Tohru Eguchi (江口徹, February 2, 1948 – January 30, 2019) was a Japanese theoretical physicist.

Life and career

Tohru Eguchi was a professor at the

University of Tokyo , abbreviated as or UTokyo, is a public research university located in Bunkyō, Tokyo, Japan. Established in 1877, the university was the first Imperial University and is currently a Top Type university of the Top Global University Project by ...

, and then at the

Yukawa Institute for Theoretical Physics The is a research institute in the field of theoretical physics, attached to Kyoto University in Japan. It was inaugurated in 1952. While the center is often referred to as "YITP", this can be confusing as YITP also stands for the C. N. Yang Inst ...

Kyoto University , mottoeng = Freedom of academic culture , established = , type = National university, Public (National) , endowment = ¥ 316 billion (2.4 1000000000 (number), billion USD) , faculty = 3,480 (Teaching Staff) , administrative_staff ...

, of which he was acting director in 2009. He dealt in particular with differential geometric methods in physics, with

Superstring theory Superstring theory is an attempt to explain all of the particles and fundamental forces of nature in one theory by modeling them as vibrations of tiny supersymmetric strings. 'Superstring theory' is a shorthand for supersymmetric string theor ...

Conformal field theory A conformal field theory (CFT) is a quantum field theory that is invariant under conformal transformations. In two dimensions, there is an infinite-dimensional algebra of local conformal transformations, and conformal field theories can sometimes ...

Topological quantum field theory In gauge theory and mathematical physics, a topological quantum field theory (or topological field theory or TQFT) is a quantum field theory which computes topological invariants. Although TQFTs were invented by physicists, they are also of mathem ...

Lattice gauge theory In physics, lattice gauge theory is the study of gauge theories on a spacetime that has been discretized into a lattice. Gauge theories are important in particle physics, and include the prevailing theories of elementary particles: quantum elec ...

Quantum gravity Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics; it deals with environments in which neither gravitational nor quantum effects can be ignored, such as in the vi ...

, and the

Theory of Gravitation In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the strong ...

. While at SLAC in 1978, Eguchi and

Andrew J. Hanson Andrew J. Hanson (born 1944) is an American theoretical physicist and computer scientist. Hanson is best known in theoretical physics as the co-discoverer of the Eguchi-Hanson Metric, the first Gravitational instanton. This Einstein metric is ...

discovered an exact Euclidean Instanton solution of the vacuum equations of general relativity, the

Eguchi–Hanson space In mathematics and theoretical physics, the Eguchi–Hanson space is a non-compact, self-dual, asymptotically locally Euclidean (ALE) metric on the cotangent bundle of the 2-sphere ''T''*''S''2. The holonomy group of this 4-real-dimensional manif ...

metric. This solution has applications, for example, in the construction of smooth compact

Calabi–Yau manifold In algebraic geometry, a Calabi–Yau manifold, also known as a Calabi–Yau space, is a particular type of manifold which has properties, such as Ricci flatness, yielding applications in theoretical physics. Particularly in superstring ...

s in superstring theory. In the early 1980s, he published an influential and widely cited review article on differential geometric methods in physics with Andrew J. Hanson and Peter Gilkey. They extensively treated the physical applications of the Atiyah-Singer index theorem and related mathematical results. With Hikaru Kawai, he developed the Eguchi-Kawai model for lattice theories with an SU(N) gauge group in the limit of large N. They showed that in this limit the lattice gauge theory for an infinite lattice and unit cube are identical and that this correspondence can also be maintained in the

continuum limit In mathematical physics and mathematics, the continuum limit or scaling limit of a lattice model (physics), lattice model refers to its behaviour in the limit as the lattice spacing goes to zero. It is often useful to use lattice models to approxi ...

of the lattice. Space-time is incorporated in this large N limit as though it were an internal degree of freedom.

Awards

*Eguchi shared second prize with Hanson in the 1979 Gravity Research Foundation competition. *In 1984 he received the Nishina Prize, and in 2009, he received the Imperial Prize and the Prize of the Japanese Academy of Sciences.

References

{{DEFAULTSORT:Eguchi, Tōru Academic staff of the University of Tokyo Academic staff of Kyoto University Japanese physicists 1948 births 2019 deaths