Poignantly, Stephen Hawking’s death at the age of 76 humanises him again. It’s not just that, as a public icon as recognisable as any A-list actor or rock star, he came to seem a permanent fixture of the cultural landscape. It was also that his physical manifestation – the immobile body in customised wheelchair, the distinctive voice that pronounced with the oracular calm of HAL from 2001: A Space Odyssey – gave him the aura of a different kind of being, notoriously described by the anthropologist Hélène Mialet as “more machine than man”.

He was, of course, not only mortal but precariously so. His survival for more than half a century after his diagnosis with motor neurone disease shortly after his 21st birthday seemed to give him only a few years to live is one of the most remarkable feats of determination and sheer medical marvels of our time. Equally astonishing was the life that Hawking wrought from that excruciatingly difficult circumstance. It was not so much a story of survival as a modern fairytale in which he, as the progress of his disease left him increasingly incapacitated, seemed only to grow in stature. He made seminal contributions to physics, wrote bestselling books, appeared in television shows, and commanded attention and awe at his every pronouncement.

Play Video 3:09 Cosmology's brightest star Stephen Hawking dies aged 76 – video

This all meant that his science was, to use a zeitgeisty word, performative. To the world at large it was not so much what he said that mattered, but the manner and miracle of its delivery. As his Reith Lectures in 2015 demonstrated, he was not in fact a natural communicator – all those feeling guilty at never having finished A Brief History of Time need not feel so bad, as he was no different from many scientists in struggling to translate complex ideas into simple language. But as I sat in the audience for those lectures (delayed because of Hawking’s faltering health), it felt more clear than ever that there was a ritualistic element of the whole affair. We were there not so much to learn about black holes and cosmology as to pay respects to an important cultural presence.

Without that performance, Hawking the scientist would be destined to become like any other after their death: a name in a citation, “Hawking S, Nature volume 248 pages 30-31 (1971).” What, then will endure?

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Quite a lot. Hawking’s published work, disconnected from the legend of the man, reveals him to be a physicist of the highest calibre, who will be remembered in particular for some startlingly inventive and imaginative contributions to the field of general relativity: the study of the theory of gravity first proposed by Albert Einstein in 1916. At the same time, they show that he has no real claim to being Einstein’s successor. The romanticising of Hawking brings, for a scientist, the temptation to want to cut him down to size. The Nobel committee never found his work quite met the mark – partly, perhaps, because it dealt in ideas that are difficult to verify, applying to objects like black holes – not easy to investigate. The lack of a Nobel seemed to trouble him; but he was, without question, in with a shout for one.

That 1974 paper in Nature will be one of the most enduring, offering a memorable contribution to our understanding of black holes. These are created when massive objects such as stars undergo runaway collapse under their own gravity to become what general relativity insists is a singularity: a point of infinite density, surrounded by a gravitational field so strong that, within a certain distance called the event horizon, not even light can escape.

The very idea of black holes seemed to many astrophysicists to be an affront to reason until a renaissance of interest in general relativity in the 1960s – which the young Hawking helped to boost – got them taken seriously. Hawking’s paper argued that black holes will radiate energy from close to the event horizon – the origin of the somewhat gauche title of one of the Reith Lectures, “Black holes ain’t as black as they are painted” – and that the process should cause “primordial” miniature black holes to explode catastrophically. Most physicists now accept the idea of “Hawking radiation”, although it has yet to be observed.

This work became a central pillar in research that has now linked several key, and hitherto disparate, areas of physical theory: general relativity, quantum mechanics, thermodynamics and information theory. Here Hawking, like any scientist, drew on the ideas of others – and not always graciously, as when he initially disparaged the suggestion of the young physicist Jacob Bekenstein that the surface area of a black hole’s event horizon is related to its thermodynamic entropy. Hawking’s recent efforts in this field have scarcely been decisive, but his colleagues were always eager to see what he had to say about it.

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Less enduring will be his passion for a “theory of everything”, a notion described in his 1980 lecture in Cambridge when he became Lucasian Professor of Mathematics, the chair once occupied by Isaac Newton. It supplied a neat title for the 2014 biopic, but most physicists have fallen out of love with this ambitious project. That isn’t just because it has proved so difficult, becoming mired in a theoretical quagmire involving speculative ideas such as string theory that are beyond any obvious means of testing. It’s also because many see the idea as meaningless: physical theory is a hierarchy in which laws emerge at each level that can’t be discerned at a more reductive one. Hawking’s enthusiasm for a “theory of everything” highlights how he didn’t share Einstein’s breadth of vision in science, but focused almost exclusively on one subdiscipline of physics.

His death brings such limits into focus. His pronouncements on the “death of philosophy” now look naive, ill-informed and hubristic – but plenty of other scientists say such things without having to cope with seeing them carved in stone and pored over. His readiness to speak out on other issues beyond his expertise has mixed results: his sparring with Jeremy Hunt over the NHS was cheering, but his vague musings about space travel, aliens and AI just got in the way of more sober debate.

As The Theory of Everything wasn’t afraid to show, Hawking was human, all too human. It feels something of a relief to be able to grant him that again: to see beyond the tropes, cartoons and cliches and to find the man who lived with great fortitude and good humour inside the oracle that we made of him.

• Philip Ball is a science writer. His latest book is The Water Kingdom: A Secret History of China