spacetime metrics

Spacetime metrics are mathematical tools that describe how distances and times are measured in the universe, considering gravity's effect on both. Instead of just separate space and time, they combine them into a four-dimensional fabric. These metrics tell us how objects move and how light travels near massive objects like stars and black holes. Essentially, spacetime metrics provide the rules for understanding the geometry of the universe and how gravity shapes it, allowing us to predict phenomena like gravitational waves and the bending of light.