Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
Questions | Answers | Discussions | Knowledge sharing | Communities & more.
Dark matter is a mysterious form of matter that does not emit, absorb, or reflect light, yet exerts gravitational influence on visible matter in the universe. Observational evidence from galactic rotation curves, gravitational lensing, and cosmic microwave background radiation supports the existence of dark matter. Leading theories propose that dark matter consists of as-yet-undiscovered particles, such as weakly interacting massive particles (WIMPs) or axions.
Dark matter is a type of matter that does not emit, absorb, or reflect light, making it invisible to current detection methods. It is called “dark” because of its invisibility and because it interacts with other matter primarily through gravity. Here’s a brief overview:
**Observational Evidence**:
1. **Galactic Rotation Curves**: The rotational speeds of stars in galaxies remain constant at distances where they should decrease according to the visible mass, suggesting the presence of additional, unseen mass¹.
2. **Gravitational Lensing**: The bending of light from distant galaxies around invisible mass further indicates the presence of dark matter².
3. **Hot Gas in Clusters**: Clusters of galaxies contain hot gas whose temperature indicates more mass is present than what is visible¹.
4. **Cosmic Microwave Background**: Fluctuations in the cosmic microwave background radiation suggest the influence of dark matter in the early universe¹.
5. **Large-Scale Structure**: The distribution and structure of the universe at large scales are consistent with simulations that include dark matter².
**Leading Theories on Composition**:
1. **WIMPs (Weakly Interacting Massive Particles)**: These hypothetical particles would interact through gravity and possibly the weak nuclear force, but not electromagnetically, making them difficult to detect⁴.
2. **Axions**: Another candidate, axions are theorized to be low-mass particles with very weak interactions with normal matter².
3. **Sterile Neutrinos**: These are neutrinos that do not interact via the weak nuclear force, unlike the known types of neutrinos⁷.
4. **Primordial Black Holes**: Some theories suggest dark matter could be made of black holes formed in the early universe².
These theories are still being explored and tested through various experiments and observations. The true nature of dark matter remains one of the most intriguing mysteries in modern astrophysics.