Cosmic Textures Squeeze Spacetime Torsion to Its Tightest Limit Yet

Spacetime may be far from the smooth, frictionless stage that Einstein imagined. In the century since Cartan first proposed that geometry could twist as well as curve, physicists have struggled to say how strong that twist—torsion—actually is in the universe around us. Now a theoretical study published in The European Physical Journal C has taken an unusual route to answering that question, using some of the most exotic structures cosmology has to offer: global textures, cosmic strings, and the gravitational waves detected by LIGO. The result is a bound on torsion so small that it outperforms even the most sensitive laboratory searches conducted to date.

The work, carried out by L. C. Garcia de Andrade of the Institute for Cosmology and Natural Philosophy, builds on the teleparallel equivalent of General Relativity, known as TEGR. Teleparallel gravity is mathematically equivalent to Einstein’s theory in its predictions, but it reformulates gravity in terms of torsion rather than curvature. Where general relativity describes gravity as the bending of spacetime, teleparallelism describes the same physics as a twisting of the internal frames that define direction and orientation at every point. Because the two pictures agree on observable outcomes, teleparallelism offers a complementary mathematical toolkit—one that makes certain questions about torsion, which are invisible in the standard formulation, suddenly tractable.

The heart of the new analysis lies in a class of topological defects called global textures. These are remnants of the early universe, formed when a quantum field that once filled all of space settled into its present state in a non-uniform way. Textures are thought to have seeded clumps of matter in galaxies and the voids between them, and they carry a characteristic energy scale set by the symmetry-breaking field. Crucially, the author treats textures not just as gravitational sources but as seeds of dynamical dark energy, drawing on earlier ideas that torsion could mimic the repulsive gravity associated with the universe’s accelerated expansion—a connection first explored by Gasperini in Einstein–Cartan cosmology and extended by Wanas to dark energy scenarios.

To extract a numerical constraint, the study matches an interior solution—a global texture obeying Einstein’s field equations—to an exterior flat spacetime, using the Israel–Lichnerowicz matching conditions generalized to Einstein–Cartan geometry. These conditions demand that the metric be continuous across the boundary and that the jump in its first derivatives be balanced by torsion. Working in null coordinates, the so-called light-cone approximation where the coordinate u equals t minus r, the author simplifies the matching equations dramatically. The texture metric used is the Notzold solution, characterized by a small parameter epsilon equal to eight pi G eta squared, where eta is the symmetry-breaking scale, bounded above by roughly ten to the eighteen GeV.

The payoff is striking. Applying the matching conditions to the angular part of the metric, and adopting the tachyonic approximation in which the radial coordinate exceeds the time coordinate, the torsion trace component T-squared-sub-1-2 comes out bounded below ten to the minus forty-four GeV. That is thirteen orders of magnitude tighter than the ten to the minus thirty-one GeV limit that Kostelecky and collaborators obtained in 2008 using dual maser experiments to search for torsion-induced Lorentz violation. The key to the estimate is identifying the texture correlation length with the inverse of the Hubble constant, roughly ten to the minus forty-two GeV in natural units, which converts the geometric matching condition into a cosmological bound. A second, independent component of the torsion trace, denoted K, is found to be approximately half of the first, confirming the internal consistency of the framework.

The analysis then turns to cosmic strings, the line-like cousins of textures. In teleparallel gravity, the connection splits into a Riemannian part and a contortion tensor, and with the teleparallel spin connection set to zero, the geodesic equation can be written entirely in terms of contortion. For a cosmic string metric with tension G mu, the contortion component K-sub-3-1-3 reduces to a simple expression involving the string tension and the radial coordinate. Plugging in the observational bound on string tension, eight G mu less than or equal to eight times ten to the minus seven, and taking a characteristic distance of one parsec, the author recovers a torsion trace bound of ten to the minus twenty-four per second—remarkably, the same order of magnitude that Nitsch derived in 1979 using metric-affine gravity and the physics of spinning particles on Earth.

Perhaps the most visually evocative result concerns what happens to particles near a torsion-carrying string. Solving the geodesic equations shows that a test particle moving in the plane orthogonal to the string follows a planar spiral, with angular velocity equal to one minus eight G mu divided by the radius. The author interprets this two-dimensional spiral as the projection of a three-dimensional Cartan spiral staircase, a structure previously explored by Alexander, Jenks, and Magueijo in the context of parity-violating cosmology. Because the radial acceleration is positive when the integration constant is positive, the teleparallel string is repulsive rather than attractive—reinforcing the picture of torsion-laden defects as candidates for the dark energy that drives cosmic acceleration. In this scenario, particles do not fall into the defect; they are flung outward while winding around it like threads on a screw.

The final strand of the argument connects torsion to gravitational waves, bringing the analysis into contact with real detector data. Gravitational waves propagating through teleparallel spacetime induce torsion waves, and the relation between the wave amplitude and the torsion component takes a simple form: the strain is proportional to the torsion divided by the gravitational-wave frequency. For cosmological gravitational waves at frequencies around ten to the minus seven hertz, a torsion of ten to the minus twenty-four per second implies a strain of order ten to the minus seventeen, comfortably within the sensitivity band of modern interferometers. For black-hole merger signals at higher frequencies near ten to the minus five hertz, the predicted torsion-induced strain drops to about ten to the minus twenty-three, close to the ten to the minus twenty-one strains actually recorded by the LIGO–Virgo collaboration. Using Rumpf’s older terrestrial bound of ten to the minus fifteen per second instead would amplify the predicted strain to ten to the minus eight, illustrating how dramatically torsion can enhance gravitational-wave amplitudes and how future detectors might discriminate between torsion scenarios.

Beyond the numbers, the study sketches a broader vision in which topological defects serve as laboratories for physics that no particle accelerator can reach. The author notes that the torsion–Hubble connection hinted at in the texture bound may even bear on the Hubble tension, the persistent discrepancy between different measurements of the universe’s expansion rate, following recent proposals that torsion condensates could alleviate the conflict. Future work, the paper suggests, will extend the framework to Einstein–Cartan–Kalb–Ramond gravity, where a fully antisymmetric three-index field introduces axion-like torsion, and to hybrid defects such as domain walls threaded by cosmic strings, including strings threading teleparallel wormholes.

For now, the headline result stands: by treating cosmic textures as gravitational matching problems in null coordinates, teleparallel gravity delivers the most stringent constraint yet on a component of Cartan torsion, pushing it below ten to the minus forty-four GeV. Whether nature actually exploits torsion at any measurable level remains open, but the study demonstrates that the universe’s largest structures—defects stretched across cosmic horizons—can probe its subtlest geometric twists with a precision that rivals, and in this case surpasses, the finest instruments ever built. If torsion exists, the spiral staircases winding through spacetime just got a great deal harder to hide.

Subject of Research: Constraints on Cartan spacetime torsion from teleparallel topological defects and gravitational waves

Article Title: Torsion constraints driven by TEGR topological defects in null coordinates, GWs and matching conditions

Article References: de Andrade, L. C. G. (2026). Torsion constraints driven by TEGR topological defects in null coordinates, GWs and matching conditions. The European Physical Journal C, 86(9), Article 1038. https://doi.org/10.1140/epjc/s10052-026-15957-w

Image Credits: AI Generated

DOI: 10.1140/epjc/s10052-026-15957-w

Keywords: torsion, teleparallel gravity, TEGR, cosmic textures, cosmic strings, topological defects, dark energy, gravitational waves, LIGO, Einstein-Cartan theory, matching conditions, contortion