Ọ gosipụtara na Lorentz's equations of electrodynamics were not fully Lorentz-covariant. N'ihi ya, ọ rụtụrụ aka na njirimara ndị otu nke mgbanwe ahụ, wee dozie usoro Lorentz maka mgbanwe nke njupụta ụgwọ na njupụta nke ugbu a (nke nwere usoro mgbakwunye ọsọ ọsọ, nke ọ gbakwunyere na May na akwụkwọ ozi na Lorentz). Poincaré jiri okwu ahụ bụ "Lorentz Event", wee nye ha usoro symmetrical. Ọ bipụtara ụbọchị a ọnwa asaa. O jiri ụkpụrụ na-abụghị nke eletriki nke a ga-ebipụta mgbe e mesịrị, na Jenụwarị 1906. O gosipụtara na nchikota nke ndị na-abụghị ndị na-agbanwe agbanwe (nke a na-akpọ "Poincaré) na-arụ ọrụ na-eme ka ọ pụta ìhè nke ọma. N'ikpeazụ, e bipụtara akwụkwọ na Jenụwarị 14, 1906 iji gosipụta ihe ngosi nke Lorentz na-arụ ọrụ nke ọma, nke a na-akpọ "Nkọwa nke ndị na-abụghị ndị na-agbanwe agbanwe". (nke a na-akpọ "Poincaré
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