Quote: "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."
Different models and theories about the origin, evolution, and structure of the Universe.
General relativity: The theory of gravity and the description of how gravity affects the curvature of space and time.
Large scale structure of the universe: The distribution of galaxies, galaxy clusters and superclusters and how they are distributed throughout the universe.
Cosmic microwave background radiation: The radiation left over from the Big Bang and its implications in understanding the origin and evolution of the universe.
Dark matter: A hypothetical form of matter which is undetectable through electromagnetic radiation but can be inferred through gravitational effects on visible objects.
Dark energy: A theoretical form of energy that permeates all of space and is thought to be driving the acceleration of the expansion of the universe.
Inflationary universe: A hypothetical theory that explains the origin of the universe's structure and the distribution of matter in the universe.
Black holes: An object with a gravitational field so strong that nothing, not even light, can escape.
Multiverse: The concept that there exist multiple universes besides our own observable universe.
Quantum mechanics: The branch of physics that deals with the behavior of subatomic particles and how they interact.
String theory: A theoretical framework in which the fundamental constituents of the universe are one-dimensional "strings" instead of point-like particles.
Big Bang: A scientific theory describing the origin and evolution of the universe from a singularity.
Cosmic inflation: A brief, exponential expansion of space that occurred in the early universe, which is hypothesized to solve several problems in modern cosmology.
Cosmic rays: High-energy charged particles that originate from outside the solar system and can provide insight into the structure and function of the universe.
Gravitational waves: Ripples in the fabric of spacetime that occur when massive objects accelerate.
Neutrinos: Subatomic particles that are almost massless and traveling near the speed of light. They are created in numerous nuclear reactions happening throughout the universe, like the Big Bang, supernovae, and others.
Neutron stars: Extremely dense objects that are created by the collapse of some massive stars after they run out of fuel for their fusion reactions.
Supermassive black holes: Large black holes with masses up to billions of times that of the sun, found at the centers of most galaxies.
Standard Model of particle physics: A theory describing the fundamental particles and forces that make up the universe.
Redshift: A phenomenon that occurs when an astronomical object's light is "stretched" to longer wavelengths as the object moves away from a viewer.
Cosmic web: The large-scale filamentary structure of the universe, formed by dark matter and visible matter.
Big Bang Theory: This theory proposes that the universe began in a hot and dense state, and has been expanding and cooling ever since. It is widely accepted by the scientific community.
Steady-state Theory: This theory posits that the universe has always existed and will continue to do so, without any major changes or expansions.
Multiverse Theory: This theory suggests that our universe is just one of many possible universes that exist in a larger multiverse.
String Theory: This theory suggests that the fundamental building blocks of the universe are not particles but tiny, string-like objects.
Dark Matter Theory: This theory proposes that there is a significant amount of matter in the universe that we cannot detect directly, but that it can be found indirectly through its gravitational effects.
Inflationary Theory: This theory suggests that in the very early stages of the universe, just after the Big Bang, there was a period of rapid expansion or inflation.
Modified Newtonian Dynamics (MOND): This theory proposes that there is no dark matter, but instead, the laws of gravity need to be modified at large distances.
Holographic Principle: This theory suggests that all the information in a three-dimensional universe can be represented on a two-dimensional surface, like a hologram.
Eternal Inflation Theory: This theory posits that our universe is just one of many "bubbles" within a larger multiverse that is constantly expanding.
Quantum Loop Gravity Theory: This theory attempts to reconcile general relativity and quantum theory by considering gravity as the result of the interaction of tiny "loops" of space.
Quote: "Initially, it was estimated that there may be 2 trillion galaxies in the observable universe."
Quote: "That number was reduced in 2021 to only several hundred billion based on data from New Horizons."
Quote: "Assuming the universe is isotropic, the distance to the edge of the observable universe is roughly the same in every direction."
Quote: "Every location in the universe has its own observable universe, which may or may not overlap with the one centered on Earth."
Quote: "It refers to the physical limit created by the speed of light itself."
Quote: "There is a maximum distance (called the particle horizon) beyond which nothing can be detected."
Quote: "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."
Quote: "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)."
Quote: "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."
Quote: "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 1.5×10^53 kg."
Quote: "In November 2018, astronomers reported that extragalactic background light (EBL) amounted to 4×10^84 photons."
Quote: "All currently observable objects, outside the local supercluster, will eventually appear to freeze in time, while emitting progressively redder and fainter light."
Quote: "Objects with the current redshift z from 5 to 10 will remain observable for no more than 4–6 billion years."
Quote: "Light emitted by objects currently situated beyond a certain comoving distance (currently about 19 billion parsecs) will never reach Earth."