2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/11804It has been a long-standing puzzle what triggers the spectral transition between the hard and soft states in Cyg X-1. Also, the origin of the frequently observed X-ray flares in the source still remains a mystery. In this paper, we will make an attempt to address these issues in light of our recent work on black hole spin and its observational consequences.4 pages. Proceedings of the 1997 Pacific Rim Conference on Stellar Astrophysics, Eds: K. L. Chan, K. S. Cheng, and H. P. Singh (PASJ), Hong Kong, China, August 13-16, 1997Astrophysicstext