Stephen Hawking

විකිපීඩියා, නිදහස් විශ්වකෝෂය වෙතින්
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Stephen Hawking
Black-and-white photograph of Stephen Hawking at NASA's StarChild Learning Center
Hawking at NASA's StarChild Learning Center, 1980s
උපත
Stephen William Hawking

8 ජනවාරි 1942(1942-01-08)
Oxford, England
මිය යාම14 March 2018(2018-03-14) (වයස 76)
Cambridge, England
උගත් ශාස්ත්‍රාලය
සංගණ්‍ය වන්නේ
කලත්‍රයා(යන්)
  • Jane Wilde
     (වි. 1965; දි. 1995)
  • Elaine Mason
     (වි. 1995; දි. 2006)
සම්මාන
Scientific career
ක්ෂේත්‍රය
ආයතන
ආචාර්ය උපදේශකDennis Sciama[1]
Other academic advisorsRobert Berman[2]
ආචාර්ය සිසුන්
අත්සන
Hawkingsig.svg

Stephen William Hawking CH CBE FRS FRSA (8 January 1942 – 14 March 2018) was an English theoretical physicist, cosmologist, and author, who was director of research at the Centre for Theoretical Cosmology at the University of Cambridge at the time of his death. He was the Lucasian Professor of Mathematics at the University of Cambridge between 1979 and 2009.

His scientific works included 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 out a theory of cosmology explained by a union of the general theory of relativity and quantum mechanics. He was a vigorous supporter of the many-worlds interpretation of quantum mechanics.[15][16]

Hawking achieved commercial success with several works of popular science in which he discusses his own theories and cosmology in general. His book A Brief History of Time appeared on the British Sunday Times best-seller list for a record-breaking 237 weeks. Hawking was a fellow of the Royal Society (FRS), 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. In 2002, Hawking was ranked number 25 in the BBC's poll of the 100 Greatest Britons. Hawking had a rare early-onset slow-progressing form of motor neurone disease (also known as amyotrophic lateral sclerosis "ALS" or Lou Gehrig's disease) that gradually paralysed him over the decades.[17][18] Even after the loss of his speech, he was still able to communicate through a speech-generating device, initially through use of a hand-held switch, and eventually by using a single cheek muscle. He died on 14 March 2018 at the age of 76.[19][20]

Early life[සංස්කරණය]

Family[සංස්කරණය]

Hawking was born on 8 January 1942 in Oxford to Frank (1905–1986)[21] and Isobel Eileen Hawking (née Walker; 1915–2013).[22][23][24] Hawking's mother was born into a family of doctors in Glasgow, Scotland.[25][26] His wealthy paternal great-grandfather, from Yorkshire, had over-extended himself buying farm land and then going bankrupt in the great agricultural depression during the early 20th century. His paternal great-grandmother saved the family from financial ruin by opening a school in their home. Despite their families' financial constraints, both parents attended the University of Oxford, where Frank read medicine and Isobel read Philosophy, Politics and Economics.[23] Isobel worked as a secretary for a medical research institute, and Frank was a medical researcher.[23][27] Hawking had two younger sisters, Philippa and Mary, and an adopted brother, Edward Frank David (1955–2003).[28][29]

In 1950, when Hawking's father became head of the division of parasitology at the National Institute for Medical Research, the family moved to St Albans, Hertfordshire.[30][31] In St Albans, the family was considered highly intelligent and somewhat eccentric;[30][32] meals were often spent with each person silently reading a book.[30] They lived a frugal existence in a large, cluttered, and poorly maintained house and travelled in a converted London taxicab.[33][34] During one of Hawking's father's frequent absences working in Africa,[35] the rest of the family spent four months in Majorca visiting his mother's friend Beryl and her husband, the poet Robert Graves.[36]

Primary and secondary school years[සංස්කරණය]

Hawking began his schooling at the Byron House School in Highgate, London. He later blamed its "progressive methods" for his failure to learn to read while at the school.[37][30] In St Albans, 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.[36][38]

Hawking attended two independent (i.e. fee-paying) schools, first Radlett School[38] and from September 1952, St Albans School,[39] after passing the eleven-plus a year early.[40] The family placed a high value on education.[30] 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.[41][42] 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,[43] and long discussions about Christianity and extrasensory perception.[44] From 1958 on, with the help of the mathematics teacher Dikran Tahta, they built a computer from clock parts, an old telephone switchboard and other recycled components.[45][46]

Although known at school as "Einstein", Hawking was not initially successful academically.[47] With time, he began to show considerable aptitude for scientific subjects and, inspired by Tahta, decided to read mathematics at university.[48][49] Hawking's father advised him to study medicine, concerned that there were few jobs for mathematics graduates.[50] He also wanted his son 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.[51][52]

Undergraduate years[සංස්කරණය]

Hawking began his university education at University College, Oxford, in October 1959 at the age of 17.[53] For the first 18 months, he was bored and lonely සැකිල්ල:Sndhe found the academic work "ridiculously easy".[54][55] 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."[2] A change occurred during his second and third year when, according to Berman, Hawking made more of an effort "to be one of the boys". He developed into a popular, lively and witty college member, interested in classical music and science fiction.[53] Part of the transformation resulted from his decision to join the college boat club, the University College Boat Club, where he coxed a rowing crew.[56][57] The rowing coach at the time noted that Hawking cultivated a daredevil image, steering his crew on risky courses that led to damaged boats.[58][56]

Hawking 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.[59][60] 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 (oral examination) necessary.[60][61] Hawking was concerned that he was viewed as a lazy and difficult student. So, when asked at the oral[පැහැදීම ඇවැසිය] to describe his 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."[60][62] 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".[60] After receiving a first-class BA (Hons.) degree in natural science and completing a trip to Iran with a friend, he began his graduate work at Trinity Hall, Cambridge, in October 1962.[63][64]

Graduate years[සංස්කරණය]

Hawking's first year as a doctoral student was difficult. He was initially disappointed to find that he had been assigned Dennis William Sciama, one of the founders of modern cosmology, as a supervisor rather than noted Yorkshire astronomer Fred Hoyle,[65][66] and he found his training in mathematics inadequate for work in general relativity and cosmology.[67] After being diagnosed with motor neurone disease, Hawking fell into a depression සැකිල්ල:Sndthough his doctors advised that he continue with his studies, he felt there was little point.[68] His disease progressed more slowly than doctors had predicted. Although Hawking had difficulty walking unsupported, and his speech was almost unintelligible, an initial diagnosis that he had only two years to live proved unfounded. With Sciama's encouragement, he returned to his work.[69][70] 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.[71][72]

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 Steady State theories.[73] 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, he wrote his thesis on this topic.[74][75] Hawking's thesis was approved in 1966. There were other positive developments: Hawking received a research fellowship at Gonville and Caius College at Cambridge;[76] he obtained his PhD degree in applied mathematics and theoretical physics, specialising in general relativity and cosmology, in March 1966;[77] and his essay "Singularities and the Geometry of Space-Time" shared top honours with one by Penrose to win that year's prestigious Adams Prize.[78][77]

Career[සංස්කරණය]

1966–1975[සංස්කරණය]

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.[79][80] 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.[81][82] In 1969, Hawking accepted a specially created Fellowship for Distinction in Science to remain at Caius.[83]

In 1970, Hawking postulated what became known as the second law of black hole dynamics, that the event horizon of a black hole can never get smaller.[84] With James M. Bardeen and Brandon Carter, he proposed the four laws of black hole mechanics, drawing an analogy with thermodynamics.[85] To Hawking's irritation, Jacob Bekenstein, a graduate student of John Wheeler, went further—and ultimately correctly—to apply thermodynamic concepts literally.[86][87] In the early 1970s, Hawking's work with Carter, Werner Israel and David C. Robinson strongly supported Wheeler's no-hair theorem, one that states 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.[88] His essay titled "Black Holes" won the Gravity Research Foundation Award in January 1971.[89] Hawking's first book, The Large Scale Structure of Space-Time, written with George Ellis, was published in 1973.[90]

Beginning in 1973, Hawking moved into the study of quantum gravity and quantum mechanics.[91][90] 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.[92] To Hawking's annoyance, his much-checked calculations produced findings that contradicted his second law, which claimed black holes could never get smaller,[93] and supported Bekenstein's reasoning about their entropy.[94][92] 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.[95] Initially, Hawking radiation was controversial. By the late 1970s and following the publication of further research, the discovery was widely accepted as a significant breakthrough in theoretical physics.[96][97][98] Hawking was elected a Fellow of the Royal Society (FRS) in 1974, a few weeks after the announcement of Hawking radiation. At the time, he was one of the youngest scientists to become a Fellow.[99][100]

Hawking was appointed to the Sherman Fairchild Distinguished visiting professorship at the California Institute of Technology (Caltech) in 1970. He worked with a friend on the faculty, Kip Thorne,[101] and engaged him in a scientific wager about whether the X-ray source Cygnus X-1 was a black hole. The wager was an "insurance policy" against the proposition that black holes did not exist.[102] Hawking acknowledged that he had lost the bet in 1990, a bet that was the first of several he was to make with Thorne and others.[103] Hawking had maintained ties to Caltech, spending a month there almost every year since this first visit.[104]

1975–1990[සංස්කරණය]

Hawking returned to Cambridge in 1975 to a more academically senior post, as reader in gravitational physics. The mid to late 1970s were a period of growing public interest in black holes and the physicists who were studying them. Hawking was regularly interviewed for print and television.[105][106] He also received increasing academic recognition of his work.[107] 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.[108][109] He was appointed a professor with a chair in gravitational physics in 1977.[110] The following year he received the Albert Einstein Medal and an honorary doctorate from the University of Oxford.[111][107]

In 1979, Hawking was elected Lucasian Professor of Mathematics at the University of Cambridge.[107][112] His inaugural lecture in this role 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.[113] His promotion coincided with a health crisis which led to his accepting, albeit reluctantly, some nursing services at home.[114] 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.[115] 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 led to years of debate, including "the Black Hole War" with Leonard Susskind and Gerard 't Hooft.[116]

Cosmological inflation සැකිල්ල:Snda theory proposing that following the Big Bang, the universe initially expanded incredibly rapidly before settling down to a slower expansion සැකිල්ල:Sndwas proposed by Alan Guth and also developed by Andrei Linde.[117] Following a conference in Moscow in October 1981, Hawking and Gary Gibbons organised a three-week Nuffield Workshop in the summer of 1982 on "The Very Early Universe" at Cambridge University, a workshop that focused mainly on inflation theory.[118] 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 සැකිල්ල:Sndor beginning or ending සැකිල්ල:Sndto the universe.[119][120] 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 සැකිල්ල:Sndit is simply the point where all north-running lines meet and end.[121][122] 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."[123]

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?"[124] 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 සැකිල්ල:Sndfor then we should know the mind of God." In the same book he suggested that the existence of God was not necessary to explain the origin of the universe. Later discussions with Neil Turok led to the realisation that the existence of God was also compatible with an open universe.[125]

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.[126] A paper by Don Page and independent calculations by Raymond Laflamme led Hawking to withdraw this concept.[127] Honours continued to be awarded: in 1981 he was awarded the American Franklin Medal,[128] and in the 1982 New Year Honours appointed a Commander of the Order of the British Empire (CBE).[129][130][131] These awards did not significantly change Hawking's financial status, and motivated by the need to finance his children's education and home expenses, he decided in 1982 to write a popular book about the universe that would be accessible to the general public.[132][133] 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.[134][135] A first draft of the book, called A Brief History of Time, was completed in 1984.[136]

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.[137] Peter Guzzardi, his editor at Bantam, pushed him to explain his ideas clearly in non-technical language, a process that required many revisions from an increasingly irritated Hawking.[138] The book was published in April 1988 in the US and in June in the UK, and it proved to be an extraordinary success, rising quickly to the top of best-seller lists in both countries and remaining there for months.[139][140] The book was translated into many languages,[141] and ultimately sold an estimated 9 million copies. Media attention was intense,[141] and a Newsweek magazine cover and a television special both described him as "Master of the Universe".[142] Success led to significant financial rewards, but also the challenges of celebrity status.[143] Hawking travelled extensively to promote his work, and enjoyed partying and dancing into the small hours.[141] A difficulty refusing the invitations and visitors left him limited time for work and his students.[144] Some colleagues were resentful of the attention Hawking received, feeling it was due to his disability.[145][146] He received further academic recognition, including five more honorary degrees,[142] the Gold Medal of the Royal Astronomical Society (1985),[147] the Paul Dirac Medal (1987)[142] and, jointly with Penrose, the prestigious Wolf Prize (1988).[148] In the 1989 Birthday Honours, he was appointed a Companion of Honour (CH).[144][149] He reportedly declined a knighthood in the late 1990s in objection to the UK's science funding policy.[150][151]

1990–2000[සංස්කරණය]

Hawking outside, in his wheelchair, talking to David Gross and Edward Witten
Hawking with string theorists David Gross and Edward Witten at the 2001 Strings Conference, TIFR, India

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.[152] In 1994, at Cambridge's Newton Institute, Hawking and Penrose delivered a series of six lectures that were published in 1996 as "The Nature of Space and Time".[153] 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" සැකිල්ල:Sndthat there could be no "naked singularities" unclothed within a horizon සැකිල්ල:Sndwas correct.[154] After discovering his concession might have been premature, a new and more refined wager was made. This one specified that such singularities would occur without extra conditions.[155] 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. A film version of A Brief History of Time, directed by Errol Morris and produced by Steven Spielberg, premiered in 1992. Hawking had wanted the film to be scientific rather than biographical, but he was persuaded otherwise. The film, while a critical success, was not widely released.[156] A popular-level collection of essays, interviews, and talks titled Black Holes and Baby Universes and Other Essays was published in 1993,[157] and a six-part television series Stephen Hawking's Universe and a companion book appeared in 1997. As Hawking insisted, this time the focus was entirely on science.[158][159]

2000–2018[සංස්කරණය]

Stephen Hawking sitting in his wheelchair inside
Hawking at the Bibliothèque nationale de France to inaugurate the Laboratory of Astronomy and Particles in Paris, and the French release of his work God Created the Integers, 5 May 2006

Notes[සංස්කරණය]

References[සංස්කරණය]

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  2. 2.0 2.1 Ferguson 2011, p. 29.
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  88. Larsen 2005, p. 33.
  89. Larsen 2005, p. 35.
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  159. Larsen 2005, p. 97.

උපුටාදැක්වීම් දෝෂය: <references> හි "whoswho" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "hawkingphd" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "royal" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-2" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-3" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-5" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-6" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-7" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-8" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "HawkingIsrael1989" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-9" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-10" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "black" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-11" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Susskind2008" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-12" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-13" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-14" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "sample" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-15" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-16" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "g2009" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "dt70" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "obs2004" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-18" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "concedbet" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "presskill" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-19" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-20" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "sundaytimes" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-21" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-22" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-23" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-24" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-25" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "books" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-26" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "bbc-bbt" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-29" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-30" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "alien" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "nyt2007" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-31" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-32" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-34" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-35" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "NYT-20130508" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "ind2007" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-37" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-38" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-39" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-40" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-42" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-43" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-44" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "tech" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "hacked" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "start" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-45" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "presidential" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "FPP-Dec2012" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-46" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-47" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-48" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-49" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "tel2012" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "sciencenews1" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-50" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-51" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-52" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-53" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-54" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "NYT-20130913" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-55" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-56" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-57" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "KirkusBaby" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-58" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-59" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-60" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "art" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-61" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-62" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-63" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-64" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-65" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.

උපුටාදැක්වීම් දෝෂය: <references> හි "Auto2J-66" නමැති <ref> ටැගය පෙර පෙළෙහි භාවිතා වූයේ නැත.
"https://si.wikipedia.org/w/index.php?title=Stephen_Hawking&oldid=427206" වෙතින් සම්ප්‍රවේශනය කෙරිණි