SUMMING UP

Frank Hawking, was a prominent research biologist.

The oldest of four children, Stephen was a mediocre student at St Albans School in London, although his innate brilliance was recognised by some classmates and teachers.

Later, at University College, Oxford, he found his studies in mathematics and physics so easy that he rarely consulted a book or took notes. He got by with a thousand hours of work in three years, or one hour a day, he estimated. “Nothing seemed worth making an effort for,” he said.

The only subject he found exciting was cosmology because, he said, it dealt with “the big question: Where did the universe come from?”

Upon graduation, he moved to Cambridge. Before he could begin his research, however, he was stricken by what his research adviser, Dennis W Sciama, came to call “that terrible thing”. The young Hawking had been experiencing occasional weakness and falling spells for several years. Shortly after his 21st birthday, in 1963, doctors told him that he had amyotrophic lateral sclerosis. They gave him fewer than three years to live.

His first response was severe depression. He dreamed he was going to be executed, he said. Then, against all odds, the disease appeared to stabilise. Although he was slowly losing control of his muscles, he was still able to walk short distances and perform simple tasks, although labouriously, like dressing and undressing. He felt a new sense of purpose. “When you are faced with the possibility of an early death,” he recalled, “it makes you realise that life is worth living and that there are a lot of things you want to do.”

In 1965, he married Jane Wilde, a student of linguistics. Now, by his own account, he not only had “something to live for” but also had to find a job, which gave him an incentive to work seriously toward his doctorate. His illness, however, had robbed him of the ability to write down the long chains of equations that are the tools of the cosmologist’s trade. Characteristically, he turned this handicap into a strength, gathering his energies for daring leaps of thought, which, in his later years, he often left for others to codify in proper mathematical language.

“People have the mistaken impression that mathematics is just equations,” Hawking said. “In fact, equations are just the boring part of mathematics.”

By necessity, he concentrated on problems that could be attacked through “pictures and diagrams,” adopting geometric techniques that had been devised in the early 1960s by mathematician Roger Penrose and a Cambridge colleague, Brandon Carter, to study general relativity, Einstein’s theory of gravity.

Black holes are a natural prediction of that theory, which explains how mass and energy “curve” space, the way a sleeping person causes a mattress to sag. Light rays will bend as they traverse a gravitational field, just as a marble rolling on the sagging mattress will follow an arc around the sleeper.

Too much mass or energy in one spot could cause space to sag without end; an object that was dense enough, like a massive collapsing star, could wrap space around itself like a magician’s cloak and disappear, shrinking inside to a point of infinite density called a singularity, a cosmic dead end, where the known laws of physics would break down: a black hole.

As part of his doctoral thesis in 1966, Hawking showed that when you ran the film of the expanding universe backwards you would find that such a singularity had to have existed sometime in cosmic history; space and time, that is, must have had a beginning. He, Penrose and a rotating cast of colleagues went on to publish a series of theorems about the behaviour of black holes and the dire fate of anything caught in them.

Hawking’s signature breakthrough resulted from a feud with Israeli theoretical physicist Jacob Bekenstein, then a Princeton graduate student, about whether black holes could be said to have entropy, a thermodynamic measure of disorder. Bekenstein said they could, pointing out a close analogy between the laws that Hawking and his colleagues had derived for black holes and the laws of thermodynamics. Hawking said no. To have entropy, a black hole would have to have a temperature. But warm objects, from a forehead to a star, radiate a mixture of electromagnetic radiation, depending on their exact temperatures. Nothing could escape a black hole, and so its temperature had to be zero. “I was very down on Bekenstein,” Hawking recalled.

To settle the question, Hawking decided to investigate the properties of atom-size black holes. This, however, required adding quantum mechanics, the paradoxical rules of the atomic and subatomic world, to gravity, a feat that had never been accomplished. Friends turned the pages of quantum theory textbooks as Hawking sat motionless staring at them for months. They wondered if he was finally in over his head.

When he eventually succeeded in doing the calculation in his head, it indicated to his surprise that particles and radiation were spewing out of black holes. Hawking became convinced that his calculation was correct when he realised that the outgoing radiation would have a thermal spectrum characteristic of the heat radiated by any warm body, from a star to a fevered forehead. Bekenstein had been right.

Hawking even figured out a way to explain how particles might escape a black hole. According to quantum principles, the space near a black hole would be teeming with “virtual” particles that would flash into existence in matched particle-and-antiparticle pairs – like electrons and their opposites, positrons – out of energy borrowed from the hole’s intense gravitational field.

They would then meet and annihilate each other in a flash of energy, repaying the debt for their brief existence. But if one of the pair fell into the black hole, the other one would be free to wander away and become real. It would appear to be coming from the black hole and taking energy away from it.

Until 1974, Hawking was still able to feed himself and to get in and out of bed. After 1980, care was supplemented by nurses. Hawking retained some control over his speech up to 1985, but on a trip to Switzerland, he came down with pneumonia. The doctors asked Jane if she wanted his life support turned off, but she said no. To save his life, doctors inserted a breathing tube. He survived, but his voice was permanently silenced.

It appeared for a time that he would be able to communicate only by pointing at individual letters on an alphabet board. But when a computer expert, Walter Woltosz, heard about Hawking’s condition, he offered him a program he had written called Equalizer. By clicking a switch with his stillfunctioning fingers, Hawking was able to browse through menus that contained all the letters and over 2,500 words.

Word by word – and, when necessary, letter by letter – he could build up sentences on the computer screen and send them to a speech synthesiser that vocalised for him. The entire apparatus was fitted to his motorised wheelchair.

Hawking’s only complaint, he confided, was that the speech synthesiser, manufactured in California, had given him an American accent.

Asked by New Scientist what he thought about most, Hawking answered: “Women. They are a complete mystery.”

In 1990, Hawking and his wife separated after 25 years of marriage. In 1995 he married Elaine Mason, a nurse who had cared for him since his bout of pneumonia. She had been married to David Mason, the engineer who had attached Hawking’s speech synthesiser to his wheelchair. They divorced in 2006.

Hawking is survived by his children, Robert, Lucy and Tim. New York Times 2018. Distributed by NYT Syndication Service

“People have the mistaken impression that mathematics is just equations. In fact, equations are just the boring part of mathematics”