"The observable universe is a ball-shaped region of the universe comprising all matter that can be observed from Earth or its space-based telescopes and exploratory probes at the present time."
The observed distribution of galaxies and galaxy clusters on very large scales, which can be used to infer the origin and evolution of the Universe.
Big Bang Theory: The prevailing scientific explanation for the origin of the universe.
Dark Matter: A hypothetical form of matter that is thought to permeate the universe and exert gravitational effects on visible matter.
Dark Energy: A mysterious force that is thought to be responsible for the accelerating expansion of the universe.
Cosmic Microwave Background Radiation: The residual radiation left over from the Big Bang which can provide clues about the early universe.
Galaxies: Massive collections of stars, gas, and dust that form enormous structures in the universe.
Clusters of Galaxies: Groups of galaxies that are bound together by gravity.
Large-scale Structure Formation: The process by which galaxies, clusters, and other structures form in the universe.
Inflation: A period of rapid expansion in the early universe that is thought to have occurred immediately after the Big Bang.
Gravitational Waves: Ripples in the fabric of space-time that are caused by cataclysmic cosmic events, such as mergers of black holes or neutron stars.
Observational Techniques: Methods used to study the large-scale structure of the universe, such as telescopes and other detectors.
Cosmic Web: The structure of the universe on large scales, consisting of filaments of galaxies separated by vast voids.
Large-Scale Simulations: Computer models used to simulate the formation of galaxies, clusters, and other structures in the universe.
Baryon Acoustic Oscillations: A feature in the distribution of matter in the universe that can be used to measure the expansion history of the universe.
Galaxy Clustering: The study of how galaxies are distributed in space, which can provide clues about the nature of dark matter and dark energy.
High Redshift Galaxies: Galaxies that are observed at large distances, corresponding to early times in the history of the universe.
Superclusters: A group of galaxy clusters that are densely packed and connected by filaments of dark matter.
Galaxy clusters: A group of galaxies that are gravitationally bound together.
Filaments: Elongated regions of matter that connect galaxy clusters and superclusters.
Voids: Vast regions of space that have no galaxies or matter in them.
Walls: Large-scale cosmic structure with a quasi-two-dimensional distribution of galaxies.
Cosmic web: The overall structure of the Universe composed of interconnected filaments, walls, voids, and superclusters.
Galaxy chains: Elongated structures of galaxies that can form bridges between clusters or filaments.
Sheets: Flat regions of the cosmic web that are composed of walls and filaments.
Bubble-like structures: The voids in cosmic web often take on a spherical shape which resemble bubbles.
Bridges: Structures that span the voids of the cosmic web and connect superclusters and filaments.
Over-densities: Regions with more matter than average density.
Under-densities: Regions with less matter than average density.
Galaxy filaments: Regions of space that are composed of dense string-like structures of galaxies.
Cosmic voids: Large regions of space that are largely devoid of matter.
Galaxy superclusters: Large groups of galaxy clusters that exhibit a high degree of spatial clustering.
Substructures: Small-scale structures within large-scale structures such as galaxies and galaxy clusters.
Large-Scale Void Galaxy migration: A stream of galaxies that appears to be moving towards a large supercluster or filament.
Laniakea Supercluster: The massive supercluster of which our own Milky Way galaxy is a member.
The Great Attractor: A massive region of space that is affecting the motion of our galaxy and other nearby galaxies.
Dark energy: The mysterious force responsible for the accelerating expansion of our universe.
"Initially, it was estimated that there may be 2 trillion galaxies in the observable universe..."
"...although that number was reduced in 2021 to only several hundred billion based on data from New Horizons."
"Assuming the universe is isotropic, the distance to the edge of the observable universe is roughly the same in every direction."
"The word observable in this sense does not refer to the capability of modern technology to detect light or other information from an object, or whether there is anything to be detected. It refers to the physical limit created by the speed of light itself."
"No signal can travel faster than light; hence there is a maximum distance (called the particle horizon) beyond which nothing can be detected."
"Sometimes astrophysicists distinguish between the visible universe, which includes only signals emitted since recombination -- and the observable universe, which includes signals since the beginning of the cosmological expansion."
"According to calculations, the current comoving distance to particles from which the cosmic microwave background radiation (CMBR) was emitted, which represents the radius of the visible universe, is about 14.0 billion parsecs (about 45.7 billion light-years)."
"The comoving distance to the edge of the observable universe is about 14.3 billion parsecs (about 46.6 billion light-years), about 2% larger."
"The radius of the observable universe is therefore estimated to be about 46.5 billion light-years."
"Using the critical density and the diameter of the observable universe, the total mass of ordinary matter in the universe can be calculated to be about 1.5×1053 kg."
"In November 2018, astronomers reported that extragalactic background light (EBL) amounted to 4×1084 photons."
"As the universe's expansion is accelerating, all currently observable objects, outside the local supercluster, will eventually appear to freeze in time..."
"For instance, objects with the current redshift z from 5 to 10 will remain observable for no more than 4–6 billion years."
"...light emitted by objects currently situated beyond a certain comoving distance (currently about 19 billion parsecs) will never reach Earth."