text: Local geometry: This relates to the curvature of the universe, primarily concerning what we can observe.
  Global geometry: This pertains to the universe's overall shape and structure.
  The observable universe (of a given current observer) is a roughly spherical region extending 46.5 billion light-years in all directions (from that observer, the observer being the current Earth, unless specified otherwise). It appears older and more redshifted the deeper we look into space. In theory, we could look all the way back to the Big Bang, but in practice, we can only see up to the cosmic microwave background (CMB) (roughly  years after the big bang) as anything beyond that is opaque. Studies show that the observable universe is isotropic and homogeneous on the largest scales.
  If the observable universe encompasses the entire universe, we might determine its structure through observation. However, if the observable universe is smaller, we can only grasp a portion of it, making it impossible to deduce the global geometry through observation. Different mathematical models of the universe's global geometry can be constructed, all consistent with current observations and general relativity. Hence, it is unclear whether the observable universe matches the entire universe or is significantly smaller, though it is generally accepted that the universe is larger than the observable universe.