Stephen Hawking, renowned physicist, famed science communicator, and all-around inspiration, has passed away at the age of 76.
Professor Stephen William Hawking passed away on the morning of March 14, 2018, in the comfort of his home in Cambridge, UK. He was 76.
The physicist-become-international-icon spent decades defying expectations after his 1963 diagnosis with Lou Gehrig’s disease. He lived a remarkably full life, with a brilliant career in physics and science communication, and is survived by three children, Robert, Lucy, and Timothy, and three grandchildren.
Hawking was born on January 8, 1942, in Oxford, England. Though he exhibited natural intelligence (his schoolfriends nicknamed him “Einstein”), he didn’t apply himself in his early years, generally ranking at the lower end of his classes. But science intrigued him and left him with a hunger to understand the universe. That early interest served as the inspiration that led to him receiving a scholarship at the University College Oxford, where he studied physics and graduated with honors. He went on to graduate school at the University of Cambridge, where he studied cosmology and in 1966 published a thesis titled, “Properties of Expanding Universes.” Hawking became a research fellow at Cambridge after graduation and remained a fellow for the rest of his life.
Yet it was during this time period, in 1963, when at age 21 Hawking was diagnosed with amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig’s disease). ALS is a motor neurone diseases, a group of disorders that affect the nerves in the brain and spinal cord. As the body’s muscles stop receiving messages from the brain, they weaken and waste away.
The diagnosis was devastating, as Hawking was told at the time that he would have one, maybe two years to live after the onset of symptoms. Decades later, doctors are realizing that the disease appears to progress differently in younger patients. Nevertheless, Hawking continued to surprise the medical community til the end: “I am not aware of anyone else who has survived with [ALS] as long,” Nigel Leigh, a professor of clinical neurology at King's College London, told the British Medical Journal in 2002.
Yet rather than slowing him down, the diagnosis only spurred him on. Hawking focused on his research more than ever before. In his best-selling A Brief History of Time, Hawking noted that in 1965, “…two years had gone by and I was not that much worse. In fact, things were going rather well for me . . .”
Indeed, that year Hawking was engaged to be married to a “very nice girl” named Jane Wilde, whom he had met at a college party in 1962. Needing a job, and hence first a PhD, he was casting about for a thesis idea when he came across the work of Roger Penrose (then at Birkbeck College in London). Penrose had used mathematical formulas to show that a star collapsing under its own gravity must become a singularity in spacetime. It didn’t take long for Hawking to cast these equations backward in time, proving that the expanding universe must have originated in a Big Bang singularity.
Black Holes: Not So Black
Hawking’s interest in singularities naturally led him to black holes. Even as ALS put him in a wheelchair by 1969, Hawking was piecing together the ideas behind the idea that earned him fame: Hawking radiation.
Hawking happened across the idea of not-so-black black holes as he was arguing against an idea posed by Jacob Bekenstein, a student at Princeton. The second law of thermodynamics tells us that the disorder of any closed system increases over time. The equations of general relativity also tell us that a black hole’s event horizon, the radius that measures the “point of no return” around the singularity, only grows as a black hole feeds on matter. So Bekenstein proposed that a black hole’s event horizon was a measure of its entropy, as both grow over time. In 1972 Hawking argued this relation couldn’t be true, as black holes don’t radiate. As he notes in A Brief History of Time, “…in writing this paper I was motivated partly by irritation with Bekenstein.”
Only, Hawking soon realized, black holes do radiate, and in a way that’s exactly in line with the second law of thermodynamics. In 1974 Hawking formalized this understanding by relating the singularities of general relativity to the peculiar notion in quantum mechanics that a vacuum isn’t empty. Rather, what appears to be empty space is, thanks to quantum uncertainty, actually a bath of virtual particles that exist for a fraction of a second. Particles can’t come from nothing, so these virtual particles come in pairs, one with positive energy and one with negative energy.
What Hawking realized was that in the presence of a black hole, the immense gravitational field will lend these vacuum particles energy, making them real. If one falls into the black hole, its partner can escape. To a distant observer, the once-virtual particle will appear to emanate from the black hole itself. And the black hole itself would appear to lose a tiny bit of mass.
Weirdly, this Hawking radiation depends on the black hole’s mass in the opposite way that you’d think: a stellar-mass black hole would take 1066 years to evaporate, just a tad bit longer than the age of the universe (which is 1010 years, roughly speaking). Only microscopic, perhaps primordial black holes could be spotted by their Hawking radiation — theoretically, anyway, as it hasn’t been done yet.
But Hawking radiation wasn’t important so much for practical observations as for what it meant for physics in general. Black holes can feed on any kind matter — gas, stars, the kitchen sink — so they hold an incredible amount of information. As Hawking told me during the inauguration of Harvard University’s Black Hole Initative in April 2016, “[Black holes] are the most efficient hard drives in the universe. All the information in Google databanks would be stored in a black hole smaller than a millionth of a millionth of an inch. Exactly how they are able to store so much information is one of the great mysteries of the universe that we are now working very hard to unravel.” Yet, if Hawking radiation is real, then all of that data is eventually sent away in a sea of informationless particles. In other words, black holes can destroy information itself. This idea, which Hawking published in 1981, led to far more controversy than the idea of Hawking radiation. Even now, physicists are still struggling to understand the implications, not just for black holes but also for the basic precepts behind quantum mechanics and general relativity.
Fame and the Future
In 1985 Hawking suffered an infection that led to a tracheotomy, a procedure that saved his life but cost him the ability to speak. He became fully reliant on a computerized voice system, first controlled by his fingers and in 2008, when the nerve that allowed his thumbs to move degraded, a muscle in his cheek.
These setbacks didn’t set him back — in 1988, he published A Brief History of Time, a survey of the complexities of general relativity, quantum mechanics, and the origin and structure of the universe. It stayed on the Sunday Times best-sellers list for 237 weeks, and is estimated to have sold 10 million copies in more than 40 languages. The clear, often witty descriptions of fundamental concepts granted him international fame, and he later made guest appearances in Star Trek: The Next Generation in 1993 and The Big Bang Theory in 2012, in addition to appearing in the Opening Ceremony of the London 2012 Paralympics.
His personal life became tumultuous following his fame: he separated from Jane, his wife of 25 years in 1990, and they divorced in 1995. He married his one-time nurse, Elaine Mason, the same year, but they divorced in 2006. Nevertheless, Jane and Stephen Hawking maintained a good working relationship. Jane’s autobiography, titled Travelling to Infinity: My Life with Stephen, resulted in the 2014 movie celebrating Hawking’s life, The Theory of Everything. Eddie Redmayne won an Oscar for his role as Hawking.
Fame may have brought some turbulence to Hawking’s life, but it also brought its perks. On April 26, 2007, Hawking had the opportunity to fly NASA’s KC-135, a modified jet fondly called the Vomit Comet, to achieve four minutes of weightlessness.
“The chance to float free in zero-g will be wonderful,” Hawking said during a pre-flight news conference. “I want to demonstrate to the public that anybody can participate in this type of weightless experience.”
In fact, in his later years, Stephen Hawking began advocating that humanity move to the stars, largely because of his concerns over global warming, overpopulation, and epidemics, not to mention the rise of “artificial intelligence.” As part of his advocacy, Hawking helped launch Breakthrough Initiatives in 2015 and was a member of the board of Breakthrough Starshot, a project founded in 2016 with designs on visiting the nearest star system, Alpha Centauri.
At the launch of Breakthrough Starshot, Hawking spoke of transcending limits, saying “Nature pins us to the ground. But I just flew to America. Nature forbids me from speaking. [Pause.] But here I am.”
Friends and colleagues have paid tribute to Stephen Hawking today. Neil de Grasse Tyson said on Twitter, “His passing has left an intellectual vacuum in his wake. But it's not empty. Think of it as a kind of vacuum energy permeating the fabric of spacetime that defies measure. Stephen Hawking, RIP 1942-2018.”
NASA’s acting administrator Robert Lightfoot also issued a statement, saying “Today, the world lost a giant among men, whose impact cannot be overstated. . . . His loss is felt around the world by all he inspired with his work and his personal story of perseverance.”
But we are perhaps best left with the words of Hawking himself, a passionate advocate for understanding the universal laws that govern us all.
“I want to share my excitement and enthusiasm about this quest. So remember to look up at the stars and not down at your feet. 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.”