Given that Professor Hawking characterized his mature epistemological outlook as one of model dependent realism, it is only appropriate to remember him here.
If he had been a character out of fiction, it would have seemed too preposterous: a man stricken at the start of a brilliant career by ALS, one of the greatest minds of his or any generation, wheelchair bound, like the benevolent incarnation of a Bond super villain who had taken up the very biggest challenge–the search for a Theory of Everything (TOE)–where the great Einstein had left off, an almost disembodied genius with a placid, computer-generated voice both mechanical and mellifluous and as recognizable as any voice in the world (and far more familiar to most of us than his actual voice, 30 years gone). He was a cutting-edge theoretical physicist and cosmologist who, more than anybody, breathed new life into General Relativity, who wrote popular books for a general audience, a scientist who disliked science fiction, a genius who did not read until he was eight. There are not many people of this dangerous and insane period of history that I would call a hero of mine, but Stephen Hawking was one of them.
A triumph of the human will, he survived motor neuron disease, superhero-like for 55 years (it killed both Lou Gehrig and Tony Judt in 2 or 3). He wrote numerous books and papers by twitching a small functioning muscle near his eye, a sole remaining interactive link between his inner cosmos and the greater external world. He had a killer (and apparently infuriating) sense of humor and appeared on “The Simpsons” at least twice (Homer: “Larry Flynt is right!”).
There were and are physicists as brilliant as he (Bohr, Richard Feynman, Murry Gell-Mann, Steven Weinberg, John Wheeler, Edward Witten), and a few modern thinkers who were even greater (Einstein, Kant, Leibniz, Newton). There were scientists who formulated more radical theories than Hawking (Julian Barbour [the “timeless universe”], Hugh Everett III [multiverse], Gerald ‘t Hooft and Leonard Susskind [the holographic principle]), and some may be identified more closely with specific ideas (Witten and M-theory, possibly Alan Guth and Andre Linde and their inflationary model built on Hawking’s ideas, perhaps Gell-Mann and quarks). And certainly there are cosmologists with whom one might agree more (for me, Lee Smolin), but there was something unique and uniquely appealing about Stephen Hawking. Even in a Golden Age of cosmological speculation–a new Pre-Socratic Era that he helped usher-in–his star shone especially bright.
He was not afraid to risk being wrong–thus embodying the kind of courage at the heart of science when done well–and he famously lost bets to Leonard Susskind (“is the information in a decaying black hole lost?”), John Preskill, and Kip Thorne. And of course his many triumphs would not have been possible without others (Dennis Sciama, Roger Penrose, Kip Thorne, and of course Jane Hawking, among the many).
When I was studying at one of Hawking’s alma maters, the College of Gonville and Caius at Cambridge (in a summer semester program in 1992), a friend came in a rush to get me in the library. “Professor Hawking is downstairs!” she said, out of breath. I almost tripped over my own feet running down the ancient spiral stairway and out to the street only to see a van pulling away. Still, the impressive painting of him stood out as a conspicuous and super-terrestrial omnipresence among the other luminaries of the college in the great medieval dinning hall (even the portrait of John Venn looked a little intimidated).
In the 1980s he grew frustrated as a TOE was not forthcoming and he lapsed from a Popperian critical rationalist perspective and a cosmological position of sophisticated realism, to something like that of an instrumentalist, and then to his mature view that he called “model dependent realism.” I think that his now-famous 2011 statement that “philosophy is dead” is incorrect (cosmology, IMO, is as much speculative philosophy as it is an extension of theoretical physics), and he embraced a kind of hard deterministic physicalism that I believe went too far in not acknowledging ideas and consciousness as ontological categories. I would contend that the very reality of his expansive but increasingly isolated consciousness and the complex ideas he interacted with and formulated (to say nothing of the fact that the physical universe seems to operate on mathematical principles) tend to corroborate my position while calling his own monism into question, but then who am I relative to Stephen Hawking?
Perhaps it is all just human conceit to think that the physical universe(s) can be integrated–reduced–to the elegant, unified sets of fundamental laws, or even a single set of laws that Newton, Maxwell, Einstein, and Hawking had hoped for. Perhaps, as Lee Smolin and Max Tegmark (among others) have suggested, there are any number of sets of fundamental laws and that these may be mutually exclusive outside of their respective realms or when used in conjunction. Still, the various efforts at devising this very biggest of ideas–a Theory of Everything–must be regarded as one of the monumental and audacious efforts of our species, even if all such efforts ultimately fail. If a unified field theory is someday discovered, “it will be the ultimate triumph of human reason…”
Hawking was one of those rare people who you simply took to be a part of the intellectual/commentary backdrop of the times, and it was easy to take him for granted. Unbelievably, he survived with one of the most dreaded of dread diseases for my entire lifetime to date, and every few months (most recently in February or early March), I found myself asking “how is this man still alive?” Although it is difficult to believe that he lived as long as he did, it is even more difficult to believe that he is really gone.
He was a commentator, an oracle of reason and intellect, whose occasional public warnings about what we are doing to the planet held the attention of the rational in an increasingly irrational time. He warned of the advanced state of the human-caused destruction of the environment and by extension, ourselves and disabused people of heady technical solutions like leaving the Earth to colonize other planets in the foreseeable future. Gone. It feels as if a responsible adult has left alone the atavistic boys of The Lord of the Flies to their island after telling them to behave themselves in his absence.
If the Block Universe is a true model, he will live forever within brackets set in 1942 and 2018; if not, he may only live as long as the historical memory of our species. One is tempted to be dramatic and put this life into Hamlet-like terms: “He was a man, taken for all…” and yet he was much more. For those of us who remain trapped in the “stubbornly persistent illusion” of the present moment, I am fairly confident that we “shall not see his like again.”