Which theory suggests that each day in the Biblical account of creation represents a much longer period of time?

The day-age theory posits that the "days" mentioned in the Biblical account of creation are not literal 24-hour periods, but rather represent extended epochs or ages. This interpretation suggests that each creative day could encompass thousands or even millions of years, allowing for an understanding of the creation narrative that aligns more closely with scientific perspectives on the age of the Earth and the development of life over geological time. This theory attempts to reconcile the Biblical text with scientific evidence, suggesting that the narrative serves to convey theological truths rather than adhere strictly to a chronological account.

By contrast, the gap theory introduces the idea of a significant time gap between the first two verses of Genesis, proposing that a long period could exist between the initial creation and the subsequent formation of Earth as described. The canopy theory posits an additional concept of a layer of water vapor above the atmosphere prior to the Flood, which is related to the environmental conditions surrounding the creation. Progressive creationism suggests ongoing creative acts by God over time, but in a different framework than that presented by the day-age theory.