Stephen Hawking lived a life that stood in defiance of finality.
In 1963, as a graduate student at Cambridge University, he was diagnosed with amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease. His doctors gave him just two years to live.
Instead, Dr. Hawking spent the next half century overturning physicists’ conceptions of black holes. In 1974, drawing on general relativity, thermodynamics, and quantum physics, he found that black holes actually emit radiation at their edges, gradually evaporating over billions of years until they explode. This insight led to the realization that whatever information falls into a black hole will eventually be released. Like a terminal diagnosis, a black hole does not always have the last word.
As a theoretical physicist, Hawking, who died early Wednesday morning, changed how we think of the cosmos. As a science communicator, he brought complex ideas of the universe to a broad audience, and kindled an entire generation of physicists.
“My grandfather gave me a copy of ‘A Brief History of Time’ when I was in junior high,” says Tanya Harrison, a planetary scientist at Arizona State University in Tempe, referring to Hawking’s 1988 bestseller about the origin and evolution of the cosmos. “That solidified it.”
A year or two later, at the age of 13 or 14, she began to have trouble walking and standing. “It was starting to affect my ability to do things I had done for a long time, like dancing and sports,” she says. “Seeing Stephen Hawking pursue theoretical physics and be a professor while not being able to move – that was really inspiring for me.”
Hawking embraced his status as a role model to others with physical disabilities. According to Time magazine, wherever Hawking traveled – he visited every continent, including Antarctica – he would ask his hosts to arrange an unpublicized meeting with children with disabilities. But his influence extended far beyond the disabled community.
“I think anybody you talk to in any field of science remotely related to space or physics and people will probably cite him as one of their big inspirations,” says Dr. Harrison.
Even as he lost physical mobility, he never ceased to counsel optimism.
“Remember to look up at the stars and not down at your feet,” he famously said, in a speech marking his 70th birthday. “Try to make sense of what you see and wonder about what makes the universe exist. Be curious. And however difficult life may seem, there is always something you can do and succeed at. It matters that you don’t just give up.”
Hawking’s preoccupations extended far beyond theoretical physics. He forcefully opposed the US-led invasion of Iraq in 2003, which he labeled a “war crime,” and he championed Britain’s National Health Service, which he credited with keeping him alive.
Hawking also showed a deep concern about the long-term future of humanity, warning that ecological collapse, the rise of artificial intelligence, or even contact with hostile aliens could bring humanity to a premature end. To avoid extinction, he argued, humanity must colonize other worlds within the next 1,000 years.
“I think his biggest contribution was to show you could think boldly about things most physicists would be reluctant to tackle, partly because they seem too far out,” says retired science writer Bob Cowen, who covered science for The Christian Science Monitor for 45 years.
Hawking also enjoyed a celebrity status rare among scientists, with guest appearances on some of television’s most acclaimed series: “Futurama,” “The Simpsons,” and “Star Trek: The Next Generation.”
“It’s hard to imagine anyone who has been more successful at not only pursuing an academic research career of enormous significance but [who] also has made such an imprint on the popular understanding of science, and even through popular culture,” says former Monitor science writer Pete Spotts. “He had a zest and zeal for what he did and that, for me personally, was as inspiring as the hard science he produced.”
This vigor – traveling through the cosmos in his mind, and diving into complicated cosmological problems with the same zeal with which he embraced pop culture – flew in the face of his physical limitations.
“Watching Stephen Hawking and the fact that he was able to do so much even as his disease was getting worse – it really resonates with me,” says Harrison. “It doesn’t matter how much your body is failing you. As long as your mind is working, you can change the world.”