# Walker Melton ![A professional headshot of Junior Fellow Walker Melton](/sites/g/files/omnuum12196/files/styles/hwp_4_5__320x400/public/2025-10/Adobe%20Express%20-%20file-10.jpg?h=5805fb65&itok=5pPwbmFS) email laptop\_windows [INSPIRE HEP](https://inspirehep.net/authors/2758669) Theoretical Physics B.S. California Institute of Technology Ph.D. Harvard University Photo courtesy of Mark James Dunn Walker Melton is a Junior Fellow of the Society of Fellows. After completing his undergraduate degree at the California Institute of Technology in 2019, he continued to Harvard, where he earned his PhD in physics under the supervision of Professor Andrew Strominger in 2025. His research seeks to apply holographic techniques to study quantum gravity and string theory in physically realistic contexts, such as asymptotically flat spacetimes. A powerful tool in modern high energy physics is the AdS/CFT correspondence, which relates string theory in a simple but physically unrealistic negatively-curved anti-de Sitter space, to a lower-dimensional conformal field theory. Because conformal field theories are well understood, the AdS/CFT correspondence provides powerful techniques to study and define quantum gravity in asymptotically anti-de Sitter spacetimes. However, because AdS spacetimes, positively-curved de Sitter spacetimes, and flat spacetimes have drastically different asymptotic structures, it has proven challenging to construct such explicit holographic dualities beyond anti-de Sitter spacetimes. Nevertheless, low-energy properties of gravity in asymptotically flat-spacetimes suggest that theories of quantum gravity in asymptotically flat spacetimes can be recast as lower-dimensional 'celestial CFTs’ living on the celestial sphere, where the dual theory calculates scattering amplitudes in the bulk theory. To date, these constructions have used properties of scattering amplitudes, such as their universal low-energy and collinear behavior, to investigate universal sectors of the hypothetical lower-dimensional dual theory. Walker’s research has helped understand how these structures, which sometimes seem unnatural from a lower-dimensional point of view, could emerge from concrete, independently defined 2D CFTs. During his postdoctoral fellowship, he hopes to connect these developments with more explicit and top-down constructions of holographic dualities and develop new, more complete models of flat space holographic dualities. These promise to give us new tools to rigorously define quantum gravity in physically realistic contexts and study processes such as black hole evaporation where both quantum mechanics and gravity are important. - ## By Term [2025-28](/term/2025-28)