Andrew Strominger


Andrew Eben Strominger is an American theoretical physicist who is the director of Harvard's Center for the Fundamental Laws of Nature. He specializes in quantum gravity and string theory; and is a pioneer of celestial holography. He co-formulated the SYZ conjecture and the CGHS model.
Strominger won a Breakthrough Prize in Fundamental Physics in 2017. He was elected as a fellow to the American Academy of Arts and Sciences in 2001, to the American Physical Society in 2018, and as a Guggenheim Fellow in 2020.

Education and early life

Strominger was born in Cambridge, England, to Jewish father Jack Strominger, a biochemist, and Ann, who had grown up on a farm in Minnesota as a Catholic. Before Strominger's first birthday, the family moved to St. Louis, Missouri, where his father was an assistant professor at Washington University. Six years later, his father was offered a chair at University of Wisconsin in Madison, Wisconsin; where they lived until he was 13. He spent the rest of his childhood in Lexington, Massachusetts, with three brothers, where his father was a professor at Harvard University. He said he and his brothers were interested in science and spent time in their father's labs. He attended The Cambridge School of Weston, but after reading The Feynman Lectures on Physics, he decided he was "done with high school," describing himself as a troubled teen who got involved in substance abuse. He stopped attending in 1970 when he was a sophomore.
At age 15, Strominger left home and moved to New Hampshire to live in a commune, until he was 18. He said he commuted home to attend Harvard classes, where he learned Chinese. He then lived in Hong Kong, where he worked in factories, farms, and wrote for a Chinese language daily until he was 20. He considered becoming an investigative journalist. Strominger then returned to Harvard College, after he decided he wanted to be a theoretical physicist. He graduated with a Bachelor of Arts in Physics in 1977.
After receiving his AB, Strominger was advised to go enter a postgraduate education program at the University of California, Berkeley, where there were several Nobel laureates at the time. He said that his advisors discouraged him from continuing in the field, so after receiving his Master of Arts in 1979, he pursued a Doctor of Philosophy at the Massachusetts Institute of Technology. He graduated in 1982.

Research and career

After receiving his PhD, Strominger joined the Institute for Advanced Study as a scholar in 1982. While at MIT, he had become interested in quantum gravity, and was working on it independently aside his thesis work on quantum chromodynamics and Yang–Mills theory. As a postdoctoral researcher at IAS, he wanted to approach quantum gravity geometrically as a general relativist; differently than had been proposed earlier by string theorists approaching the problem from particle physics. During this work, in 1985 he co-discovered Calabi–Yau manifold compactifications. This showed that a superstring theory could simultaneously incorporate gravity and all known particle types, reproducing the observed particle spectrum in four dimensions, suggesting it could unify the fundamental laws of physics. This paper is considered one of string theory's seminal works.
Strominger was then offered a professorship at the University of California, Santa Barbara, where he had relocated to for the founding of the Kavli Institute for Theoretical Physics in 1979. He joined the faculty in 1986. While there, he developed with collaborators the CGHS model, and in 1991, Strominger was a co-discoverer of brane solutions in string theory, higher-dimensional objects that arise in string theory when the equations allow not just vibrating strings but also extended surfaces on which strings can end. This work extended the idea that extra dimensions of superstring theory could be shaped to reproduce realistic particle physics and turned those geometries into precise counting tools for microscopic configurations. This work was the basis for his 1996 collaboration with Cumrun Vafa on black hole thermodynamics. Strominger and Vafa used M-theory, a superstring theory framework, to provide the first microscopic derivation of black hole entropy by counting the brane-bound states that correspond to a black hole's quantum microstates. This result gave a microscopic explanation of how black holes are able to store information and connected string theory, for the first time, to a physical problem. The same year, Strominger, with Shing-Tung Yau and Eric Zaslow, co-formulated the SYZ conjecture. It proposes a geometric explanation for mirror symmetry by claiming that every Calabi–Yau manifold can be decomposed into fibrations of tori, and that its mirror manifold is obtained by dualizing those tori.
Strominger then joined Harvard as a professor and director of the Center for the Fundamental Laws of Nature in 1997. While there, in 2001, Strominger introduced the dS/CFT correspondence, proposing a version of the AdS/CFT adapted to de Sitter space, a spacetime with a positive cosmological constant thought to describe the very early universe. The work suggested that techniques from holography could be extended beyond anti-de Sitter space to more realistic cosmological settings. Later, in 2009, Strominger and collaborators showed that ideas from AdS/CFT could also be applied to certain astrophysical black holes, demonstrating that extremal Kerr black holes admit a dual description in terms of a conformal field theory. Their Kerr/CFT correspondence provided a new theoretical framework for studying rapidly rotating black holes using two-dimensional conformal symmetries.
While at Harvard, in 2016, Strominger, Stephen Hawking, and Malcolm Perry published Soft Hair on Black Holes, a major contribution to the study of black holes. The paper showed that a black hole's event horizon possesses the same infinite supertranslation symmetries on asymptotically flat spacetime, implying that anything falling into the hole leaves a permanent gravitational memory effect on its geometry. They suggested that black holes have "soft hair", electromagnetic and gravitational radiation of negligible energy that is released as black holes evaporate, which can be measured by the memory effects. This provided a mechanism by which information about infalling matter could be stored on the event horizon, offering a possible route toward resolving the black hole information paradox. With his doctoral student Sabrina Pasterski and collaborator, also in 2016, he co-discovered a novel spin memory affect, involving a connection which Pasterski found between symmetries and a spin that can be observed in gravitational waves.
In 2020, Strominger said he wanted to use the infrared triangle, an equivalence relation he created between soft theorems in quantum field theory, gravitational memory effects, and the Bondi–Metzner–Sachs group, to show that the holographic principle occurs in flat space, which is the geometry of the universe, and is not limited to the anti-de Sitter space. He and his colleagues then developed the subfield of celestial holography. He emphasized the bottom-up nature of the framework, which provides falsifiability through the potential for observation and testable frameworks, particularly by gravitational wave detectors like LIGO or LISA. In 2021, Strominger and his colleagues derived the symmetry algebra governing celestial conformal field theories, showing that the symmetry structure expected on the celestial sphere matches a well studied algebra that appears in string theory and condensed matter systems, thereby placing strong constraints on the possible form of a flat space holographic dual.
Strominger is the collaboration director and a principal investigator of the Simons Foundation Collaboration on Celestial Holography. He is considered a pioneer of the subfield.

Awards and honors