Dark matter definition
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Dark Matter: Definition and Fundamental Properties
Dark matter is a mysterious and invisible substance that does not emit, absorb, or reflect light, making it undetectable by conventional telescopes or electromagnetic observations. Despite its invisibility, dark matter is known to exist because of its significant gravitational effects on visible matter, such as stars and galaxies, and on the structure of the universe as a whole H.D2021Randall2018Balázs2024+1 MORE.
Astrophysical Evidence and Role in the Universe
The concept of dark matter was introduced to explain anomalies in the motion of cosmic objects, such as the unexpected rotation speeds of stars at the edges of galaxies and the movement of galaxies within clusters, which cannot be explained by Newton’s law of universal gravitation or Einstein’s theory of general relativity alone Randall2018Balázs2024Einasto2009+1 MORE. Observations like galactic rotation curves, gravitational lensing, and the cosmic microwave background all provide strong evidence for the existence of dark matter Balázs2024Einasto2009Bi2018. Dark matter is believed to make up about 25% of the universe’s energy density and is the dominant form of matter in the cosmos Wilson2014Einasto2009Le2024.
Nature and Candidates of Dark Matter
Dark matter is hypothesized to be made up of new, unknown particles that do not interact with light or ordinary matter except through gravity and possibly weak nuclear forces. These particles are not part of the Standard Model of particle physics. Leading candidates include weakly interacting massive particles (WIMPs), axions, and other non-baryonic particles Wilson2014Balázs2024Einasto2009+2 MORE. The true nature and identity of dark matter remain unknown, and it is still a major focus of research in both astrophysics and particle physics Wilson2014Balázs2024Einasto2009+2 MORE.
Experimental Searches and Theoretical Models
Despite decades of research and advanced experiments, such as the Large Underground Xenon (LUX) experiment and other direct and indirect detection efforts, dark matter has not yet been directly observed Balázs2024Bi2018Le2024. Researchers continue to use indirect evidence and theoretical models to infer its properties and search for possible particle candidates Balázs2024Bi2018Le2024+1 MORE. Some models suggest dark matter could be a dual-component system or have properties similar to a superfluid, but these ideas are still under investigation .
Conclusion
In summary, dark matter is an invisible, non-luminous substance that exerts gravitational influence on visible matter and the structure of the universe. It is a fundamental but still unidentified component of the cosmos, essential for explaining a wide range of astrophysical and cosmological phenomena H.D2021Randall2018Wilson2014+5 MORE. The search for its true nature continues to be one of the most important challenges in modern science.
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