Key figures: Saul Perlmutter, Brian P. Schmidt, Adam G. Riess (Physics); Dan Shechtman (Chemistry); Bruce Beutler, Jules Hoffmann, Ralph Steinman (Physiology or Medicine); Tomas Tranströmer (Literature); Ellen Johnson Sirleaf, Leymah Gbowee, Tawakkol Karman (Peace); Thomas J. Sargent, Christopher A. Sims (Economics)
Summary
The 2011 Nobel Prizes, announced in the first two weeks of October, recognized transformative work across physics, chemistry, immunology, literature, and international peacebuilding. The Physics Prize honored the discovery that the expansion of the universe is accelerating — a finding that overturned cosmological assumptions and pointed toward the existence of “dark energy.” The Chemistry Prize went to a discovery that had, when first announced, been dismissed by the scientific establishment as impossible. The Physiology or Medicine Prize carried an unusual posthumous dimension: laureate Ralph Steinman had died three days before the announcement, prompting an exceptional Nobel Committee ruling to honor the award. The Peace Prize was awarded to three women human rights advocates — two Liberian and one Yemeni — in direct recognition of their roles in 2011’s global democracy movements.
Significance
The 2011 prizes collectively illustrated the Nobel Foundation’s role in crystallizing scientific consensus and amplifying activism at globally decisive moments. The Physics Prize for cosmic acceleration — based on observations made in 1998 — represented a 13-year lag between discovery and recognition, typical for prizes requiring extensive independent verification. The Chemistry Prize for quasicrystals vindicated a scientist who had been mocked and professionally marginalized for a discovery that ultimately transformed materials science. The Peace Prize’s focus on women in nonviolent democracy movements resonated with 2011’s defining geopolitical theme: the Arab Spring (see Arab Spring) and its demonstration that mass civil mobilization could topple entrenched authoritarian regimes.
Categories
Physics: Discovery of the Accelerating Expansion of the Universe
The 2011 Nobel Prize in Physics was awarded to Saul Perlmutter (Supernova Cosmology Project, Lawrence Berkeley National Laboratory, University of California Berkeley), Brian P. Schmidt (Australian National University), and Adam G. Riess (Johns Hopkins University / Space Telescope Science Institute), “for the discovery of the accelerating expansion of the Universe through observations of distant supernovae.”
The prize recognized research published in 1998. Both the Supernova Cosmology Project (led by Perlmutter) and the High-Z Supernova Search Team (led by Schmidt and including Riess) independently used Type Ia supernovae as “standard candles” — sources of predictable peak luminosity that allow precise distance measurements — to map the expansion history of the universe. Both teams expected their observations of distant supernovae to show the expansion of the universe decelerating under gravity. Instead, both found that distant supernovae were dimmer than expected — indicating they were farther away than a decelerating model would predict. The universe’s expansion, they concluded, was not slowing but accelerating.
This acceleration requires an explanation: scientists have labeled the unknown energy driving it dark energy, which appears to constitute approximately 68% of the total energy content of the universe. The discovery overturned the prevailing cosmological model and won rapid acceptance precisely because two independent competing teams, using the same methods, obtained the same unexpected result. The prize split gave Perlmutter half, with Schmidt and Riess sharing the other half.
Chemistry: Discovery of Quasicrystals
Dan Shechtman of the Technion – Israel Institute of Technology received the 2011 Nobel Prize in Chemistry “for the discovery of quasicrystals.”
On April 8, 1982, Shechtman was examining a rapidly cooled aluminium-manganese alloy sample using electron diffraction at the National Bureau of Standards in Washington, D.C., when he observed a diffraction pattern with tenfold rotational symmetry. Classical crystallography held this to be impossible: periodic crystals — by definition — could only display 2-, 3-, 4-, or 6-fold rotational symmetry (the crystallographic restriction theorem). Ten-fold symmetry was structurally forbidden. Shechtman wrote in his notebook: “10 fold???” — a note that has since become famous.
His colleagues were initially contemptuous. Linus Pauling, two-time Nobel laureate and arguably the most influential chemist of the 20th century, publicly declared: “There are no quasicrystals, only quasi-scientists.” Shechtman was asked to leave his research group. When he published his findings in Physical Review Letters in November 1984, the paper triggered a scientific controversy that was resolved over the following decade as other researchers replicated and extended his observations. Quasicrystals — ordered but non-periodic atomic structures exhibiting forbidden symmetries — were eventually recognized as a distinct state of matter. The Nobel Committee’s Chemistry Prize to Shechtman 29 years later acknowledged both the discovery and the institutional vindication of a scientist who had refused to retract a correct but unconventional finding.
Quasicrystals have since been found in nature (in meteorites, including the Khatyrka meteorite analyzed in 2011), developed for industrial applications (non-stick coatings, surgical tools), and have influenced theoretical mathematics through their connection to Penrose tilings.
Physiology or Medicine: Innate and Adaptive Immunity
The 2011 Nobel Prize in Physiology or Medicine was awarded to Bruce A. Beutler (University of Texas Southwestern Medical Center / Scripps Research Institute) and Jules A. Hoffmann (Institut de Biologie Moléculaire et Cellulaire, CNRS, Strasbourg), sharing one half of the prize “for their discoveries concerning the activation of innate immunity,” and to Ralph M. Steinman (Rockefeller University), awarded the other half “for his discovery of the dendritic cell and its role in adaptive immunity.”
The Posthumous Award: Ralph Steinman
Ralph Steinman died of pancreatic cancer on September 30, 2011 — three days before the Nobel Committee announced the prize on October 3, 2011. Nobel regulations since 1974 have prohibited posthumous awards; however, the Committee’s statutes make an exception when the prize has already been decided and the laureate dies between the decision and the announcement. The Nobel Assembly at the Karolinska Institute convened an emergency ruling and determined that the award to Steinman would stand, as the decision had been made without knowledge of his death. Steinman thereby became the first laureate honored posthumously since the 1974 prohibition took effect; the only earlier posthumous laureates were Erik Axel Karlfeldt (Literature, 1931) and Dag Hammarskjöld (Peace, 1961), both decided before the rule existed.
Steinman had discovered dendritic cells in 1973 while at Rockefeller University. Dendritic cells are immune sentinels that capture antigens from pathogens, process them, and present them to T-lymphocytes, activating the adaptive immune system — the antigen-specific, memory-forming branch of immunity that is the basis for vaccines. His discovery linked the innate immune system (the body’s immediate, non-specific first-responder system, studied by Beutler and Hoffmann) with adaptive immunity. Steinman spent his final years attempting to treat his own pancreatic cancer using experimental dendritic cell-based immunotherapy — an approach now recognized as foundational to cancer immunotherapy.
Beutler and Hoffmann were recognized for work identifying Toll-like receptors (TLRs), the molecular sensors through which innate immune cells recognize pathogens. Hoffmann first identified the function of the Toll gene in Drosophila (fruit flies) in 1996; Beutler discovered TLR4 — the mammalian receptor for bacterial lipopolysaccharide (LPS) — in 1998, explaining the molecular mechanism behind septic shock.
Literature: Tomas Tranströmer
Swedish poet Tomas Tranströmer was awarded the 2011 Nobel Prize in Literature “for his concise and translucent images that, with uncompromising insight, give us fresh access to reality.” Tranströmer, born April 15, 1931, in Stockholm, had been publishing poetry since 17 Poems (1954) and was widely considered one of the most important European poets of the postwar era, though his work was little known to English-language readers before the Prize.
Tranströmer had suffered a severe stroke in 1990 that left him largely unable to speak and with partial paralysis of his right hand; he continued to compose poetry (with his left hand) and to play piano. His collection The Great Enigma: New Collected Poems (translated by Robin Fulton) made his work accessible in English. His poetry — imagistic, spare, bridging the everyday and the transcendent — drew comparisons to Emily Dickinson. The 2011 prize for a poet marked only the second time in 20 years the Literature Prize went to a poet (Wisława Szymborska, 1996, was the previous recent example).
Tranströmer died March 26, 2015, at age 83.
Peace: Women’s Rights and Democratic Participation
The 2011 Nobel Peace Prize was jointly awarded to Ellen Johnson Sirleaf, Leymah Gbowee, and Tawakkol Karman “for their non-violent struggle for the safety of women and for women’s rights to full participation in civil and political life.”
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Ellen Johnson Sirleaf — Born October 29, 1938, in Monrovia, Liberia. Elected President of Liberia in November 2005, she became the first woman to be democratically elected head of state on the African continent. She had previously served in government positions under different administrations, been imprisoned twice under military rule, and spent time in exile. Her presidency focused on rebuilding Liberia’s infrastructure and institutions after the devastation of two civil wars (1989–2003). She received the prize while serving her first presidential term; she was re-elected in November 2011 (just days after the prize announcement) and served until 2018.
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Leymah Gbowee — Born February 1, 1972, in Monrovia, Liberia. A social worker and women’s rights activist, she organized Women of Liberia Mass Action for Peace in 2003, a movement that brought together Christian and Muslim women to demand an end to the Second Liberian Civil War. Their sustained nonviolent protest — including a sex strike and a sit-in at the peace talks in Ghana — is credited with helping bring Charles Taylor’s government to the negotiating table. Her memoir Mighty Be Our Powers (2011, published the same year as the prize) documented her work.
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Tawakkol Karman — Born February 7, 1979, in Mekhlaf, Yemen. A journalist and co-founder of Women Journalists Without Chains (established 2005), Karman became the leading public figure of Yemen’s pro-democracy uprising during the Arab Spring. She organized weekly demonstrations in Sana’a’s Freedom Square from 2007 onward, was arrested briefly by Yemeni authorities in January 2011, and became internationally known as “the mother of the revolution.” She was 32 years old when she received the prize — the youngest Nobel Peace Prize laureate in history at the time, and the first Arab woman to win the prize. Her activism directly connected to the broader Arab Spring (see Arab Spring and Libyan Civil War 2011).
Economics: Cause and Effect in the Macroeconomy
The Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel 2011 was awarded to Thomas J. Sargent (New York University) and Christopher A. Sims (Princeton University) “for their empirical research on cause and effect in the macroeconomy.” The prize recognized their development of statistical methodologies — particularly vector autoregression (VAR, developed by Sims) and rational expectations models (associated with Sargent) — for understanding how economies respond to policy changes, with particular relevance to monetary policy and the analysis of inflation and unemployment. The prize announcement on October 10 coincided with international debate about central bank responses to the eurozone debt crisis (see Eurozone Debt Crisis).
Sources
- Nobel Prize Official Announcements, October 3–10, 2011: nobelprize.org/prizes/lists/all-nobel-prizes-2011/
- Perlmutter, S. et al. “Measurements of Ω and Λ from 42 High-Redshift Supernovae.” Astrophysical Journal 517 (1999): 565–586.
- Shechtman, D. et al. “Metallic Phase with Long-Range Orientational Order and No Translational Symmetry.” Physical Review Letters 53 (1984): 1951–1953.
- Nobel Assembly at Karolinska Institutet, “Statement on Ralph Steinman Award,” October 3, 2011
- “Tomas Tranströmer — Nobel Laureate in Literature 2011,” Swedish Academy press release
- “Tawakkol Karman: 2011 Nobel Peace Prize Laureate Profile,” Nobel Foundation
- Britannica Encyclopedia, 2011 Nobel Prize entries (all disciplines)