Abstract

For more than three centuries, physics treated space and time as essential components of the universe’s fundamental architecture. Newtonian mechanics placed events within an immutable spatial arena governed by universal time. Special relativity unified space and time into a four-dimensional structure, while general relativity transformed that structure into a dynamic gravitational field. Yet the conceptual triumph of relativistic spacetime has generated one of modern physics’ deepest problems: the geometric continuum of general relativity does not appear to remain fundamental under the extreme quantum conditions associated with black holes, cosmological singularities, and the Planck scale.

A growing range of quantum-gravity programs therefore proposes that spacetime is emergent rather than fundamental. In these approaches, familiar geometry may arise from more primitive structures such as quantum entanglement, spin networks, causal relations, strings, branes, matrices, tensor networks, or collective quantum states. This article traces the historical development of spacetime concepts, analyzes the present crisis in quantum gravity, examines the principal theoretical frameworks supporting spacetime emergence, evaluates the available evidence, and considers the paradigm’s scientific and technological implications. It argues that emergent spacetime is not yet an experimentally established theory, nor even a single unified hypothesis. It is instead a convergent research program in which geometry, locality, dimensionality, gravitational dynamics, and perhaps time itself are treated as effective large-scale properties of a deeper quantum system.

Keywords: emergent spacetime, quantum gravity, quantum entanglement, holography, loop quantum gravity, causal set theory, string theory, black-hole thermodynamics

Introduction: When the Stage Becomes Part of the Play

Physics has repeatedly revised its answer to one of the most elementary questions imaginable: What are space and time? For Isaac Newton, space was an absolute container and time a universal parameter flowing independently of matter. For Albert Einstein, space and time became inseparable, observer-dependent, and ultimately dynamical. Matter no longer moved through an indifferent background; its energy and momentum altered the geometry through which it moved. Spacetime had ceased to be merely the stage of physics and had become one of its principal actors. Newton’s distinction between absolute and relative space and time framed classical mechanics, whereas Einstein’s general theory replaced that framework with a gravitational field represented by spacetime geometry itself (Einstein, 1916; Newton, 1999).

General relativity has been spectacularly successful. It accounts for the anomalous precession of Mercury, gravitational redshift, the bending of light, time dilation in gravitational fields, gravitational lensing, black holes, the dynamics of the expanding universe, and gravitational waves. The 1919 eclipse observations supplied an early test of gravitational light deflection, while a century of increasingly precise measurements has continued to support the theory. The joint detection of gravitational waves and gamma rays from the neutron-star merger GW170817, for example, constrained the propagation speeds of gravity and light to agree to an extraordinary degree (LIGO Scientific Collaboration et al., 2017).

Yet general relativity’s success may conceal the limits of the ontology it appears to describe. Its spacetime is a smooth differentiable manifold whose curvature responds continuously to matter and energy. Quantum mechanics, by contrast, describes systems through operators, probability amplitudes, superposition, uncertainty, and entanglement. When gravitational fields themselves enter the quantum regime, the classical concept of a definite geometry becomes difficult to sustain. A quantum mass can occupy a superposition of configurations; if gravity responds to that mass, the gravitational field—and perhaps spacetime geometry—must somehow participate in the superposition.

The problem is frequently summarized by saying that general relativity and quantum mechanics are incompatible. That formulation is useful but incomplete. General relativity can be treated consistently as a quantum effective field theory at ordinary energies. The genuine crisis arises in the ultraviolet regime, where curvatures and energies approach the Planck scale and the effective description ceases to be predictive without an infinite hierarchy of additional parameters. The challenge is therefore not that quantum theory and gravity can never coexist, but that their familiar low-energy combination does not supply a complete microscopic account of spacetime (Donoghue, 1994, 2012).

This conceptual crisis has encouraged a radical reversal. Instead of quantizing spacetime as though it were unquestionably fundamental, researchers increasingly ask whether spacetime resembles temperature, pressure, elasticity, or fluid flow: real and measurable, yet meaningful only at a collective scale. Temperature is not a microscopic constituent of matter. It is a statistical property arising from many microscopic degrees of freedom. Similarly, spacetime might be the macroscopic organization of quantum information or other nonclassical structures.

The purpose of this article is to examine that proposed shift from fundamental spacetime to emergent spacetime. It first traces the historical evolution from Newtonian absolutes to Einsteinian geometry and quantum uncertainty. It then analyzes the quantum-gravity crisis, explains the different meanings of emergence, evaluates the principal theoretical programs, and distinguishes mathematical evidence from observational confirmation. Finally, it considers what the paradigm could imply for cosmology, black-hole physics, quantum information, scientific methodology, and future technologies.

A crucial qualification will guide the discussion: “emergent spacetime” does not identify one theory. It can mean that a smooth continuum emerges from discrete geometric units, that metric distance emerges from quantum correlations, that gravitational dynamics emerges from thermodynamics, that spatial connectivity emerges from entanglement, or that all geometric concepts disappear from the fundamental description. Recent analyses have emphasized that the emergence of metric structure, topology, and Einsteinian dynamics are distinct claims and must not be treated as interchangeable (Jaksland, 2026).

I. Historical Context: The Evolving Conception of Spacetime

A. Spacetime as a Static Absolute: Newtonian Mechanics

1. Absolute Space and Universal Time

In the Newtonian worldview, physical objects possess positions in three-dimensional Euclidean space, while their configurations evolve according to a separate universal time parameter. Newton distinguished “absolute, true, and mathematical” space and time from the relative measurements made using clocks, bodies, and coordinate systems. Absolute time was presumed to flow uniformly, regardless of physical events. Absolute space provided the inertial structure needed to distinguish genuine acceleration from mere relative motion (Newton, 1999).

This structure made classical mechanics extraordinarily powerful. If the position and velocity of every body were specified at one moment, Newton’s laws could, in principle, determine the system’s future and reconstruct its past. Space and time were not dynamical variables. They did not absorb energy, fluctuate, bend, or respond to matter. They constituted the fixed reference architecture in which matter interacted.

Newtonian mechanics therefore implied a sharp separation between ontology and arena. Matter and forces were physical; space and time supplied the coordinates. Gravity acted instantaneously across the arena through the inverse-square law, but Newton did not provide a mechanical medium explaining that action. The resulting system was empirically successful while retaining a metaphysical asymmetry: material objects acted upon one another, but the spatial and temporal framework remained untouched.

2. Implications for the Structure of the Universe

The Newtonian universe was structurally intelligible because it was decomposable. A system could be divided into bodies, forces, positions, trajectories, and an external time parameter. Local events could be described against a global simultaneity: observers might disagree about coordinates, but they would agree on which events happened at the same time.

This framework deeply influenced later physical thinking. Even after the rise of field theory, fields were usually regarded as entities existing in space and evolving through time. The possibility that geometry itself might be a physical field—and later, that geometry might not be fundamental at all—required two conceptual revolutions.

B. From Separate Coordinates to Relativistic Spacetime

Einstein’s 1905 special theory of relativity rejected universal simultaneity. Measurements of spatial distance and temporal duration depend on the observer’s state of motion, while the speed of light remains invariant for inertial observers. Hermann Minkowski subsequently expressed the theory geometrically: space and time are not independent absolutes but components of a unified four-dimensional spacetime. Different observers divide the same spacetime into “space” and “time” differently while agreeing on invariant spacetime intervals (Minkowski, 1909).

Minkowski spacetime remained fixed and nondynamical, but it transformed the conceptual grammar of physics. A particle was no longer represented simply by a position changing in time; it traced a worldline through spacetime. Causal structure was encoded geometrically by light cones. The invariant separation between events replaced independent absolute measures of space and time.

This was more than a change in notation. It implied that simultaneity, temporal order for spacelike-separated events, and measured length are relational rather than universal. Nevertheless, the geometry of special relativity still functioned as a pre-existing background. Einstein’s next step was to remove that final rigidity.

C. The Dynamic Fabric of Reality: General Relativity

1. Spacetime as a Relational and Dynamical Structure

General relativity combines the relativity principle with the equivalence between gravitational and inertial effects. Locally, a freely falling observer experiences no uniform gravitational force. Gravity can therefore be represented not as a conventional force transmitted through spacetime, but as the manifestation of curved spacetime.

Mathematically, the gravitational field is encoded in the metric tensor (g_{\mu\nu}), which determines intervals, causal relations, volumes, clock rates, and geodesic motion. The Einstein field equations relate spacetime curvature to stress-energy:

[
G_{\mu\nu} + \Lambda g_{\mu\nu}

\frac{8\pi G}{c^4}T_{\mu\nu}.
]

The left side describes geometry; the right side represents matter and energy. The relationship is reciprocal: matter influences geometry, and geometry governs the motion of matter. Spacetime is no longer an inert container. It is a dynamical physical system (Einstein, 1916).

2. Gravitation as Curvature

A freely falling body follows a geodesic: the closest analogue to a straight path in curved spacetime. Planetary orbits, light deflection, and falling objects can therefore be described without introducing a gravitational force in the Newtonian sense. Locally, the object follows inertial motion. Globally, its trajectory appears curved because the geometry is curved.

This geometric description also changes the meaning of time. Clocks at different gravitational potentials accumulate different amounts of proper time. A clock closer to a massive body generally runs more slowly relative to one farther away. Time is not merely coordinated differently by observers; its physical rate is coupled to geometry.

3. Experimental Evidence and Theoretical Success

General relativity’s predictions have survived an extensive range of tests. These include gravitational redshift, the Shapiro time delay, frame dragging, binary-pulsar orbital decay, gravitational lensing, black-hole observations, and the direct detection of gravitational waves. The 2015 observation of GW150914 inaugurated gravitational-wave astronomy, while subsequent detections have enabled increasingly precise tests of relativistic waveforms, black-hole dynamics, and gravitational-wave propagation.

The theory’s success creates an important methodological constraint: any deeper theory must recover general relativity in the appropriate macroscopic limit. Emergent spacetime cannot merely replace Einsteinian geometry; it must explain why Einstein’s equations are such an accurate effective description across enormous ranges of scale.

D. The Quantum Realm and the Planck Scale

1. The Breakdown of Smooth Geometry

Quantum mechanics destabilizes the classical assumption that physical quantities always possess definite values. A quantum system may exist in a superposition of energy, momentum, position, or field configurations. If the source of gravity is quantum mechanical, the geometry correlated with that source may also lack a single definite classical configuration.

At ordinary energies, these effects are extremely small, and semiclassical approximations work well. Quantum fields can be studied on a prescribed curved background, and low-energy quantum corrections to general relativity can be calculated. Near the Planck scale, however, the separation between quantum matter and classical geometry becomes unreliable.

The Planck length,

[
\ell_{\mathrm{P}}=\sqrt{\frac{\hbar G}{c^3}},
]

is approximately (1.616\times10^{-35}) metres. It does not automatically prove that spacetime is discrete at that scale, but it identifies the regime in which the constants of quantum theory, relativity, and gravitation combine naturally. At such scales, attempts to localize enough energy within a sufficiently small region risk creating intense gravitational curvature or a black hole. The operational meaning of arbitrarily precise distance may therefore fail.

2. Wheeler’s Quantum Foam

John Wheeler proposed that quantum fluctuations could become so strong at the Planck scale that spacetime geometry and topology would fluctuate violently. Instead of a smooth manifold, the microscopic structure might resemble a “spacetime foam” of transient geometries, handles, and causal configurations. Wheeler’s idea was heuristic rather than a completed quantum theory, but it established a lasting intuition: the smoothness of spacetime may be a large-scale approximation, comparable to the apparent smoothness of water despite its molecular composition (Wheeler, 1957).

Modern analyses of spacetime foam investigate possible loss of coherence, phase fluctuations, modified propagation, and limits on spatial resolution. Astronomical observations have placed strong constraints on simple foam models that would generate cumulative blurring or energy-dependent photon delays. These negative results do not eliminate all microscopic spacetime structure, but they rule out or restrict some naïve phenomenological implementations (Carlip, 2023).

II. The Current Relevance: The Crisis in Quantum Gravity

A. The Tension Between General Relativity and Quantum Theory

1. Divergent Fundamental Principles

General relativity and quantum theory differ not only mathematically but conceptually. Standard quantum field theory ordinarily assumes a causal background on which fields are defined. General relativity makes the causal background itself dynamical. Quantum theory describes physical states using Hilbert spaces and operators; general relativity describes spacetime using differential geometry. Quantum evolution is normally expressed relative to time, yet in general relativity time is part of the dynamical gravitational field.

This produces the “problem of time.” In canonical approaches to quantum gravity, imposing the gravitational constraint equations can yield a formalism without an external time parameter. The universe’s quantum state appears stationary, even though observers experience change. Time may therefore need to be reconstructed relationally from correlations among subsystems rather than assumed as a fundamental background parameter.

A second tension concerns locality. Locality in quantum field theory is defined through spacetime separation. If spacetime is quantum, fluctuating, or emergent, the meaning of spatial separation may itself be state-dependent. A deeper theory may need to derive locality rather than presuppose it.

2. Singularities as Boundaries of Classical Description

General relativity predicts geodesic incompleteness under broad conditions associated with gravitational collapse and cosmology. The Hawking–Penrose singularity theorems do not necessarily establish that reality contains literal points of infinite density. They demonstrate that classical spacetime cannot be extended indefinitely under the theorem’s assumptions. The theory loses its own predictive continuation (Hawking & Penrose, 1970).

Black-hole singularities and the classical Big Bang therefore mark more than mathematically inconvenient infinities. They indicate regimes in which the smooth spacetime description becomes incomplete. A successful quantum-gravity theory should explain whether singularities are resolved, replaced by new phases, avoided through modified dynamics, or reinterpreted as boundaries of an emergent description.

B. Quantum Field Theory and Its Limits

1. Perturbative Nonrenormalizability

If the gravitational field is quantized perturbatively in the same manner as familiar particle fields, higher-energy calculations generate divergences requiring increasingly many counterterms. Pure Einstein gravity is finite on shell at one loop in special circumstances but diverges at two loops. The appearance of the Goroff–Sagnotti counterterm established that conventional perturbative quantization of general relativity is not renormalizable as a fundamental theory (Goroff & Sagnotti, 1986).

Nonrenormalizability does not make low-energy quantum gravity meaningless. Effective field theory organizes corrections as an expansion in energy divided by a high-energy scale. At sufficiently low energies, only a finite number of terms matter to a desired precision. General relativity is therefore a valid quantum effective field theory, just as hydrodynamics remains valid without being molecular physics (Donoghue, 1994).

The limitation is ultraviolet completeness. Effective field theory does not reveal the fundamental degrees of freedom responsible for its higher-order coefficients. It cannot by itself settle the microscopic nature of black holes, the initial cosmological state, or the ultimate structure of spacetime.

2. The Search for a More Complete Framework

A quantum theory of gravity must satisfy several demanding requirements:

Recover general relativity and ordinary quantum field theory in their tested domains.
Provide a consistent account of black-hole entropy and information.
Explain or resolve classical singularities.
Preserve or appropriately generalize causality and unitarity.
Identify physical observables without relying on an externally fixed geometry.
Generate testable consequences.
Explain why the observed universe has its dimensionality, signature, locality, and approximate Lorentz invariance.

A “theory of everything” is sometimes imagined as a single equation unifying all forces. The deeper challenge may be structural rather than merely algebraic. The theory may need to explain why spacetime, particles, interactions, and classical reality emerge together from a common quantum substrate.

III. The Emergent Spacetime Paradigm

A. Emergence: From Microscopic Degrees of Freedom to Macroscopic Order

1. Defining Emergence in Physics

A property is emergent when it is robustly instantiated at a collective scale but is not a property of individual microscopic components. A single molecule has no temperature, viscosity, or sound velocity. These concepts describe organized ensembles and become meaningful through coarse-graining, statistics, and long-range regularities.

Emergence does not mean illusion. Temperature is fully real despite not being fundamental. A bridge’s elastic deformation is real despite arising from electromagnetic interactions among atoms. An emergent property can possess autonomous laws that are insensitive to many microscopic details. This robustness is often explained through universality: very different microscopic systems can exhibit the same macroscopic behavior near a collective regime.

Applied to spacetime, this analogy suggests that the metric (g_{\mu\nu}) and Einstein’s equations might resemble macroscopic variables and constitutive relations. Quantizing the metric directly could then be analogous to quantizing pressure waves without recognizing atoms. Jacobson’s derivation of Einstein’s equation from horizon entropy, heat flow, and the Clausius relation strengthened this analogy by interpreting the Einstein equation as an equation of state (Jacobson, 1995).

2. Different Levels of Spacetime Emergence

The phrase “spacetime emerges” can express several different propositions:

Continuum emergence: A smooth manifold arises from discrete elements.
Metric emergence: Distance and curvature arise from correlations or information-theoretic relations.
Topological emergence: Connectivity and the number of spatial regions arise dynamically.
Dimensional emergence: The effective number of spacetime dimensions changes with scale or phase.
Dynamical emergence: Einstein’s equations arise as thermodynamic, entanglement, or hydrodynamic laws.
Temporal emergence: Time arises relationally from correlations, change, or entanglement.
Locality emergence: Local interactions arise from an underlying system that is not spatially organized.
Full ontological emergence: The fundamental theory contains no spacetime variables at all.

These claims are not equivalent. A causal set retains a primitive causal order. Loop quantum gravity quantizes geometric quantities. AdS/CFT can describe a gravitational spacetime through a nongravitational theory living in fewer dimensions. Group field theory may begin from quantum building blocks whose collective phase resembles a continuum. Each realizes a different relationship between fundamental and effective structure (Jaksland, 2026; Oriti, 2021).

B. Spacetime from Quantum Entanglement

1. Entanglement as Geometric Glue

Quantum entanglement describes correlations that cannot be reduced to independently existing states of subsystems. In holographic theories, the entanglement structure of a nongravitational quantum state is mathematically related to geometric areas in an emergent gravitational spacetime.

The central relation is the Ryu–Takayanagi formula:

[
S_A=\frac{\mathrm{Area}(\gamma_A)}{4G_N\hbar},
]

where (S_A) is the entanglement entropy of a boundary region (A), and (\gamma_A) is an extremal surface in the higher-dimensional gravitational bulk. The equation extends the logic of black-hole entropy: geometric area encodes quantum information (Ryu & Takayanagi, 2006).

Van Raamsdonk argued that reducing entanglement between sectors of a holographic quantum system causes the corresponding bulk regions to separate geometrically. In the limit of vanishing entanglement, a connected spacetime can pinch apart. Entanglement therefore appears to function as a form of geometric connectivity or “glue” in these models (Van Raamsdonk, 2010).

This does not prove that all spacetime in our universe is literally made of entanglement. The best-developed results occur in holographic settings, especially asymptotically anti-de Sitter spacetimes, which differ from the observed accelerating universe. Nevertheless, the mathematical precision of the correspondence has transformed entanglement from a peripheral quantum phenomenon into a central candidate for explaining geometry.

2. Qubits and Spacetime Networks

Popular descriptions sometimes claim that spacetime is “made of qubits.” This is suggestive but should be qualified. A qubit is an abstract two-level quantum system, not necessarily a literal microscopic object occupying a pre-existing location. In tensor-network and quantum-error-correction models, qubits or higher-dimensional quantum variables can represent the underlying information from which geometric relationships are reconstructed.

A network’s pattern of entanglement can encode effective adjacency, scale, and distance. Strongly correlated subsystems may correspond to nearby bulk regions, while weakly correlated sectors may appear geometrically distant. The network is not embedded in the emergent space in the ordinary sense. Rather, the pattern of quantum relations helps define what “near” and “far” mean.

Takayanagi’s recent synthesis emphasizes that an enormous entangled quantum system can encode a gravitational bulk, while also noting unresolved problems involving realistic cosmology, time dependence, reconstruction, and the microscopic interpretation of the degrees of freedom (Takayanagi, 2025).

C. Loop Quantum Gravity

1. Discreteness of Quantum Geometry

Loop quantum gravity begins from general relativity’s background independence and seeks a nonperturbative quantization of geometry. Its fundamental variables are related to connections and fluxes rather than small perturbations around a fixed metric.

Geometric operators such as area and volume possess discrete spectra. This does not mean that space is a simple cubic lattice. The quantum states of geometry are combinatorial and relational, with possible superpositions of graphs, labels, and connectivity. Smooth geometry is expected to arise in semiclassical states involving large numbers of quantum-geometric excitations.

Rovelli and Smolin showed that spin-network states provide a basis in which geometric operators can be expressed and that these states support a discrete picture of quantum geometry at the Planck scale (Rovelli & Smolin, 1995).

2. Spin Networks and Spin Foams

A spin network is a graph whose edges carry representations of a symmetry group and whose vertices carry invariant coupling data. Roughly, edges contribute quanta of area, while vertices contribute quanta of volume. The graph does not merely sit inside an independently existing classical space; it represents a quantum state of spatial geometry.

Spin-foam models describe histories or transitions among spin networks. In this sense, a spin foam is analogous to a sum over quantum spacetime histories. The central challenge is demonstrating that the collective large-scale limit reliably reproduces four-dimensional general relativity, realistic matter, and observed low-energy physics.

Loop quantum gravity illustrates a relatively conservative form of emergence. Geometry remains central at the microscopic level, but its smooth continuum form is not fundamental. Related group-field-theory approaches can advance a stronger emergence claim: a macroscopic universe may behave like a condensate of many quantum-geometric constituents excited above a “no-space” vacuum (Gielen & Sindoni, 2016).

3. Singularity Resolution in Loop Quantum Cosmology

Loop quantum cosmology applies symmetry-reduced techniques inspired by loop quantum gravity to cosmological models. In important homogeneous and isotropic models, quantum-geometric effects replace the classical Big Bang singularity with a bounce connecting a contracting branch to an expanding branch (Ashtekar et al., 2006).

This is significant evidence that discrete quantum geometry can alter the classical singular regime. It is not, however, a general proof that the full theory resolves every cosmological or black-hole singularity. Symmetry reduction, state selection, quantum backreaction, inhomogeneity, and the relationship between reduced models and full loop quantum gravity remain active research problems.

D. String Theory and M-Theory

1. Strings, Branes, and Extra Dimensions

String theory replaces pointlike fundamental particles with one-dimensional strings whose vibrational modes correspond to different particles. A massless spin-two excitation behaves like a graviton, allowing gravity to arise naturally within the spectrum.

Consistency requires additional structures, including extra dimensions, supersymmetry in many formulations, and extended objects known as branes. D-branes became central after Polchinski demonstrated that they carry Ramond–Ramond charges and are intrinsic nonperturbative objects in string theory (Polchinski, 1995).

M-theory is believed to unify the five consistent superstring theories through dualities. In certain limits, spatial dimensions can grow, shrink, or exchange physical interpretations. What counts as geometry in one description may appear as field content, matrix variables, or strongly coupled dynamics in another.

2. Why String Dualities Suggest Emergent Spacetime

Duality means that two apparently different theories describe the same physics. If equivalent formulations use different geometries, dimensions, or topologies, no single classical spacetime description can be regarded as uniquely fundamental.

The BFSS matrix-model conjecture, for example, proposes that aspects of eleven-dimensional M-theory can be defined through the large-(N) limit of supersymmetric matrix quantum mechanics. Extended spatial objects and gravitational interactions then arise from matrix degrees of freedom rather than being inserted as a fundamental continuous spacetime (Banks et al., 1997).

The strongest realization of spacetime emergence in string theory is the anti-de Sitter/conformal field theory correspondence. Maldacena proposed that certain gravitational string theories in a higher-dimensional anti-de Sitter bulk are equivalent to nongravitational conformal field theories on the lower-dimensional boundary (Maldacena, 1998).

The radial bulk dimension has no direct counterpart as an ordinary spatial direction in the boundary theory. It is associated with scale and renormalization-group structure. Bulk geometry, gravity, and locality therefore emerge from a quantum system formulated without dynamical gravity in the same number of dimensions.

3. Black-Hole Microstates

String theory achieved an important milestone when Strominger and Vafa counted microscopic states for a class of extremal five-dimensional black holes and reproduced the Bekenstein–Hawking entropy. The calculation did not solve the entropy problem for every astrophysical black hole, but it demonstrated that a geometric entropy formula could arise from counting underlying quantum states (Strominger & Vafa, 1996).

This result supports the general proposition that horizon geometry is thermodynamic and statistical. The area of a black-hole horizon appears to summarize a deeper microscopic organization rather than constitute the final level of explanation.

E. Causal Set Theory

1. Discrete Spacetime Elements

Causal set theory proposes that the fundamental structure is a locally finite partially ordered set. Its elements represent elementary events, while the order relation represents causal precedence. Local finiteness ensures that a finite spacetime volume corresponds to a finite number of elements.

The guiding intuition is that causal order and volume are sufficient, under suitable conditions, to reconstruct much of Lorentzian geometry. The continuum is not fundamental; it is an approximation to a discrete causal order, much as a fluid continuum approximates molecular matter (Bombelli et al., 1987; Surya, 2019).

2. Causal Ordering as Fundamental

Causal set theory preserves a primitive notion of “before” and “after” while abandoning continuous distance. This distinguishes it from theories in which even causal structure is emergent.

A major concern for discrete theories is Lorentz invariance. A regular lattice would select preferred directions and frames. Causal sets instead use random Lorentz-invariant sprinklings into continuum spacetimes. This avoids a simple preferred lattice frame but introduces characteristic nonlocality. Recovering local continuum dynamics and identifying manifold-like causal sets remain major challenges.

F. Entanglement-Based Models and ER=EPR

1. Entanglement and Geometry

Holographic entanglement has encouraged models in which geometry is reconstructed from mutual information, entanglement entropy, modular flow, tensor networks, or quantum error-correcting codes. In such models, geometric distance is not imposed first. It is inferred from the structure of correlations.

Work on “space from Hilbert space” has explored conditions under which locality and approximate spatial geometry can be recovered from factorization and entanglement patterns in a quantum state. These approaches are valuable because they formulate the problem in information-theoretic terms: what properties must a quantum system possess for observers within it to experience a smooth local space?

2. ER=EPR and Wormhole Connectivity

The ER=EPR conjecture proposes a relationship between Einstein–Rosen bridges and Einstein–Podolsky–Rosen entanglement. Maldacena and Susskind argued that two maximally entangled black holes can be interpreted as connected by a nontraversable wormhole, suggesting that geometric connection and quantum entanglement are two descriptions of related underlying structure (Maldacena & Susskind, 2013).

ER=EPR is a conjecture, not a universal theorem. Ordinary entangled particles have not been shown to be connected by traversable microscopic tunnels in familiar spacetime. The proposal is best understood as a statement about the encoding of connectivity in a quantum-gravitational description, particularly within holographic models.

A 2022 quantum-processor experiment simulated the dynamics of a simplified holographic system mathematically dual to a traversable-wormhole protocol. The experiment did not create a physical wormhole in laboratory spacetime. It demonstrated that quantum computation can reproduce dynamics with both a quantum-information interpretation and a dual gravitational interpretation (Jafferis et al., 2022).

IV. Evidence and Support for Emergent Spacetime

A. Theoretical Consistency and Explanatory Power

1. Black-Hole Thermodynamics

The most persuasive general evidence for spacetime microstructure comes from black-hole thermodynamics. Bekenstein proposed that black holes possess entropy proportional to horizon area. Hawking subsequently showed that quantum fields near black holes produce thermal radiation, assigning black holes a physical temperature (Bekenstein, 1973; Hawking, 1975).

The resulting entropy relation,

[
S_{\mathrm{BH}}=\frac{k_{\mathrm{B}}c^3A}{4G\hbar},
]

is remarkable because it combines thermodynamics, quantum theory, gravitation, and geometry. Entropy normally counts microscopic possibilities compatible with a macroscopic state. If black-hole entropy follows the same logic, horizon area is a coarse-grained measure of hidden quantum degrees of freedom.

The area law does not uniquely identify those degrees of freedom. String theory, loop quantum gravity, induced-gravity models, entanglement entropy, and other programs provide different microscopic interpretations. Nevertheless, the existence of a universal geometric entropy strongly suggests that classical geometry has an underlying statistical description.

2. Einstein’s Equation as Thermodynamic or Entanglement Dynamics

Jacobson’s derivation of Einstein’s field equation from local horizon thermodynamics suggests that gravitational dynamics may be analogous to hydrodynamic laws. Later work connected variations of entanglement entropy with linearized gravitational equations in holographic settings.

These results do not establish that all gravity is “just entropy,” nor do they mean that gravity is a conventional force caused by disorder. They demonstrate that Einsteinian dynamics can emerge as a consistency condition linking information, energy flow, horizons, and geometry. That structural convergence is difficult to dismiss as accidental.

3. Singularity Resolution

Several quantum-gravity models replace classical singularities with finite quantum phases, bounces, transitions, or extended objects. Loop quantum cosmology provides explicit bounce solutions in symmetric models. String theory replaces pointlike probes with extended strings and introduces dual descriptions that can smooth some geometric pathologies. Causal and discrete approaches avoid assuming arbitrarily small continuum regions.

However, “singularity resolution” can mean different things: bounded curvature, deterministic evolution, finite observables, geodesic extension, absence of divergent states, or replacement by nongeometric dynamics. A model satisfying one criterion may fail another. Claims of complete resolution should therefore be limited to the relevant class of models rather than generalized to full quantum gravity.

4. Holography and the Black-Hole Information Problem

Holographic methods have generated major progress on the entropy of Hawking radiation. Calculations involving quantum extremal surfaces, entanglement islands, and replica wormholes reproduce the Page curve expected for unitary black-hole evaporation in tractable models (Almheiri et al., 2020; Penington, 2020).

These calculations imply that the division between a black-hole interior and its external radiation is subtler than semiclassical locality suggests. Information associated with an apparently interior region can be encoded in distant radiation degrees of freedom. Geometry behaves like a quantum error-correcting representation rather than a fundamental partition of independent spatial subsystems.

The island results are powerful theoretical evidence for the holographic organization of quantum gravity. Yet they are principally derived in simplified gravitational models and controlled anti-de Sitter settings. They do not constitute direct observations of evaporating astrophysical black holes.

B. Observational Hints and Null Results

1. Cosmological Signatures

The early universe is a natural laboratory for quantum gravity because its classical description approaches extreme density and curvature. Candidate signatures include:

modifications of the primordial scalar or tensor power spectra;
suppression or oscillations at large angular scales;
non-Gaussian correlations;
a primordial gravitational-wave background;
scale-dependent dimensionality;
remnants of a cosmological bounce;
modified dispersion or propagation;
topological defects or nonlocal correlations.

Loop quantum cosmology and related models can produce characteristic modifications to primordial perturbations. Some parameter choices remain compatible with cosmic-microwave-background observations, and certain models have been explored as explanations for low-multipole anomalies. Compatibility, however, is not detection. Inflationary initial conditions, cosmic variance, foregrounds, and model flexibility create substantial degeneracy.

Causal dynamical triangulation provides another theoretical hint: numerical models exhibit scale-dependent spectral dimension, with effective dimension decreasing near the microscopic regime. Similar dimensional reduction appears in several otherwise different quantum-gravity programs. This convergence is intriguing, although it has not yet been observationally established (Ambjørn et al., 2005).

2. Gravitational-Wave Astronomy

Gravitational waves offer several possible tests of quantum-gravity-inspired physics. Researchers search for modified dispersion, Lorentz violation, extra polarizations, deviations in black-hole ringdowns, near-horizon echoes, frequency-dependent propagation, and departures from the Kerr geometry.

To date, gravitational-wave observations have remained broadly consistent with general relativity. Catalog analyses have tightened constraints on modified dispersion and other deviations without producing compelling evidence for quantum-spacetime effects. This absence is scientifically valuable: it eliminates parameter regions and forces emergent-spacetime models to reproduce relativistic propagation with high precision.

The multi-messenger observation GW170817/GRB 170817A was particularly restrictive. The gravitational-wave and gamma-ray signals arrived within seconds after travelling for roughly 130 million years, constraining fractional differences between the speeds of gravity and light to approximately parts in (10^{15}), subject to assumptions about source-emission timing (LIGO Scientific Collaboration et al., 2017).

3. Lorentz-Invariance Tests

Some models of discrete or foamy spacetime predict energy-dependent photon speeds or modified particle dispersion. Gamma-ray bursts and ultrahigh-energy photons provide long propagation distances and extreme energies with which to test such effects.

Observations of GRB 090510 with the Fermi Gamma-ray Space Telescope found no evidence for the simplest linear Planck-scale variation in photon speed and imposed strong lower bounds on the associated quantum-gravity scale (Abdo et al., 2009).

PeV gamma rays observed by LHAASO have generated still stronger constraints on classes of Lorentz-violating particle and photon dispersion. These results do not disprove emergent spacetime as a category. Many emergent or discrete models preserve Lorentz invariance exactly or approximately. They do show that microscopic discreteness cannot automatically be equated with observable preferred-frame effects (Li & Ma, 2022).

4. Quantum-Gravity Experiments with Mesoscopic Masses

Proposed tabletop experiments aim to place small masses in spatial quantum superpositions and test whether their gravitational interaction generates entanglement. Under locality assumptions, entanglement mediated between two systems is often interpreted as evidence that the mediator possesses nonclassical degrees of freedom (Bose et al., 2017; Marletto & Vedral, 2017).

A successful experiment could provide evidence that gravity cannot be described solely as a classical channel. It would not by itself prove that spacetime is emergent, identify the correct microscopic theory, or distinguish every model of quantum gravity. Recent analyses have emphasized that the inference depends on assumptions about locality, mediation, and the allowed classical–quantum dynamics (Martín-Martínez & Perche, 2023).

V. Practical and Future Implications

A. A Conceptual Revolution in Physics

1. Redefining Fundamental Reality

If spacetime is emergent, physical existence cannot be fundamentally organized by objects occupying locations at moments. Location and duration would be derived properties. The deeper ontology might consist of algebraic relations, quantum states, causal order, information-processing constraints, amplitudes, or combinatorial structures.

This would challenge the ordinary hierarchy in which matter exists inside spacetime. Matter and spacetime might instead emerge together from a common substrate. A particle could be an excitation pattern within the same underlying system whose collective correlations generate geometry.

The paradigm would also revise reductionism. Traditional reduction seeks smaller objects inside larger objects. Emergent spacetime suggests that deeper description may not mean smaller objects located at shorter distances, because distance itself may cease to be fundamental. The ultraviolet limit could be more abstract rather than merely smaller.

2. Implications for Cosmology

An emergent-spacetime cosmology may replace the question “What happened at the first instant?” with “Under what conditions did a spacetime phase become meaningful?” The Big Bang could represent a transition between phases, the onset of geometric order, a bounce, or the boundary of a classical approximation rather than the creation of everything from a point.

Dimensionality may also be dynamical. Some models exhibit an effective dimension that changes with scale, while others allow phases with no continuum geometry. The familiar three spatial dimensions may be selected by stability, entropy, renormalization-group flow, or the dynamics of the underlying quantum state.

Emergence could also reshape the interpretation of inflation and dark energy. It is conceivable that accelerated expansion reflects collective properties of quantum geometry or horizon information. Such ideas remain highly speculative and must compete with the empirical success of standard cosmology.

3. Implications for Black Holes

Black holes are likely to remain the principal theoretical laboratories of spacetime emergence. They combine strong gravity, horizons, thermodynamics, quantum fields, information, and causal structure.

If interior geometry is encoded nonlocally in external quantum degrees of freedom, then classical localization fails in a controlled way. The black-hole information problem becomes not merely a question about radiation but a question about how spacetime regions are encoded in quantum states.

Future advances may clarify whether horizons represent phase boundaries, quantum error-correcting structures, entanglement patterns, condensate interfaces, or transitions between geometric and nongeometric regimes.

B. Potential Technological Advancements

1. Quantum Simulation of Gravitational Models

The most credible near-term technological connection lies in quantum simulation. Quantum processors may simulate strongly coupled systems with holographic gravitational descriptions, tensor networks, lattice gauge theories, matrix models, or simplified black-hole dynamics.

Such simulations do not generate astrophysical gravity or manipulate real wormholes. Their value is epistemic and computational: they allow researchers to study quantum systems whose dual mathematical description resembles gravitational dynamics.

The Jafferis et al. experiment illustrates this possibility. A small quantum circuit reproduced signatures associated with a traversable-wormhole teleportation protocol in a simplified holographic model. Future fault-tolerant processors could explore larger models, test conjectured dualities, and calculate strongly coupled dynamics that are inaccessible to classical computation.

2. Quantum Error Correction and Robust Information

Holographic spacetime has been fruitfully interpreted through quantum error correction. Bulk information can be redundantly encoded in boundary degrees of freedom so that the same bulk operator may be reconstructed from different boundary regions. This resembles the robustness of spacetime: local geometric information can persist despite the loss of some microscopic data.

Even if the emergent-spacetime hypothesis is ultimately incomplete, its mathematical tools may advance quantum coding, many-body physics, tensor-network algorithms, and fault-tolerant computation. The flow of influence is bidirectional: quantum information helps explain gravity, while gravitational duality inspires new quantum-information structures.

3. Why “Engineering Spacetime” Remains Speculative

Claims that emergent spacetime will enable warp drives, macroscopic wormholes, antigravity devices, or controllable changes to geometry are not supported by current evidence. No accepted theory shows that manipulating entanglement in laboratory systems directly reshapes external spacetime on useful scales.

The energy, coherence, and control required to influence genuine quantum-gravitational degrees of freedom may be unattainable. Moreover, if spacetime emerges collectively, its macroscopic stability may make it exceptionally resistant to local microscopic manipulation—just as rearranging a few molecules does not redirect an ocean current.

Responsible technological discussion should therefore distinguish:

simulations of gravitational duals;
precision tests of quantum gravity;
quantum-information tools inspired by holography;
actual manipulation of physical spacetime.

Only the first three belong to credible current research.

C. Ongoing Research and Expert Communities

Emergent-spacetime research is distributed across institutions and disciplinary boundaries. Major communities work in holography and string theory, loop quantum gravity and spin foams, causal sets, group field theory, quantum cosmology, tensor networks, quantum information, mathematical relativity, gravitational-wave phenomenology, and laboratory tests of gravity.

Researchers associated with foundational developments include Abhay Ashtekar, Jacob Bekenstein, Raphael Bousso, Sumati Surya, Juan Maldacena, Carlo Rovelli, Lee Smolin, Rafael Sorkin, Leonard Susskind, Tadashi Takayanagi, Mark Van Raamsdonk, Erik Verlinde, and many others. The field is not organized around one consensus model. Its strength lies partly in the interaction among programs that begin from different assumptions.

Institutions such as the Perimeter Institute, the Institute for Advanced Study, the Max Planck Institute for Gravitational Physics, the Kavli Institute for Theoretical Physics, CERN theory groups, Caltech, Harvard, Cambridge, Penn State, and numerous international quantum-information laboratories support relevant research. Perimeter’s tensor-network initiative, for example, explicitly connects entangled quantum matter, holography, and emergent spacetime.

D. Unanswered Questions and Major Debates

1. What Is the Fundamental Substrate?

Entanglement is a relation among quantum subsystems, but a decomposition into subsystems is often required before entanglement can be defined. If spatial regions emerge from entanglement, what determines the initial subsystem structure? Are the fundamental entities qubits, algebras, matrices, causal events, spin-network nodes, strings, or something not yet conceived?

This is not semantic. Different substrates generate different dynamics, symmetries, observables, and experimental predictions.

2. Can Time Emerge?

Spatial emergence is conceptually difficult, but temporal emergence is harder. Quantum mechanics ordinarily presupposes evolution in time. A theory in which time emerges must explain change without relying circularly on a prior temporal parameter.

Relational approaches define time through correlations: one subsystem functions as a clock relative to another. Other programs treat the arrow of time as thermodynamic or entanglement-driven. Whether these methods recover the full causal, temporal, and experiential structure of relativistic spacetime remains unresolved.

3. How Does Lorentzian Signature Emerge?

A realistic theory must explain why the observed universe has one temporal and three large spatial dimensions and why its local geometry has Lorentzian rather than Euclidean signature. It is insufficient to produce an abstract graph or metric. The theory must recover light cones, causal propagation, stable matter, and approximate Lorentz invariance.

4. Why Does Einstein Gravity Dominate?

Many microscopic models can produce collective behavior, but few demonstrate convincingly that their low-energy limit is precisely general relativity with the observed matter content and cosmological constant. Recovering Einstein’s equations is therefore a central selection criterion.

Universality may help. Just as many molecular systems exhibit the same hydrodynamic equations, many quantum substrates might flow toward Einsteinian gravity at large scales. Demonstrating such a universality class would be a major breakthrough.

5. Is AdS/CFT Applicable to Our Universe?

AdS/CFT is the most precise framework for emergent gravitational spacetime, but the observed universe is not asymptotically anti-de Sitter. It has a positive cosmological constant and appears to approach de Sitter-like expansion.

A complete theory must generalize holographic insights to realistic cosmology. Proposals involving de Sitter holography, celestial holography, finite-region holography, and observer-dependent descriptions are active but less developed.

6. Is Emergence Explanatory or Merely Dual?

In an exact duality, both descriptions are mathematically equivalent. Calling one side “fundamental” and the other “emergent” may introduce an interpretive hierarchy not contained in the mathematics.

Some researchers therefore argue that holography shows the non-uniqueness of spacetime descriptions rather than a simple one-way derivation of space from information. Others maintain that a nongravitational boundary formulation provides a genuine microscopic definition of the gravitational bulk.

7. Where Are the Distinctive Predictions?

The largest criticism of quantum-gravity research is the scarcity of decisive experiments. Many candidate theories reproduce known low-energy physics and differ only near inaccessible scales. A scientific paradigm becomes compelling when it generates risky, distinctive predictions rather than post hoc compatibility.

Progress therefore depends on linking microscopic proposals to observables in cosmology, gravitational waves, black holes, particle propagation, quantum sensors, and laboratory entanglement experiments.

VI. Research Priorities for the Next Phase

A. Bridging Theoretical Frameworks

The major programs may describe different sectors or phases of a deeper theory rather than mutually exclusive alternatives. Spin networks, tensor networks, causal structures, matrix models, and holographic codes all employ relational or combinatorial information. Establishing precise mappings among them could reveal shared universality classes.

Promising bridges include:

group field theory as a second-quantized formulation related to spin networks;
tensor-network representations of holographic geometry;
quantum-error-correction interpretations of bulk locality;
causal structures within path-integral and discrete approaches;
thermodynamic and entanglement derivations of gravitational dynamics;
matrix and brane models providing nonperturbative definitions of string/M-theory.

The goal should not be to blur genuine differences. It should be to identify which features are model-dependent and which recur because they are necessary for any viable quantum spacetime.

B. Developing Testable Predictions

A credible test should distinguish a theory from both general relativity and competing quantum-gravity models. Useful targets include:

model-specific primordial spectra;
polarization patterns in a stochastic gravitational-wave background;
frequency-dependent gravitational-wave propagation;
black-hole ringdown deviations;
horizon-scale correlations in next-generation imaging;
controlled violations or deformations of locality;
distinctive decoherence laws;
discrete-spectrum effects in quantum geometry;
quantum-gravity-induced entanglement;
scale-dependent effective dimensionality.

Predictions must be accompanied by uncertainty estimates, environmental noise models, and clear statements of what a null result excludes.

C. Experimental and Observational Strategies

Future progress will likely come from combining several observational windows rather than relying on a single Planck-scale experiment.

Next-generation gravitational-wave observatories—including space-based interferometers, third-generation ground-based instruments, and pulsar-timing arrays—will test propagation and strong-field dynamics across broad frequency ranges. Precision cosmology may constrain primordial tensor modes, non-Gaussianity, and large-scale anomalies. Black-hole imaging may test near-horizon structure. Atomic interferometry, optomechanics, levitated masses, and quantum clocks may probe increasingly weak gravitational effects in coherent systems.

Quantum computers will provide a complementary route. They can simulate holographic models, lattice gauge theories, matrix systems, and strongly entangled states. These experiments will not replace astronomical observation, but they may expose the internal dynamics of candidate models and help determine which theoretical signatures are robust.

Conclusion: Beyond the Geometry of the Familiar

The history of spacetime is a history of progressively removing structures once assumed to be self-evident. Newton transformed motion into a mathematical science but retained absolute space and universal time. Einstein dissolved universal simultaneity, unified space and time, and made geometry dynamical. Quantum theory then challenged the assumption that any physical structure—including geometry—must possess a single definite classical state.

The present quantum-gravity crisis does not invalidate general relativity. It places the theory in a new explanatory hierarchy. General relativity may be to quantum spacetime what elasticity is to atomic matter: an extraordinarily accurate macroscopic theory whose variables are collective rather than fundamental.

Several independent lines of reasoning motivate this possibility. Black-hole entropy associates geometry with microscopic information. Hawking radiation unites horizons and thermodynamics. Jacobson’s argument relates Einstein’s equation to an equation of state. String dualities show that different spacetime descriptions can encode the same physics. AdS/CFT provides explicit examples in which a gravitational bulk is represented by a nongravitational quantum theory. Holographic entanglement connects area to entropy. Loop quantum gravity replaces smooth geometry with quantum-geometric states. Causal set theory reconstructs a continuum from discrete causal order. Group field theory explores spacetime as a condensate. Replica wormholes and entanglement islands reveal that semiclassical spatial partitions do not coincide straightforwardly with the underlying quantum encoding.

These achievements amount to substantial theoretical support—but not experimental proof. No observation has yet demonstrated that spacetime is emergent, identified its microscopic constituents, or selected one candidate theory. Many apparent signatures, including Lorentz-violating dispersion, have instead been tightly constrained. The empirical situation demands intellectual discipline: emergence is a serious scientific paradigm, not a license to treat every geometric metaphor as established physics.

The most important future task is to convert structural insight into discriminating prediction. Candidate theories must recover known spacetime, explain why Einstein gravity is universal at large scales, and identify observations that could prove them wrong. Quantum sensors, gravitational-wave astronomy, precision cosmology, black-hole observations, and quantum simulation provide complementary paths toward that goal.

If the paradigm is correct, the deepest layer of reality may contain no distances, durations, locations, or geometric objects in the familiar sense. Space may be an expression of relationship. Time may be an ordering extracted from correlation and change. Gravity may be the collective dynamics of information or quantum geometry. The universe would not fundamentally consist of things placed within spacetime. Things and spacetime would be mutually emergent patterns within a deeper quantum architecture.

Such a transition would rival the Newtonian and Einsteinian revolutions. It would not simply add a new component to physics. It would change the framework within which the word component has meaning.

References

Abdo, A. A., Ackermann, M., Ajello, M., Asano, K., Atwood, W. B., Axelsson, M., Baldini, L., Ballet, J., Barbiellini, G., Baring, M. G., Bastieri, D., Bechtol, K., Bellazzini, R., Berenji, B., Bignami, G. F., Blandford, R. D., Bloom, E. D., Bonamente, E., Borgland, A. W., … Fermi LAT Collaboration. (2009). A limit on the variation of the speed of light arising from quantum gravity effects. Nature, 462, 331–334.

Almheiri, A., Hartman, T., Maldacena, J., Shaghoulian, E., & Tajdini, A. (2020). Replica wormholes and the entropy of Hawking radiation. Journal of High Energy Physics, 2020(5), Article 13.

Ambjørn, J., Jurkiewicz, J., & Loll, R. (2005). The spectral dimension of the universe is scale dependent. Physical Review Letters, 95(17), Article 171301.

Ashtekar, A., Pawlowski, T., & Singh, P. (2006). Quantum nature of the Big Bang. Physical Review Letters, 96(14), Article 141301.

Banks, T., Fischler, W., Shenker, S. H., & Susskind, L. (1997). M theory as a matrix model: A conjecture. Physical Review D, 55(8), 5112–5128.

Bekenstein, J. D. (1973). Black holes and entropy. Physical Review D, 7(8), 2333–2346.

Bombelli, L., Lee, J., Meyer, D., & Sorkin, R. D. (1987). Space-time as a causal set. Physical Review Letters, 59(5), 521–524.

Bose, S., Mazumdar, A., Morley, G. W., Ulbricht, H., Toroš, M., Paternostro, M., Geraci, A. A., Barker, P. F., Kim, M. S., & Milburn, G. (2017). Spin entanglement witness for quantum gravity. Physical Review Letters, 119(24), Article 240401.

Cao, C., Carroll, S. M., & Michalakis, S. (2017). Space from Hilbert space: Recovering geometry from bulk entanglement. Physical Review D, 95(2), Article 024031.

Carlip, S. (2023). Spacetime foam: A review. Reports on Progress in Physics, 86(6), Article 066001.

Donoghue, J. F. (1994). General relativity as an effective field theory: The leading quantum corrections. Physical Review D, 50(6), 3874–3888.

Donoghue, J. F. (2012). The effective field theory treatment of quantum gravity. AIP Conference Proceedings, 1483, 73–94.

Einstein, A. (1916). Die Grundlage der allgemeinen Relativitätstheorie [The foundation of the general theory of relativity]. Annalen der Physik, 49, 769–822.

Gielen, S., & Sindoni, L. (2016). Quantum cosmology from group field theory condensates: A review. SIGMA, 12, Article 082.

Goroff, M. H., & Sagnotti, A. (1986). The ultraviolet behavior of Einstein gravity. Nuclear Physics B, 266(3–4), 709–736.

Hawking, S. W. (1975). Particle creation by black holes. Communications in Mathematical Physics, 43(3), 199–220.

Hawking, S. W., & Penrose, R. (1970). The singularities of gravitational collapse and cosmology. Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences, 314(1519), 529–548.

Jacobson, T. (1995). Thermodynamics of spacetime: The Einstein equation of state. Physical Review Letters, 75(7), 1260–1263.

Jafferis, D., Zlokapa, A., Lykken, J. D., Kolchmeyer, D. K., Davis, S. I., Lauk, N., Neven, H., & Spiropulu, M. (2022). Traversable wormhole dynamics on a quantum processor. Nature, 612, 51–55.

Jaksland, R. (2026). Spacetime from entanglement: The emergence of metric, gravitational dynamics, and topological connectivity. arXiv preprint arXiv:2607.09823.

LIGO Scientific Collaboration, Virgo Collaboration, Fermi Gamma-Ray Burst Monitor, & INTEGRAL. (2017). Gravitational waves and gamma-rays from a binary neutron star merger: GW170817 and GRB 170817A. The Astrophysical Journal Letters, 848(2), Article L13.

Maldacena, J. (1998). The large (N) limit of superconformal field theories and supergravity. Advances in Theoretical and Mathematical Physics, 2, 231–252.

Maldacena, J., & Susskind, L. (2013). Cool horizons for entangled black holes. Fortschritte der Physik, 61(9), 781–811.

Marletto, C., & Vedral, V. (2017). Gravitationally induced entanglement between two massive particles is sufficient evidence of quantum effects in gravity. Physical Review Letters, 119(24), Article 240402.

Martín-Martínez, E., & Perche, T. R. (2023). What gravity-mediated entanglement can really tell us about quantum gravity. Physical Review D, 108(10), Article L101702.

Minkowski, H. (1909). Raum und Zeit [Space and time]. Physikalische Zeitschrift, 10, 104–111.

Newton, I. (1999). The Principia: Mathematical principles of natural philosophy (I. B. Cohen & A. Whitman, Trans.). University of California Press. (Original work published 1687)

Oriti, D. (2021). Tensorial group field theory condensate cosmology as an example of spacetime emergence in quantum gravity. Studies in History and Philosophy of Science, 90, 236–250.

Penington, G. (2020). Entanglement wedge reconstruction and the information paradox. Journal of High Energy Physics, 2020(9), Article 2.

Polchinski, J. (1995). Dirichlet-branes and Ramond–Ramond charges. Physical Review Letters, 75(26), 4724–4727.

Rovelli, C., & Smolin, L. (1995). Spin networks and quantum gravity. Physical Review D, 52(10), 5743–5759.

Ryu, S., & Takayanagi, T. (2006). Holographic derivation of entanglement entropy from AdS/CFT. Physical Review Letters, 96(18), Article 181602.

Strominger, A., & Vafa, C. (1996). Microscopic origin of the Bekenstein–Hawking entropy. Physics Letters B, 379(1–4), 99–104.

Surya, S. (2019). The causal set approach to quantum gravity. Living Reviews in Relativity, 22, Article 5.

Takayanagi, T. (2025). Emergent holographic spacetime from quantum information. Physical Review Letters. Advance online publication.

Van Raamsdonk, M. (2010). Building up spacetime with quantum entanglement. General Relativity and Gravitation, 42(10), 2323–2329.

Wheeler, J. A. (1957). On the nature of quantum geometrodynamics. Annals of Physics, 2(6), 604–614.

From Fundamental Spacetime to Emergent Spacetime: A Paradigm Shift in the Architecture of Reality