Talk:Spherical wave transformation

The sentence at the end of the 1st paragraph is contradictory. If the Poincare group is applicable to all phenomena, then it is applicable to ED. But if the conformal group is applicable only to ED (as asserted by the final phrase) then since the Poincare group is a sub of the Conformal group, ED is also applicable. Fix the antecedents whoever wrote this. — Preceding unsigned comment added by YouRang? (talk • contribs) 18:39, 16 July 2015 (UTC)
 * Hopefully, the text is more clear now. --D.H (talk) 19:35, 11 July 2017 (UTC)

Conformal groups
The section relating Lorentz and Mobius says:
 * "While the 15-parameter conformal group of R4 contains the Lorentz group as a subgroup,"

as introduction. This statement may be misinterpreted as the signature on R^4 makes a difference, and an all positive signature generates a conformal group involving only Euclidean angles. The reference here must be more specific to eliminate that view. The spacetime conformal group does include the Lorentz group, but the indefinite planes in R^4 involve hyperbolic angles that are respected by the Lorentz transformations. — Rgdboer (talk) 23:04, 20 July 2017 (UTC)
 * That's true - but the Lorentz group being a subgroup is already pointed out in the section "Relation to electrodynamics". So I removed that line in the new section. Please feel free to make some changes to improve the text. --D.H (talk) 06:53, 21 July 2017 (UTC)

Kelvin transform
Not many articles in this Project have as long a list of references as this one. For completeness, the origin of reciprocal radius transformation in potential theory may be acknowledged. There the term Kelvin transform is used. According to Andrew Warwick in Masters of Theory, preparations for Mathematical Tripos stimulated development of differential geometry. Coach Robert Alfred Herman taught James Jeans, and others, some of the methods that unfolded in spacetime theory later. — Rgdboer (talk) 21:06, 21 July 2017 (UTC)

Now I see it:"became better known when Thomson (1845, 1847)", citing Kastrup. The suggestive method of image charges is also mentioned by Warwick as a precursor.—Rgdboer (talk) 02:22, 22 July 2017 (UTC)