Hello All, I wondered if anyone could fill in some details about the timeframe of FRW derivation. Was it derived to purposefully address the expansion of a universe? and if so, how did anyone know about this prior to Hubble's observations? Or was it derived for some other purpose and then applied after Hubble? I am keenly interested in this and would love to hear any information in this forum regarding the reasons for deriving this cosmological equation. Regards Acker edit. And was it derived using Newton before Einstein's gr or between gr and Hubble's observations?