Gravitational-Wave Memory from G-Equivariance: A Ward Derivation with a Geometric Algebra Interpretation
Year: 2025
Type: article
Abstract: This preprint develops the framework of Observer-Equivariance (OE) in the context of gravitational-wave memory. Starting from the Bondi–Sachs formalism, the memory effect is derived in a way that emphasizes observer equivalence rather than background structures. The derivation clarifies the relation between the Christodoulou (nonlinear) and linear memory contributions, and shows how the OE-principle constrains asymptotic symmetries. The work also provides an interpretation in geometric algebra, where the net memory can be understood as a residual rotor. Beyond offering a novel derivation, the paper illustrates how OE unifies physical law through equivalence across perspectives. Keywords: gravitational-wave memory, BMS symmetries, observer-equivariance, asymptotic flatness, geometric algebra
Author: Ullman, Gustaf
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7081967668
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