One of the deepest mysteries of the universe is dark matter. It is a type of matter that cannot be directly seen, does not emit light, or interact with light in any way. Ordinary matter, which we can see and which makes up stars, planets, and galaxies, only makes up about 5% of the total matter in the universe. The remaining about 27% is dark matter, and 68% is dark energy. This dark matter is called ‘dark’ because it does not interact with any part of the electromagnetic spectrum. Scientists are trying to understand exactly what role it plays in the universe and why it is so important.
What is dark matter?
Dark matter is a type of hypothetical matter that is identified by its gravitational effects, but cannot be directly observed. This means that we cannot see it through a telescope, or detect any radiation from it. Scientists call it ‘dark’ or ‘tamo’ because it does not absorb, reflect, or emit light. If it interacted with light in any way, we could detect it. Ordinary matter, which we see every day, such as atoms, electrons, protons, neutrons—all of these are known as baryonic matter. This baryonic matter is what makes up stars, planets, galaxies, and our own bodies. But scientists have found that there is much more in the universe that is invisible and that only makes its existence known through its gravitational influence. This invisible matter is called dark matter.
Evidence for the existence of dark matter:
The concept of dark matter is not a hypothetical, but rather is based on various observations of the universe. The idea of dark matter was first proposed by Swiss astronomer Fritz Zwicky in the 1930s. He observed the motion of galaxy clusters and found that they required much more mass than visible matter to hold them together. Then, in the 1970s, Vera Rubin and her colleagues observed similar anomalies in the rotation curves of spiral galaxies. They found that stars in the outer regions of galaxies were spinning so fast that if only visible matter were present, the stars would be ejected from the galaxy. The existence of invisible matter became essential to explain this additional gravitational pull.
In addition, there is some other strong evidence for the existence of dark matter:
Gravitational Lensing:
The gravitational field of a massive object bends light rays, a phenomenon known as gravitational lensing. Scientists have observed the lensing effect of galaxy clusters and found that they contain much more mass than visible matter, made up of invisible dark matter.
Cosmic Microwave Background – CMB:
The CMB is a snapshot of the early state of the universe after the Big Bang. By analyzing subtle variations in the CMB, scientists have determined the ratio of dark matter to dark energy. The presence of dark matter has influenced the structure of the universe.
Large-scale Structure of the Universe:
The way galaxies and galaxy clusters are distributed in the universe is impossible to explain in the absence of the gravitational pull of dark matter. Dark matter provides a ‘framework’ upon which galaxies are formed.
Why is dark matter important?
Here are some reasons why dark matter is so important:
- Structure of the universe:
Dark matter plays an essential role in shaping the large-scale structure of the universe. After the Big Bang, ordinary matter could not have been held together by gravity because the universe was so hot and dense that radiation pressure would have pushed matter apart. Dark matter does not interact with radiation, so it begins to coalesce under the influence of gravity to form an invisible ‘scaffolding’ or structure. The pull of this dark matter structure is what allows ordinary matter to come together to form galaxies, galaxy clusters, and other cosmic structures. Without dark matter, the universe would probably not have the galaxy and stellar structures it has today.
- Stability of galaxies:
The rotation speed of galaxies proves that they have a vast ring of invisible dark matter around them. The gravitational pull of this dark matter is what keeps galaxies stable in their current form, otherwise the galaxies would have drifted apart due to their rapid rotation due to the lack of visible mass at the center.
- New Horizons in Physics: The existence of dark matter challenges the Standard Model of modern physics. The Standard Model describes all currently known particles and forces, but dark matter exists outside this model. This means that dark matter may be composed of new types of fundamental particles (such as WIMPs – Weakly Interacting Massive Particles, or Axions) that do not interact with the particles we currently know. The discovery of dark matter could open up unknown areas of physics and expand our understanding of the fundamental laws of the universe.
- Future Research:
Dark matter research is an active field in astronomy and particle physics. Scientists are trying to detect dark matter particles in the laboratory and observe their effects in space in more detail. Uncovering its true nature will completely change our knowledge of the origin, evolution, and ultimate fate of the universe.
Conclusion:
In short, dark matter is a vast part of the universe, which, although directly invisible, is evidenced by its gravitational influence. It is essential in forming the large-scale structure of the universe, maintaining the stability of galaxies, and expanding the Standard Model of modern physics. Unraveling the mysteries of dark matter is more than just discovering a new particle. It will deepen our understanding of the fundamental structure of the universe and its mysterious behavior.