Composition of the universe
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Main Components of the Universe: Dark Energy, Dark Matter, and Ordinary Matter
Current research shows that the universe is made up of three main components: dark energy, dark matter, and ordinary (baryonic) matter. Dark energy is the largest component, making up about 68% of the universe. Dark matter accounts for roughly 27%, while ordinary matter—the stuff that makes up stars, planets, and living things—comprises only about 5% of the universe 1347.
Ordinary Matter: Elements and Their Abundance
Ordinary matter, also called baryonic matter, consists of atoms and the elements we are familiar with. The most common elements in the universe are hydrogen (about 75%) and helium (about 24%), with all other heavier elements making up just about 1% 28. This composition is remarkably consistent across the Earth, the Sun, other stars, and even distant galaxies . The early universe was primarily made of hydrogen and helium, with small amounts of deuterium, lithium, and helium-3 .
Dark Matter: The Invisible Mass
Dark matter does not emit, absorb, or reflect light, making it invisible and detectable only through its gravitational effects. It is essential for explaining the structure and behavior of galaxies and the universe as a whole. Although it makes up about 27% of the universe, its exact nature remains unknown. The standard model of particle physics does not account for dark matter, so its discovery and study rely on astronomical observations 134.
Dark Energy: The Force Behind Expansion
Dark energy is a mysterious form of energy that fills space and accelerates the expansion of the universe. It is the dominant component, making up about 68% of the universe. Its properties are not well understood, but it is thought to be similar to vacuum energy 134.
Radiation and the Early Universe
Radiation, including light and other forms of electromagnetic energy, was a significant component in the early universe. Today, it makes up only a tiny fraction of the universe's total energy content, but it played a crucial role in the universe's evolution, especially during the first moments after the Big Bang 1710.
Uniformity and Structure
The chemical composition of the universe is remarkably uniform, with only minor variations due to local conditions. This uniformity is observed in stars, planets, interstellar material, and distant galaxies 25. The distribution of matter, including dark matter and ordinary matter, shapes the large-scale structure of the universe, such as galaxies and cosmic voids .
Conclusion
In summary, the universe is primarily composed of dark energy and dark matter, with ordinary matter making up only a small fraction. Hydrogen and helium dominate the ordinary matter, and the overall composition is consistent across the cosmos. While much has been learned about the universe's makeup, the true nature of dark matter and dark energy remains one of the biggest mysteries in modern science 134.
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