I don’t usually do obituaries. I didn’t do one when Joseph Polchinksi died, though his textbook is sitting an arm’s reach from me right now. I never collaborated with Polchinski, I never met him, and others were much better at telling his story.
I never met Stephen Hawking, either. When I was at Perimeter, I’d often get asked if I had. Visitors would see his name on the Perimeter website, and I’d have to disappoint them by explaining that he hadn’t visited the institute in quite some time. His health, while exceptional for a septuagenarian with ALS, wasn’t up to the travel.
Was his work especially relevant to mine? Only because of its relevance to everyone who does gravitational physics. The universality of singularities in general relativity, black hole thermodynamics and Hawking radiation, these sharpened the questions around quantum gravity. Without his work, string theory wouldn’t have tried to answer the questions Hawking posed, and it wouldn’t have become the field it is today.
Hawking was unique, though, not necessarily because of his work, but because of his recognizability. Those visitors to Perimeter were a cross-section of the Canadian public. Some of them didn’t know the name of the speaker for the lecture they came to see. Some, arriving after reading Lee Smolin’s book, could only refer to him as “that older fellow who thinks about quantum gravity”. But Hawking? They knew Hawking. Without exception, they knew Hawking.
Who was the last physicist the public knew, like that? Feynman, at the height of his popularity, might have been close. You’d have to go back to Einstein to find someone who was really solidly known like that, who you could mention in homes across the world and expect recognition. And who else has that kind of status? Bohr might have it in Denmark. Go further back, and you’ll find people know Newton, they know Gaileo.
Einstein changed our picture of space and time irrevocably. Newton invented physics as we know it. Galileo and Copernicus pointed up to the sky and shouted that the Earth moves!
Hawking asked questions. He told us what did and didn’t make sense, he showed what we had to take into account. He laid the rules of engagement, and the rest of quantum gravity came and asked alongside him.
We live in an age of questions now. We’re starting to glimpse the answers, we have candidates and frameworks and tools, and if we’re feeling very optimistic we might already be sitting on a theory of everything. But we haven’t turned that corner yet, from asking questions to changing the world.
These ages don’t usually get a household name. Normally, you need an Einstein, a Newton, a Galileo, you need to shake the foundations of the world.
Somehow, Hawking gave us one anyway. Somehow, in our age of questions, we put a face in everyone’s mind, a figure huddled in a wheelchair with a snarky, computer-generated voice. Somehow Hawking reached out and reminded the world that there were people out there asking, that there was a big beautiful puzzle that our field was trying to solve.
Deep down, I’m not sure we deserved that. I hope we deserve it soon.