Bibliographic record
Abstract
Abstract Hořava gravity is a Lorentz-violating modification of general relativity (GR) with a preferred spacelike foliation. Observational evidence has put strong constraints on the parameter values in this model, so that the remaining viable sector is well-characterized by the Newton constant and a single additional parameter. We analyze this restricted theory, which is called minimal Hořava gravity, from the Hamiltonian point of view. We find that in order to eliminate a pathological mode that is unstable at high frequencies and strongly coupled at low frequencies the theory must be further restricted so that the slices of the preferred foliation each have constant mean curvature. We dub this theory minimal minimal Hořava gravity. It has two regimes; one in which the mean curvature is time independent, in which case it is equivalent to a particular foliation of GR with nonzero cosmological constant, and another in which the mean curvature is time dependent. In the latter there is an infinite propagation speed since the lapse evolves via an elliptic equation, and the theory thus differs from GR in a peculiar nonlocal fashion. To probe the viability of the sector with time dependent mean curvature, we study in detail the problem of spherical collapse of a thin dust shell. The solution is determined unambiguously from initial conditions until the slice on which the shell first contracts to a point. Afterwards, there is an instantaneously propagating spherical mode with undetermined evolution, demonstrating a failure of the Cauchy problem.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.003 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".