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Roger Penrose
1965· Person
ProvenTested many times; part of working physics.
British mathematical physicist (born 1931), Oxford professor, who proved black holes are an unavoidable outcome of gravity; Nobel Prize 2020.
See it on the Science map →How it works
Penrose brought new geometric tools to relativity. Instead of solving equations exactly, he reasoned about the shape of all possible paths of light. In 1965 he introduced the "trapped surface," a region where even outward light is dragged inward, and proved that once one forms, a singularity must follow. He also invented Penrose diagrams, which map infinite spacetime onto a page, and the non-repeating Penrose tilings.
Why it matters
He turned black holes from a mathematical oddity into a firm prediction of general relativity, and changed how physicists reason about spacetime.
How the work held up
His theorems are accepted mathematical proofs. Observations of black holes since the 1970s, and the 2020 Nobel Prize, confirmed that nature does form them.
Still a mystery
His later ideas, a cyclic universe and a quantum origin of consciousness, are speculative and not accepted by most physicists.
Connections (3)
▸Roger Penrose proved the inevitability of Singularities: where physics breaksProven
The relationship
Before 1965 many assumed singularities appeared only because models were perfectly symmetric, and real lumpy collapse would avoid them. Penrose defined a "trapped surface," where even outward-aimed light is pulled inward, and proved that once such a surface forms, relativity with ordinary positive energy guarantees a singularity. No symmetry is needed. This made singularities a general prediction.
How the link was found
Roger Penrose, "Gravitational collapse and space-time singularities," Physical Review Letters, January 1965, using new global geometric methods.
Why it's proven
It is a mathematical theorem, checked and extended by many. The Nobel committee in 2020 cited it as the discovery that black hole formation is a robust prediction of relativity.
Open questions and mysteries
The theorem says relativity breaks, not what replaces it. Quantum effects may evade its energy assumptions.
▸Roger Penrose showed they really form (Nobel 2020) Black holesProven
The relationship
Penrose proved that black holes are not a fragile result of perfect symmetry but the general fate of enough collapsing mass. Before his work, many, including Einstein earlier, doubted nature would ever make them. After it, astronomers had strong reason to search for black holes, and observations from the 1970s onward found them in X-ray binaries and galaxy centers.
How the link was found
Roger Penrose's 1965 theorem. He received half the 2020 Nobel Prize in Physics; Reinhard Genzel and Andrea Ghez shared the other half for the Milky Way's central black hole.
Why it's proven
The theorem is mathematical proof. Observations since have shown black holes to be common, from star-sized ones in binary systems to giants in nearly every large galaxy.
Open questions and mysteries
Penrose also conjectured that every singularity is hidden by a horizon ("cosmic censorship"). That remains unproven.
▸Roger Penrose proposed one version of Cyclic universes (ekpyrotic and Penrose's CCC)Speculative
The relationship
Penrose noticed that in the far future, after black holes evaporate, only massless particles like light remain. They experience no time or distance, so the universe loses any sense of scale. The same holds in the earliest universe. Rescaled, an infinite, empty late universe looks just like a hot, tiny early one, so one can become the next.
How the link was found
Penrose developed Conformal Cyclic Cosmology from about 2005, motivated by his 1979 argument that the Big Bang was extraordinarily orderly: by his estimate, one chance in 10 raised to the power 10¹²³.
Is it proven?
Unconfirmed. Penrose and colleagues reported concentric circles (2010) and 'Hawking points' (2018), spots supposedly left by an earlier aeon's evaporated black holes. Several independent teams found such patterns consistent with chance.
Open questions and mysteries
It requires electrons and every other massive particle eventually to lose their mass, which no known physics provides. How information passes between aeons is also unclear.