Stephen Hawking died Wednesday after complications due to amyotrophic lateral sclerosis, a progressive neurodegenerative disease. He was 76.
The world-renowned theoretical physicist and cosmologist was best known for his work on black holes. Hawking theorized that, contrary to the prevailing scientific belief that black holes were inescapable for all forms of matter and energy, they actually emitted a form of radiation ― now known as Hawking radiation. He also played a key role in the mathematical effort to unify Einstein's general theory of relativity with the emergent field of quantum physics.
Hawking used his position as one of the world's most famous scientists as a platform to discuss a wide range of issues, from the existence of extraterrestrial life to the nature of philosophy. He skyrocketed to public prominence in 1988, when he published his first general-audience book, A Brief History of Time: From the Big Bang to Black Holes. The cosmology treatise has sold approximately 10 million copies worldwide, making it one of the best-selling science books of all time.
In 1963, when he was just 21 years old, Hawking was famously diagnosed with the debilitating motor neuron disease amyotrophic lateral sclerosis. Though 80 percent of those with ALS die within five years of diagnosis, and Hawking's own doctors gave him roughly two years to live, he survived for decades, perhaps longer than any other patient with the disease in medical history. Hawking used a wheelchair to move around and a sophisticated computer system to speak for much of his time as a public figure.
The physicist's inspiring ― and turbulent ― personal story was dramatized in the 2014 movie "The Theory of Everything," which was based on a memoir by Hawking's first wife, Jane Wilde. Actor Eddie Redmayne's portrayal of Hawking in the film won him an Oscar for best actor.
Stephen Hawking through the years
Stephen Hawking through the years
PRINCETON, NJ - OCTOBER 10: Cosmologist Stephen Hawking on October 10, 1979 in Princeton, New Jersey. (Photo by Santi Visalli/Getty Images)
Stephen Hawking (born in 1942), British mathematician and scientist, 1989. (Photo by Jean-Regis Rouston/Roger Viollet/Getty Images)
Professor Stephen Hawking poses for a photograph in his office at the University of Cambridge in Cambridge, U.K, in April 1991. Hawking has written countless scientific papers as well as books, receiving 12 honorary degrees and becoming Cambridge's Lucasian Professor of Mathematics, a post held by Sir Isaac Newton over 300 years earlier. (Photo by Bryn Colton/Getty Images)
SF.Hawking.1.bv.2Â5/PASADENA ÂÂ Theoretical physicist Stephen Hawking in his Cal Tech office. (Photo by Brian Vander Brug/Los Angeles Times via Getty Images)
(GERMANY OUT) - COL*08.01.1942-Physiker, Mathematiker, Grossbritannien- PortrÃ¤t (Photo by LS-PRESS/ullstein bild via Getty Images)
LONDON - DECEMBER 16: (EMBARGOED FOR PUBLICATION IN UK TABLOID NEWSPAPERS UNTIL 48 HOURS AFTER CREATE DATE AND TIME) Scientist Stephen Hawking and wife Elaine Mason arrive at the European Premiere of 'Lemony Snicket's A Series Of Unfortunate Events' at the Empire Leicester Square on December 16, 2004 in London. (Photo by Dave Benett/Getty Images)
OVIEDO, SPAIN: British astrophysicist Stephen Hawking gives his conference to open the XXV Prince of Asturias Awards Anniversary event in Oviedo, Northern Spain, 12April 2005. Stephen Hawking won the Prince of Asturias Award for Concord in 1989. AFP PHOTO / Miguel RIOPA (Photo credit should read MIGUEL RIOPA/AFP/Getty Images)
FRANKFURT, GERMANY - OCTOBER 19: Professor Stephen Hawking (L) and his wife Elaine Mason attend the international bookfair on October 19, 2005 in Frankfurt, Germany. South Korea is the guest of honour at the 57th annual Frankfurt Book Fair where 270.000 people are expected to visit the world's most important book fair, and 7000 exhibitors from 100 countries are present. (Photo by Ralph Orlowski/Getty Images)
FRANKFURT/MAIN, Germany: British physicist Stephen Hawking visits his German publisher Rowohlt's stand at the Frankfurt Book Fair 19 October 2005. The Frankfurt book fair opened its doors for the 57th time with the focus on authors from the Korean peninsula, but the presence of some 60 writers from the South and none from the North spoke as much of politics as literature. AFP PHOTO DDP/THOMAS LOHNES GERMANY OUT (Photo credit should read THOMAS LOHNES/AFP/Getty Images)
BEIJING, CHINA - JUNE 18: (CHINA OUT) Cosmologist Stephen Hawking visits the Temple of Heaven on June 18, 2006, in Beijing, China. Hawking has arrived in Beijing prior to his lecture at the Great Hall of the People today where he will discuss the origins of the universe at the Strings 2006 International Conference, hosted by the Chinese Academy of Sciences Institute of Theoretical Physics. The conference runs from June 19 ?24 at the Beijing Friendship Hotel. (Photo by ChinaFotoPress/Getty Images)
BEIJING - JUNE 19: (CHINA OUT) British scientist Stephen Hawking, delivers a lecture entitled 'The Origin of the Universe' at the Great Hall of the People June 19, 2006 in Beijing, China. British scientist Stephen Hawking is also visiting Beijing to attend the conference on the riddle of string theory which, if solved, could help unlock the mysteries of black holes and the creation of the universe, according to reports. (Photo by China Photos/Getty Images)
BEIJING - JUNE 21: British scientist Stephen Hawking attends a conference during the 2006 International Conference on String Theory on June 21, 2006 in Beijing, China. Hawking is visiting Beijing to attend the conference on the riddle of string theory which, if solved, could help unlock the mysteries of black holes and the creation of the universe, according to reports. (Photo by Cancan Chu/Getty Images)
JERUSALEM, -: British scientist Stephen Hawking is helped to turn his head as he arrives 10 December 2006 at the Israeli premier's offices to meet with Ehud Olmert in Jerusalem. Hawking is in Jerusalem for a lecture at the Bloomfield Museum of Science. AFP PHOTO/Yoav LEMMER (Photo credit should read YOAV LEMMER/AFP/Getty Images)
LONDON - JANUARY 17: Professor Stephen Hawking delivers his speech at the release of the 'Bulletin of the Atomic Scientists' on January 17, 2007 in London, Ebgland. A group of scientists assessing the dangers posed to civilisation have moved the Doomsday Clock forward two minutes closer to midnight as an indication and warning of the threats of nuclear war and climate change. (Photo by Bruno Vincent/Getty Images)
KENNEDY SPACE CENTER, UNITED STATES: British cosmologist Stephen Hawking(L) has his communication device adjusted by an aide at a pre-flight press conference 26 April 2007 at Kennedy Space Center, FLorida. Hawking, who has spent his career pondering the nature of gravity from a wheelchair, is set to experience weightlessness during a 'vomit comet' flight in Florida Thursday. The idea is to give 'the world's expert on gravity the opportunity to experience zero gravity' said Peter Diamandis the chief executive of the Zero Gravity Corporation. Hawking, 65, the British author of the blockbuster 'A Brief History of Time,' will be surrounded by a medical team on the padded plane as it flies a roller-coaster trajectory to produce periods of weightlessness. AFP PHOTO / ROBERT SULLIVAN (Photo credit should read ROBERT SULLIVAN/AFP/Getty Images)
KENNEDY SPACE CENTER, UNITED STATES: British cosmologist Stephen Hawking passes well wishers before boarding a plane 26 April 2007 at Kennedy Space Center, Florida. Hawking, who has spent his career pondering the nature of gravity from a wheelchair, is set to experience weightlessness during a 'vomit comet' flight in Florida Thursday. The idea is to give 'the world's expert on gravity the opportunity to experience zero gravity' said Peter Diamandis the chief executive of the Zero Gravity Corporation. Hawking, 65, the British author of the blockbuster 'A Brief History of Time,' will be surrounded by a medical team on the padded plane as it flies a roller-coaster trajectory to produce periods of weightlessness. AFP PHOTO / ROBERT SULLIVAN (Photo credit should read ROBERT SULLIVAN/AFP/Getty Images)
Professor Stephen Hawking gives a lecture entitled 'Why We Should Go Into Space' during the 50 Years of NASA lecture series at George Washington University in Washington, DC, April 21, 2008. AFP PHOTO/Jim WATSON (Photo credit should read JIM WATSON/AFP/Getty Images)
South Africa former President Nelson Mandela (R) meets with British scientist Professor Stephen Hawking (L) in Johannesburg on May 15, 2008. Hawking, who has devoted his career to finding the origins of the universe, is in the country to begin a search for Africa?s answer to Einstein. Some of the world?s leading high-tech entrepreneurs and scientists have backed a ?75m plan to create Africa?s first postgraduate centres for advanced math and physics, after the British government declined to provide funding. AFP Photo/Denis Farrell / POOL (Photo credit should read DENIS FARRELL/AFP/Getty Images)
(FILES) British scientist Stephen Hawking attends the 2008 Cambridge Honnorary Degrees 2008's procession on June 23, 2008 at Cambridge University in east England. Renowned British astrophysicist Stephen Hawking has bet 100 dollars (70 euros) that a mega-experiment this week will not find an elusive particle seen as a holy grail of cosmic science, he said Tuesday September 9, 2008. In the most complex scientific experiment ever undertaken, the Large Hadron Collider (LHC) will be switched on Wednesday, accelerating sub-atomic particles to nearly the speed of light before smashing them together. AFP PHOTO/SHAUN CURRY/FILES (Photo credit should read SHAUN CURRY/AFP/Getty Images)
WASHINGTON - AUGUST 12: U.S. President Barack Obama (R) presents the Medal of Freedom to physicist Stephen Hawking during a ceremony in the East Room of the White House August 12, 2009 in Washington, DC. Obama presented the medal, the highest civilian honor in the United States, to 16 recipients during the ceremony. (Photo by Chip Somodevilla/Getty Images)
US President Barack Obama presents the Presidential Medal of Freedom to British theoretical physicist Stephen Hawking during a ceremony in the East Room at the White House on August 12, 2009. Obama awarded 16 individuals the 2009 Presidential Medal of Freedom, the highest civilian honor. AFP PHOTO/Jewel SAMAD (Photo credit should read JEWEL SAMAD/AFP/Getty Images)
PASADENA, CA - JANUARY 14: Scientist Stephen Hawking of 'Into The Universe With Stephen Hawking' speaks via satellite during the Science Channel portion of the 2010 Television Critics Association Press Tour at the Langham Hotel on January 14, 2010 in Pasadena, California. (Photo by Frederick M. Brown/Getty Images)
NEW YORK - JUNE 02: Physicist Stephen Hawking onstage during the 2010 World Science Festival Opening Night Gala at Alice Tully Hall, Lincoln Center on June 2, 2010 in New York City. (Photo by Jemal Countess/Getty Images)
Physicist Stephen Hawking attends the 2010 World Science Festival Opening Night Gala at Alice Tully Hall, Lincoln Center on June 2, 2010 in New York City.
LOS ANGELES - MARCH 9: 'The Hawking Excitation' -- When Wolowitz gets to work with Stephen Hawking (left), Sheldon (Jim Parsons, right) is willing to do anything to meet his hero, on THE BIG BANG THEORY, Thursday, April 5 (8:00-8:31 PM, ET/PT) on the CBS Television Network. (Photo by Sonja Flemming/CBS via Getty Images)
LONDON, ENGLAND - AUGUST 29: Professor Stephen Hawking speaks during the Opening Ceremony of the London 2012 Paralympics at the Olympic Stadium on August 29, 2012 in London, England. (Photo by Dan Kitwood/Getty Images)
Theoretical physicist Stephen Hawking poses for a picture ahead of a gala screening of the documentary 'Hawking', a film about the scientist's life, at the opening night of the Cambridge Film Festival in Cambridge, eastern England on September 19, 2013. Hawking tells the extraordinary tale of how he overcame severe disability to become the most famous living scientist in a new documentary film premiered in Britain. AFP PHOTO / ANDREW COWIE (Photo credit should read ANDREW COWIE/AFP/Getty Images)
British actor Eddie Redmayne (R) pose with British scientist Stephen Hawking (L) at the UK premiere of the film 'The Theory of Everything' in London on December 9, 2014. The film is based on the memoir Travelling to Infinity: My Life with Stephen, by Jane Hawking, and stars Eddie Redmayne protraying the renowned astrophysicist Stephen Hawking. AFP PHOTO / JUSTIN TALLIS (Photo credit should read JUSTIN TALLIS/AFP/Getty Images)
LONDON, UNITED KINGDOM - DECEMBER 09: (EMBARGOED FOR PUBLICATION IN UK NEWSPAPERS UNTIL 48 HOURS AFTER CREATE DATE AND TIME) Professor Stephen Hawking attends the UK Premiere of 'The Theory Of Everything' at Odeon Leicester Square on December 9, 2014 in London, England. (Photo by Max Mumby/Indigo/Getty Images)
LONDON, ENGLAND - FEBRUARY 08: Lucy Hawking and Stephen Hawking attend the EE British Academy Film Awards at The Royal Opera House on February 8, 2015 in London, England. (Photo by Samir Hussein/WireImage)
LONDON, ENGLAND - FEBRUARY 18: The world's best know scientist Professor Stephen Hawking takes VisitLondon.com's Official Guest of Honour Adaeze Uyanwah on a personal guided tour of his favourite places in the city's famous Science Museum on February 18, 2015 in London, England. On the tour Professor Hawking said he was pleased to lend his synthesised 'voice' to actor Eddie Redmayne for his Oscar-nominated performance in The Theory of Everything but added ' unfortunatley Eddie did not inherit my good looks.' (Photo by Tristan Fewings/Getty Images for London & Partners)
LONDON, ENGLAND - MARCH 30: (SUN NEWSPAPER OUT. MANDATORY CREDIT PHOTO BY DAVE J. HOGAN GETTY IMAGES REQUIRED) Stephen Hawking attends 'Interstellar Live' at Royal Albert Hall on March 30, 2015 in London, England. (Photo by Dave J Hogan/Getty Images)
At the St. Albans School, Hawking was an indifferent student, preferring to spend his time playing board games and tinkering with computers. But he nonetheless gained admittance to his father's alma mater, University College at Oxford University, in 1959, at the age of 17.
Upon arriving at Oxford, Hawking toyed with the idea of studying either math or medicine before eventually settling on physics. His attitude toward academic work remained lackadaisical in college. He rarely attended lectures and has said that he spent only 1,000 hours on studies during his three years at Oxford, or just an hour a day.
Still, Hawking's natural brilliance started to shine through as an undergraduate ― and he apparently felt that his tutors resented him for doing so well with so little work. When he submitted his final thesis, it was given a grade on the border between first-class honors and second-class honors, so Hawking had to face an oral exam that would determine his grade. Knowing his reputation, he reportedly told his examiners, "If you award me a First, I will go to Cambridge. If I receive a Second, I shall stay in Oxford, so I expect you will give me a First."
He got a First. And, as promised, Hawking enrolled in graduate school at Trinity College, Cambridge in 1962, studying under the physicist Dennis Sciama and the famed astronomer Fred Hoyle. He became interested in the then-nascent study of black holes and singularities, the existence of which had been implied by Einstein's general theory of relativity.
While studying at Cambridge, Hawking met Wilde, a fellow St. Albans native who was a student in modern languages at Westfield College in London at the time. Before the two started dating, Hawking collapsed while ice skating and couldn't get up. His mother made him go to the doctor, who diagnosed him with ALS and estimatedhe had just over two years to live.
Years later, during a symposium at Cambridge on his 70th birthday, Hawking reflected on how much he struggled to stay motivated after his diagnosis. Why work so hard for a Ph.D. when you could be dead in two years?
However difficult life may seem, there is always something you can do, and succeed at. It matters that you don't just give up.Stephen Hawking, as he celebrated his 70th birthday
"Remember to look up at the stars and not down at your feet," he said. "Try to make sense of what you see and 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 motor control deteriorated rapidly; he was soon walking to class on crutches. Yet the disease spurred him to deepen his relationship with Wilde quickly. They married in 1965.
After receiving his doctorate in cosmology, Hawking stayed at Cambridge to continue studying some of the most essential questions about the structure of the universe. In 1968, a year after Jane gave birth their eldest son, Roger, Hawking took a post at the Institute of Astronomy at Cambridge and began the mature phase of his academic career.
Over the next decade, Hawking published a string of groundbreaking papers on cosmology and theoretical physics that made him a celebrity in the scientific community.
He and English mathematician Roger Penrose wrote key papers in the late 1960s that related the Big Bang ― the event that created the universe ― and black holes, proving that both were the result of singularities in the fabric of space-time. In the early 1970s, Hawking and several other physicists co-wrote a proof of the hypothesis that all black holes can be described in terms of just their mass, angular momentum and electric charge.
It was in 1974 that Hawking proposed what is widely considered his most significant theory: that black holes can emit subatomic particles, now known as Hawking radiation. Prior to his paper, physicists had been sure that nothing could escape the crushing gravity of a black hole. The existence of Hawking radiation also implies that black holes can eventually wither away and die, something that had previously been inconceivable to scientists.
Soon after publishing his paper, Hawking, just 32 years old, was named a fellow of the prestigious Royal Society. He briefly taught at the California Institute of Technology before assuming the position of Lucasian Professor of Mathematics at Cambridge, a post dating back more than 400 years that was once held by Isaac Newton.
Though Hawking's family life flourished during this time ― he and Jane Hawking went on to have two more children ― his health did not. He reluctantly started using a wheelchair in 1969, and by the mid-70s, he could no longer feed or clothe himself.
In 1985, Hawking contracted pneumonia while on a trip to Switzerland. Doctors performed a tracheotomy that allowed him to breathe but rendered him unable to speak naturally. At first, he communicated using word cards, which was agonizingly slow. But in 1986, computer scientist Walter Woltosz gave him a device that would vocalize words he typed using a joystick. Hawking called this system, which has since been upgraded several times, "The Computer." Its electronic voice was an integral part of the physicist's public image.
Hawking first came up with the idea of writing a book about cosmology for a general audience in 1982. He said he conceived of the project to "earn money to pay [his] daughter's school fees." The first draft of A Brief History of Time was finished in 1984, but Hawking's publisher felt it was too difficult for laypeople to understand, so he went back to work. The revision process became more complicated after Hawking lost his voice in 1985, but he managed to publish the book in 1988.
It was a massive hit: The book was on The New York Times' best-seller list for three years and The Sunday Times' U.K. best-seller list for nearly five. Its publication propelled Hawking to international fame that's endured to this day. He published five additional general-audience books on science, plus one memoir and four children's books. He also guest-starred on both "The Simpsons" and "Star Trek: The Next Generation."
Stephen and Jane Hawking separated after several years of tension in 1990, which Jane said was exacerbated by her husband's newfound "fame and fortune." The physicist began a relationship with Elaine Mason, one of his nurses. After his divorce from Jane Hawking, he married Mason in 1995.
In 2011, Hawking appeared on the Discovery Channel TV series "Curiosity," in which he reflected on the origins of the universe and rejected the likelihood of both a God and an afterlife. (He once dismissed the latter as "a fairy story for people afraid of the dark.") Only in confronting the finite nature of death, he said, do we appreciate the remarkable beauty of life in the present.
"There is probably no heaven, and no afterlife either," Hawking said. "We have this one life to appreciate the grand design of the universe, and for that, I am extremely grateful."
In addition to his two former wives, Hawking is survived by three children and three grandchildren.