Einstein's general theory of relativity introduced a beautiful and complex understanding of the cosmos. It revealed that the universe cannot simply exist in a static state. Instead, his equations pointed out that for the universe to remain stable, it must either expand or contract, as the gravitational forces would otherwise cause all matter to collapse inward.

This realization posed a challenge for Einstein, as he originally sought a static universe. To address this dilemma, he introduced a cosmological constant to his equations, an adjustment he later referred to as his "greatest blunder." Despite this, his groundbreaking theory fundamentally changed our perception of the universe's structure and behavior.