Reproduce Mercury's 42.98 arcsec/century GR precession from the Schwarzschild geodesic, in your browser.
See it run - a worked example, 100% in this browser tab
The problem
Reproducing the classic general-relativity test - Mercury's anomalous perihelion advance - normally lives in a notebook with no in-browser, verifiable path.
The local-first solution
This plugin integrates the Schwarzschild geodesic orbit equation with RK4 in the browser, measures the per-orbit perihelion shift, and reproduces Einstein's published 42.98 arcsec/century as an earned residual against the literature value.
What it does
RK4 integration of u'' + u = GM/L^2 + 3GM u^2/c^2 over many orbits
Newton-refined perihelion detection where u'(phi) crosses zero
Measured per-orbit advance scaled to arcsec/century via Mercury's 415.2 orbits/century
Comparison to the closed-form 6 pi GM / c^2 a(1-e^2) and the published 42.98 arcsec/century
3D rosette visualization with a labeled, exaggeration-free measurement path
Honest scope
This is the weak-field, test-particle Schwarzschild result for a single planet around a static point mass - NOT full numerical relativity, NOT an N-body ephemeris, and it excludes the planetary perturbations that dominate Mercury's total observed precession. The 42.98 arcsec/century is specifically the GR residual; the 3D rosette may exaggerate the GR term for visibility, labeled, while the reported number uses true constants.
Authorities cited
A. Einstein (1915). Erklarung der Perihelbewegung des Merkur aus der allgemeinen Relativitatstheorie. Sitzungsber. Preuss. Akad. Wiss., 831-839 (perihelion of Mercury: 43 arcsec/century).
C. W. Misner, K. S. Thorne, J. A. Wheeler (1973). Gravitation. W. H. Freeman, Sec. 25.3 - Delta_phi = 6 pi G M / (c^2 a (1-e^2)).
Run the integration in the browser and save the result to Sandbox, attach it to a Worklog case, or route it into a Gate client portal. Nothing is uploaded to anyone's cloud.