Magnetic effects in general relativity: quadrupoles, shear and memory

Adam D. Helfer

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Magnetic effects in general relativity: quadrupoles, shear and memory

Adam D. Helfer

General Relativity and Quantum Cosmology · Submitted 18 Jul 2019

abstract compiled · 2026-09-23 · no language-model review

The authors' main claim It is shown that the "memory tensor" is equivalent to the change in Bondi shear, from before to after the emission of radiation.

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The paper's own sentences, arranged. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

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Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-09-23: 1 request, 7,671 input tokens.

What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.90 · human participants 0.01 · controlled comparison 0.04 · randomized assignment 0.01 · states quantitative result 0.13 · compares with prior results 0.16 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; show every role.

Gravitational effect of "magnetic type" -- those having a curl-like character over large spheres -- are investigated, for isolated systems. The Bondi-Sachs-Newman-Penrose formalism clarifies a number of points, especially related to radiation memory. It is shown that the "memory tensor" is equivalent to the change in Bondi shear, from before to after the emission of radiation. This means that if magnetic radiation memory is present, at least one of the intervals bracketing the radiation must have non-zero magnetic shear but vanishing radiation. Such intervals, called here CPMS regimes, are shown to be necessarily non-stationary, however, raising a variety of technical and interpretative issues. In linearized general relativity, the gravitational fields due to point magnetic quadrupoles with arbitrary time-dependence are computed, and some of their physics studied. In the far zone, there is a red-shift effect which could be searched for astrophysically: light coming from behind a source generating magnetic shear would be red-shifted by an amount varying with the angle around the source of shear, and in the far-field limit this red-shift goes inversely with the impact parameter. Induction-zone effects are also considered. An induction-zone memory effect should exist which could possibly be within the reach of laboratory experiments, but no good candidates for astrophysically detectable effects are found. Also a quadrupole will induce test particles to move in such a fashion as to create an opposing quadrupole, an effect reminiscent of Lenz's law.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	Gravitational effect of "magnetic type" -- those having a curl-like character over large spheres -- are investigated, for isolated systems.	contribution 0.79	0.66	0.05	asserted 0.71
s1	The Bondi-Sachs-Newman-Penrose formalism clarifies a number of points, especially related to radiation memory.	method 0.90	0.27	0.04	asserted 0.99
s2	It is shown that the "memory tensor" is equivalent to the change in Bondi shear, from before to after the emission of radiation.	result 0.97	0.83	0.37	asserted 1.00
s3	This means that if magnetic radiation memory is present, at least one of the intervals bracketing the radiation must have non-zero magnetic shear but vanishing radiation.	interpretation 0.90	0.78	0.27	asserted 0.95
s4	Such intervals, called here CPMS regimes, are shown to be necessarily non-stationary, however, raising a variety of technical and interpretative issues.	result 0.54	0.87	0.14	asserted 1.00
s5	In linearized general relativity, the gravitational fields due to point magnetic quadrupoles with arbitrary time-dependence are computed, and some of their physics studied.	contribution 0.95	0.92	0.06	asserted 1.00
s6	In the far zone, there is a red-shift effect which could be searched for astrophysically: light coming from behind a source generating magnetic shear would be red-shifted by an amount varying with the angle around the source of shear, and in the far-field limit this red-shift goes inversely with the impact parameter.	result 0.96	0.84	0.09	hedged possibility 0.83
s7	Induction-zone effects are also considered.	contribution 0.98	0.69	0.02	asserted 0.65
s8	An induction-zone memory effect should exist which could possibly be within the reach of laboratory experiments, but no good candidates for astrophysically detectable effects are found.	result 0.53	0.87	0.17	hedged possibility 0.94
s9	Also a quadrupole will induce test particles to move in such a fashion as to create an opposing quadrupole, an effect reminiscent of Lenz's law.	result 0.93	0.78	0.08	asserted 0.97

What kind of paper the classifier reports this is: theoretical result 1.00 · evidence from proof or derivation 1.00.

What was examined, and what was not

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arXiv listing abstract v1

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full text
figures and tables
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T body sentences
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Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

The paper

Original abstract

Gravitational effect of "magnetic type" -- those having a curl-like character over large spheres -- are investigated, for isolated systems. The Bondi-Sachs-Newman-Penrose formalism clarifies a number of points, especially related to radiation memory. It is shown that the "memory tensor" is equivalent to the change in Bondi shear, from before to after the emission of radiation. This means that if magnetic radiation memory is present, at least one of the intervals bracketing the radiation must have non-zero magnetic shear but vanishing radiation. Such intervals, called here CPMS regimes, are shown to be necessarily non-stationary, however, raising a variety of technical and interpretative issues. In linearized general relativity, the gravitational fields due to point magnetic quadrupoles with arbitrary time-dependence are computed, and some of their physics studied. In the far zone, there is a red-shift effect which could be searched for astrophysically: light coming from behind a source generating magnetic shear would be red-shifted by an amount varying with the angle around the source of shear, and in the far-field limit this red-shift goes inversely with the impact parameter. Induction-zone effects are also considered. An induction-zone memory effect should exist which could possibly be within the reach of laboratory experiments, but no good candidates for astrophysically detectable effects are found. Also a quadrupole will induce test particles to move in such a fashion as to create an opposing quadrupole, an effect reminiscent of Lenz's law.

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Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

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