Dark matter and dark energy in the universe
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Composition of the Universe: Dark Matter and Dark Energy
Current research shows that only about 5% of the universe is made up of ordinary matter (atoms), while the remaining 95% consists of dark matter and dark energy. Dark matter makes up roughly 23-30% of the universe, and dark energy accounts for about 70-80% Turner1998Paul2014Oks2021+1 MORE. This distribution is consistent with observations of cosmic background radiation and the inflationary model, which predicts a flat universe Turner1998Paul2014.
Dark Matter: Properties, Evidence, and Candidates
Dark matter is a mysterious substance that does not emit, absorb, or reflect light, making it invisible to current telescopes. Its existence is inferred from its gravitational effects, such as the rotation curves of galaxies, the motion of galaxy clusters, and the cosmic microwave background Sarkar2007Nadar2024Wu2023. Dark matter is not made of baryonic particles (protons and neutrons) but is thought to be composed of new, non-classical particles or substances Turner1998Nadar2024Masperi2001.
Several candidates for dark matter have been proposed, including:
- Cold dark matter particles like axions or neutralinos Turner1998Masperi2001
- Sterile neutrinos, self-interacting dark matter, and primordial black holes
- New theoretical models suggest dark matter could be a new physical element or "dark substance" filling the universe Delort2015Delort2016
Alternative theories, such as Modified Newtonian Dynamics (MOND), have also been considered to explain the effects attributed to dark matter Sarkar2007Oks2021.
Dark Energy: Accelerating Expansion and Theoretical Models
Dark energy is the term used for the unknown force driving the accelerated expansion of the universe. Observations of distant supernovae and the cosmic microwave background support the existence of dark energy Turner1998Paul2014Wu2023. The most common explanation is the cosmological constant (vacuum energy), but other models include:
- Rolling scalar fields (quintessence)
- Braneworld models
- Chaplygin gas
- Phantom energy Turner1998Sarkar2007
Some new models propose that the effects of dark energy could be explained by properties of dark matter or by alternative forms of matter with magnetic-type interactions, potentially removing the need for a separate dark energy component Delort2015Delort2016Oks2021.
Interactions and Evolution: Dark Matter and Dark Energy Together
The balance between dark matter and dark energy determines the fate of the universe. More dark energy leads to accelerated expansion, while more dark matter could slow or reverse expansion . Some models suggest that dark energy and dark matter may interact, with dark matter being generated from decaying dark energy, leading to stable ratios of both components over time .
Detection and Experimental Progress
Detecting dark matter and dark energy remains a major challenge. Experiments using particle colliders, astrophysical observations, and studies of the cosmic microwave background are ongoing to uncover the nature of these components Nadar2024Wu2023. Progress has been made in constraining the properties of dark matter and in developing new models to explain dark energy, but their true nature remains one of the biggest mysteries in physics and astronomy Sarkar2007Oks2021Wu2023.
Conclusion
Dark matter and dark energy together make up the vast majority of the universe, shaping its structure and evolution. While their existence is supported by strong observational evidence, their fundamental nature is still unknown. Ongoing research continues to explore new models, candidates, and detection methods, aiming to solve these profound cosmic mysteries Turner1998Delort2015Delort2016+7 MORE.
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