Aetheria/docs/aetheria-gravity-target.md

Aetheria gravity: target

Campaign aetheria-gravity. Opened 2026-10-14 on operator ruling aetheria-release:ruling:gravity-honest-wells-agreed. Its invariants, not-in-scope list and canonical implementations are the typed target aetheria-gravity:target:r1; this page keeps the rationale.

Why

The orbit probe (docs/research/2026-10-13-orbit-probe/report.md) measured today's wells against the real code:

• The heightfield is not a potential. Each well is a positive core plus an equal negative-density ring (antimass) out to its rim, so it is mass-neutral and nothing is felt outside the rim.
• The force is S*R*|grad h|^2 behind a slope gate (|n_xz|^2 > 0.001), which zeroes it in every core, at every rim, and in every zone bowl wider than about 3117 units.
• The outer half of every well has unstable circular orbits, and about 40% of moons sit there.
• The wells pull 20 to 70 times harder than the OrbitPeriod rail implies, so holding a rail orbit costs a real fraction of a ship's thrust.

The operator's frame (2026-10-13): bodies sit above the grid so there is always room to fly beneath them, so being within a sun's radius is not being inside it; gravity is shaped that way on purpose, and the picture is why it looks as it does. "We can use correct wells and simply exaggerate the height."

The shape

One scalar potential per zone owns gravity. Each body contributes a 2D point-mass well: logarithmic potential and force falling as 1/r outside the body's radius, softened inside it (force linear to zero at the centre, matched in value and slope at the radius, Plummer-like). Wells add. Force is the potential's gradient, with no gate. The drawn height is the potential times one exaggeration factor, so what the player sees and what the ship feels are the same function. With a 1/r tail every circular orbit is stable.

Ink zones are not under this law. Their pillars stand where suns would (aetheria-fauna:ruling:ink-pillars-are-suns), but the Ink need not obey flatspace gravity: the operator sketched a pillar as a negative-gravity singularity with a bowl around it, a Bundt tin, plus a swell ships feel (aetheria-fauna:ruling:ships-feel-swell). That law is aetheria-release:follow_up:ink-gravity-law, and it plugs into the potential owner this campaign builds.

Rulings of 2026-10-14

The forks the first Imagination pass raised were ruled the same day (aetheria-gravity:ruling:*-ruled): the field owns the orbits; gravity starts at about 0.5 u/s^2 at a median planet's orbit; pull comes from mass through an authored compressed curve; children are placed within their parent's reach; each well's soft core has its own authored radius and never levels the field out where bodies orbit; one global exaggeration; the grid's height carries gravity only, and the wormholes' presentation is provisional; ships feel only the potential. The flatspace bowl and ripples are deleted, not disabled: the map found them live in Settings.asset and Zone.GetHeight. The model page and body facts are in docs/aetheria-gravity-map.md.

Not here

Portals and portal gravity, and non-Euclidean zone geometry, belong to the pseudospace-flavours line (aetheria-release:follow_up:portals-and-portal-gravity, aetheria-release:follow_up:pseudospace-geometry-owner).