A flat universe is a model of the cosmos where space-time is not curved. In this model, the geometry of the universe follows Euclidean principles and parallel lines remain parallel infinitely.
5 Must Know Facts For Your Next Test
The concept of a flat universe comes from Einstein's theory of general relativity and has been supported by observations of the cosmic microwave background (CMB).
Measurements of the CMB by missions like WMAP and Planck indicate that the universe is very close to being flat with only a small margin of error.
In a flat universe, the total density of matter and energy is exactly equal to the critical density.
A flat universe will expand forever, but at a rate that slows down over time without ever actually stopping.
The shape and geometry of the universe are crucial for understanding its fate, including whether it will continue expanding or eventually collapse.
The exact density needed for the geometry of the universe to be flat; it separates models where the universe will expand forever from those where it will eventually collapse.