Spacetime Architecture — Unified Scaffold
Parent scaffold with space and time siblings: inheritance, symmetry, necessary asymmetry, and cross-disciplinary structural templates
Author: U. Warring Affiliation: Institute of Physics, University of Freiburg Domain: Spacetime parent and its space/time sibling projections Epistemic status: Unified structural scaffold Version: 0.4.4 Last updated: 2026-01-09 License: CC BY 4.0 Status: Constitutional invariant framework Domain: Epistemic governance (human-bound, tool-mediated) Non-status: ❌ Not a curriculum · ❌ Not pedagogy · ❌ Not tool-specific
[ENDORSEMENT MARKER]
Parent scaffold (metric, causality, comparison envelope): The metric structure and causal ordering carry broad community endorsement in relativistic physics. The comparison envelope L_comparison ≤ cτ is a candidate boundary (v1.0, falsifiable); no parity implied with externally validated laws.
Sibling projections: Structural framework; inherits endorsement status from parent and from cited external constraints.
Cross-disciplinary applications: Foundational disciplines define or stress-test scaffold tiers. Applied disciplines inherit structure without modifying it. Domain authority remains with domain experts.
[COUNCIL ACTION REQUIRED]
Registry naming convention requires ratification before coastline drafting proceeds. See §13 Open Items. Guardian recommendation: Option A (parent-first) with alias stub for backward compatibility.
1. Purpose and Scope
This document specifies a single architectural scaffold from which spatial and temporal frameworks project. It proceeds parent-first: the shared causal-metric structure is established before either sibling is introduced. Both siblings then appear together, permitting direct inspection of what they share and where they necessarily differ.
The scaffold is designed to serve two audiences:
Specialists in foundational disciplines requiring precise structural definitions for metrology, relativistic physics, distributed systems, and quantum information
Researchers in applied disciplines seeking a rigorous structural template for reasoning about events, ordering, and comparison (entry point: §10.2)
Both audiences share a common problem: how to establish when something happened, where it happened, and how to compare observations made at different times and places.
In scope:
Parent scaffold: metric neighbourhoods, causal structure, comparison envelope
Sibling projections: space ("where") and time ("when")
Tier structure for each sibling
Explicit symmetry and asymmetry analysis
Foundational and applied discipline mappings
Out of scope:
Detailed coastline content (deferred to tier documents)
Metrological procedures, apparatus specifications (external constraints, citation-only)
Metaphysical interpretation of spacetime ontology
Domain-specific applications (deferred to discipline handbooks)
Note on terminology: This document uses a deliberative Council framework (Guardian, Architect, Integrator stances) as a governance structure for epistemic quality control. These terms map to standard roles: Guardian ≈ ethics/clarity editor; Architect ≈ structural reviewer; Integrator ≈ process coordinator. The framework ensures balanced, auditable deliberation but does not affect the technical content of the scaffold.
2. Parent Scaffold
2.1 The spacetime stage
Events in the universe are located by specifying where and when they occur. The collection of all events forms a four-dimensional manifold: three dimensions answer "where"; one dimension answers "when." This manifold is the spacetime stage on which all physical processes unfold.
Structural note: In any domain, reasoning involves event claims (what/where/when) and comparison procedures. The physics scaffold provides the most explicit template for separating causal constraints from conventions. Cross-disciplinary applications use this template structurally; they do not require that domain events be redescribed as relativistic world-points.
2.2 Metric structure
The metric g_{μν} is the rule for measuring separation between nearby events. It encodes:
how spatial distances combine with temporal intervals
how "nearness" is defined in each neighbourhood
the local geometry that physical apparatus must respect
The metric is governed by General Relativity (external constraint, citation-only). This scaffold presupposes but does not re-derive relativistic field equations.
Open frontier: Approaches seeking to unify quantum field theory with gravity (string theory, loop quantum gravity, causal set theory, asymptotic safety) may modify or replace the smooth metric at extreme scales. This scaffold remains agnostic: it specifies structure at scales where the metric description is empirically validated. Future refinements would enter as updated external constraints, not as changes to scaffold architecture. See §11.1 for further discussion.
2.3 Causal structure
Light cones partition all events relative to any given event P into three classes:
Causal past
Can send signal to P
May influence P
Causal future
Can receive signal from P
May be influenced by P
Spacelike separated
Cannot exchange signals with P
Causally disconnected from P
Causal cones are defined locally by the metric. Global causal accessibility can be constrained by curvature and horizons (e.g., black hole event horizons, cosmological horizons), but the local light-cone structure never permits superluminal signalling. This constraint does not depend on observer, coordinate choice, or apparatus.
Structural note: Causal structure is the most portable element of this framework. Any domain concerned with cause and effect—tracing influence, establishing liability, reasoning about consequences—implicitly invokes causal ordering. The light-cone formalism provides the physics-grounded version; domain-specific causal models are approximations or projections suited to their evidence base.
2.4 Comparison envelope (candidate boundary, v1.0)
When any two readings—whether clock ticks or ruler markings—are to be compared, the comparison process itself is bounded by causality. A reading at location A can only be meaningfully compared with a reading at location B if a signal can traverse the separation within the comparison interval.
Candidate boundary statement:
During a comparator interval τ, the region over which comparison is causally possible satisfies:
L_comparison ≤ cτwhere c is the speed of light and τ is proper time along the comparator's worldline.
Operational anchor: A comparison event is a protocol that outputs a decision variable D (e.g., phase difference estimate, baseline ratio, synchronisation verdict) whose computation requires classical communication during τ (including local wiring or internal signal paths for co-located comparisons). The envelope bounds the spatial support of that communication graph. This definition excludes inferential use of pre-established correlations, which do not require communication during the comparison interval.
Delayed comparison: If readings are recorded now but compared later, τ refers to the later comparison interval—not the interval during which the readings were taken. The envelope then applies to that later interval's communication graph. This prevents the envelope from being trivially satisfied by delaying comparison indefinitely; the constraint binds whenever comparison actually occurs.
Status: This is a design boundary for comparison geometry—a constraint on what can be coherently compared, not a claim about what exists. It is Council-cleared, version-tagged (v1.0), and falsifiable.
Falsifiable by: Any verified experiment demonstrating a comparison event (as defined above) beyond this envelope without violating causal order.
Clarification on quantum-assisted protocols: Entanglement-based synchronisation and similar protocols do not violate the envelope. Correlations are established within causal access (during state preparation) and later exploited (during measurement); no classical information is transmitted faster than light during the comparison interval. A future handbook will specify a syndrome set defining operationally what constitutes a comparison event, including quantum-assisted cases.
2.5 What the parent scaffold provides
4-D manifold
Structural container
Endorsed (standard relativity)
Metric g_{μν}
Neighbourhood geometry
Endorsed (GR, citation-only)
Light cones
Causal partitioning
Endorsed (SR/GR, citation-only)
Comparison envelope
Causal access boundary
Candidate (v1.0, falsifiable)
Both siblings inherit all four elements. Neither sibling may contradict the parent.
3. Sibling Projections: Introduction
The parent scaffold answers: "What is the causal-geometric stage?"
The siblings answer: "How do we separately address the 'where' and the 'when'?"
A projection extracts one aspect of spacetime while presupposing the full parent structure. Projections are not reductions; the parent is not discarded when a sibling is invoked.
3.1 Why two siblings?
Operationally, "where" and "when" are addressed by distinct apparatus:
Clocks accumulate phase or count oscillations → answer "when"
Rulers compare lengths or baselines → answer "where"
The distinction is not ontological (spacetime is unified) but operational (measurement protocols differ).
3.2 Sibling inheritance rule
Every spatial or temporal tier inherits the parent scaffold in full. No tier may:
violate causal ordering
contradict metric structure
exceed the comparison envelope without causal justification
4. Sibling Tier Structure
Both siblings share a three-layer architecture:
Tier 1a
Logical labels
Conventional (no metric content)
Tier 1b
Physical measurement
External constraints (metrology)
Tier 2
Coordination lock
Conventional (naming, organisation)
The comparison envelope resides at the parent, not at Tier 1. Both siblings inherit it; neither re-derives it.
5. Time Sibling ("When")
5.1 Tier T1a — Logical temporal ordering
Purpose: Establish "before" and "after" without metric duration.
Realisation: Lamport clocks, vector clocks, happened-before relations, logical timestamps in distributed systems.
Lamport clocks provide a single scalar counter incremented on local events and updated on message receipt. They establish a partial order: if event A causally precedes event B, then the Lamport timestamp of A is less than that of B (but not conversely).
Vector clocks extend Lamport clocks by maintaining a vector of counters (one per process). They capture the full causal history: two events are causally ordered if and only if their vector timestamps are comparable. Vector clocks detect concurrency (when neither event causally precedes the other).
Properties:
Provides partial order over events (Lamport) or full causal history (vector clocks)
No seconds, no oscillator, no proper time
Sufficient for sequencing and concurrency detection; insufficient for duration
Boundary with T1b: Logical order does not determine how much time elapses. Transition to T1b requires physical clocks.
Foundational discipline: Distributed systems and computer science provide the mathematical proofs that Lamport and vector clocks prevent causal violations in non-metric environments. These are not approximations of physical clocks; they are the canonical solution to ordering without duration.
5.2 Tier T1b — Physical clocks
Purpose: Read proper time τ from the spacetime metric using physical apparatus.
Realisation: Atomic clocks (caesium, optical), Earth rotation (UT1 via VLBI), pulsar timing.
Properties:
Proper time is a path integral: τ = ∫ ds along the clock's worldline
Clocks measure τ, not coordinate time
Drift between clocks reveals relative spacetime geometry
External constraints (citation-only):
SI second (BIPM)
TAI/UTC conventions (IERS)
Pulsar timing models
Inheritance from parent: Physical clocks operate within the comparison envelope. Comparing tick N at clock A with tick N at clock B requires causal access within one period.
Foundational discipline: Metrology and relativistic physics provide the SI standards and the operational definition of the second that anchor this tier to the metric g_{μν}. If the SI second were redefined, Tier T1b would update accordingly.
5.3 Tier T2 — Calendar Lock (coordination)
Purpose: Convert proper-time readings into named intervals for human coordination.
Lock structure:
Partition
Divide time into days, months, years
Hierarchy
Nest intervals (second → minute → hour → day → year)
Epoch
Anchor to reference event (e.g., CE epoch, Unix epoch)
Enumeration
Assign names and numbers to intervals
Intercalation
Insert leap seconds, leap days as convention updates
Properties:
Calendars are conventions, not physics
Intercalation corrects drift between Tier 1b readings and Tier 2 labels
Calendar changes do not alter proper time
Foundational discipline: Timekeeping authorities (IERS, BIPM) and astronomical conventions define the Calendar Lock's reference points and update rules. These are the "memory" layer that converts physical measurements into coordination tools.
6. Space Sibling ("Where")
6.1 Tier S1a — Logical spatial labels
Purpose: Assign coordinate indices without metric distance.
Realisation: Grid coordinates, simulation meshes, address systems, graph-node identifiers, spatial adjacency vectors.
Properties:
Labels provide identity and adjacency (topology) without scale
"Node 7 is adjacent to Node 8" does not imply any physical distance
Sufficient for addressing; insufficient for length
Topology note: S1a may encode metric topology (which points are neighbours) without encoding metric scale (how far apart neighbours are). Purely combinatorial graphs are a permitted special case.
Structural parallel to vector clocks: Just as vector clocks capture a process's complete causal history relative to all other processes, spatial adjacency vectors (SAVs) capture a topological signature of a node relative to a chosen reference structure (all nodes, a landmark set, or a neighbourhood), sufficient for connectivity and routing tasks. This enables concurrency detection in time (vector clocks) and connectivity analysis in space (adjacency vectors). Where vector clocks answer "what is my causal relationship to every other process?", SAVs answer "what is my topological relationship to my reference structure?"
Key realisations of SAVs include:
Vivaldi coordinates: Self-organising coordinate systems where nodes estimate positions based on round-trip latencies (Dabek et al. 2004). Note: Vivaldi uses RTT as a physical proxy but without SI calibration; it is a hybrid structure sitting at the S1a/S1b boundary. Treat as approximate/heuristic until calibrated.
Graph embeddings: Mapping graph nodes to coordinate spaces preserving adjacency structure
Landmark-based routing vectors: Node distances to a fixed set of reference nodes enabling greedy routing
These structures operate entirely within Tier S1a: they encode topology and connectivity, not metric distance. The transition to physical distance (S1b) requires calibration against a metric observable (e.g., light travel time with SI traceability).
Note on formal guarantees: Vector clocks provide provably minimal causal history: they are the canonical, mathematically complete solution to distributed ordering. SAVs vary in formal strength. Some implementations (graph embeddings with bounded distortion, exact distance oracles) offer provable guarantees on topological fidelity. Others (Vivaldi coordinates, heuristic embeddings) are statistical approximations that converge under assumptions but do not guarantee uniqueness or minimality. The tier-s1a-logical-grids.md coastline will specify which SAV classes satisfy S1a requirements for different application contexts, distinguishing between:
Exact SAVs: provably complete topological representation (e.g., full distance matrix, exact graph embedding)
Approximate SAVs: statistically accurate under specified conditions (e.g., Vivaldi with convergence bounds)
Heuristic SAVs: useful for routing/addressing but without formal guarantees
Boundary with S1b: Logical labels and adjacency vectors do not determine physical separation. Transition to S1b requires physical rulers. Logical topology cannot claim proximity that would exceed causal reach (comparison envelope) when validated at S1b.
Calibration criterion: Transition from S1a to S1b is achieved when logical coordinates map to metric observables with documented SI traceability and stated measurement uncertainty. Until this criterion is satisfied, coordinates remain S1a structures regardless of whether they use physical proxies (e.g., RTT).
Foundational discipline: Graph theory and network science provide the mathematical structures for logical spatial labelling and adjacency vectors. Database indexing, memory addressing, and overlay network routing in computer science are direct applications of S1a structure.
6.2 Tier S1b — Physical rulers
Purpose: Read proper length from the spacetime metric using physical apparatus.
Realisation: Interferometers, optical cavities, VLBI baselines, satellite laser ranging (SLR).
Properties:
Proper length is defined with respect to a specified simultaneity slice (typically the ruler's instantaneous rest frame in flat spacetime); the slice choice is part of the measurement protocol (details deferred to coastline)
Rulers measure metric separation, not coordinate distance
Baseline comparisons reveal spatial geometry
External constraints (citation-only):
SI metre (BIPM, defined via c and second)
ITRF realisations (IERS)
Geodetic reference ellipsoids
Inheritance from parent: When comparing baselines using any probe (light-based, clock-based, or other), the comparison is bounded by L_comparison ≤ cτ. The envelope is inherited, not re-derived.
Foundational discipline: Geodesy and space geodetic techniques (VLBI, SLR, GNSS) provide the operational infrastructure for Tier S1b. These disciplines define how the SI metre is realised on planetary scales.
6.3 Tier S2 — Map Lock (coordination)
Purpose: Convert spatial measurements into named regions for human coordination.
Lock structure:
Partition
Divide space into nameable regions
Hierarchy
Nest regions (continent → country → city → address)
Reference point
Anchor to datum (meridian, reference ellipsoid, origin marker)
Enumeration
Assign names, codes, postal identifiers
Updates
Revise for datum shifts, boundary changes, tectonic motion
Properties:
Maps are conventions, not physics
Reference-frame realisations (e.g., ITRF2020) are external constraints, citation-only
Administrative boundary changes do not alter metric structure
Foundational discipline: Geodesy and navigation provide the ITRF and geodetic datums that anchor the Map Lock to physical measurements. Cartographic conventions and administrative geography then build coordination layers on this foundation.
7. Symmetry and Asymmetry
7.1 Structural symmetries
Logical layer
T1a (Lamport/vector clocks)
S1a (grids/SAVs)
✔ both provide relational structure without metric
Physical layer
T1b (clocks)
S1b (rulers)
✔ both read metric via apparatus
Coordination lock
T2 (Calendar)
S2 (Map)
✔ both use identical lock structure
Comparison envelope
inherited
inherited
✔ both bounded by parent envelope
7.2 Necessary asymmetries
Dimensionality
1 dimension
3 dimensions
Space admits direction; time does not branch
Proper quantity
Proper time τ (path integral along worldline)
Proper length (rest-frame, slice-specified)
τ accumulates along path; length requires simultaneity slice
Causal role
Time orders cause and effect
Space separates simultaneous events
Causal precedence is temporal, not spatial
Reversibility
Thermodynamic arrow (out of scope)
Spatial isotropy (no preferred direction)
Time has an arrow; space (locally) does not
Apparatus
Oscillators accumulate phase
Interferometers compare paths
Fundamentally different measurement operations
Logical structure
Causal history (vector clocks) — provably minimal
Topological signature (SAVs) — varies in formal strength
Both metric-free; differ in guarantee level
7.3 Asymmetry implications
The asymmetries are not defects in the architecture; they reflect genuine physical differences between temporal and spatial aspects of spacetime:
Clocks integrate; rulers compare. A clock accumulates proper time along its worldline. A ruler compares two endpoints at (approximately) the same coordinate time. These operations are not interchangeable.
Causal order is temporal. The statement "A caused B" implies A is in B's past light cone—a temporal relation. Spatial separation alone cannot establish causation.
Dimensionality affects coordination. Calendar Lock manages one-dimensional enumeration (past → future). Map Lock manages three-dimensional hierarchy (nested regions). The lock structure is identical; the dimensionality of the partitioned space differs.
Logical structures serve different purposes with different guarantees. Vector clocks answer "what happened before what?" with provable minimality. SAVs answer "what is adjacent to what?" with varying formal strength depending on implementation. Both are metric-free but address distinct organisational needs with distinct rigour profiles.
Proper quantities differ in character. Proper time τ is a path integral—it accumulates along a worldline and is observer-independent once the path is specified. Proper length requires specifying a simultaneity slice (which events count as "simultaneous" endpoints); in curved spacetime or under relativistic motion, this slice choice is part of the measurement protocol. This asymmetry is fundamental, not merely procedural.
Cross-disciplinary implication: These asymmetries persist in structural analogues. Causal ordering is always temporal in character; spatial adjacency cannot substitute for temporal priority. Domain frameworks that conflate the two lose the structure this scaffold provides.
8. Degradation Pathways
Both siblings degrade toward the parent scaffold, not away from it:
Degradation rule: Loss of a higher tier does not invalidate lower tiers or the parent. An agent who loses calendar conventions retains clock readings; losing clock access retains logical ordering; losing all temporal coordination retains local causal structure.
The same applies spatially: losing maps retains measurement; losing measurement retains SAVs and logical labels; losing all spatial coordination retains local causal structure.
Terminal state: An agent reduced to parent-only access can still distinguish causal past from causal future and recognise local metric neighbourhoods. This is the irreducible minimum.
Structural template for epistemic reliability: The degradation pathway models fallback under uncertainty:
When calendar dating is disputed, fall back to relative chronology (T1a)
When timestamps are contested, fall back to causal sequence (vector clocks detect what is concurrent vs ordered)
When synchronised systems fail, fall back to Lamport ordering
When maps are unavailable, fall back to physical measurement or SAV-based topology
When metric distance is unknown, fall back to adjacency vectors for connectivity
9. Architectural Control Parameter
The parameter:
η(τ) = L_comparison / cτ
measures the fraction of the causal envelope utilised during any comparison process. It applies equally to temporal comparisons (clock-to-clock) and spatial comparisons (baseline-to-baseline), since both are bounded by the same parent envelope.
η near 1: comparison approaches the causal limit (maximum reach, highest noise susceptibility)
η near 0: comparison well within causal access (shorter reach, lower noise susceptibility)
Dual status of η:
As derived observable: Given a comparison protocol, η can be measured empirically. It characterises where within the comparison envelope a given protocol operates.
As design coordinate: Protocols can be designed to target specific η values, trading reach against noise susceptibility.
The comparison envelope (L_comparison ≤ cτ) is the falsifiable constraint. η is not itself a candidate boundary but a parameter that describes protocol behaviour within that boundary. The scaffold takes no position on whether any particular η value is "optimal"—this depends on apparatus, noise environment, and application requirements.
Domain of validity: η's optimal value depends on the dominant noise sources (oscillator instability, channel noise, latency jitter) and on whether the protocol is communication-limited or oscillator-limited. Different apparatus classes and comparison strategies will have different η_opt values.
Deferred to handbooks: Optimisation of η for specific apparatus (optical clocks, VLBI, interferometers) and determination of η_opt under various noise models belongs in comparison-protocol handbooks, not in this structural scaffold.
10. Cross-Disciplinary Structural Templates
This section distinguishes between foundational disciplines that define or stress-test scaffold tiers and applied disciplines that inherit the structure without modifying it. This prevents the scaffold from becoming a "theory of everything" while preserving its utility as a "theory of measurement and comparison."
10.1 Foundational disciplines (explicit anchors)
Foundational disciplines are custodians of registry constraints for one or more scaffold tiers. They maintain the standards, proofs, and reference-frame realisations that the scaffold cites. If the scaffold's constraints were violated, these disciplines would lose their primary methodology.
Distributed systems / Computer science
T1a, S1a
Custodian of Lamport clock proofs, vector clock correctness, graph-embedding guarantees
Metrology / Relativistic physics
T1b, S1b
Custodian of SI second, SI metre, and operational definitions anchoring measurement to g_{μν}
Geodesy / Navigation
S1b, S2
Custodian of ITRF realisations, VLBI/SLR infrastructure, geodetic datums
Quantum information theory
Parent scaffold
Custodian of no-signalling theorem; clarifies entanglement/envelope interaction
Timekeeping authorities (IERS, BIPM)
T2
Custodian of Calendar Lock reference points (epochs, leap seconds) and update rules
These disciplines are first responders: changes to their standards propagate through the scaffold via the external constraints registry (§12). A redefinition of the SI second would update Tier T1b; a new ITRF realisation would update Tier S2.
10.2 Applied disciplines (downstream consumers)
Applied disciplines inherit the scaffold's structure without modifying it. They stress-test consistency within their evidentiary regimes but do not revise the registry. Their domain authority does not extend to redefining scaffold tiers.
History / Archaeology
Use Calendar Lock and causal structure to organise timelines. Consumers of "when" but do not define the second.
T1a (sequence), T2 (periodisation)
Archival sciences / Provenance
Use causal chain of custody for documentary evidence. Apply T1a ordering to records.
T1a, T2, S1a, S2
Law / Jurisprudence
Use Map Lock and Calendar Lock for jurisdiction and evidence. Consume "where/when" for social order but do not define the metre.
T2, S2
Neuroscience
Use causal partitioning to map neural information flow. Operate within the parent scaffold's causal structure.
Parent (causality), T1a (spike ordering)
Sociology / Politics
Use coordination locks for administrative partitioning. Tier 2 consumers of the architecture.
T2, S2
Economics
Use Calendar Lock for fiscal periods and Map Lock for market boundaries.
T2, S2
Applied disciplines retain full domain authority over their evidence standards, interpretive frameworks, and explanatory models. The scaffold offers structure, not jurisdiction. A historian judges what counts as adequate dating evidence; a lawyer determines legal standards of proof; a neuroscientist decides what constitutes neural causation.
10.3 The shared problem
Every discipline that reasons about events faces three questions:
When did it happen? (temporal location)
Where did it happen? (spatial location)
How do we compare observations made at different times and places? (comparison procedure)
Foundational disciplines provide the most rigorous answers at their respective tiers. Applied disciplines inherit these answers and adapt them to domain-specific evidence bases.
10.4 What the scaffold provides as template
Tier separation: Distinguish logical ordering/labelling (Tier 1a) from physical measurement (Tier 1b) from coordination conventions (Tier 2). This prevents conflation of what is observed with how it is named.
Lock patterns: The five-stage lock (Partition → Hierarchy → Reference → Enumeration → Updates) applies wherever raw observations are converted into named, sharable categories.
Degradation logic: When higher-tier conventions fail or are disputed, fall back to lower tiers. This models epistemic reliability under uncertainty.
Inheritance: Domain frameworks can be checked for consistency with more fundamental layers. A legal timeline that violates causal ordering is internally incoherent; a historical chronology that ignores physical dating constraints is epistemically weaker.
10.5 Caution on cross-disciplinary mapping
Domain-specific applications are structural analogues, not identity claims. The scaffold provides:
a template for tier separation
a model for inheritance and fallback
a pattern for coordination locks
It does not claim that historical chronology is relativistic proper time, that legal jurisdiction is spacetime localisation, or that neural spike ordering is Lamport timestamping. The mapping is structural: the same organisational pattern applied to different evidence bases with different authority structures.
Domain authority remains with domain experts. Foundational disciplines are custodians of registry constraints; applied disciplines stress-test consistency within their domains. Neither subsumes the other.
11. Open Frontiers
11.1 Physics frontiers
Quantum field theory + gravity
Parent scaffold specifies classical limit; emergent proposals must recover metric + causality
Discrete spacetime (causal sets, spin foams)
Comparison envelope may require reformulation if continuum assumption fails
Quantum reference frames
Sibling projections may require superposition of frames; parent scaffold remains backdrop
Relativistic quantum information
Comparison envelope interpretation must accommodate entanglement-assisted protocols (see §2.4)
11.2 Cross-disciplinary frontiers
AI temporal reasoning
Extend Lamport/vector clock ordering to continuous time; integrate with physical clock access
Distributed spatial systems
Extend SAV frameworks to dynamic topologies; integrate with physical distance calibration
Neural causality
Map spike-timing windows onto comparison envelope analogues
Computational history
Formalise chronological reasoning using tier structure
Legal AI
Automate jurisdiction determination using Map Lock / Calendar Lock patterns
Multi-agent coordination
Generalise comparison envelope to distributed consensus bounds
12. External Constraints Registry
Relativity
Special relativity, causal structure
Einstein 1905; Minkowski 1908
Relativity
General relativity, metric dynamics
Einstein 1915; standard texts
Time metrology
SI second
BIPM SI Brochure
Time metrology
TAI/UTC, leap seconds
IERS Conventions
Time metrology
Pulsar timing
IPTA data releases
Space metrology
SI metre
BIPM SI Brochure
Space metrology
ITRF realisations
IERS Conventions
Space metrology
VLBI, SLR techniques
IERS Technical Notes
Geodesy
Reference ellipsoids, datums
IAG resolutions
Distributed systems
Lamport clocks
Lamport 1978
Distributed systems
Vector clocks
Fidge 1988; Mattern 1989
Distributed systems
Vivaldi coordinates
Dabek et al. 2004
Graph theory
Graph embeddings, landmark routing
Standard texts
Quantum information
No-signalling theorem
Standard QIT texts
All entries are citation-only: this scaffold presupposes them but does not govern, re-derive, or modify them.
13. Open Items
Registry naming convention
Council ratification
BLOCKING
Critical
Tier T1a coastline (Lamport/vector clocks)
tier-t1a-logical-clocks.md
Drafted
—
Tier S1a coastline (logical grids/SAVs)
tier-s1a-logical-grids.md
Not drafted
High
Tier T1b coastline (physical clocks)
tier-t1b-physical-clocks.md
Not drafted
Medium
Tier T2 coastline (Calendar)
tier-t2-calendar.md
Drafted
—
Tier S1b coastline (physical rulers)
tier-s1b-physical-rulers.md
Not drafted
Medium
Tier S2 coastline (Maps)
tier-s2-maps.md
Not drafted
Medium
Comparison-envelope falsifiability
Research note
Deferred
Low
Syndrome set: "meaningful comparison"
Handbook (incl. quantum-assisted protocols)
Deferred
Medium
SAV syndrome set
Handbook (minimum graph data for topological position)
Deferred
Medium
SAV formal classification
Coastline specification (exact/approximate/heuristic)
Deferred to S1a coastline
High
η optimisation protocols
Handbook
Deferred
Low
Applied-discipline handbooks
Domain-specific applications (history, law, neuro)
Not drafted
Low
Foundational-discipline liaison
Coordinate with IERS, BIPM, distributed systems community
Ongoing
Medium
Registry naming convention — Council decision required:
The navigation footer implements parent-scaffold-causal-structure.md (parent-first naming), while legacy documents use tier-0-causal-structure.md (tier-only naming). Council must ratify one convention before coastline drafting proceeds:
A (parent-first)
parent-scaffold-..., tier-t1a-..., tier-s1a-...
Reflects parent-first architecture; legacy Tier 0 superseded
B (tier-only)
tier-0-..., tier-t1a-..., tier-s1a-...
Maintains backward compatibility; parent = Tier 0
C (hybrid)
spacetime-parent-scaffold.md + tier-...
Compromise naming
Guardian recommendation: Option A with alias stub. Ratify parent-first naming; retain tier-0-causal-structure.md as a thin redirect/alias stub that forwards to parent-scaffold-causal-structure.md. This preserves backward compatibility without compromising parent-first semantics.
Note on document types: Overviews and summaries are handbooks (navigation documents). Coastlines are boundary-defining documents with falsifiability targets. The two are complementary but not interchangeable.
Note on tier naming: This document uses T1a/T1b/T2 for temporal tiers and S1a/S1b/S2 for spatial tiers. All coastline filenames should follow this convention.
14. Risk Register
Cross-disciplinary layer misread as physics claim
§10.5 caution; endorsement marker distinguishes interpretive mappings; foundational/applied split clarifies authority
Mitigated
Foundational disciplines not consulted
§13 includes liaison item; external constraints registry cites authoritative sources
Ongoing
Applied disciplines feel subsumed
§10.2 explicitly preserves domain authority; scaffold offers structure, not jurisdiction
Mitigated
"Foundational" criterion read as gatekeeping
§10.1 reframed as registry custodianship; operationally checkable
Mitigated
Comparison envelope falsifiability underspecified
§2.4 operational anchor defines comparison event; delayed-comparison clause added; syndrome set deferred to handbook
Mitigated
"True by definition" attack on envelope
§2.4 delayed-comparison clause shows envelope binds whenever comparison occurs
Mitigated
Co-located comparison misreading
§2.4 parenthetical clarifies "classical communication" includes local wiring
Mitigated
Proper length definition contested in curved spacetime
§6.2 notes slice-dependence; §7.2 updated; details deferred to coastline
Mitigated
η parameter appears tautological
§9 clarifies dual status (observable + design coordinate) and cost-function dependence
Mitigated
Registry evolution creates version confusion
§13 flags Council decision as BLOCKING; recommends Option A + alias stub
Active
S1a lacks formal depth relative to T1a
SAV framework explicit in §6.1 with formal-guarantee classification; detailed specification deferred to coastline
Mitigated
SAV "complete topological position" overstates rigour
§6.1 reframed as "topological signature relative to chosen reference structure"
Mitigated
Vivaldi coordinates boundary ambiguity
§6.1 explicitly marks Vivaldi as hybrid proxy at S1a/S1b boundary
Mitigated
S1a→S1b transition criterion unclear
§6.1 calibration criterion added: SI traceability + stated uncertainty
Mitigated
"Ruler" terminology collision
"Ruler" reserved for S1b (physical measurement); SAV terminology adopted for S1a
Monitored
Council/Guardian idioms unfamiliar to external readers
§1 note added mapping idioms to standard roles
Mitigated
15. Council Sufficiency
Parent scaffold established before siblings
✔
Both siblings introduced together
✔
Tier boundaries explicit for both siblings
✔
Symmetries enumerated
✔
Asymmetries enumerated and justified
✔
Comparison envelope at parent level
✔
Comparison event operationally defined
✔
Co-located comparison clarified
✔
Delayed-comparison clause included
✔
η parameter dual status clarified
✔
Quantum-assisted protocols clarified
✔
Proper length slice-dependence explicit
✔
Vector clocks explicitly included (T1a)
✔
Spatial adjacency vectors explicitly included (S1a)
✔
SAV "topological signature" phrasing (no overclaim)
✔
SAV formal-guarantee classification introduced
✔
S1a→S1b calibration criterion explicit
✔
T1a/S1a structural parallel established
✔
T1a/S1a formal-rigour asymmetry acknowledged
✔
Foundational disciplines as registry custodians
✔
Applied disciplines' domain authority preserved
✔
External constraints citation-only
✔
Degradation pathways parent-consistent
✔
Cross-disciplinary caution prominent
✔
Risk register included and updated
✔
No metaphysical overreach
✔
Tier naming standardised
✔
Registry naming flagged for Council ratification
✔
Option A + alias stub recommended
✔
Council/Guardian idioms glossed for external readers
✔
16. How to Use This Document
For foundational-discipline specialists
Your discipline is a custodian of registry constraints for one or more scaffold tiers. Sections 5–6 specify the tier structure; §10.1 identifies your custodianship role. Changes to your standards (e.g., SI redefinition, new ITRF realisation, updated vector-clock proofs) propagate through the scaffold via the external constraints registry (§12).
For physicists and metrologists
Begin with Sections 2–7. The comparison envelope (§2.4) and architectural control parameter (§9) are the novel contributions requiring scrutiny. Tier T1b and S1b coastlines will specify apparatus-level detail.
For quantum gravity researchers
Section 2.2 (metric structure) and Section 11.1 (physics frontiers) frame the scaffold as a classical benchmark. The scaffold does not prejudge emergence vs. fundamentality; it specifies what must be recovered at scales where classical structure is observed.
For distributed systems researchers
Sections 5.1 (Lamport and vector clocks), 6.1 (SAVs and logical grids), and 10.1 (foundational disciplines) show how your work anchors Tier 1a for both siblings. The scaffold formalises the relationship between logical ordering/topology and physical measurement. Note the formal-guarantee classification in §6.1—your input on SAV rigour requirements is welcome.
For applied-discipline researchers
Section 10.2 is your entry point. Identify which tiers your discipline consumes. The tier structure (logical → physical → conventional) and lock patterns (Calendar, Map) offer organisational templates. Section 8 (degradation) models epistemic reliability under uncertainty. Your domain authority is preserved; the scaffold offers structure, not jurisdiction.
For historians, archivists, and legal scholars
You are applied-discipline consumers (§10.2). The Calendar Lock and Map Lock patterns (§5.3, §6.3) provide templates for organising temporal and spatial evidence. Section 8 (degradation) models what to do when dating or localisation is contested.
For everyone
The scaffold answers: "What is the most rigorous available framework for locating events in time and space, and for comparing observations across separation?" Foundational disciplines are custodians of the registry; applied disciplines stress-test consistency within their domains. Whatever your domain, if you reason about when, where, and how to compare, this scaffold provides structural templates. Adapt them to your evidence base and standards of proof.
Spacetime Architecture — Unified Scaffold | Open-Science Harbour
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