{ "meta": { "api_type": "NWO Projects API", "version": "1.0.2", "licence": { "name": "CC0 1.0 Universal", "url": "https://creativecommons.org/publicdomain/zero/1.0", "description": "To the extent possible under law, all copyright and related or neighbouring rights have been waived worldwide to the data made available through this API." }, "documentation": "https://doi.org/10.5281/zenodo.14918287", "release_date": "2025-08-20T00:00:00", "funder": "https://doi.org/10.13039/501100003246", "ror_id": "https://ror.org/04jsz6e67", "date": "2026-11-05T00:00:00", "count": 1, "per_page": 100, "pages": 1, "page": 1 }, "projects": [ { "project_id": "680-47-434", "title": "On the Origin of Time and Scale: Quantum Shape Dynamics Through Holographic Renormalization", "funding_scheme_id": 473, "funding_scheme": "NWO-Talentprogramma Veni 2013 N", "department": "Exacte en Natuurwetenschappen", "sub_department": "Natuurkunde", "start_date": "2013-09-20T00:00:00", "end_date": "2016-12-20T00:00:00", "reporting_year": 2013, "summary_nl": "Classical gravity can be formulated in terms of a theory, called Shape Dynamics (SD), of dynamic locally scale-invariant geometry. SD, discovered by myself and two other collaborators, can be proven to be equivalent to General Relativity (GR), despite having a different fundamental symmetry, because local foliation invariance is traded for local scale (or conformal) invariance. Broadly, the purpose of my proposed research is to try to understand the structure and implications, both classical and quantum, of SD. Towards this end, I have identified three distinct, but related, research directions.\n\nThe first is an attempt to formulate SD, in the presence of a cosmological constant, in terms of conformally invariant connection variables. The hope is to generalize work done in 2+1 dimension to the physical case, which presents important new difficulties. Discovering such a formulation would: i) help to understand the mechanism behind the symmetry trading, and ii) allow for Loop Quantum Gravity-like methods of quantization to be utilized.\n\nThe second direction would be to explore the effect of the unimodular condition (i.e., the condition that sets the local volume to a fixed density) on the quantization of SD. The unimodular condition is known not to modify the classical theory; but, because it excludes degenerate spacetime metrics that would otherwise be integrated over, the quantum theory could be very different. \n\nThe last project is to understand the Hamiltonian of SD from knowledge only of conformal spatial geometry. Currently, the Hamiltonian is chosen uniquely to reproduce GR evolution. However, Mach's principles suggest that physics should only depend upon scale-invariant information. Thus, we propose to search for a holographic definition of SD where Hamiltonian evolution is reproduced by the Renormalization Group flow in a Conformal Field Theory in one less dimension.", "summary_en": "Classical gravity can be formulated in terms of a theory, called Shape Dynamics (SD), of dynamic locally scale-invariant geometry. SD, discovered by myself and two other collaborators, can be proven to be equivalent to General Relativity (GR), despite having a different fundamental symmetry, because local foliation invariance is traded for local scale (or conformal) invariance. Broadly, the purpose of my proposed research is to try to understand the structure and implications, both classical and quantum, of SD. Towards this end, I have identified three distinct, but related, research directions.\n\nThe first is an attempt to formulate SD, in the presence of a cosmological constant, in terms of conformally invariant connection variables. The hope is to generalize work done in 2+1 dimension to the physical case, which presents important new difficulties. Discovering such a formulation would: i) help to understand the mechanism behind the symmetry trading, and ii) allow for Loop Quantum Gravity-like methods of quantization to be utilized.\n\nThe second direction would be to explore the effect of the unimodular condition (i.e., the condition that sets the local volume to a fixed density) on the quantization of SD. The unimodular condition is known not to modify the classical theory; but, because it excludes degenerate spacetime metrics that would otherwise be integrated over, the quantum theory could be very different. \n\nThe last project is to understand the Hamiltonian of SD from knowledge only of conformal spatial geometry. Currently, the Hamiltonian is chosen uniquely to reproduce GR evolution. However, Mach's principles suggest that physics should only depend upon scale-invariant information. Thus, we propose to search for a holographic definition of SD where Hamiltonian evolution is reproduced by the Renormalization Group flow in a Conformal Field Theory in one less dimension.", "project_members": [ { "role": "Project leader", "member_id": 262693, "last_name": "Gryb", "degree_pre_nominal": "dr.", "initials": "S.", "first_name": "Sean", "organisation": "Radboud Universiteit Nijmegen||Faculteit der Natuurwetenschappen, Wiskunde en Informatica||Institute for Mathematics, Astrophysics and Particle Physics (IMAPP)", "organisation_id": 73889, "ror": "https://ror.org/016xsfp80", "active": false }, { "role": "Researcher", "member_id": 262693, "last_name": "Gryb", "degree_pre_nominal": "dr.", "initials": "S.", "first_name": "Sean", "organisation": "Radboud Universiteit Nijmegen||Faculteit der Natuurwetenschappen, Wiskunde en Informatica||Institute for Mathematics, Astrophysics and Particle Physics (IMAPP)", "organisation_id": 73889, "ror": "https://ror.org/016xsfp80", "active": false }, { "role": "Main Applicant", "member_id": 262693, "last_name": "Gryb", "degree_pre_nominal": "dr.", "initials": "S.", "first_name": "Sean", "organisation": "Radboud Universiteit Nijmegen||Faculteit der Natuurwetenschappen, Wiskunde en Informatica||Institute for Mathematics, Astrophysics and Particle Physics (IMAPP)", "organisation_id": 73889, "ror": "https://ror.org/016xsfp80", "active": true } ], "products": [ { "title": "A Shape Dynamical Approach to Holographic Renormalization", "year": 2015, "edition": "75", "start": 3, "end": 4, "type": "Wetenschappelijk artikel", "journal_title": "European Physics Journal", "authors": [ { "last_name": "Mercati", "initials": "F", "role": "Auteur" }, { "last_name": "Gomes", "initials": "H", "role": "Auteur" }, { "last_name": "Smolin", "initials": "L", "role": "Auteur" }, { "last_name": "Gryb", "initials": "S", "role": "Auteur" }, { "last_name": "Koslowski", "initials": "T", "role": "Auteur" } ] }, { "title": "The gravity/CFT correspondence", "year": 2013, "edition": "73", "start": 2275, "end": 2276, "type": "Wetenschappelijk artikel", "journal_title": "European Physics Journal", "authors": [ { "last_name": "Mercati", "initials": "F", "role": "Auteur" }, { "last_name": "Gomes", "initials": "H", "role": "Auteur" }, { "last_name": "Gryb", "initials": "S", "role": "Auteur" }, { "last_name": "Koslowski", "initials": "T", "role": "Auteur" } ] }, { "title": "Right about time?", "year": 2015, "edition": "1", "start": 87, "end": 102, "type": "Wetenschappelijk artikel", "journal_title": "Questioning the Foundations of Physics, Springer International.", "authors": [ { "last_name": "Mercati", "initials": "F", "role": "Auteur" }, { "last_name": "Gryb", "initials": "S", "role": "Auteur" } ] }, { "title": "Schrodinger Evolution for the Universe: Reparametrization", "year": 2016, "edition": "33", "start": 65004, "end": 65005, "type": "Wetenschappelijk artikel", "journal_title": "Classical and Quantum Gravity", "authors": [ { "last_name": "Thebault", "initials": "K", "role": "Auteur" }, { "last_name": "Gryb", "initials": "S", "role": "Auteur" } ] }, { "title": "Symmetry and Evolution in Quantum Gravity", "year": 2014, "edition": "44", "start": 305, "end": 348, "type": "Wetenschappelijk artikel", "journal_title": "Foundations of Physics", "authors": [ { "last_name": "Thebault", "initials": "K", "role": "Auteur" }, { "last_name": "Gryb", "initials": "S", "role": "Auteur" } ] }, { "title": "Time Remains", "year": 2015, "edition": "67", "start": 663, "end": 664, "type": "Wetenschappelijk artikel", "journal_title": "British Journal for the Philosophy of Science", "authors": [ { "last_name": "Thebault", "initials": "K", "role": "Auteur" }, { "last_name": "Gryb", "initials": "S", "role": "Auteur" } ] }, { "title": "Regarding the ‘hole argument’ and the ‘problem of time’", "year": 2016, "edition": "83", "start": 563, "end": 584, "type": "Wetenschappelijk artikel", "url_open_access": "https://arxiv.org/abs/1606.07265", "journal_title": "Philosophy of Science", "authors": [ { "last_name": "Thebault", "initials": "K", "role": "Auteur" }, { "last_name": "Gryb", "initials": "S", "role": "Auteur" } ] }, { "title": "Is spacetime countable?", "year": 2015, "edition": "1", "start": 153, "end": 168, "type": "Wetenschappelijk artikel", "journal_title": "It From Bit or Bit From It?, Springer International Publishing", "authors": [ { "last_name": "Gryb", "initials": "S", "role": "Auteur" } ] }, { "title": "Observing Shape in Spacetime", "year": 2015, "edition": "47", "start": 37, "end": 38, "type": "Wetenschappelijk artikel", "journal_title": "General Relativity and Gravitation", "authors": [ { "last_name": "Gryb", "initials": "S", "role": "Auteur" } ] } ] } ] }