arXiv:1102.5192gr-qc
On the unreasonable effectiveness of the post-Newtonian approximation in gravitational physics
Early discovery. Linked by one identifiable commenter. This paper is outside the main ranking; a mention is not an endorsement.
Abstract
The post-Newtonian approximation is a method for solving Einstein's field equations for physical systems in which motions are slow compared to the speed of light and where gravitational fields are weak. Yet it has proven to be remarkably effective in describing certain strong-field, fast-motion systems, including binary pulsars containing dense neutron stars and binary black hole systems inspiraling toward a final merger. The reasons for this effectiveness are largely unknown. When carried to high orders in the post-Newtonian sequence, predictions for the gravitational-wave signal from inspiraling compact binaries will play a key role in gravitational-wave detection by laser-interferometric observatories.
tl;dr on this long comment: the article is about a 1960s mistake and how a paper demonstrates an improved model Earth that has non-uniform density can do better than the simplest fix. New Scientist gets an important bit of science wrong, surprise. And some links to even deeper…
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