to everything from quantum mechanics to spaceship design, became a professor at Cornell with no more than a BA but has received more than twenty honorary PhD degrees, contributed enough as a consultant to the defense establishment to receive the Fermi Award, was a close colleague of both Oppenheimer and Feynman and has penned superb books on topics ranging from poetry to extraterrestrial life. He is a mathematician who is as adept at calculating continued fractions and shock absorber stresses as the energy levels in atoms. Even if you consider his purely technical ideas, his range is astonishing.

What truly sets Dyson apart though is his command of the English language and his understanding and concern for human problems. These are qualities that are rare among scientists, and especially among physical scientists. His autobiography "Disturbing the Universe" is a must-read for every literate person. It combines prose that flows like silk with a panoramic view of science, history, poetry, politics and literature. He evidences an intimate understanding of war that is filled with empathy and revelatory human stories. Dyson is as equally at home talking about the S-matrix and about diplomacy with the Soviets as he is mulling over T. S. Eliot's "Murder in the Cathedral". In his writing he offers at least as many original ideas in various fields as in his research. He pens endearing - and enduring - portraits of his close friends Richard Feynman, Robert Oppenheimer and Edward Teller and demonstrates a rare grasp of the value of human imperfection.

In other books he has shown himself sympathetic to religion, thinking it to be as necessary to hope and survival as the tools of science. Unlike the so-called "New Atheists" Dyson believes that religion, with all its evils and flaws, has demonstrated itself at the very minimum to be a useful glue that binds human beings to each other in times of adversity. Taken as a whole Dyson's books are primarily about science as an instrument of human progress, but they are also equally about the role of history, poetry, literature and politics in making sure that science functions responsibly. His writings glow with optimism and project a bright future for the human species, both on earth and in outer space. I agree with his biographer Philip Schewe that far and beyond, Dyson will be best remembered as an original essayist.

Over the past few years Dyson has become much more well-known in the public eye for his skepticism regarding climate change, a view made popular in a lengthy 2009 New York Times magazine profile. This was always unfortunate. Both his views and the article were blown out of proportion. In reality, as can be readily judged when you talk to him, Dyson's opinion of climate change is mildly proffered, moderate to a fault and in the best tradition of the same skepticism that has guided science since its inception. He disapproves of faith in computer models and of the zealous dogmatism exhibited by some climate change activists, and both these points are extremely well taken. Ultimately Dyson is saying something simple; that science progresses only when there is a critical mass of skeptics challenging the status quo. It's not about whether the skeptics are right or wrong, it's about whether their voices are drowned out by the consensus.

My own relationship with Dyson and his work goes way back to when I was college, before I ever met him. One afternoon when classes were getting characteristically dull I stepped into the library for my weekly random stroll through the stacks. There, lying on the floor and covered with dust and neglect, was "Disturbing the Universe". I was so struck by Dyson's wide-ranging mind and the economy and beauty of his prose that I plowed through the book in a night. Much later when I was living in New Jersey I decided to ask him for an audience. In keeping with one of his signature habits, not only did he reply to my email almost instantly but invited me over for lunch and a conversation in his office.

When I met him I realized that Dyson is probably the most approachable and modest scientist I have met. Like many others who have met him, I was struck by his slight but impressively energetic frame, honest cackles of laughter, studied powers of concentration and most of all, his striking and intent gray-blue eyes full of endless curiosity. He is pointedly opinionated but also consummately cordial. What followed was a uniquely memorable meeting lasting several hours. Talking to him was like taking a random walk around an exotic garden filled with intellectual treats. Our conversation ranged over a huge spectrum of topics ranging from politics and family to physics and biology. Discussions about science were punctuated by warm reminiscences about colleagues and fond stories about his grandchildren. The meeting reminded me of what I had already learnt from his books; Freeman Dyson is one of the most human of all scientists and thinkers, imbibed as much with a concern for the well-being of humanity as for the mysteries of the universe.

I met him again over the next few years. Since then our meetings and email correspondence have provided me with inspiration and ideas by the truckload. I am extremely thankful to him for being a role model of science and humanism. I hope he lives long and continues to offer his wisdom and insights to humanity and I look forward to congratulating him on this milestone.

Note: As time permits, I will be tweeting about the event using the hashtag #dysonfest.