The Identification Bridge

Status: open hypothesis, not a claim. The unit bridge is by construction (cell = ℓ_P, tick = t_P, c = 1 hop/tick); the structural identification — what the substrate's registers and objects physically are — is what this page hunts. Units are assigned; the emergent numbers are measured.

The measured numbers under the bridge

Substrate quantity	Engine value	Under ℓP/tP	Physical reading
Grid spacing	1 cell	1.62×10⁻³⁵ m	spatial granularity
Tick	1 tick	5.39×10⁻⁴⁴ s	update period
Link speed	1 hop/tick	3.0×10⁸ m/s	c by construction
Bound lump	R≈5 cells	~8×10⁻³⁵ m	Planck-scale knot / geon-scale defect
E4 cavity clock	23 ticks	1.24×10⁻⁴² s	Planck-frequency resonator
Excitation iE	n = 1,2,3…	n·E_P (E_P≈2×10⁹ J)	oscillator occupation number — Planck's n verbatim
Thermal decay	~1/8 per tick	τ≈8t_P	Planckian radiative width
Cavity photon gas (E24)	~0.31 photons/cell	~10³² K equivalent	a radiation field sitting at Planck/Hagedorn temperature

The emergent entries are the interesting ones: the equilibrium photon density, the decay width, and the cavity period are measured, not dialed — they are the substrate's own answers once units are applied.

Two candidate identifications

A — Primordial Planck vacuum. The substrate is spacetime itself at the Planck epoch: lumps are topological defects of the lattice (geons, vortex knots), n is local oscillator occupation, the photon field is the primordial radiation bath. Under this reading, real atoms and laboratory clocks are statistical ensembles 10²⁰–10³⁰ scales above the grid — the substrate can never be "a proton" because a proton is a coarse-grained object built of ~10¹⁹ lattice spacings.

B — Condensed-matter analog. The lattice is a crystal; iE is a vibrational quantum (phonon occupation), photons are polariton-like propagating modes, lumps are self-trapped defects (polarons, skyrmions), and the E23 filament is ordinary phonon conduction. This reading is weaker as cosmology but stronger as physics — every mechanism has an established solid-state precedent.

What would settle it

• A discriminating prediction. An experiment where the two readings give different answers — e.g., does the equilibrium photon density scale like a blackbody spectrum under density change (Planck-vacuum reading) or like a Debye phonon gas bounded by the lattice's channel cap (crystal reading)?
• A falsifiable constant. If any measured substrate number (decay width, detention factor, equilibrium density) can be pinned to a dimensionless real-world ratio, the bridge graduates from "units by construction" to "a constant of the system."
• The missing leg. Closed (E27, 29c4ec0). IPHOT>=8 fires Breit-Wheeler on the lattice: antipodal photon pairs at a shared site crystallize into rest mass — head-on beams in vacuum produce real rest (control: zero). The mass↔photon↔n triangle is now fully closed — every energy form interconverts with integer conservation.

The first measured law — the partition equation of state

Under IPHOT>=7 (per-quantum decay — Einstein A-coefficient on the lattice), sweeping the bar's mass density at fixed energy yields a clean partition curve (T_total conserved at 43,200 throughout):

density m	photons	f_rad	regime
16	28,110	65%	radiation-dominated
32	20,242	47%	~equality
64	11,880	28%	matter-leaning
128	4,791	11%	matter-dominated

The data fits f_rad(m) = m_eq / (m + m_eq) with m_eq ≈ 30 — the equilibrium exchange curve (the 128-point dips under it where channel saturation bites). The real invariant is the matter- radiation equality density m_eq ≈ 30: the crossover where the substrate flips regimes — a direct analog of the cosmological equality epoch, and the substrate's first anchored parameter.

Until more land: the substrate is a conserved integer ontology that resembles Planck-scale physics the way a wind tunnel resembles weather — the measurements are real, the identification is still hunting.