1983 Nobel Prize in Physics(2)
Reason for Award
for his theoretical and experimental studies of the nuclear reactions of importance in the formation of the chemical elements in the universe (Rev. Mod. Phys. 29 (1957) 547-650)
Laureates
United States of America
Explanation
The iron, oxygen, and other materials that make Earth and our bodies were first created inside stars. Mr. Fowler studied what kind of “atomic building games” happen in those stars. In the laboratory he smashed nuclei together to mimic stellar conditions. He discovered how light hydrogen can join up to become heavier elements. Thanks to his work we now know how the universe produced the stuff we are made of.
Related Keywords
stellar nucleosynthesis
Stellar nucleosynthesis refers to the suite of fusion reactions inside stars that build elements from hydrogen up to iron. Under extreme temperature and pressure nuclei collide and form new species. Reaction types and rates depend strongly on temperature, density, and composition. Fowler’s laboratory cross-section data quantified each pathway’s contribution. Consequently stellar-evolution models could reproduce both energy output and elemental composition simultaneously.
B2FH paper
The B2FH paper, published in 1957 in Rev. Mod. Phys., is named after its authors Burbidge, Burbidge, Fowler, and Hoyle. It systematically classified nucleosynthesis from hydrogen burning to supernova explosions. Notably, it introduced clear definitions of the s-process, r-process, and p-process for heavy-element formation. The paper established the practice of comparing observed isotope patterns with theoretical models. It remains a foundational “road map” of cosmic chemistry.
s-process
The s-process, or slow neutron-capture process, occurs in relatively mild environments such as AGB stars, where nuclei slowly capture neutrons. Because captures are infrequent, β-decays return nuclei to stability, moving stepwise down the valley of β-stability. This produces isotope patterns with characteristic “s-peaks.” From measured reaction rates Fowler inferred neutron densities and timescales that match observations. Modern AGB wind models still build on his parameter sets.
r-process
The r-process, or rapid neutron-capture process, occurs in extreme environments such as supernovae or neutron-star mergers, where nuclei capture neutrons at a furious rate. Nuclei are driven far from stability and later decay back via β-chains. This pathway produces the heaviest elements like gold, platinum, and uranium. Fowler’s classification first highlighted its importance, prompting astronomers to search for r-process signatures in spectra. Recent gravitational-wave observations support neutron-star mergers as a primary r-process site.
nuclear reaction rate
The nuclear reaction rate specifies the number of reactions per unit volume per unit time and is derived from plasma temperature and cross section. Astrophysics convolves the Maxwell-Boltzmann distribution with the cross section, correcting low-energy shielding via the astrophysical S-factor. Fowler measured or extrapolated S-factors for many reactions and compiled standard tables. This dramatically improved predictions of stellar energy output and neutrino fluxes. The widely used REACLIB database is an extension of Fowler’s original datasets.
Big Bang nucleosynthesis
Big Bang nucleosynthesis refers to the fusion reactions during the first three minutes of the universe, mainly producing hydrogen, helium, and trace lithium. Fowler clarified its distinction from stellar nucleosynthesis and noted that observed abundances could constrain the primordial baryon density. The persistent ³He and ⁷Li abundance problems still benchmark his datasets. Coupled with precise cosmic microwave background data, this framework solidified the standard cosmological model. Light-element observations remain a probe for potential new physics today.