Stephen Hawking at the University of Potsdam, near Berlin, in 1999. (Markus Schreiber/AP)

Alan Lightman is a physicist, novelist, and professor of the practice of the humanities at MIT.

Carl Sagan, Steve Jobs, James Watson, Jane Goodall, Stephen Hawking. There are more, but the list is short. Even though we live in the age of smartphones, GPS and gene therapy, celebrities in science are rarer than those in music, film, sports and politics.

Hawking, who passed away Wednesday after a 50-year battle with the motor neuron disease called ALS, became a cultural icon after he appeared on the cover of the New York Times magazine in the late 1980s and, shortly thereafter, published his best-selling “A Brief History of Time.” Later, he appeared on “The Simpsons,” “Alien Planet,” “Star Trek: The Next Generation.” More recently, there was James Marsh’s 2014 dramatic film about Hawking, “The Theory of Everything.”

There’s no doubt Hawking’s severe physical disability figured into his celebrity status and impact on the public. Almost completely paralyzed, able to communicate in his last decades only through a computer-controlled voice, Hawking appears to us as a crumpled figure of a man, slumped in a wheelchair, gazing out at the dark night sky and fathoming its secrets — the ultimate image of mind over matter.

And he was that. Hawking worked in the study and application of Einstein’s theory of gravity. Einstein understood gravity as a geometrical phenomenon, as a bending of time and space. Hawking went further. Partly because of his physical difficulty in working with equations as most theoretical physicists do, Hawking developed new graphical methods that allowed him to visualize the physics of black holes, the paths of light rays in warped space, and the convulsions of the universe as a whole.

Hawking was one of the first people to apply quantum physics to black holes and predict that these bizarre objects, previously thought to voraciously swallow matter and energy in a one-way path to oblivion, could also expel matter and energy in a process that became known as “Hawking radiation.” His other greatest scientific achievement was in the field of cosmology. Working with the brilliant British mathematician Roger Penrose, Hawking significantly strengthened the scientific conviction that our universe began in a “Big Bang” of ultra-high compression some 14 billion years ago, in which all of the galaxies we see were compressed into a region smaller than a single atom. Previously, such conclusions were based on calculations that assumed highly idealized conditions, such as that the matter of the universe is smoothly spread out in all directions. Hawking and Penrose proved the Big Bang hypothesis under much more realistic conditions and assumptions.

The details of this science are formidable, but Hawking was blessed with something else that helped make him accessible to millions: He was a wit. Even in his withered and paralyzed condition, he took pleasure in making jokes, and you glimpsed a slight impish grin pass over his face when he did so. In late 1974, he made a bet with physicist Kip Thorne that a newly discovered X-ray emitting star called Cygnus X-1 was not a black hole. According to the bet, which was framed on the wall in the hallway outside Thorne’s office at Caltech, if Cygnus X-1 did indeed turn out to be a black hole, Hawking would reward Thorne with a subscription to a particular adult magazine. If Hawking won the bet, Thorne would reward Hawking with a subscription to Private Eye magazine. Hawking later explained that the bet was a kind of insurance policy. If he lost (which he eventually did) and black holes were indeed proved real, then his life’s work would not have been in vain. If he won the bet and black holes were found to be only a theorist’s pipe dream, he would at least have several years of Private Eye as a consolation.

Astoundingly, Hawking remained active to the end of his life. Despite the extreme difficulty of moving from A to B with his wheelchair and life-support systems, Hawking regularly made international trips to attend conferences and give lectures. He continued to write books. He continued collaborating with students, postdoctoral fellows and other scientists, although some of the scientific research naturally slowed in his later years.

The passing of Stephen Hawking gives us the opportunity to celebrate the best in ourselves, to reaffirm the power of the human mind and the majesty of our desire to know and to understand this strange universe we find ourselves in. With so much brutish and divisive behavior in the world at the moment, it is good to remind ourselves of who we are.