# Presence Terminology Bridge: Synchronism ↔ Web4

**Date**: 2026-02-26
**Context**: Nova's refinement of ρ from "density" to "presence" in Synchronism creates a terminological collision with Web4's existing use of "presence" (LCT-witnessed existence). This document explains why the collision is actually a consistency, not a conflict.

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## Two Meanings of "Presence"

### In Synchronism (Physics Layer)

**Presence (ρ)**: A scalar representation of compatible structural elements available within a Markov Relevancy Horizon, sufficient to support emergent coherence.

- ρ = f(compatibility vector) — scalar projection of multidimensional compatibility space
- Physical density is one form of presence
- Also encompasses temperature, energy levels, catalytic surfaces, field gradients
- Defined relative to an MRH; change the MRH, presence changes
- Source: `synchronism-site/forum/nova/Refining-From-Density-to-Presence.md`

### In Web4 (Trust/Identity Layer)

**Presence (LCT)**: Witnessed existence of an entity in the trust graph. The Linked Context Token is Web4's foundational presence primitive.

- "An LCT is not an identity. It is a presence — witnessed, contextualized, and witness-hardened."
- Birth Certificates = foundational presence documents
- Presence is accumulated through witnessing, not intrinsic
- Source: `web4-standard/core-spec/LCT-linked-context-token.md`

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## Why This Is the Same Concept at Different Fractal Scales

Both definitions answer the same question: **"What is relevantly here within this boundary?"**

| Aspect | Synchronism | Web4 |
|--------|-------------|------|
| What is present? | Compatible structural elements (DOF) | Witnessed entities (LCTs) |
| Boundary | MRH (physics: correlation decay horizon) | MRH (social: RDF graph traversal depth) |
| Compatibility | Energy state alignment, field structure | Trust tensor alignment, role compatibility |
| How measured | Observable physics + domain mapping | Witnessing events + trust accumulation |
| Drives what | Coherence (collective behavior C ∈ [0,1]) | Trust (collaboration potential) |

The coupling-coherence experiment already demonstrated this bridge: the coupling parameter p (rate of information sharing between agents) maps directly to "rate of compression trust events" in Web4 terms (per `COUPLING-COHERENCE-IMPLICATIONS.md`). This IS the presence-as-compatibility framing applied to social/trust networks.

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## No Code Changes Needed

Web4's use of "presence" is not wrong — it's the social-graph instantiation of the same underlying concept. Synchronism's physics-level presence (compatible DOF within a physics MRH) and Web4's trust-level presence (witnessed entities within a social MRH) are self-similar patterns at different scales.

This is fractal leverage: the same mechanism (compatible elements within a relevancy boundary driving collective behavior) applied at the physics scale and the trust-network scale.

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## For Web4 Sessions

When working with Web4's presence/LCT system, the Synchronism refinement offers one useful insight: **presence is not just existence but compatibility**. An LCT that exists but has no compatible trust relationships within its MRH has low effective presence in the Synchronism sense. This aligns with Web4's existing "witness-hardened" model — presence accumulates through compatible witnessing, not mere creation.

## Source Documents

- `synchronism-site/forum/nova/Refining-From-Density-to-Presence.md`
- `synchronism-site/forum/nova/Refining-Markov-Relevancy-Horizon.md`
- `synchronism-site/forum/nova/linking-MRH-to-gamma.md`
- `web4-standard/core-spec/LCT-linked-context-token.md`
- `docs/history/design_decisions/COUPLING-COHERENCE-IMPLICATIONS.md`
