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Hawking at NASA, 1980s
|Born||Stephen William Hawking|
8 January 1942
|Doctoral advisor||Dennis Sciama|
|Other academic advisors||Robert Berman|
Hawking at NASA, 1980s
|Born||Stephen William Hawking|
8 January 1942
|Doctoral advisor||Dennis Sciama|
|Other academic advisors||Robert Berman|
Stephen William Hawking CH CBE FRS FRSA (i/ /; born 8 January 1942) is an English theoretical physicist, cosmologist, author and Director of Research at the Centre for Theoretical Cosmology within the University of Cambridge. Among his significant scientific works have been a collaboration with Roger Penrose on gravitational singularity theorems in the framework of general relativity, and the theoretical prediction that black holes emit radiation, often called Hawking radiation. Hawking was the first to set forth a cosmology explained by a union of the general theory of relativity and quantum mechanics. He is a vocal supporter of the many-worlds interpretation of quantum mechanics.
He is an Honorary Fellow of the Royal Society of Arts, a lifetime member of the Pontifical Academy of Sciences, and a recipient of the Presidential Medal of Freedom, the highest civilian award in the United States. Hawking was the Lucasian Professor of Mathematics at the University of Cambridge between 1979 and 2009.
Hawking has achieved success with works of popular science in which he discusses his own theories and cosmology in general; his A Brief History of Time stayed on the British Sunday Times best-sellers list for a record-breaking 237 weeks. Hawking has a motor neuron disease related to amyotrophic lateral sclerosis (ALS), a condition that has progressed over the years. He is almost entirely paralysed and communicates through a speech generating device. He married twice and has three children.
Stephen Hawking was born on 8 January 1942 to Frank and Isobel Hawking. Despite their families' financial constraints, both parents attended the University of Oxford, where Frank studied medicine and Isobel, Philosophy, Politics and Economics. The two met shortly after the beginning of the Second World War at a medical research institute where she was working as a secretary and he as a medical researcher. They lived in Highgate, but as London was under attack in those years, his mother went to Oxford to give birth in greater safety. Stephen has two younger sisters, Philippa and Mary, and an adopted brother, Edward. He began his schooling at the Byron House School; he later blamed its "progressive methods" for his failure to learn to read while at the school.
In 1950, when his father became head of the division of parasitology at the National Institute for Medical Research, Hawking and his family moved to St Albans, Hertfordshire. The eight-year-old Hawking attended St Albans High School for Girls for a few months; at that time, younger boys could attend one of the houses. In St Albans, the family were considered highly intelligent and somewhat eccentric; meals were often spent with each person silently reading a book. They lived a frugal existence in a large, cluttered, and poorly maintained house, and travelled in a converted London taxicab. During one of Hawking's father's frequent absences working in Africa, the rest of the family spent four months in Majorca visiting his mother's friend Beryl and her husband, the poet Robert Graves.
On their return to England, Hawking attended Radlett School for a year and from September 1952, St Albans School. The family placed a high value on education. Hawking's father wanted his son to attend the well-regarded Westminster School, but the 13-year-old Hawking was ill on the day of the scholarship examination. His family could not afford the school fees without the financial aid of a scholarship, so Hawking remained at St Albans. A positive consequence was that Hawking remained with a close group of friends with whom he enjoyed board games, the manufacture of fireworks, model aeroplanes and boats, and long discussions about Christianity and extrasensory perception. From 1958, and with the help of the mathematics teacher Dikran Tahta, they built a computer from clock parts, an old telephone switchboard and other recycled components. Although at school he was known as "Einstein," Hawking was not initially successful academically. With time, he began to show considerable aptitude for scientific subjects, and inspired by Tahta, decided to study mathematics at university. Hawking's father advised him to study medicine, concerned that there were few jobs for mathematics graduates. He wanted Hawking to attend University College, Oxford, his own alma mater. As it was not possible to read mathematics there at the time, Hawking decided to study physics and chemistry. Despite his headmaster's advice to wait until the next year, Hawking was awarded a scholarship after taking the examinations in March 1959.
Hawking went up to Oxford University in October 1959 at the age of 17. For the first 18 months, he was bored and lonely: he was younger than many other students, and found the academic work "ridiculously easy." His physics tutor Robert Berman later said, "It was only necessary for him to know that something could be done, and he could do it without looking to see how other people did it." A change occurred during his second and third year when, according to Berman, Hawking made more effort "to be one of the boys". He developed into a popular, lively and witty college member, interested in classical music and science fiction. Part of the transformation resulted from his decision to join the college Boat Club, where he coxed a rowing team. The rowing trainer at the time noted that Hawking cultivated a daredevil image, steering his crew on risky courses that led to damaged boats. Hawking has estimated that he studied about 1,000 hours during his three years at Oxford. These unimpressive study habits made sitting his Finals a challenge, and he decided to answer only theoretical physics questions rather than those requiring factual knowledge. A first-class honours degree was a condition of acceptance for his planned graduate study in cosmology at the University of Cambridge. Anxious, he slept poorly the night before the examinations and the final result was on the borderline between first- and second-class honours, making a viva necessary. Hawking was concerned that he was viewed as a lazy and difficult student, so when asked at the oral examination to describe his future plans, he said, "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 was held in higher regard than he believed: as Berman commented, the examiners "were intelligent enough to realise they were talking to someone far cleverer than most of themselves." After receiving a first-class BA (Hons.) degree, and following a trip to Iran with a friend, he began his graduate work at Trinity Hall, Cambridge, in October 1962.
Hawking's first year as a doctoral student was difficult. He was initially disappointed to find that he had been assigned Dennis William Sciama as a supervisor rather than Fred Hoyle, and he found his training in mathematics inadequate for work in general relativity and cosmology. He also struggled with his health. Hawking had experienced increasing clumsiness during his final year at Oxford, including a fall on some stairs and difficulties when rowing. The problems worsened, and his speech became slightly slurred; his family noticed the changes when he returned home for Christmas and medical investigations were begun. The diagnosis of motor neurone disease came when Hawking was 21. At the time, doctors gave him a life expectancy of two years. After his diagnosis, Hawking fell into a depression; though his doctors advised that he continue with his studies, he felt there was little point. At the same time, however, his relationship with Jane Wilde, friend of his sister, and whom he had met shortly before his diagnosis, continued to develop. The couple were engaged in October 1964. Hawking later said that the engagement "gave him something to live for." Despite the disease's progression—Hawking had difficulty walking without support, and his speech was almost unintelligible—he now returned to his work with enthusiasm. Hawking started developing a reputation for brilliance and brashness when he publicly challenged the work of Fred Hoyle and his student Jayant Narlikar at a lecture in June 1964.
When Hawking began his graduate studies, there was much debate in the physics community about the prevailing theories of the creation of the universe: the Big Bang and the Steady State theories. Inspired by Roger Penrose's theorem of a spacetime singularity in the centre of black holes, Hawking applied the same thinking to the entire universe, and during 1965 wrote up his thesis on this topic. There were other positive developments: Hawking received a research fellowship at Gonville and Caius College, and he and Jane were married on 14 July 1965. He obtained his D.Phil. degree in March 1966, and his essay entitled "Singularities and the Geometry of Space-Time" shared top honours with one by Penrose to win that year's Adams Prize.
The first years of marriage were hectic: Jane lived in London during the week as she completed her degree and they travelled to the United States several times for conferences and physics-related visits. The couple had difficulty finding housing that was within Hawking's walking distance to the Department of Applied Mathematics and Theoretical Physics (DAMTP). Jane began a Ph.D. program, and a son, Robert, was born in May 1967. In his work, and in collaboration with Penrose, Hawking extended the singularity theorem concepts first explored in his doctoral thesis. This included not only the existence of singularities but also the theory that the universe might have started as a singularity. Their joint essay was the runner-up in the 1968 Gravity Research Foundation competition. In 1970 they published a proof that if the universe obeys the general theory of relativity and fits any of the models of physical cosmology developed by Alexander Friedmann, then it must have begun as a singularity.
During the late 1960s, Hawking's physical abilities declined once more: he began to use crutches and ceased lecturing regularly. As he slowly lost the ability to write, he developed compensatory visual methods, including seeing equations in terms of geometry. The physicist Werner Israel later compared the achievements to Mozart composing an entire symphony in his head. Hawking was, however, fiercely independent and unwilling to accept help or make concessions for his disabilities. He preferred to be regarded as "a scientist first, popular science writer second, and, in all the ways that matter, a normal human being with the same desires, drives, dreams, and ambitions as the next person." Jane Hawking later noted that "Some people would call it determination, some obstinacy. I've called it both at one time or another." He required much persuasion to accept the use of a wheelchair at the end of the 1960s, but ultimately became notorious for the wildness of his wheelchair driving. Hawking was a popular and witty colleague, but his illness as well as his reputation for brashness and intelligence distanced him from some. In 1969, Hawking accepted a specially created 'Fellowship for Distinction in Science' to remain at Caius.
A daughter, Lucy, was born in 1970. Soon after Hawking discovered what became known as the second law of black hole dynamics, that the event horizon of a black hole can never get smaller. With James M. Bardeen and Brandon Carter, he proposed the four laws of black hole mechanics, drawing an analogy with thermodynamics. To Hawking's irritation, Jacob Bekenstein, a graduate student of John Wheeler, went further—and ultimately correctly—applying thermodynamic concepts literally. In the early 1970s, Hawking's work with Carter, Werner Israel and David C. Robinson strongly supported Wheeler's no-hair theorem that no matter what the original material from which a black hole is created it can be completely described by the properties of mass, electrical charge and rotation. His essay titled "Black Holes" won the Gravity Research Foundation Award in January 1971. Hawking's first book The Large Scale Structure of Space-Time written with George Ellis was published in 1973.
Beginning in 1973, Hawking moved into the study of quantum gravity and quantum mechanics. His work in this area was spurred by a visit to Moscow and discussions with Yakov Borisovich Zel'dovich and Alexei Starobinsky, whose work showed that according to the uncertainty principle rotating black holes emit particles. To Hawking's annoyance, his much-checked calculations produced findings that contradicted his second law, which claimed black holes could never get smaller, and supported Bekenstein's reasoning about their entropy. His results, which Hawking presented from 1974, showed that black holes emit radiation, known today as Hawking radiation, which may continue until they exhaust their energy and evaporate. Initially, Hawking radiation was controversial. However by the late 1970s and following the publication of further research, the discovery was widely accepted as a significant breakthrough in theoretical physics. In March 1974, a few weeks after the announcement of Hawking radiation, Hawking was invested as a Fellow of the Royal Society, one of the youngest scientists to be so honoured.
Hawking rarely discussed his illness and physical challenges, even—in a precedent set during their courtship—with Jane. Hawking's disabilities meant that the responsibilities of home and family rested firmly on his wife's increasingly overwhelmed shoulders, leaving him more time to think about physics. When in 1974 Hawking was appointed to the Sherman Fairchild Distinguished Scholar visiting professorship at the California Institute of Technology (Caltech), Jane proposed that a graduate or post-doctoral student live with them and help with his care. Hawking accepted, and Bernard Carr travelled to California with them as the first of many students who fulfilled this role. The family spent a generally happy and stimulating year in Pasadena. Hawking worked with his friend on the faculty, Kip Thorne, and engaged him in a scientific wager about whether the dark star Cygnus X-1 was a black hole. The wager was a surprising "insurance policy" against the proposition that black holes did not exist. Hawking acknowledged that he had lost the bet in 1990, which was the first of several that he was to make with Thorne and others. Hawking has maintained ties to Caltech, spending a month there almost every year since this first visit.
Hawking returned to Cambridge in 1975 to a new home, a new job—as Reader. Don Page, with whom Hawking had begun a close friendship at Caltech, arrived to work as the live-in graduate student assistant. With Page's help and that of a secretary, Jane's responsibilities were reduced so she could return to her thesis and her new interest in singing. The mid to late 1970s were a period of growing public interest in black holes and of the physicist who was studying them. Hawking was regularly interviewed for print and television. He also received increasing academic recognition of his work. In 1975 he was awarded both the Eddington Medal and the Pius XI Gold Medal, and in 1976 the Dannie Heineman Prize, the Maxwell Prize and the Hughes Medal. Hawking was appointed a professor with a chair in gravitational physics in 1977. The following year he received the Albert Einstein Medal and an honorary doctorate from the University of Oxford.
Hawking's speech deteriorated, and by the late 1970s he could only be understood by his family and closest friends. To communicate with others, someone who knew him well would translate his speech into intelligible speech. Spurred by a dispute with the university over who would pay for the ramp needed for him to enter his workplace, Hawking and his wife campaigned for improved access and support for those with disabilities in Cambridge, including adapted student housing at the university. In general, however, Hawking had ambivalent feelings about his role as a disability rights champion: while wanting to help others, he sought to detach himself from his illness and its challenges. His lack of engagement led to some criticism. The Hawking family welcomed a third child, Timothy, in April 1979. That autumn Hawking was appointed the Lucasian Professor of Mathematics at the University of Cambridge.
Hawking's inaugural lecture as Lucasian Professor of Mathematics was titled: "Is the end in sight for Theoretical Physics" and proposed N=8 Supergravity as the leading theory to solve many of the outstanding problems physicists were studying. Hawking's promotion coincided with a health crisis which led to Hawking accepting, albeit reluctantly, some nursing services at home. At the same time he was also making a transition in his approach to physics, becoming more intuitive and speculative rather than insisting on mathematical proofs. "I would rather be right than rigorous" he told Kip Thorne. In 1981 he proposed that information in a black hole is irretrievably lost when a black hole evaporates. This information paradox violates the fundamental tenet of quantum mechanics, and was to lead to years of debate, including "the Black Hole War" with Leonard Susskind and Gerard 't Hooft.
In December 1977, Jane had met organist Jonathan Hellyer Jones when singing in a church choir. Hellyer Jones became close to the Hawking family, and by the mid-1980s, he and Jane had developed romantic feelings for each other. According to Jane, her husband was accepting of the situation, stating "he would not object so long as I continued to love him." Jane and Hellyer Jones determined not to break up the family and their relationship remained platonic for a long period.
Cosmological inflation—a theory proposing that following the Big Bang the universe initially expanded incredibly rapidly before settling down to a slower expansion—was proposed by Alan Guth and also developed by Andrei Linde. Following a conference in Moscow in October 1981, Hawking and Gary Gibbons organized a three-week Nuffield Workshop in the summer of 1982 on the Very Early Universe at Cambridge University, which focussed mainly on inflation theory. Hawking also began a new line of quantum theory research into the origin of the universe. In 1981 at a Vatican conference he presented work suggesting that there might be no boundary—or beginning or ending—to the universe. He subsequently developed the research in collaboration with Jim Hartle, and in 1983 they published a model, known as the Hartle–Hawking state. It proposed that prior to the Planck epoch, the universe had no boundary in space-time; before the Big Bang, time did not exist and the concept of the beginning of the universe is meaningless. The initial singularity of the classical Big Bang models was replaced with a region akin to the North Pole. One cannot travel north of the North Pole, but there is no boundary there—it is simply the point where all north-running lines meet and end. Initially the no-boundary proposal predicted a closed universe which had implications about the existence of God. As Hawking explained "If the universe has no boundaries but is self-contained... then God would not have had any freedom to choose how the universe began."
Hawking did not rule out the existence of a Creator, asking in A Brief History of Time "Is the unified theory so compelling that it brings about its own existence?" In his early work, Hawking spoke of God in a metaphorical sense. In A Brief History of Time he wrote: "If we discover a complete theory, it would be the ultimate triumph of human reason—for then we should know the mind of God." In the same book he suggested the existence of God was unnecessary to explain the origin of the universe. Later discussions with Neil Turok led to the realisation that it is also compatible with an open universe.
Further work by Hawking in the area of arrows of time led to the 1985 publication of a paper theorising that if the no-boundary proposition were correct, then when the universe stopped expanding and eventually collapsed, time would run backwards. A paper by Don Page and Raymond Laflamme led Hawking to withdraw this concept. Honours continued to be awarded: in 1981 he was awarded the American Franklin Medal, and in 1982 made a Commander of the Order of the British Empire (CBE). Awards do not pay the bills, however, and motivated by the need to finance the children's education and home expenses, in 1982 Hawking determined to write a popular book about the universe that would be accessible to the general public. Instead of publishing with an academic press, he signed a contract with Bantam Books, a mass market publisher, and received a large advance for his book. A first draft of the book, called A Brief History of Time, was completed in 1984.
During a visit to CERN in Geneva in the summer of 1985, Hawking contracted pneumonia which in his condition was life-threatening; he was so ill that Jane was asked if life support should be terminated. She refused but the consequence was a tracheotomy, which would require round-the-clock nursing care, and remove what remained of his speech. The National Health Service would pay for a nursing home but Jane was determined that he would live at home. The cost of the care was funded by an American foundation. Nurses were hired for the three shifts required to provide the round-the-clock support he required. One of those employed was Elaine Mason, who was to become Hawking's second wife. For his communication, Hawking initially raised his eyebrows to choose letters on a spelling card. But he then received a computer program called the "Equalizer" from Walt Woltosz. In a method he uses to this day, using a switch he selects phrases, words or letters from a bank of about 2500–3000 that are scanned. The program was originally run on a desktop computer. However, Elaine Mason's husband David, a computer engineer, adapted a small computer and attached it to his wheelchair. Released from the need to use somebody to interpret his speech, Hawking commented that "I can communicate better now than before I lost my voice." The voice he uses has an American accent and is no longer produced. Despite the availability of other voices, Hawking has retained his original voice, saying that he prefers his current voice and identifies with it. At this point, Hawking activated a switch using his hand and could produce up to 15 words a minute. Lectures were prepared in advance, and sent to the speech synthesiser in short sections as they were delivered.
One of the first messages Hawking produced with his speech generating device was a request for his assistant to help him finish writing A Brief History of Time. Peter Guzzardi, his editor at Bantam, pushed him to explain his ideas clearly in non-technical language, a process that required multiple revisions from an increasingly irritated Hawking. The book was published in April 1988 in the US and in June in the UK, and proved to be an extraordinary success, rising quickly to the top of bestseller lists in both countries and remaining there for weeks and months. The book was translated into multiple languages, and ultimately sold an estimated 9 million copies. Media attention was intense, and Newsweek magazine cover and a television special both described him as "Master of the Universe". Success led to significant financial rewards, but also the challenges of celebrity status. Hawking travelled extensively to promote his work, and enjoyed partying and dancing into the small hours. He had difficulty refusing the invitations and visitors which left limited time for work and his students. Some colleagues were resentful of the attention Hawking received, feeling it was due to his disability. He received further academic recognition, including five further honorary degrees, the Gold Medal of the Royal Astronomical Society (1985), the Paul Dirac Medal (1987) and, jointly with Penrose, the prestigious Wolf Prize (1988). In 1989, he was named a Companion of Honour by Queen Elizabeth II.
Hawking's marriage had been strained for many years. Jane felt overwhelmed by the intrusion into their family life of the required nurses and assistants. The impact of his celebrity was challenging for colleagues and family members, and in one interview Jane described her role as "simply to tell him that he's not God." Hawking's agnostic views of religion also contrasted with her strong Christian faith, and resulted in tension. In the late 1980s Hawking had grown close to one of his nurses, Elaine Mason, to the dismay of some colleagues, caregivers and family members who were disturbed by her strength of personality and protectiveness. Hawking told Jane that he was leaving her for Mason, and departed the family home in February 1990. Following his divorce from Jane in the spring of 1995, Hawking married Mason in September, declaring "It's wonderful—I have married the woman I love."
Hawking pursued his work in physics: in 1993 he co-edited a book on Euclidean quantum gravity with Gary Gibbons, and published a collected edition of his own articles on black holes and the Big Bang. In 1994 at Cambridge's Newton Institute, Hawking and Penrose delivered a series of six lectures, which were published in 1996 as "The Nature of Space and Time". In 1997 he conceded a 1991 public scientific wager made with Kip Thorne and John Preskill of Caltech. Hawking had bet that Penrose's proposal of a "cosmic censorship conjecture"—that there could be no "naked singularities" unclothed within a horizon—was correct. After discovering his concession might have been premature, a new, more refined, wager was made. This specified that such singularities would occur without extra conditions. The same year, Thorne, Hawking and Preskill made another bet, this time concerning the black hole information paradox. Thorne and Hawking argued that since general relativity made it impossible for black holes to radiate and lose information, the mass-energy and information carried by Hawking Radiation must be "new", and not from inside the black hole event horizon. Since this contradicted the quantum mechanics of microcausality, quantum mechanics theory would need to be rewritten. Preskill argued the opposite, that since quantum mechanics suggests that the information emitted by a black hole relates to information that fell in at an earlier time, the concept of black holes given by general relativity must be modified in some way.
Hawking also maintained his public profile, including bringing science to a wider audience. In 1992 a film version of "A Brief History of Time"—directed by Errol Morris and produced by Steven Spielberg—was premiered. Hawking had wanted the film to be scientific rather than biographical, but was persuaded otherwise. The film, while a critical success, was however not widely released. A popular-level collection of essays, interviews and talk titled Black Holes and Baby Universes and Other Essays was published in 1993 and six-part television series Stephen Hawking's Universe and companion book appeared in 1997. As Hawking insisted, this time the focus was entirely on science. He also made several appearances in popular media. At the release party for the home video version of the "A Brief History of Time", Leonard Nimoy, who had played Spock on Star Trek, learnt that Hawking was interested in appearing on the show. Nimoy made the necessary contact and Hawking appeared as himself on Star Trek: The Next Generation in 1993. The same year, his synthesiser voice was recorded for the Pink Floyd song "Keep Talking", and in 1999 for an appearance on The Simpsons.
In the 1990s, Hawking accepted more openly the mantle of role model for disabled people, including lecturing on the subject and participating in fundraising activities. At the turn of the century, he and eleven other luminaries signed the "Charter for the Third Millennium on Disability" which called on governments to prevent disability and protect disabled rights. In 1999 Hawking was awarded the Julius Edgar Lilienfeld Prize of the American Physical Society. The same year, Jane Hawking published a memoir, Music to Move the Stars, describing her marriage to Hawking and its breakdown. Its revelations caused a sensation in the media, but as was his usual practice regarding his personal life, Hawking made no public comment except to say that he did not read biographies about himself.
Following his second marriage, Hawking's family felt excluded and marginalised from his life. For a period of about five years in the early 2000s, his family and staff became increasingly worried that he was being physically abused. Police investigations took place, but were closed as Hawking refused to make a complaint.
Hawking continued his writings for a popular audience, publishing The Universe in a Nutshell in 2001,  and A Briefer History of Time which he wrote in 2005 with Leonard Mlodinow to update his earlier works to make them accessible to a wider audience, and God Created the Integers, which appeared in 2006. Along with Thomas Hertog at the European Organization for Nuclear Research (CERN) and Jim Hartle, from 2006 on Hawking developed a theory of "top-down cosmology", which says that the universe had not one unique initial state but many different ones, and therefore that it is inappropriate to formulate a theory that predicts the universe's current configuration from one particular initial state. Top-down cosmology posits that the present "selects" the past from a superposition of many possible histories. In doing so, the theory suggests a possible resolution of the fine-tuning question.
The same year Hawking and Elaine quietly divorced, following which Hawking resumed closer relationships with Jane, his children and grandchildren. Reflecting this happier period a revised version of Jane's book called Travelling to Infinity, My Life with Stephen appeared in 2007. That year Hawking and his daughter Lucy published George's Secret Key to the Universe, a children's book designed to explain theoretical physics in an accessible fashion and featuring characters similar to those in the Hawking family. The book was followed by sequels in 2009 and 2011.
Hawking continued to feature regularly on the screen: documentaries entitled :The Real Stephen Hawking: (2001) and "Stephen Hawking: Profile" (2002),  a TV film Hawking about the period around the onset of Hawking's illness (2004), and a documentary series Stephen Hawking, Master of the Universe (2008). Hawking made further appearances in animated form on The Simpsons, and Futurama in which he does his own voice acting, and in person on The Big Bang Theory. Hawking continued to travel widely, including trips to Chile, Easter Island, South Africa and Spain (to receive the Fonseca Prize in 2008)  Canada and multiple trips to the United States. For practical reasons related to his disability Hawking increasingly travelled by private jet, and by 2011 that had become his only mode of international travel.
Over the years, Hawking maintained his public profile with a series of attention-getting and often controversial statements: he has asserted that computer viruses were a form of life, that humans should use genetic engineering to avoid being outsmarted by computers, and that aliens likely exist and contact with them should be avoided. Hawking has expressed his concerns that life on earth is at risk due to "a sudden nuclear war, a genetically engineered virus or other dangers we have not yet thought of". He views spaceflight and the colonisation of space as necessary for the future of humanity. Motivated by the desire to increase public interest in spaceflight and to show the potential of people with disabilities, in 2007 he participated in zero-gravity flight in a "Vomit Comet", courtesy of Zero Gravity Corporation, during which he experienced weightlessness eight times.
A longstanding Labour Party supporter, Hawking has also increasingly made his views known on a variety of political subjects. He recorded a tribute for the 2000 Democratic presidential candidate Al Gore, called the 2003 invasion of Iraq a "war crime", boycotted a conference in Israel due to concerns about Israel's policies towards Palestinians, maintained his longstanding campaigning for nuclear disarmament, and has supported stem cell research, universal health care, and action to prevent climate change. Hawking has also used his fame to advertise products, including a wheelchair, National Savings, British Telecom, Specsavers and Egg Banking, and Go Compare.
In the area of physics, by 2003, consensus was growing that Hawking was wrong about the loss of information in a black hole. In a 2004 lecture in Dublin, the physicist conceded his 1997 bet with Preskill, but described his own, somewhat controversial solution, to the information paradox problem, involving the possibility that black holes have more than one topology. In the 2005 paper he published on the subject, he argued that the information paradox was explained by examining all the alternative histories of universes, with the information loss in those with black holes being cancelled out by those without. In January 2014 he called this his "biggest blunder." 
As part of another longstanding scientific dispute, Hawking had emphatically argued, and bet, that the Higgs Boson would never be found. The particle, proposed to exist as part of the Higgs Field theory by Peter Higgs in 1964, became discoverable with the advent of the Fermilab near Chicago and the Large Electron Positron and the Large Hadron Collider at CERN. Hawking and Higgs engaged in a heated and public debate over the matter in 2002 and again in 2008, with Higgs criticising Hawking's work and complaining that Hawking's "celebrity status gives him instant credibility that others do not have." The particle was discovered at CERN in July 2012: Hawking quickly conceded that he had lost his bet and said that Higgs should win the Nobel Prize for Physics.
In 2007 he posed this open question on the Internet: “In a world that is in chaos politically, socially and environmentally, how can the human race sustain another 100 years?” A month later he confessed: “I don’t know the answer. That is why I asked the question, to get people to think about it, and to be aware of the dangers we now face.” The Guardian, Britain.
Hawking's disease-related deterioration has continued, and in 2005 he began to control his communication device with movements of his cheek muscles, with a rate of about one word per minute. With this decline there is a risk of him acquiring locked-in syndrome, so Hawking is collaborating with researchers on systems that could translate Hawking's brain patterns or facial expressions into switch activations. By 2009 he could no longer drive his wheelchair independently. He has increased breathing difficulties, requiring a ventilator at times, and has been hospitalized several times. In 2002, following a UK-wide vote, the BBC included him in their list of the 100 Greatest Britons. Hawking was awarded the Copley Medal from the Royal Society (2006), America's highest civilian honour, the Presidential Medal of Freedom (2009), and the Russian Fundamental Physics Prize (2012).
Several buildings have been named after him, including the Stephen W. Hawking Science Museum in San Salvador, El Salvador, the Stephen Hawking Building in Cambridge, and the Stephen Hawking Centre at Perimeter Institute in Canada. Appropriately, given Hawking's association with time, he unveiled the mechanical "Chronophage" (or time-eating) Corpus Clock at Corpus Christi College Cambridge in September 2008.
As required by university regulations, Hawking retired as Lucasian Professor of Mathematics in 2009. Despite suggestions that he might leave the United Kingdom as a protest against public funding cuts to basic scientific research, Hawking has continued to work as director of research at the Department of Applied Mathematics and Theoretical Physics, and has indicated no plans to retire.
Hawking has stated that he is "not religious in the normal sense" and he believes that "the universe is governed by the laws of science. The laws may have been decreed by God, but God does not intervene to break the laws." In an interview published in The Guardian, Hawking regarded the concept of Heaven as a myth, believing that there is "no heaven or afterlife" and that such a notion was a "fairy story for people afraid of the dark."
We are each free to believe what we want and it is my view that the simplest explanation is there is no God. No one created the universe and no one directs our fate. This leads me to a profound realization. There is probably no heaven, and no afterlife either. We have this one life to appreciate the grand design of the universe, and for that, I am extremely grateful.
At Google's Zeitgeist Conference in 2011, Hawking said that "philosophy is dead." He believes that philosophers "have not kept up with modern developments in science" and that scientists "have become the bearers of the torch of discovery in our quest for knowledge." He said that philosophical problems can be answered by science, particularly new scientific theories which "lead us to a new and very different picture of the universe and our place in it". In August 2012 Hawking narrated the "Enlightenment" segment of the 2012 Summer Paralympics opening ceremony. In 2013, the biographical documentary film Hawking, in which Hawking himself is featured, was released. In September 2013, he expressed support for the legalization of assisted suicide for the terminally ill.
We are all different – but we share the same human spirit. Perhaps it's human nature that we adapt – and survive.
Co-written with his daughter Lucy.
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