Friedmann-Lemaître-Robertson-Walker Metric

The Friedmann-Lemaître-Robertson-Walker (FLRW) metric is a mathematical model used in cosmology to describe the universe's shape, size, and expansion over time. It assumes the universe is uniform and isotropic—meaning looks the same in all directions and locations. The metric provides a way to measure distances and time intervals, accounting for how space itself stretches as the universe expands. It forms the foundation for understanding cosmic evolution, helping scientists explain phenomena like the Big Bang, cosmic microwave background, and the observed acceleration of the universe's expansion.