Answer:The Big Bang Theory explains how the universe began from an extremely dense and hot state. If we connect this to mass, volume, and density, imagine that the entire mass of the universe was once squeezed into an incredibly tiny volume—almost like a single point. Because density is calculated as mass divided by volume ( = ⁄), this point had unimaginably high density, since its mass was massive but its volume was nearly zero.This super-dense point—sometimes called a singularity—underwent a rapid expansion about 13.8 billion years ago. As it expanded, the volume of the universe increased dramatically while the same total mass was spread out over a larger space, causing its density to decrease over time. That expansion allowed matter to cool down, form atoms, stars, galaxies, and eventually us.