Talk:Einstein field equations
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Whether the geodesic equation is dependent on EFE?
To Michael C Price (talk · contribs): You said "GE is independent of EFE." and provided a reference. Although many people say that they are independent, none-the-less they are not. See Post-Newtonian expansion which has an external link to "ON THE MOTION OF PARTICLES IN GENERAL RELATIVITY THEORY" by Albert Einstein and Leopold Infeld. Basically, each elementary particle is viewed as a (possibly charged) (possibly rotating) black-hole — a gravitational monopole. The ability to match these local solutions to the surrounding metric field, without introducing gravitational dipoles and thus negative energy, uniquely determines the motion of the particles. JRSpriggs (talk) 21:02, 27 September 2011 (UTC)
- That shows that disturbances in the metric are determined by the EFEs, as we would expect, but says nothing about actual particles. I think most physicists would concede that particles are more than just metric distortions, despite Einstein's love of the idea. -- cheers, Michael C. Price talk 21:47, 27 September 2011 (UTC)
Please note the image,
Meanwhile there is an invariant (basis free) formulation of curvature structures (by Singer and Thorpe) and hence an invariant formulation of the field equations. In this formulation the Lorentzgroup easily is chased around the structures. The index notation here is disgusting and not very powerful! — Preceding unsigned comment added by 220.127.116.11 (talk) 18:12, 29 June 2012 (UTC)
EFE in spinor formalism
- I would be interested in that, if you know enough about it to write a section on it. JRSpriggs (talk) 06:41, 23 December 2013 (UTC)
Should the equations be named after Einstein, Hilbert, or both?
IP user 12.72.186.xx has twice changed the name of the equations from "Einstein field equations (EFE)" to "Einstein-Hilbert field equations (EHFE)". His edit summaries explain this by saying "Einstein field equations should correctly read Einstein-Hilbert field equations with Hilbert having them before Einstein in the form of Hamilton's principle" and "Hilbert had the same equations before Einstein in the form of Hamilton's principle with the Ricci curvature scalar as the Lagrange density". As I said when I reverted him the first time, "whether or not Hilbert deserves credit, it is called EFE, not HFE or EHFE".
To aid the users' understanding and searches for terms, we are required to use the most common names for things (in reliable sources) regardless of the origin or technical accuracy of the name. See WP:AT for the application of this to article names. It is not appropriate to re-argue here the issues discussed at Relativity priority dispute#General relativity and History of general relativity#Einstein and Hilbert.
If you wish to change the name, please provide evidence that most reliable sources refer to the equations by a different name than that which has historically been used in this article (i.e. EFE). JRSpriggs (talk) 01:17, 31 March 2014 (UTC)
Proper definition of trace
- Calling it a trace at all is a misnomer, IMO, the result of a degree of sloppiness in terminology. A trace is really only defined on a tensor over a pair of indices of opposite variance, and the term "trace with respect to the metric" is probably an attempt to find a brief description that sort of works. I agree with the sentiment, and have made the suggested change, but would like to see a more precise description, perhaps a term involving "contraction" rather than "trace". —Quondum 20:33, 14 April 2015 (UTC)