If the universe is expanding today, it must have been smaller and denser in the past. The suggests that approximately 13.8 billion years ago, the entire observable universe was concentrated in a state of infinite density and heat called a singularity.
The ultimate fate of the cosmos depends on the battle between gravity and dark energy. Current data suggests we live in a "flat" universe dominated by dark energy, leading to a scenario known as the In this future, galaxies will move so far apart they become invisible to one other, stars will run out of fuel, and the universe will eventually become a cold, dark, and empty void. Conclusion Introduction to Cosmology
An invisible form of matter that does not emit light but exerts gravitational pull, holding galaxies together. If the universe is expanding today, it must