Stephen Hawking

Stephen Hawking
Known for	Black hole thermodynamics; Hawking radiation; singularity theorems
Occupation	Physicist
Notable works	A Brief History of Time
Institutions	University of Cambridge
Field	Theoretical physics; cosmology; gravitation
Wikidata	Q17714

Stephen Hawking (1942–2018) was a British theoretical physicist whose work reshaped our understanding of gravity, black holes, and the cosmos. He is best known for showing that black holes are not completely black but emit radiation (“Hawking radiation”) and for proving that the universe began in an initial singularity under general relativity. Hawking’s research spanned cosmology, quantum gravity, and fundamental physics, and he became a cultural icon through his popular books and public lectures. Diagnosed in early adulthood with amyotrophic lateral sclerosis (ALS), he nonetheless pursued a prolific research career, communicating by means of a speech synthesizer. His contributions to black hole thermodynamics, cosmology, and singularity theorems are widely regarded as profound steps toward a unified picture of physics.

Early Life and Education

Stephen William Hawking was born on January 8, 1942, in Oxford, England, and grew up in a family with scientific interests. He attended the progressive Byron House School and later St Albans School in Hertfordshire. Despite modest grades early on, friends nicknamed him “Einstein” for his curiosity about the universe Hawking won a scholarship to University College, Oxford, where he studied physics and earned a first-class degree in natural science In 1962 he went to Cambridge University to pursue graduate studies in cosmology under Dennis Sciama. There he worked on general relativity and submitted a doctoral thesis, Properties of Expanding Universes, in 1966.

By his mid-twenties, Hawking began losing motor function to ALS (also known as motor neuron disease). In 1963 he was diagnosed with the disease and given only a few years to live The illness progressed slowly, but eventually confined him to a wheelchair and left him unable to speak without assistance Remarkably, Hawking continued his research despite these challenges, communicating through a computer interface and remaining active in scientific life until the end of his career.

After earning his PhD, Hawking became a research fellow at Gonville and Caius College, Cambridge, where he remained for life His early collaborators included phenomenally gifted physicists like Roger Penrose, whose work on gravitational singularities inspired Hawking’s first major discoveries. In 1979 he was appointed Lucasian Professor of Mathematics at Cambridge (a chair once held by Isaac Newton) He retired from the Lucasian Chair in 2009 and continued research as Director of Research in Cambridge’s Department of Applied Mathematics and Theoretical Physics.

Major Works and Ideas

Hawking’s central scientific contributions fall into three interlocking areas: the study of spacetime singularities, the physics of black holes, and cosmological theories of the universe’s origin. These contributions often intertwine concepts from Einstein’s general relativity and quantum mechanics. Below we summarize his key ideas.

Big Bang Singularity and the Origins of the Universe. Inspired by Roger Penrose’s 1965 singularity theorem, Hawking applied similar reasoning to the universe as a whole Penrose had shown that, in general relativity, a collapsing star must produce a singularity (a point where spacetime curvature becomes infinite). Hawking realized that reversing time in Penrose’s argument implied the Big Bang originated in a singularity as well In other words, under Einstein’s equations, tracing cosmic expansion backward inevitably leads to a state of infinite density – a singular “beginning” of spacetime. This result implied that the classical laws of gravity must break down at the origin of the universe Hawking’s theorem (often called the Penrose–Hawking singularity theorem) showed that if general relativity is correct, then the universe began in a singularity (the Big Bang) This discovery cemented the idea that understanding the origin of the cosmos requires a quantum theory of gravity, since the singularity lies beyond the reach of known physics.

Black Hole Theorems and Mechanics. Hawking turned from cosmology to black holes in the late 1960s and early 1970s, again using mathematical relativity. A black hole is a region of spacetime where gravity is so strong that nothing – not even light – can escape its event horizon (the boundary of no return) While studying rotating black holes, Hawking and collaborators discovered that one could extract energy from the hole by “spinning it down,” but he proved a remarkable conservation law: the total surface area of all black hole horizons can never decrease in any physical process This result is known as Hawking’s area theorem. It means that when two black holes merge, the horizon area of the final black hole exceeds the sum of the original areas In terms of gravitational waves, this theorem even limits how much energy can be carried away, since losing energy in a collision increases the horizon area rather than shrinking it.

This monotonic growth of horizon area drew Hawking’s insight to thermodynamics. He noticed that the area theorem is directly analogous to the second law of thermodynamics, which states that entropy (disorder) never decreases in an isolated system Working with James Bardeen and Brandon Carter, Hawking formulated laws of black hole mechanics that parallel the ordinary laws of heat and energy For example, the first law of black hole mechanics expresses conservation of energy (mass) in black holes. The second law becomes precisely Hawking’s area theorem: horizon area always grows This analogy suggested that black holes have an entropy proportional to their horizon area. Jacob Bekenstein had earlier conjectured that a black hole’s entropy equals a quarter of its horizon area, and Hawking’s work confirmed and quantified this idea.

Hawking Radiation and Black Hole Thermodynamics. The analogy to thermodynamics suggested that if black holes have an entropy, they should also have a temperature. Hawking famously derived that black holes radiate heat due to quantum effects near the horizon. In 1974 he showed that particle-antiparticle pairs spontaneously form near the event horizon: one falls in and the other escapes to infinity, so the black hole emits a steady radiation of particles This effect gives a black hole a temperature inversely proportional to its mass, and implies that over vast timescales a black hole can evaporate by losing mass as radiation This was a profound and surprising result: it meant black holes obey thermodynamics – they have temperature, entropy, and even a heat flow – despite their purely classical definition. The escaping particles, now called Hawking radiation, carry away energy and information (in principle) from the black hole. Hawking’s prediction is widely regarded as one of his greatest contributions.

Importantly, Hawking recognized that this radiation leads to a paradox. In quantum mechanics, information about a physical system cannot be truly destroyed, but classical black holes appeared to destroy information about anything that fell in. Hawking initially concluded information was irretrievably lost inside black holes, a viewpoint that sparked decades of debate. He later revised this stance, famously conceding in 2004 that information must somehow escape The black hole information paradox remains an open problem: how to reconcile the smooth radiation output with the preservation of quantum information. Physicists still consider Hawking’s insight into this paradox as a crucial clue to unifying gravity with quantum theory.

Cosmology and the Early Universe. Hawking’s work also extended traditional cosmology. He, along with collaborators like James Hartle, applied quantum mechanics to the entire universe. In 1983 Hawking and Hartle proposed the famous “no-boundary” proposal the idea that the universe could be finite and self-contained without a singular boundary in time. They described the birth of the cosmos using a mathematical “wave function of the universe,” picturing spacetime like a smooth “shuttlecock” that rounds off at the origin In this model, asking what happened before the Big Bang becomes as meaningless as asking what is south of the South Pole because time itself is defined only after the very first moments. This elegant proposal has inspired much research in quantum cosmology, though it has also faced critique. Some physicists in recent years have identified technical ambiguities in the no-boundary calculation Defenders of the idea continue to refine or replace it with new quantum cosmological models, but Hawking’s original no-boundary idea remains a landmark attempt to marry quantum physics with the Big Bang.

Hawking also contributed to understanding cosmic inflation. In the early 1980s he suggested that quantum fluctuations during inflation – a brief explosive expansion in the first fraction of a second – could seed the irregularities that later grew into galaxies This insight, worked out with others, helped turn inflation into a testable theory. Indeed, satellite measurements of the cosmic microwave background (from COBE, WMAP, and Planck) have confirmed that the seeds of structure match what inflation plus quantum physics predict Thus Hawking’s ideas formed an important bridge between abstract theory and observable features of the universe (such as the distribution of galaxies).

Methodology

Hawking was a theoretical physicist, meaning he worked with equations and thought experiments rather than laboratory apparatus. His approach was highly mathematical: he relied on Einstein’s field equations of general relativity and the methods of differential geometry. Proving precise theorems about spacetime was central to his work. For example, his singularity theorems and black hole theorems were rigorous mathematical proofs under broad assumptions about matter and gravity At the same time, he had strong physical intuition, often rephrasing problems in novel ways. For instance, he exploited analogies between gravity and thermodynamics, or invented thought experiments (like particle pairs at the horizon) to reach insights that equations alone didn’t immediately give.

Collaboration played a key role. Hawking worked closely with many leading cosmologists and relativists. Early on, his supervisor Dennis Sciama and fellow student George Ellis were influential. He teamed up with Penrose on the singularity work, with Bardeen and Carter on black hole mechanics, and with Jacob Bekenstein in the famous entropy discussions Later he collaborated with Jim Hartle on cosmology and with other colleagues on later problems. Notes from classes and discussions were vital, and Hawking often communicated ideas by writing on a board, exchanging letters, or talking by computer link once his ALS made speech impossible. Even when bedridden, he would pore over equations (or have students help him do so) and dictate results via his speech synthesizer. In his own words, when he “lost the ability to write out long, complicated equations,” he began to tackle problems by reimagining them in geometric form in his head.

Hawking’s methods always reflected a search for fundamental principles. When confronting paradoxes – like the fate of information in black holes – he was willing to question cherished laws (he even joked he’d happily discard the second law of thermodynamics if necessary) His style combined empirical respect (trying to honor established laws) with readiness for radical ideas (like black hole evaporation or a universe without a beginning). Over his career he kept all relevant physics in play: general relativity, quantum theory, statistical mechanics. This breadth of vision is why he sometimes advanced speculative ideas (e.g. on aliens or time travel), for which he became a popular commentator. (Colleagues noted his pronouncements outside his research area were more personal opinions, but they reflected his broad curiosity.

Influence

Hawking’s work has left a lasting impact on physics and beyond. In the scientific community, he is credited with deepening our understanding of gravity more than anyone since Einstein His black hole theorems and the discovery of Hawking radiation gave a clear direction for much of theoretical physics. As Sean Carroll put it, Hawking’s prediction that black holes emit radiation “is the single biggest clue we have to the ultimate reconciliation of quantum mechanics and gravity” In other words, Hawking’s insights identify the key puzzles that modern physicists must solve to unify the forces of nature. Rafael Bousso remarked that Hawking “put his finger on the key difficulty in the search for a theory of everything”

In practice, many research threads trace back to Hawking. Research on quantum gravity and black holes often starts from Hawking’s results. The term Hawking radiation and the area theorem are fundamental concepts taught in relativity courses. His prediction that BH area never decreases was only confirmed observationally in 2021, when gravitational wave data from merging black holes showed exactly that behavior (Motivated by Hawking’s theorem, scientists checked LIGO’s 2015 data and found the final horizon area went up as predicted The ongoing debates about black hole information – including ideas like “firewalls” and holography – all build on the questions Hawking raised. In cosmology, his early work helped launch the field of quantum cosmology. His no-boundary model and related studies influenced a generation of cosmologists exploring the quantum origin of spacetime.

Hawking’s influence extended strongly into education and popular culture. His 1988 bestseller A Brief History of Time has sold millions of copies and introduced lay readers to deep cosmological ideas The Cambridge University noted that this single book “revolutionised theoretical physics” for the public He made frequent TV appearances and even cameos in shows like Star Trek, bringing scientific concepts to a broad audience Colleagues often remarked that Hawking inspired more people than any physicist in a century His memorable phrases – like “look up at the stars, not down at your feet” – and his automated voice made him an iconic figure. After his death hundreds of scientists and public figures paid tribute, noting that few since Einstein had captured the popular imagination so fully In short, Hawking helped “bring cosmology to the masses,” sowing interest in topics (black holes, quantum gravity, the Big Bang) that were previously niche (as one tribute put it. His influence also appeared in science policy and advocacy. Hawking used his fame and platform to speak on issues like climate change and technology. In later years he warned about global warming, artificial intelligence, and other challenges to humanity While these were outside his strict research domain, they kept the spotlight on him and on science. Additionally, Hawking championed open access to knowledge. He once said that everyone, everywhere should have free access not only to his work but to “the research of every great and enquiring mind” In 2017 he made his English-language 1965 PhD thesis Properties of Expanding Universes freely available online, which thousands of people downloaded in the first day These acts underscored his view of science as a global and collaborative endeavor.

Critiques and Controversies

Though widely admired, Hawking’s legacy has also attracted critique and debate. In science, one must be careful to distinguish public praise from peer evaluation. Some physicists have argued that Hawking’s public image sometimes outshone his technical achievements. For instance, a 1999 survey of physicists found that Hawking, though famous, was not rated among the top contributors of his generation (Richard Feynman ranked first, and Hawking received only a few votes) Being a theorist on partly speculative topics meant he did not receive a Nobel Prize – a point Hawking himself noted. He often quipped that Hawking radiation is too feeble to detect for real black holes, which is why “it is for this reason that I was never awarded a Nobel Prize” In factual terms, the Nobel committee awards experimental confirmation, and to date no experiment can directly test Hawking radiation, so he was passed over for that reason.

In research, some of Hawking’s ideas have been challenged. The black hole information paradox he helped formulate remains unresolved. In 2012–2014 he proposed that real black holes might lack true event horizons (having only temporary “apparent horizons”) so that information could eventually escape Several experts pointed out that his brief paper did not fully resolve known issues like the “firewall paradox” – the conflict between a smooth horizon and quantum information conservation Others noted that the notion of horizon-free black holes is not new and that Hawking’s 2014 idea did not yet form a complete theory In other words, some of Hawking’s later hypotheses stirred controversy but remain untested or inconclusive. Similarly, Hawking’s no-boundary universe proposal has undergone rigorous debate. In 2019 a group led by Neil Turok published an analysis arguing the original calculation was ill-defined, calling it a “failure” Defenders of Hawking’s idea responded that the critics misinterpreted quantum methods These discussions show how cutting-edge proposals in theoretical cosmology naturally engender vigorous scrutiny; none of them yet disproves Hawking’s overall contributions, but they do remind us that his speculative ideas are not settled science.

Hawking also faced more general criticism about celebrity and authorship. Writers like James Gleick and others have pointed out that after A Brief History of Time Hawking became a cultural phenomenon whose public persona sometimes eclipsed his ongoing research Some biographers noted that several of his later popular books (e.g. A Briefer History of Time, Brief Answers to the Big Questions) were compiled with the help of collaborators or ghostwriters (This is common for public figures, but it raised questions about how closely Hawking was involved in each word.) His illness and distinctive voice gave him an almost mythical status; a few critics argued that media hype inflated comparisons to Einstein or Newton Within the physics community, however, Hawking was always respected for his genuine early breakthroughs. Even those who emphasize his flaws concede that his work on black holes and cosmology was “brilliant and influential” In short, the critiques revolve around how his fame and later years are portrayed, but none deny the significance of his core scientific achievements.

Legacy

Stephen Hawking’s legacy is vast. In science, his name is attached to multiple fundamental concepts: Hawking radiation, Hawking temperature, Hawking entropy, and the Penrose–Hawking singularity theorems, among others. These laybooks of modern relativity and quantum gravity remain in use. He helped establish the field of quantum cosmology and sparked countless research projects seeking to explain black hole evaporation and unify physics. Efforts like the recent LIGO tests of black hole mergers explicitly verify predictions Hawking first made. Future generations of physicists will build on or refine the puzzles he identified.

Hawking also established Cambridge as a center for theoretical cosmology: he founded the Centre for Theoretical Cosmology in 2007, which continues bringing together students and researchers in the areas he studied. The university and others have named institutes, lectureships, and awards in his honor. Public outreach will also remember him: A Brief History of Time is still widely read as an introduction to cosmology. After his death, figures like Neil deGrasse Tyson and others paid tribute, and even a film (The Theory of Everything, 2014) reached a broad audience with Hawking’s life story.

Cultural impact remains strong too. Hawking’s image – the wheelchair scientist with an electronic voice – changed how a disabled person could appear in science. Many have noted that his determination made him “a champion for those with disabilities” Quotes attributed to him continue to circulate, and even his grave (unveiled in 2018) became an object of popular interest. At the same time, his worries about climate, AI, and space exploration echo today, keeping his name in current debates.

In sum, Hawking’s intellectual legacy is that he showed new ways to probe deep problems in physics – singularities and horizons – and he inspired scientists and the public to wonder about the origins and fate of the cosmos. The questions he raised (Why do black holes have entropy? How did the universe begin?) still guide research. As one commentator noted, Hawking’s discoveries may prove to be “key clues to a theory of everything” He passed away on March 14, 2018, but the tools and puzzles he gave us continue to shape fundamental research. Historians will remember him as the rare scientist whose blend of bold ideas and public outreach left an indelible mark on both physics and human culture.

Selected Works

Properties of Expanding Universes (PhD thesis, Cambridge, 1966). Hawking’s doctoral dissertation studying solutions of the expanding cosmos.
The Large Scale Structure of Space-Time (Cambridge Univ. Press 1973, with G. F. R. Ellis). A foundational text on global properties of spacetimes, including singularity theorems.
General Relativity: An Einstein Centenary Survey (1980, ed. with W. Israel). A collection of essays on relativity marking 100 years since Einstein’s birth.
The Very Early Universe (1983, with G. Gibbons and S. Siklos). A conference volume exploring inflation and the beginning of the universe.
300 Years of Gravitation (1987, ed. with others). A compendium of modern developments in gravity, published on the tercentenary of Newton’s death.
A Brief History of Time (Bantam 1988). Hawking’s world-famous popular book explaining cosmology and black holes for general readers.
Black Holes and Baby Universes and Other Essays (Bantam 1993). A collection of essays and lectures on physics and his life.
The Universe in a Nutshell (Bantam 2001). A sequel to Brief History summarizing modern physics in accessible terms.
A Briefer History of Time (Bantam 2005, with Lucy Hawking). A revised, more accessible edition of Brief History.
My Brief History (Bantam 2013). Hawking’s autobiography recounting his life and career.
Brief Answers to the Big Questions (Bantam 2018, posthumous). A collection of Hawking’s popular writings on science and society, edited from unfinished materials.

Timeline

1942 – Born January 8 in Oxford, England.
1959 – Moves with family to St Albans, Hertfordshire; attends St Albans School (nicknamed “Einstein” in class.
1960 – Enters University College, Oxford, on scholarship; studies physics.
1962 – Begins graduate work at Cambridge University under Dennis Sciama. Diagnosed with amyotrophic lateral sclerosis (ALS).
1965–1966 – Completes PhD at Cambridge (thesis Properties of Expanding Universes).
1967 – Appointed Research Fellow at Gonville and Caius College, Cambridge.
1970 – Publishes groundbreaking work with Roger Penrose on cosmological singularity, showing the Big Bang must be a singular beginning of space-time
1971 – Derives the area theorem for black holes (horizon area non-decrease.
1974 – Discovers that black holes emit thermal radiation (announcing Hawking radiation) Dennis Sciama hails it as “the new revolution in our understanding”
1973 – Publishes The Large Scale Structure of Space-Time with G. Ellis, formalizing the mathematics of cosmic singularities.
1979 – Named Lucasian Professor of Mathematics at Cambridge (Newton’s chair.
1983 – Proposes the “no-boundary” model of the universe with J. Hartle
1988 – Releases A Brief History of Time, which becomes an international bestseller
2001 – The Universe in a Nutshell published.
2007 – Founds Cambridge’s Centre for Theoretical Cosmology.
2009 – Retires as Lucasian Professor; becomes Director of Research in applied mathematics/theoretical physics at Cambridge.
2013 – Publishes autobiography My Brief History.
2014 – Biographical film The Theory of Everything is released.
2015–2016 – Gravitational wave observations (LIGO) test Hawking’s area theorem for the first time, consistent with his prediction.
2017 – Celebrates 75th birthday with conference on his work. Makes his 1965 PhD thesis available online, attracting very large public interest
2018 – Dies March 14 in Cambridge at age 76. His ashes are interred in Westminster Abbey. Posthumous book Brief Answers to the Big Questions is published.

References:.

Cambridge University (2018), Professor Stephen Hawking 1942–2018. New Scientist (2018), A brief history of Stephen Hawking: A legacy of paradox (Levine. Quanta Magazine (2019), Physicists Debate Hawking’s Idea That the Universe Had No Beginning (Wolchover. MIT News (2021), Physicists observationally confirm Hawking’s black hole theorem for the first time. Space.com (2014), Some Scientists Not Convinced by Stephen Hawking's New Black Hole Proposal (M. Kramer. University of Cambridge (2018), Stephen Hawking estate: The Large Scale Structure of Space-Time. OpenCulture (2017), Stephen Hawking’s PhD Thesis… Now Free to Read/Download Online (C. Caldwell. Brewminate (2018), Stephen Hawking, Who Brought Cosmology to the Masses, Dies at 76 (J. Conley. Preposterous Universe (2018), Stephen Hawking’s Scientific Legacy (S. Carroll.