Receipt 6 — the road home: three zones, invert the inversion at each horizon

ATLAS-RECEIPT-6-THE-ROAD-HOME.md

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+# ATLAS-RECEIPT-6 — the road home: winding 3I/ATLAS backwards, 2026-08-04
+
+The backward path to origin has THREE ZONES, each owned by a different instrument.
+The method: when an inversion hits its horizon, do not push it harder — INVERT THE
+INVERSION: change instruments. Dynamics unwinds millions of years; chemistry unwinds
+billions.
+
+## Zone 1 — EXACT (now back to ~10 Myr) · instrument: orbital integration
+- Backtrail rate: 58 km/s = 59.3 pc per Myr.
+- The traced road (2509.03361): 25 stellar encounters, median < 1 pc; closest a wide
+  M-dwarf binary, 0.242 pc, 1.64 Myr ago, 28.39 km/s; cumulative deflection WEAK
+  (arcsecond-scale bends). The visitor arrived unfished.
+- Horizon: ~10 Myr / ~600 pc of backtrail — beyond this, encounter chaos makes the
+  road unknowable IN PRINCIPLE, not merely in practice.
+
+## Zone 2 — STATISTICAL (10 Myr to ~Gyr) · instrument: galactic kinematics
+- Velocity distribution matches the THIN DISK (2509.03361): the recent neighbourhood,
+  not the birthplace. In 10-12 Gyr at ~230 Myr per galactic orbit the object has
+  lapped the galaxy ~45 times: fully phase-mixed. The road is an ensemble here —
+  a torus of possible histories, honestly a cloud.
+
+## Zone 3 — THE BIRTH (10-12 Gyr) · instrument: THE KEYS (isotopes)
+- Where dynamics is blind forever, chemistry still reads: D/H = 0.95±0.06% (58 sigma
+  above solar comets) -> formed at <= 30 K under ~100x local cosmic-ray flux;
+  12C/13C 123-191 -> an early, less-evolved, metal-poor epoch; accretion ~10-12 Gyr
+  ago (2603.06911). The birth CONDITIONS recovered without the birth ROAD.
+
+## The tension, held honestly
+Kinematics (thin-disk velocities) and isotopes (ancient metal-poor epoch) point at
+different depths: Zone 2 names the recent NEIGHBOURHOOD, Zone 3 names the BIRTH.
+Both hold; the field has not sealed their join; neither do we.
+
+## The finding
+Its home no longer exists as a place. Open clusters dissolve within ~100-600 Myr;
+its natal cluster dispersed >9 Gyr ago; its siblings are scattered through the whole
+disk, unidentifiable — for 10-12 Gyr even in principle. The road home terminates not
+at coordinates but at chemistry:
+
+**The keys in its ice are the only surviving record of its home. The rock is its own
+birthplace's last receipt.**
+
+Boundary: Zone 1 numbers are published measurements; Zone 2 is the papers' stated
+kinematic inference; Zone 3 is measured isotopes plus standard galactic chemical
+evolution; cluster-dissolution timescales are standard values. No origin coordinates
+are claimed by anyone, including us.