Final answer:
Einstein's cosmological constant was introduced to maintain a static universe but was reconsidered after the universe's expansion was discovered. Later observations suggest the possibility of an accelerating universe, potentially validating the cosmological constant's relevance.
Step-by-step explanation:
The cosmological constant is a term introduced by Albert Einstein in his field equations of general relativity, to represent a repulsive force that would counterbalance the attraction of gravity and allow for a static universe. This constant (Ω) was thought to maintain galaxies at fixed distances from each other. However, after Edwin Hubble discovered that the universe was actually expanding, Einstein famously referred to the introduction of the cosmological constant as his "biggest blunder." In recent years, observations have suggested that the universe's expansion is accelerating, which might imply that a force consistent with the cosmological constant is at work after all, indicating Einstein might have been on the right track despite his initial reservations.
This historical context and growth of understanding surrounding the cosmological constant showcases the evolving nature of scientific theories as new evidence comes to light. Despite being discarded after the discovery of the expanding universe, the concept of the cosmological constant has been revisited, suggesting that the universe's fate—whether it is open or closed—is influenced by the interplay between gravity and this constant.