GDBS Validation Package

NASA SBIR INSTALG.3.S26B - Large-Scale Computing and Computational AI for NASA Science and Mission Applications. Technical review package prepared for Dr. Scott Noble (GSFC-6630, Gravitational Astrophysics Lab).

Summary

GDBS is a browser-resident scientific computing platform built around the GeoNum precision substrate. This package documents the platform's current numerical relativity capability, the technical plan for closing the remaining gap to LISA-precision waveform extraction, and the substrate-level precision methodology that distinguishes GDBS from f64-only NR codes.

All measurements below were produced by the harness at harness/run-noble-validation.mjs against the same WASM binary deployed at gdbs.getvaultsync.com. Every value links to its raw JSON below.

Measured results (this run)

Gauge wave convergence 16 to 24
p = 4.05
Ratio of Hamiltonian constraint L2 norms; 4th-order FD scheme verified.
Gauge wave convergence 24 to 32
p = 3.88
Asymptotic order recovered at finer refinement.
Minkowski Hamiltonian L2 floor
1.17 × 10-28
Test gate is 10-6; floor is 22 orders of magnitude below.
Robust-noise 100-step stability
67.9× growth
Bounded (test gate 106×); regulator fires = 0.
GeoNum drift on constraints
PRECISE
All three resolutions; drift < 1 shade (sub-ULP).
Analytic IMRPhenomD pipeline
20 ms
End-to-end template + matched filter + Q-transform + posterior + sky.

Result artifacts

Each measurement above is reproducible from its JSON artifact. Click to view raw output:

bssn_gauge_wave_resolution_scan.json bssn_convergence_order.json bssn_minkowski_constraint_floor.json bssn_robust_noise_stability.json geonum_drift_on_constraints.json analytic_waveform_phenomd.json summary.json

Scope honestly stated

Sections clearly partition what is measured from what is planned. Section A reports values produced by the current deployed engine. Section B describes the Phase I scope required to deliver end-to-end BBH evolution and waveform extraction at the precision relevant to future gravitational wave missions; each task references the specific module in the GDBS codebase that gets extended. Section C describes the substrate precision model that underlies both.

Status note (2026-05): the Weyl ψ4 extraction operator and its spin-weighted −2Yℓm projection are implemented, validated to ~2×10−6 against an analytic linearized wave, and now surfaced — binary GPU runs emit real mode coefficients Cℓm(t) (verified on hardware with the physical head-on structure). The remaining Phase I items are: demonstrated multi-orbit BBH inspiral cross-validated against an SXS reference, and per-RK4-substage drift propagation. A calibrated merger waveform - gated by evolution accuracy - is not claimed as current capability.

Reproducibility

The full measurement set regenerates with one command at the repository root:

node docs/nasa/noble/harness/run-noble-validation.mjs

The same engine is reachable interactively through the HPC Lab tab at gdbs.getvaultsync.com; the run_bssn and run_bssn_gpu bindings produce the JSON shape used in results/.

Industry-standard references cited

  1. Alcubierre, M. (2008). Introduction to 3+1 Numerical Relativity. Oxford University Press. Gauge-wave convergence methodology, 1+log slicing, gamma-driver shift.
  2. Alcubierre et al. (2004). Towards standard testbeds for numerical relativity. Class. Quantum Grav. 21, 589. Apples-with-Apples / Mexico City tests.
  3. Brugmann et al. (2008). Calibration of moving puncture simulations. Phys. Rev. D 77, 024027. BAM puncture benchmarks.
  4. Bernuzzi & Hilditch (2010). Constraint violation in free evolution schemes. Phys. Rev. D 81, 084003. Z4c constraint damping.
  5. Khan, Husa, et al. (2016). Frequency-domain gravitational waves from non-precessing binaries. Phys. Rev. D 93, 044007. PhenomD model.
  6. Reisswig & Pollney (2011). Notes on the integration of numerical relativity waveforms. Class. Quantum Grav. 28, 195015. Strain extraction method.
  7. Boyle & Mroue (2009). Extrapolating gravitational-wave data from numerical simulations. Phys. Rev. D 80, 124045. Richardson extrapolation to scri-plus.