Observables in effective gravity

By S. Giddings, D. Marolf, James B. Hartle. 2005

232 citations recorded by the source corpus.

We address the construction and interpretation of diffeomorphism-invariant observables in a low-energy effective theory of quantum gravity. The observables we consider are constructed as integrals over the space of coordinates, in analogy to the construction of gauge-invariant observables in Yang-Mills theory via traces. As such, they are explicitly nonlocal. Nevertheless we describe how, in suitable quantum states and in a suitable limit, the familiar physics of local quantum field theory can be recovered from appropriate such observables, which we term ''pseudolocal.'' We consider measurement of pseudolocal observables, and describe how such measurements are limited by both quantum effects and gravitational interactions. These limitations support suggestions that theories of quantum gravity associated with finite regions of spacetime contain far fewer degrees of freedom than do local field theories.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/9dc563cf8fc11c9b294f55e0df9c9cb4acce3cc4

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. S. Raju
2. D. Harlow
3. J. Polchinski
4. K. Papadodimas
5. J. Sully
6. D. Marolf
7. S. Giddings
8. L. Randall

In Atomic and Molecular Physics, and Optics

1. S. Raju
2. S. Giddings
3. K. Papadodimas
4. H. Geng
5. A. Karch
6. J. Polchinski
7. William Donnelly
8. L. Freidel

In Statistical and Nonlinear Physics

1. D. Harlow
2. S. Raju
3. K. Papadodimas
4. J. Polchinski
5. D. Marolf
6. J. Sully
7. D. Stanford
8. Idse Heemskerk

Citations in the corpus

• Local subsystems in gauge theory and gravity (2016, background): “There are strong arguments that such locally supported commuting operators simply cannot exist in quantum gravity [10, 11].”
• Noncommutative Geometry, Quantum Fields and Motives (2007, background): “We refer to [143] for other more complicated examples of such invariants, where those of the form (1.”
• Black hole information, unitarity, and nonlocality (2006, background): “This viewpoint[16-18,15] emerges from apparent gravitational limits in Gedanken experiments where one tries to locaize very high-energy particles.”
• Quantum graphity: A model of emergent locality (2008, background): “However, there are a number of indications that this may not be correct (a thorough investigation of this question can be found in [14]).”
• State-Dependent Bulk-Boundary Maps and Black Hole Complementarity (2013, background): “The authors of [9] have suggested (at the discussion in the “Fuzz, Fire or Complementarity” workshop in August 2013 at KITP) that it may be possible to write down a state-independent operator that has the correct behaviour in a given state, presumably along the lines of the gauge-invariant relationa”
• Local bulk operators in AdS/CFT: A holographic description of the black hole interior (2006, background): “Even with interactions included, one can hope to recover quasi-local observables in the gravitational theory [5].”
• Observables, gravitational dressing, and obstructions to locality and subsystems (2016, methodology): “Even in states where this approach works, there are significant questions about how it extends to the quantum theory; some initial discussion of these issues appears in [5, 23].”
• Information Transfer with a Gravitating Bath (2020, result): “This is in accordance with the well-known result that there are no local gauge-invariant observables in quantum gravity [53–55].”
• Lessons from the information paradox (2020, background): “) This is a consequence of the fact that there are no local gauge-invariant operators in gravity [47–49].”
• Semiclassical relations and IR effects in de Sitter and slow-roll space-times (2010, background): “While this would eliminate the contradiction producing a paradox, it leaves an information problem, which is to determine the non-perturbative mechanics that (10)Moreover, a more basic description of such local questions may be through relational observables, such as the proto-local observables of [”
• Bulk and transhorizon measurements in AdS/CFT (2012, background): “But it is supported by bulk investigations of locality in quantum gravity [41, 42] which argued that precisely local observables fail to exist in a dramatic sense even at first non-trivial order in the bulk Planck length.”
• Diffeomorphism-invariant observables and their nonlocal algebra (2015, background): “Indeed, one way to think of constructing such operators has a close parallel to construction of other relational operators[9]; we can demand that the point at which a field operator acts is a fixed geodesic distance from a fixed feature (or “platform”), which we may take to approach infinity.”
• A Measure of de Sitter entropy and eternal inflation (2007, background): “, [8, 9, 10] for related discussions with somewhat different accents).”