TORONTO -- Scientists, educators and leaders across the country are paying tribute to Stephen Hawking, celebrating a man whose connections to Canada helped elevate the global profiles of national research institutes.

Hawking, who died Wednesday at age 76, was known as one of the greatest scientific minds of his generation, celebrated for his theories on black holes and the nature of time and for his defiance of amyotrophic lateral sclerosis, or ALS -- a degenerative disease of the nervous system that cost him his voice and most of his physical mobility.

Hawking boosted Canada's profile in the physics community in 2008 when he took on the title of distinguished research chair at the Perimeter Institute for Theoretical Physics in Waterloo, Ont., which he visited in 2010 and 2012.

"Stephen's life was heroic, in so many ways," said Neil Turok, director of the institute and a friend of Hawking's who worked with him at Cambridge University.

"He was a brilliant visionary in theoretical physics, setting an incredibly bold agenda for the field ... His incredible power and determination to overcome the constraints of his condition was the ultimate example of mind over matter."

Hawking had lauded the work of the Perimeter Institute, which now has a research building and a theoretical cosmology fellowship named after him.

"Perimeter is a grand experiment in theoretical physics and the institute's twin focus, on quantum theory and gravity, is very close to my heart and central to explaining the origin of the universe," Hawking said after his first trip to the facility.

Hawking shone a spotlight on the work of another Canadian research project when he featured the SNOLAB neutrino observatory in Sudbury, Ont., in his 2011 documentary mini-series, "Brave New World with Stephen Hawking."

Hawking had visited SNOLAB, where researchers in underground facilities study subatomic particles, in 1998 and was fascinated by their work, staff recalled.

"It was obvious he completely understood everything because he asked the most relevant and interesting question in response to what I had described and I was very taken by that," said Richard Ford, the director of program development at SNOLAB who had been a graduate student at the time of Hawking's 1998 visit.

During his second visit to SNOLAB, in 2012, Hawking spoke of the need for physics to be accessible to ordinary people.

"I believe everyone can and should have a broad picture of how the universe operates and our place in it," he said at the time. "This is what I have tried to convey in my books."

Robert Brandenberger, a McGill University professor who did his post-doctoral work under Hawking's supervision in the 1980s, described the famous physicist as optimistic and sociable.

"He was really the father of the (students)," Brandenberger said of his time with Hawking at Cambridge University.

Hawking had lost his voice by that point and was just beginning to use a computer-based communication system, Brandenberger recalled. In spite of those challenges, Hawking made sure he joined his students for afternoon tea each day, eager to hear about their academic and personal lives, Brandenberger said.

"He was always keen on finding out what everyone was doing, both in terms of physics research but also personally," Brandenberger said.

"One afternoon a couple of students were talking about the movie they were planning to see that evening and he interjected and said, 'Can I come with?"' he recalled. "So then in the evening he and his nurse came with."

Hawking was "playful, and invited you to be playful," said Nobel prize-winning chemist John Polanyi, a long-time professor at the University of Toronto.

"Over the years I met him a few times and every time was charmed and, of course, enormously impressed," Polanyi said. "He was a mythic figure in science who will be remembered for generations to come because he faced incredible handicaps and did what a great scientist does: namely, asked the most enormous questions."

ALS Canada CEO Tammy Moore said Hawking was a "vision of hope" for people with the disease.

"He was not defined by his disease, and in many ways his thinking was definitely not confined by it either," she said.

"It allowed people to see that yes, even with a terminal diagnosis -- for the majority of people that means two to five years when given a diagnosis of ALS -- that they can, in fact, have hope that maybe they have slow progression and then with some supports they are able to live very full lives."

Prime Minister Justin Trudeau also paid tribute to Hawking on Twitter Wednesday.

"Like so many, I was inspired by his first book to learn more about science, physics and the edges of our universe," Trudeau said. "His life and work taught us to dream big, to think nothing was impossible, and to forever change how we perceive our world."

Gov. Gen. Julie Payette, a former astronaut and computer systems engineer, thanked Hawking for his work.

"Knowledge is a richness that is acquired through a combination of rigour, logic, hard work and an inquisitive mind," Payette said. "One of these wonderful minds has departed this world, but leaves behind a wealth of profound insight."