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Harding Distinguished Postgraduate Scholars Programme


  Jun Liu


  Applied Mathematics and Theoretical Physics, Pembroke College

  PhD thesis: Emergence of Space from Matrix Quantum Mechanics (TBC)



Research interests:

  1. Gauge/Gravity duality
  2. Holographic principle for non-conformal field theories
  3. Holographic formulation of Superstrings and M-theory
  4. Black holes and quantum cosmology

The AdS/CFT correspondence was discovered in the late 1990s. At first it specifically meant a duality between quantum field theories (conformal field theories) and gravity in asymptotically Anti-de-Sitter spacetimes. Observables on one side can be mapped to those on the other. Nowadays people have recognised many dualities beyond AdS and CFT. An interesting model consists of supersymmetric large matrices living in 0 space plus 1 time dimension (quantum mechanics). It was conjectured (BFSS conjecture) as a holographic description of M-theory, describing gravitational physics with 10 spatial dimensions. Although the original matrix theory has no “space”, “space” emerges in the dual gravitational theory. Such emergence of space also appears in many other matrix models. My PhD project will aim to decipher how local interactions and entanglements on a dynamical spacetime background can be defined as quantum matrices with no “space”.

Who or what inspired you to pursue your research interests?

Initially I was interested in black holes in classical general relativity. Black hole as a region of spacetime can be shown to have an entropy which must come from counting quantum microstates. The framework of gauge/gravity duality is so powerful that it maps this problem of black hole microstates simply to thermodynamics of a heat bath in the dual field theory. Difficulties with a “quantum theory of gravity” seem to be by-passed with this sort of dualities. Thus, I am inspired to explore this direction in hope that we can fully describe quantum gravity more easily with field theories.