Dark matter is a mysterious and invisible substance that makes up a significant portion of the universe's mass and plays a crucial role in the formation and structure of galaxies. Despite its importance, dark matter does not emit, absorb, or reflect electromagnetic radiation (such as light), which makes it undetectable by conventional means. Its existence is primarily inferred from its gravitational effects on visible matter and the large-scale structure of the universe.
Here are some key points about dark matter.
Gravitational Evidence: Dark matter was first postulated in the 1930s by Swiss astronomer Fritz Zwicky when he observed that the visible matter in the Coma Cluster of galaxies did not provide enough gravitational force to hold the cluster together. There had to be some invisible, massive substance providing the additional gravitational pull. Since then, various lines of evidence, such as the rotation curves of galaxies and the behavior of galaxy clusters, have supported the existence of dark matter.
Composition: The true nature of dark matter remains one of the most significant unsolved mysteries in astrophysics and cosmology. It is called "dark" because it does not interact with electromagnetic forces, so it neither emits nor reflects light. It is not composed of ordinary matter (protons, neutrons, electrons) or any known particles in the Standard Model of particle physics.
Amount in the Universe: Dark matter is estimated to make up about 27% of the total mass-energy content of the universe. The majority of the universe's mass-energy is dark energy (about 68%), which is responsible for the accelerated expansion of the universe. Ordinary matter, the stuff we can see and interact with, accounts for only about 5% of the universe's content.
Role in Galaxy Formation: Dark matter is believed to have played a crucial role in the formation of galaxies and large-scale cosmic structures. Its gravitational influence helps in pulling together gas and ordinary matter, allowing galaxies to form and maintain their observed structures.
Detection Efforts: Scientists have been trying to detect and study dark matter using various experimental approaches, such as underground detectors, particle accelerators, and astronomical observations. To date, direct detection of dark matter particles has not been successful, but these efforts continue.
Theoretical Candidates: Several theoretical candidates for dark matter particles have been proposed, including Weakly Interacting Massive Particles (WIMPs), axions, sterile neutrinos, and more. These particles are hypothesized to interact very weakly with ordinary matter, which makes their detection challenging.
The study of dark matter is an active and ongoing area of research in astrophysics and particle physics, and its existence is a fundamental puzzle that could provide critical insights into the nature of the universe and the fundamental forces that govern it.
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Негізгі бет Dark Matter ඇත්තක් ද? | Discussion with Malinda Alahakoon
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