2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/19609Optical experiments by Molegraaf et al reveal that the superconducting condensation energy of Bi_2Sr_2CaCu_2O_{8+δ} originates in lowering of kinetic energy of the carriers. A perspective on the significance of these results is given.Perspective on paper "Superconductivity-induced Transfer of In-plane Spectral Weight in Bi_2Sr_2CaCu_2O_{8+δ}", by H.J.A. Molegraaf et al, Science Vol. 295, p. 2239 (2002)Strongly Correlated Electronstext