In 1990, while on assignment for Scientific American, I had a close encounter with Stephen Hawking, who just died at the age of 76. I had bulled my way into a symposium, sponsored by the Nobel Foundation, on “The Birth and Early Evolution of Our Universe.” Thirty of the world’s top physicists and cosmologists, including Hawking, had gathered in a rustic, isolated resort in northern Sweden to ponder the riddle of the cosmos.

I arrived late on the first day of the meeting, just as everyone was heading outside for a cocktail party. Hawking, already paralyzed by amyotrophic lateral sclerosis, led the procession in his motorized wheelchair. We were within sight of picnic tables bearing reindeer jerky and a potent local brew called wolf’s blood when Hawking’s wheelchair jammed in a rut. His nurse, Elaine Mason (whom Hawking later married), tried to budge the wheelchair, without success. Fixing her eyes on me, she asked if I would carry “Stephen” the rest of the way.

Hawking, when I scooped him up, was disconcertingly light and stiff, like a bundle of sticks. I glanced at him out of the corner of my eye and found him eyeing me suspiciously. I was uneasy too, even more so moments later when Hawking’s body shuddered violently. His face contorted into an agonized grimace and he emitted a terrible gargling noise. I froze, thinking, Stephen Hawking is dying in my arms!

Mason, noticing Hawking’s distress, and mine, hustled up to us. “Don’t worry,” she said briskly, gathering Hawking into her arms. “This happens to him all the time. He’ll be all right.” Hawking suffered several other seizures during the symposium. Each time I was sure that this was the end.

Hawking not only survived. He was a powerful presence at the meeting. He exuded, somehow, a mysterious, mischievous charisma. He seemed more amused than distressed by his physical plight. His Mick Jagger mouth often curled up at one corner in a grin. He communicated with his left forefinger, laboriously selecting letters, words or sentences from a menu on his computer screen. Many of his utterances were jokes, which a voice synthesizer delivered in an incongruously deep, authoritative voice. He liked responding to colleagues’ cosmic conjectures with one word: “Trivial.”

A high point of the symposium was Hawking’s lecture on quantum cosmology, a field he helped create. Quantum cosmology assumes that at very small scales, matter and energy and even the fabric of space and time flicker between different states. These space-time fluctuations might give rise to wormholes, which could link one region of space-time with another one very far away, or to “baby universes.”

Hawking had stored the hour-long speech, titled “The Alpha Parameters of Wormholes,” in his computer. He had merely to tap a key to prompt his voice synthesizer to read it, sentence by sentence. In his eerie cyber-voice, Hawking discussed whether we might someday be able to slip into a wormhole in our galaxy and pop out the other end in a galaxy far, far away. Probably not, he concluded, because quantum effects would scramble our constituent particles beyond recognition.

He wrapped up his lecture with an upbeat riff on string theory. Although all we see around us is the “mini-superspace” that we call space-time, “we are really living in the infinite-dimensional superspace of string theory.” This ending choked me up. Trapped in a crippled body in this world, Hawking’s imagination could still roam through other realities with infinite degrees of freedom.

Toward the end of the symposium everyone piled into a bus and drove to a nearby village to hear a concert in a Lutheran church. When the scientists entered the church, it was already packed. The orchestra, a motley assortment of blond-haired youths and wizened, bald elders clutching violins, clarinets and other instruments, was seated at the front of the church. Their neighbors jammed the balconies and seats at the rear of the building.

The scientists filed down the center aisle to pews reserved for them at the front of the church. Once again, Hawking led the way in his wheelchair. The townspeople started to clap, tentatively at first, then passionately. These religious folk seemed to be encouraging the scientists, and especially Hawking, in their quest to solve the riddle of existence.

Hawking was a leader of this quest. As early as 1980 he predicted that physics was on the verge of a final theory, which would unite relativity and quantum mechanics into one tidy package and “describe all possible observations.” It would tell us why the big bang banged and spawned this particular cosmos, which allowed for our existence.

In his mega-bestseller A Brief History of Time, Hawking famously declared that a final theory “would be the ultimate triumph of human reason—for then we should know the mind of God.” I could be critical of Hawking. I sometimes doubted whether he actually believed in the possibility of a theory of everything, but his vision thrilled me. He was a giant, a man of immense imagination, courage and ambition. Science will be less exciting without him.

Further Reading: I described my encounter with Hawking in my book The End of Science. The poet Nestor Diaz de Villegas has written a poem based on my story about carrying Hawking in my arms. See also my review of “Theory of Everything,” the 2014 film about Hawking’s life, and my post “How Physics Lost Its Fizz.”