Sir Roger Penrose (born 8 August 1931) is an English mathematician, mathematical physicist, and philosopher of science. He is Emeritus Rouse Ball Professor of Mathematics at the University of Oxford, an emeritus fellow of Wadham College, Oxford, and an honorary fellow of St John's College, Cambridge, and University College London. (See Box 34.2.) He shared the 1988 Wolf Prize in Physics with Stephen Hawking for the Penrose–Hawking singularity theorems, and the 2020 Nobel Prize in Physics "for the discovery that black hole formation is a robust prediction of the general theory of relativity". He proposed the Penrose triangle and corresponded with M. C. Escher, influencing his Waterfall and Ascending and Descending. Penrose's eponymous aperiodic tiling presaged Dan Shechtman's discovery of quasicrystals.
Penrose won the Royal Society Science Book Prize for The Emperor's New Mind (1989), which outlines his views on physics and consciousness. He expanded on these ideas in Shadows of the Mind (1994) and The Large, the Small and the Human Mind (1997), the latter written with Stuart Hameroff. His The Road to Reality, (2004), billed as "A Complete Guide to the Laws of the Universe", is an overview of mathematical physics.
Early life and education Born in Colchester, Essex, Roger Penrose is a son of Margaret (née Leathes), a physician, and Lionel Penrose, a psychiatrist and geneticist. His paternal grandparents were J. Doyle Penrose, an Irish-born painter, and the Hon. Elizabeth Josephine Peckover, daughter of Alexander Peckover, 1st Baron Peckover; his maternal grandparents were John Beresford Leathes, a physiologist, and Sonia Marie Natanson, a concert pianist. His uncle was the artist Sir Roland Penrose, whose son with the American photographer Lee Miller is Antony Penrose. Penrose is the brother of the physicist Oliver Penrose, of the geneticist Shirley Hodgson and of the chess grandmaster Jonathan Penrose. Their stepfather was the mathematician and computer scientist Max Newman. He found inspiration in George Gamow's Mr. Tompkins books: "I remember reading (or being read) the Tompkins stories as a quite young child, and I'm sure that their magic was responsible, to a very considerable extent, for the great excitement that fundamental physics has held for me for the rest of my life."Introduction by Roger Penrose
Penrose spent the Second World War in Canada where his father worked in London, Ontario, at the Ontario Hospital and Western University. Penrose studied at University College School. He then attended University College London, where he obtained a BSc degree with First Class Honours in mathematics in 1952.UCL alumnus Professor Sir Roger Penrose awarded Nobel Prize, website of the University College London.
In 1955, Penrose reintroduced the E. H. Moore generalised matrix inverse, also known as the Moore–Penrose inverse, after it had been reinvented by Arne Bjerhammar in 1951. Having started research under the professor of geometry and astronomy W. V. D. Hodge, Penrose received his PhD in algebraic geometry at St John's College, Cambridge, in 1957, with his thesis "Tensor Methods in Algebraic Geometry" supervised by the algebraist and geometer John A. Todd. He devised and popularised the Penrose triangle in collaboration with his father, describing it as "impossibility in its purest form". He corresponded with the artist M. C. Escher, whose earlier depictions of impossible objects partly inspired it. Escher's Waterfall and Ascending and Descending were in turn inspired by Penrose.
As Manjit Kumar puts it:
Penrose later presented the documentary The Art of the Impossible: M. C. Escher and Me.
Research and career Penrose spent the academic year 1956–57 as an assistant lecturer at Bedford College (now Royal Holloway, University of London) and was a research fellow at St John's College, Cambridge. Before the fellowship ended Penrose won a NATO Research Fellowship for 1959–61, first at Princeton University and then at Syracuse University. Returning to the University of London, Penrose spent 1961–1963 as a researcher at King's College, London, before returning to the United States to spend 1963–64 as a visiting associate professor at the University of Texas at Austin. He later held visiting positions at Yeshiva University, Princeton and Cornell University during 1966–67 and 1969.
Dennis Sciama drew his attention from mathematics to physics. In 1964, while a reader at Birkbeck College, Penrose, per Kip Thorne, "revolutionised the mathematical tools that we use to analyse the properties of spacetime". Until then, work on the curved geometry of general relativity had been confined to configurations with sufficiently high symmetry for Einstein's equations to be solvable explicitly, and there was doubt about whether such cases were typical. One approach to this issue was by the use of perturbation theory, as developed under the leadership of John Archibald Wheeler at Princeton. The other, and more radically innovative, approach initiated by Penrose was to overlook the detailed geometrical structure of spacetime and instead concentrate attention just on the topology of the space, or at most its conformal structure, since it is the latter – as determined by the lay of the lightcones – that determines the trajectories of lightlike geodesics, and hence their causal relationships. The importance of Penrose's paper "Gravitational Collapse and Space-Time Singularities" (summarised roughly as that if an object such as a dying star implodes beyond a certain point, then nothing can prevent the gravitational field getting so strong as to form a singularity) was not its only result. It also showed a way to obtain similarly general conclusions in other contexts, notably that of the cosmological Big Bang, which he dealt with in collaboration with Sciama's student Stephen Hawking.
In 1969, he proposed his cosmic censorship conjecture, that any ensuing singularities would be confined within a well-behaved event horizon surrounding a black hole, leaving a visible exterior region with strong but finite curvature. The paper also suggested that gravitational energy may be extractable by what is now known as the Penrose process; he followed up that suggestion with more details in 1971. In 1979, he formulated the "strong censorship hypothesis".
Together with the Belinski–Khalatnikov–Lifshitz conjecture and issues of nonlinear stability, settling the censorship conjectures is one of the most important outstanding problems in general relativity. That year, Penrose formulated his influential Weyl curvature hypothesis on the initial conditions of the observable universe and the origin of the second law of thermodynamics. Penrose and James Terrell independently realised that objects travelling near the speed of light will appear to undergo a peculiar skewing or rotation. This effect has come to be called the Terrell rotation or Penrose–Terrell rotation.
In 1967, Penrose developed twistor theory, which maps geometric objects in Minkowski space into the 4-dimensional complex space with the metric signature (2,2).
In 1971, he discovered spin networks, which later came to form the geometry of spacetime in loop quantum gravity. In 1974, Penrose discovered Penrose tilings, which are formed from two tiles that can only tile the plane nonperiodically, and are the first tilings to exhibit fivefold rotational symmetry. In 1984 such patterns were observed in the arrangement of atoms in quasicrystals. He was influential in popularising what are commonly known as Penrose diagrams (causal diagrams).
In 1983, Penrose was invited to teach at Rice University in Houston, by the then provost Bill Gordon. He worked there until 1987. His doctoral students have included Andrew Hodges, Lane Hughston, Richard Jozsa, Claude LeBrun, John McNamara, Tristan Needham, Tim Poston, Asghar Qadir and Richard S. Ward.
Penrose published The Road to Reality: A Complete Guide to the Laws of the Universe (2004), a guide to the Laws of Physics from Euclid's axioms to Penrose's own theories. The Penrose Interpretation predicts the relationship between quantum mechanics and general relativity, and proposes that a quantum state remains in superposition until the difference of space-time curvature attains a significant level.
Penrose is the Francis and Helen Pentz Distinguished Visiting professor of Physics and Mathematics at Pennsylvania State University.
Conformal cyclic cosmology
In 2010 Penrose reported possible evidence, based on concentric circles found in Wilkinson Microwave Anisotropy Probe data of the cosmic microwave background sky, of an earlier universe existing before the Big Bang of the present universe. He mentions this evidence in the epilogue of Cycles of Time (2010),Roger Penrose, Cycles of Time, Vintage; Reprint edition (1 May 2012) a book in which he presents his reasons, to do with Einstein's field equations, the Weyl curvature C,and the Weyl curvature hypothesis (WCH), that the transition at the Big Bang could have been smooth enough for a previous universe to survive it. He made several conjectures about C and the WCH, some of which were subsequently proved by others, and he also popularized conformal cyclic cosmology (CCC). Penrose postulates that at the end of the universe all matter is eventually contained within black holes, which subsequently evaporate via Hawking radiation. At this point, everything contained within the universe consists of photons, which "experience" neither time nor space. There is essentially no difference between an infinitely large universe consisting only of photons and an infinitely small universe consisting only of photons. Therefore, a singularity for a Big Bang and an infinitely expanded universe are equivalent.
Penrose believes that the singularity in Einstein's field equation at the Big Bang is only an apparent singularity, similar to the well-known apparent singularity at the event horizon of a black hole. The latter singularity can be removed by a change of coordinate system, and Penrose proposes a different change of coordinate system that will remove the singularity at the big bang. One implication of this is that the major events at the Big Bang can be understood without unifying general relativity and quantum mechanics, and therefore we are not necessarily constrained by the Wheeler–DeWitt equation, which disrupts time. Alternatively, one can use the Einstein–Maxwell–Dirac equations.
Consciousness
Penrose has written on the connection between physics and consciousness. In The Emperor's New Mind (1989), he argues that known laws of physics are inadequate to explain consciousness. Penrose proposes the characteristics this new physics may have and specifies the requirements for a bridge between classical and quantum mechanics (what he calls correct quantum gravity). Penrose uses a variant of Turing's halting theorem to demonstrate that a system can be deterministic without being algorithmic. (For example, imagine a system with only two states, ON and OFF. If the system's state is ON when a given Turing machine halts and OFF when the Turing machine does not halt, then the system's state is completely determined by the machine; nevertheless, there is no algorithmic way to determine whether the Turing machine stops.)