- "Dark matter is a hypothetical form of matter thought to be the predominant type of matter in the universe."
This is a subfield that studies the role of dark matter in the structure and evolution of the universe.
Big Bang Theory: The widely accepted theory that the universe began with a massive explosion around 13.8 billion years ago. Dark matter is believed to have played a vital role in the evolution and structure of the universe.
General Relativity: The theory of gravity proposed by Albert Einstein that describes the curvature of spacetime by massive objects. It forms the basis of modern cosmology and makes predictions about the behavior of dark matter.
Newtonian Gravity: The classical theory of gravity that describes the attraction between two masses. Although it is a less accurate theory compared to general relativity, it is still useful in some cases.
Matter: The physical substance that occupies space and possesses mass. Dark matter is believed to present as the majority of matter in the universe.
Energy: The capacity of a physical system to perform work. Dark energy is believed to occupy about 70% of the total energy density in the universe.
Observational Cosmology: The study of the observable properties of the universe, such as its structure, composition, and evolution. It provides valuable data for the validation and refinement of theoretical models, including dark matter cosmology.
Galactic Dynamics: The study of the movement of stars and gas within galaxies. The rotation curves of galaxies are used to determine the distribution of dark matter and its influence on the structure and behavior of galaxies.
Cosmological Constant: A term introduced by Einstein in his theory of general relativity to maintain a static universe. It is now interpreted as a form of dark energy that causes the universe's expansion to accelerate.
Large Scale Structure: The study of the distribution and clustering of matter on scales of millions of light years. It provides insights into the evolution of the universe, especially concerning the role of dark matter.
Particle Physics: The study of subatomic particles and their interactions. Dark matter particles are believed to be elementary particles that do not interact strongly with electromagnetic forces, making them difficult to detect.
CMB Radiation: Cosmic microwave background radiation is the oldest light in the universe, and it is the heat left over from the Big Bang. It provides a snapshot of the early universe and an important tool for validating cosmological models, including dark matter.
Gravitational Lensing: The bending of light by gravity. It is a useful tool for mapping the distribution of dark matter in the universe.
Dark Matter Candidates: Candidates for dark matter include weakly interacting massive particles (WIMPs), axions, sterile neutrinos, and other hypothetical particles.
Modified Gravity Theories: Alternative theories to general relativity that attempt to explain the behavior of the universe without introducing dark matter or dark energy. They are still under active research and debate, with varying levels of success.
Dark Matter Searches: Experiments designed to detect dark matter directly or indirectly. They involve a range of technologies, such as underground detectors or telescopes that observe cosmic rays or gamma rays.
Cold Dark Matter (CDM): In this model, dark matter particles are assumed to be non-relativistic or cold. This model predicts that large-scale structures in the universe form first, with small structures forming later.
Warm Dark Matter (WDM): In this model, dark matter particles are assumed to be less massive and more relativistic than in CDM. This model predicts that smaller structures form first, with larger structures forming later.
Ultra-cold Dark Matter (UCDM): This model proposes a scenario where dark matter particles are ultralight and can behave like a wave, resulting in different properties than traditional CDM.
Self-Interacting Dark Matter (SIDM): In this model, dark matter particles can interact with each other through new yet unknown properties, leading to the formation of dense structures.
Fuzzy Dark Matter (FDM): In this model, dark matter particles are assumed to be ultra-light and have wave-like behavior, like UCDM. However, FDM behaves more like a Bose-Einstein condensate on a galactic scale, which could explain some astrophysical observations.
Axion Dark Matter (ADM): ADM models propose an alternative to WIMPs as a possible candidate for dark matter, involving extremely lightweight elementary particles. Axions are motivated by physics beyond the Standard Model, and their behavior could have interesting cosmological implications.
Modified Gravity: Some scientists propose that dark matter may be explained by modifying the laws of gravity on extended scales, rather than assuming the existence of new particles.
- "It is called 'dark' because it does not appear to interact with the electromagnetic field, which means it does not absorb, reflect, or emit electromagnetic radiation and is, therefore, difficult to detect."
- "Its existence is implied by various astrophysical observations which cannot be explained by general relativity unless more matter is present than can be seen."
- "Evidence for dark matter comes from many different angles, such as galaxy dynamics and formation, gravitational lensing, and the cosmic microwave background, along with astronomical observations of the observable universe's current structure, the formation and evolution of galaxies, mass location during galactic collisions, and the motion of galaxies within galaxy clusters."
- "In the standard Lambda-CDM model of cosmology, the total mass–energy content of the universe contains 5% ordinary matter, 26.8% dark matter, and 68.2% of a form of energy known as dark energy."
- "Dark matter constitutes 85% of the total mass, while dark energy and dark matter constitute 95% of the total mass–energy content."
- "Its existence is not known to interact with ordinary baryonic matter and radiation except through gravity, making it difficult to detect in the laboratory."
- "The leading explanation is that dark matter is some as-yet-undiscovered subatomic particle, such as weakly interacting massive particles (WIMPs) or axions."
- "The other main possibility is that dark matter is composed of primordial black holes."
- "Many experiments to detect and study dark matter particles directly are being actively undertaken, but none have yet succeeded."
- "Dark matter is classified as 'cold', 'warm', or 'hot' according to its velocity (more precisely, its free streaming length)."
- "Recent models favored a cold dark matter scenario, in which structures emerge by the gradual accumulation of particles."
- "Recent gravitational wave and James Webb Space Telescope observations have considerably strengthened the case for primordial and direct collapse black holes."
- "Although the astrophysics community generally accepts dark matter's existence, a minority of astrophysicists, intrigued by specific observations that are not well-explained by ordinary dark matter, argue for various modifications of the standard laws of general relativity."
- "These include modified Newtonian dynamics, tensor–vector–scalar gravity, or entropic gravity."
- "So far, none of the proposed modified gravity theories can successfully describe every piece of observational evidence at the same time."
- "suggesting that even if gravity has to be modified, some form of dark matter will still be required." These quotes provide answers to the specified study questions based on the information in the paragraph.