Growing document · September 2026

Discrete Emergent Gravity

An emergent picture of time, entropy, and matter coupling, derived from a single Hamiltonian constraint on discrete spacetime atoms.

Every claim tagged: postulate, definition, derivation, or proposed choice — nothing asserted by citation or analogy alone.

Matteo Pinna · Independent researcher, Madrid · ORCID 0009-0004-4078-9015 · Get in touch

The single postulate

\[H = \sum_{n=1}^{N} \left[\frac{p_n^2}{2m_{\text{atom}}} - \frac{\alpha_{\exp}}{2}\,a_n^2\right] = 0\]
The atomsSpacetime consists of \(N\) discrete constituents — "spacetime atoms." Each carries a size parameter \(a_n>0\), a conjugate momentum \(p_n\), and \(g\) internal quantum states. \(g\)'s value is left entirely free: nothing derived in this document depends on it, only on its being finite and positive. A group-theoretic origin for \(g\) is a separate, currently open question, not assumed anywhere here.
The constraintThe atoms' dynamics is governed by this single global constraint, with \(\alpha_{\exp}\) a positive constant. Nothing below depends on its numerical value, only on its existence and sign — the value itself is a disclosed, calibrated input to the cosmological sector, not derived anywhere in this document.
What this gives us, and where it's headedFrom this single postulate: emergent time and entropy, singularity avoidance, the dark energy equation of state \(w=-1\), Wheeler–DeWitt unitarity, and a proposed matter–spacetime coupling. The next target is a genuine equation of motion for matter, and from it, Newton's law and the Einstein field equations themselves. Not yet reached; the open question that gates it is below.

Results

Key results — derived from the single postulate

Result Value Status Note
Emergent time–entropy relation \(dS/d\tau = 9k_B N\) Exact algebraic identity Only a "second law" once a proposed choice fixes an expanding branch
Singularity avoidance (single atom) \(h_n(0)\le0 \Leftrightarrow\) never singular Exact condition, derived Whether a given atom itself avoids the singularity isn't fixed by the global constraint alone — it depends on that atom's own individual starting condition, not one shared across the whole system
Dark energy equation of state \(w = -1\) exactly Exact, same argument as a cosmological constant Testable now — see below
Wheeler–DeWitt unitarity York-time evolution exactly unitary; \(S_{\rm vN}\) conserved Exact, given \(H_{\rm York}\) self-adjoint Self-adjointness is one proposed choice
Matter–spacetime overlap \(O_{mn}\) Non-negative & normalized Derived, given the Born-rule coupling The coupling itself is a proposed choice, not forced
Population-level singularity statistics 72.9% of 1,404 populations, \(p=1.7\times10^{-119}\) Statistical, not deterministic 12,000 simulated atoms; rests on disclosed astrophysical inputs
Matter's reverse coupling (force law) Settles at \(r^{-2}\) only under one further proposed choice Honest partial result Coefficient off by \(\sim4.8\times\), uncalibrated — not a derivation of Newton's law

The constraint's own \(\alpha_{\exp}\) term plays the same structural role as a cosmological constant; its magnitude is a calibrated input, not derived — \(w=-1\) is the exact consequence regardless of that value. This is also this document's one falsifiable, near-term prediction — see "On falsifiable predictions" below.

By section — derived, and what each result rests on

Foundations

  • Single global constraint \(H=0\) on \(N\) discrete atoms [postulate]
  • York time \(\tau\) and Boltzmann entropy \(S\) defined from the same postulate [definition]
  • \(dS/d\tau = 9k_BN\) — exact algebraic identity, structural not dynamical [derived]
  • Reading this as a genuine second law needs the disclosed expanding-branch choice
  • Homogeneous-case singularity avoidance: exact \(C_2=0\) condition [derived]
  • General \(N\)-atom exact singularity condition, atom by atom [derived]
  • \(w=-1\) exactly, by the same argument used for an ordinary \(\Lambda\) [derived]
  • Finite-dim Hilbert space, unitary evolution, \(S_{\rm vN}\) exactly conserved [derived, given one proposed choice]

Matter coupling

  • Born-rule overlap \(O_{mn}\) (Voronoi cells) proposed as the coupling [proposed choice]
  • Non-negativity and exact normalization of \(O_{mn}\) [derived]
  • Coupling Hamiltonian \(H_{\rm coupling}\), and its \(a_n^2\) scaling — two independent proposed choices
  • More local matter monotonically pushes an atom away from singularity, toward a "bounce" instead of a collapse — a clean, one-directional effect [derived]
  • Accreting vs. receding matter: opposite fates from identical initial data [derived asymmetry; doesn't unify with the expanding-branch choice]
  • Real (Einstein–Straus) shielding from cosmic expansion: a shielding-degree threshold separates crash from rescue [disclosed toy, imported physics]
  • 12,000-atom Monte Carlo: singular atoms are statistically drawn from the more diffuse tail [derived, statistical not deterministic]

Matter dynamics investigation

  • Discrete hopping-and-recoil construction, made energy-conserving and detailed-balance-satisfying simultaneously [derived, several proposed choices]
  • Coarse-grained drift law: net attractive at large momentum, but matches neither Hooke's nor Newton's exponent, vanishes at long range [derived]
  • Independent entropic-force route (Verlinde-style construction): the identical "fits neither, vanishes at range" signature [derived]
  • Root cause traced to the source profile's Gaussian tail; a power-law profile settles the force at \(r^{-5}\), not Newton's \(r^{-2}\) [derived]
  • A further proposed choice — cumulative rather than single-atom screen entropy — reproduces the \(r^{-2}\) exponent exactly [derived, given that choice]
  • Coefficient falls short of Newton's own by \(\sim4.8\times\); not fixable by anything else on record [honest audit]
  • No equation of motion is supplied anywhere in this investigation — a genuine partial success, not a claimed derivation

On falsifiable predictions

This document offers exactly one falsifiable, near-term prediction: the dark energy equation of state \(w=-1\) exactly — testable now, since any \(5\sigma\) detection of \(w\neq-1\) by DESI or Euclid would rule it out. Everything else here is a derivation, a proposed choice, or an honest partial result: real content, but not yet a falsifiable prediction in its own right. This is a foundational, derivational core, not a phenomenology programme, and isn't trying to be judged by how many predictions it offers.

Open problems

The first three below are explicit exclusions stated in Section 9 of the document. The five after that are further open questions raised elsewhere in its body — real gaps, but not formal exclusions.

Gating open question

The \(g_{\rm eff}=1\) holographic-reduction question

Whether an atom's internal states fully decohere once information reaches a holographic screen is genuinely open, and it gates the recovery of both Newton's law and the Einstein field equations entirely — neither is derived or assumed anywhere in this document. The trend across successive, better-motivated coupling choices points toward less, not more, decoherence. This is the single most consequential open question in the current document.

Calibrated, not derived

The cosmological constant's magnitude, \(\alpha_{\exp}^{\rm cosm}\)

A fitted, calibrated input to the constraint's cosmological sector, not derived anywhere in this document. Multiple candidate first-principles derivations have been tried and found not to work; this document does not add another attempt.

Candidate — not yet decided

The area quantum, \(\Delta_A = 4\ln(g)\,\ell_P^2\)

Not excluded for being broken or for depending on the open \(g_{\rm eff}=1\) question — it is valid under the same bare postulate used throughout. What keeps it out is that its derivation imports one further external input, the Bekenstein–Hawking coefficient \(1/4\), not yet incorporated or tagged anywhere in this document. No decision has been made to add it.

Open question

The number of internal states, \(g\)

\(g\)'s value is left entirely free throughout this document — nothing derived depends on it, only on its being finite and positive. A group-theoretic origin for \(g\) from some internal symmetry structure is a separate, currently open question, not assumed or argued anywhere here.

Left symbolic

The lattice spacing, \(d\)

The spacing between neighbouring atoms is left fully symbolic everywhere it appears — not fixed by anything derived in this document. It is one of the two quantities (with the auxiliary mass parameter \(m_{\rm atom}\)) whose absence keeps the matter-dynamics investigation's force-law coefficient from being calibrated against real gravity.

Undischarged choice

\(H_{\rm York}\)'s self-adjointness

Adopted as a disclosed assumption, not derived from \(H=0\), for Wheeler–DeWitt unitarity to go through. What remains a genuine, undischarged choice is an operator-ordering convention for quantizing the leftover relative degrees of freedom, needed before self-adjointness could even be posed as a question.

Real, but unresolved

Accretion/recession asymmetry doesn't unify with the expanding branch

Whether a matter-rich atom is rescued from singularity depends, directionally and consistently, on whether its local matter is accreting or receding — a real, mechanistically-understood effect. But it does not follow from the already-adopted expanding-branch choice, and if anything argues against that choice being the source of the rescuing direction. A preferred direction still needs its own separate proposed choice, or a genuinely missing physical mechanism this document does not yet have.

No equation of motion

Matter's reverse coupling onto spacetime

The full matter-dynamics investigation — internally consistent, energy-conserving, and detailed-balance-satisfying by construction — still supplies no equation of motion for matter, and every quantitative result in it rests on several proposed choices, none forced by the bare postulate. Reported here as a genuine partial success, not a claimed derivation of any known force law.

Framework & context

DEG postulates that spacetime consists of \(N\) discrete constituents — "spacetime atoms" — each with a size parameter \(a_n\), a conjugate momentum \(p_n\), and \(g\) internal quantum states, with \(g\)'s value left entirely free. The dynamics is governed by a single global Hamiltonian constraint — no background metric, no continuous fields at the fundamental level.

From this postulate alone, the document derives: an emergent notion of time (York time) and an exact algebraic link between that time and a Boltzmann entropy; the precise condition under which a spacetime atom avoids a finite-time singularity; that the dark energy equation of state \(w=-1\) follows by the same argument used for an ordinary cosmological constant; that the theory's time evolution is exactly unitary, so a closed DEG universe loses no information; and a proposed, Born-rule-motivated matter–spacetime coupling, together with its consequences for which atoms remain singular — including a large-scale, population-level statistical result.

What is not claimed. DEG is not a complete theory of quantum gravity, and this document is a small, self-checked core that grows only as further results meet its own stated standard — every claim an explicit postulate, definition, step-by-step derivation, or proposed choice, never an assertion resting on citation or analogy alone. One calibrated numeric input is used, \(\alpha_{\exp}^{\rm cosm}\), fit to the cosmological constant's observed magnitude, not derived. Newton's law and the Einstein field equations are not derived, or assumed, anywhere in this document — their recovery is contingent on the still-open \(g_{\rm eff}=1\) question.

Active research directions

  • PriorityResolving the \(g_{\rm eff}=1\) holographic-reduction question — gates Newton's law and the Einstein field equations entirelyopen
  • PriorityDeriving \(\alpha_{\exp}^{\rm cosm}\) from first principles — several candidate routes already tried and ruled outopen
  • OpenA group-theoretic, or other, origin for \(g\) — currently left entirely freeopen
  • OpenFixing a preferred direction for the accretion/recession asymmetry, or finding the missing mechanismopen
  • OpenWhether the matter-dynamics investigation's force law can be extended into a genuine equation of motionopen

This page is updated as the document develops.

Situating the approach

Like loop quantum gravity and causal set theory, DEG takes discreteness as fundamental. It differs in using a statistical-mechanics approach: time, and its exact link to entropy, emerge from counting microstates of the atom configuration itself, not from geometric quantisation. Gravity's own recovery — Newton's law and the Einstein field equations — is not attempted here; it remains contingent on the open \(g_{\rm eff}=1\) question (see Open problems).

The dark energy equation of state \(w=-1\) follows as an exact consequence of the constraint's own structure, by the identical argument used for an ordinary cosmological constant in general relativity — independent of the calibrated input's numerical value. That input, \(\alpha_{\exp}^{\rm cosm}\), fixes only the magnitude; the exponent of state does not depend on it.

As noted above, \(w=-1\) is also the one result here with a near-term experimental handle.

The document's own standard. Every substantive claim is tagged as an explicit postulate, definition, derivation, or proposed choice. Results that don't yet meet this standard — including anything contingent on \(g_{\rm eff}=1\) — are tracked separately (Open problems) rather than discarded, and may be added here later once they do.

About

Matteo Pinna is a theoretical physicist working independently on quantum gravity and emergent spacetime. His interest in emergent gravity began during his thesis work in 2018, shaped by a conviction that the foundations of physics should admit a simple, parameter-free description — and a specific dissatisfaction with the treatment of time in general relativity.

The starting point was a refusal to accept time as a curved fourth dimension behaving differently from the other three. If space is emergent, time should be too — and the arrow of time, rather than being imposed by initial conditions, should follow from the statistics of whatever is fundamental. DEG is the formalisation of that programme, developed over several years alongside a career in technology.

Matteo Pinna

Independent researcher

Madrid, Spain

ORCID 0009-0004-4078-9015

LinkedIn

Document

DOI
Discrete Emergent Gravity: Time, Entropy, and Matter Coupling from a Single Constraint
Every derivation, proposed choice, and open question tagged throughout · doi:10.5281/zenodo.22306976
Working document · September 2026 Zenodo

This document is the primary reference for the programme. Not peer-reviewed.

Presentations

2026
Poster · Physicum, University of Tartu, Estonia · 29 June – 3 July 2026
Poster 2026 Zenodo

Poster material will be made available here via Zenodo once uploaded.

Contact

If you work in quantum gravity, emergent spacetime, or related areas and find this programme of interest, I would welcome correspondence — critical feedback especially.

matteo@deg-gravity.com

I am an independent researcher based in Madrid. Collaboration enquiries and comments from researchers with relevant expertise are very welcome.

The document above contains full derivations, every claim tagged as postulate, definition, derivation, or proposed choice, and a complete, plainly-stated list of open problems. Nothing is behind a paywall or submission requirement.

The current document — every derivation, proposed choice, and open question — is listed under Document above; DOI: 10.5281/zenodo.22306976.

If you are a physicist encountering DEG for the first time and would like to discuss the approach, its foundations, or its limitations, please feel free to write. I am also happy to share notes on specific points not fully developed in the document.