Several developments in recent years strongly suggest a macroscopic breakdown of local effective field theory, but as yet we lack a precise understanding of this breakdown, its consequences, and the physics that replaces local theory. Aspects of this breakdown are indicated by the necessity of resolving the black hole information paradox, by limitations on local observation, by high-energy gravitational scattering, and are also suggested by facets of string theory such as the AdS/CFT correspondence. Such breakdown is potentially a profound aspect of fundamental physics, with important implications.

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Nonlocality, observables, black holes, cosmology: some questions

Nonlocality - regime and dynamics

How do we parametrize the regime where local QFT plus GR breaks down?

What is the mechanism for its failure?
(Is it stringy, gravitational, a combination, or something else?)

Does the physics of high-energy scattering serve as an accurate guide to this breakdown?

Observables

Are there other approaches to physically realizable local observation besides relational observables?

What are the basic limitations on local observation?

Do such limitations on local observation imply restrictions on the states and/or dynamics of the theory? What elements of current theory are in principle unobservable, and can/should we formulate a theory that doesn't predict such unobservable quantities?

Black holes and information

By what mechanism is the black hole information paradox avoided?

Are there any viable alternatives to a non-local resolution of the paradox?

How are singularities resolved?

Cosmology

Does de Sitter space have a finite-dimensional Hilbert space?

What is the analogous statement for more general states such as those of an eternally inflating multiverse?

What implications does this have for measures in eternal inflation?

How is local observation described in such a context?

AdS/CFT

Can AdS/CFT directly address the preceding questions?

Can one recover a local description of physics on scales small as compared to the AdS radius?

Does AdS/CFT clearly resolve the information paradox? How?

Fundamental theory

What implications do limitations on locality and observation have for the structure of a more fundamental theory?

What other properties are expected to characterize such a theory?

How can a fundamentally nonlocal theory reduce to local QFT plus GR in the appropriate limit?