Sergio Doplicher

Sergio Doplicher (Italian: [ˈsɛrdʒo ˈdɔpliker]; 30 December 1940 – 9 September 2025) was an Italian mathematical physicist, who mainly dealt with the mathematical foundations of quantum field theory and quantum gravity.

Sergio Doplicher was born on 30 December 1940 in Trieste and graduated in Physics at the Sapienza University of Rome in 1963 under the supervision of Giovanni Jona-Lasinio. From 1976 to 2011 he was full professor of quantum mechanics in the mathematics department of Sapienza University, retiring there in 2011 as professor emeritus.

He was known for his research based on the Haag–Kastler axioms and for his collaboration with Rudolf Haag. With John E. Roberts and Haag, he examined superselection rules in the algebraic quantum field theory, providing the first proof of the spin–statistics theorem entirely based only on first principles. Doplicher and Roberts also proved a reconstruction theorem for the algebra of quantum fields and the compact group of global internal symmetries from the algebra of the observables. In other collaborations, Doplicher studied the local aspects of superselection rules. After introducing the split-property, he derived exact current algebras and a weak form of a quantum Noether theorem.

Later in his career, Doplicher dealt with the mathematical foundations of quantum gravity in terms of the quantum structure of space-time at the Planck scale. He also addressed the problem of measurement in local quantum physics.

He was the author of the first article of the first number of the scientific journal Communications in Mathematical Physics.

Doplicher died in Boves on 9 September 2025, at the age of 84.

Doplicher was an Invited Speaker at the International Congress of Mathematicians in Kyoto in 1990. He was awarded in 2004 the Humboldt Prize and in 2011 the Italian National Prize Presidente della Repubblica of the Lincei National Academy. In 2013 he was elected a Fellow of the American Mathematical Society and in 2019 a member of the Academia Europaea.