Mysterious Building Blocks of the Universe: Dark Matter

As we understand from the first urban community established in Göbeklitepe 11,000 years ago and whose ruins we examine today, human beings have always been interested in the universe, stars and space since the day they were born. We can see this in the ancient civilizations of the Sumerians, Egyptians and Mayans. In fact, some of the scientific assumptions that the Sumerians came up with are also used in extremely complex theories explaining the universe, such as String Theory. The scientific studies conducted by the Egyptians and Mayans on Astronomy are also a watertight fact and we still use some of their findings today. Of course, we now have a lot of information about the Universe with the help of modern physicists. With the studies of Einstein, Hawking and many other scientists, we have made great progress in understanding the Universe and its formation. Thus, we are aware of many physical phenomena from the formation of the Universe to the present day. Of course, the interest of human beings in the spaces and stars that have existed since the very beginning also plays a serious role in this regard. Of course, understanding the universe also means understanding the fundamental forces and elements such as dark matter.

Big Bang Theory

One of the theories that currently explains the formation of the universe is the Big Bang Theory. This theory is currently one of the most important theories explaining the existence and development of the universe. Many studies are being conducted in this sense, and serious findings are being reached on this subject with the experiments and observations made. We know with our current observations and measurements that the universe expanded rapidly after the Big Bang and was very hot at the beginning, and then grew by both expanding and cooling.

However, when we measure all the atoms and mass and even energy in the universe with various techniques, we can see that it only corresponds to less than 5% of what it should be. This shows that there must be some types of matter and energy other than the matter and energy that we can see, that is, that can be measured. Scientists think that these missing parts are dark matter and dark energy, and some observations support these findings. Since Dark Matter cannot be seen in the current electromagnetic spectrum, we cannot observe it directly, but we can see its interaction with various methods. We think that Dark Energy is the most important element that enables the expansion of the universe. We have also determined with some studies that both of them correspond to 95% of the universe.

Dark Matter: The Universe’s Excess Mass

Dark matter is a mysterious type of matter that is thought to make up about 27% of the universe, but cannot be observed directly. Dark matter makes up five times more of the universe than ordinary matter. However, we know very little about it other than that it interacts with ordinary matter through gravity. Despite our lack of knowledge, we can see from our studies that scientists have a great deal of indirect evidence for dark matter. For example, scientists can explain how galaxies rotate and how the large-scale structure of the universe is formed and developed by the presence of dark matter. The term dark matter was coined in 1933 by Fritz Zwicky of the California Institute of Technology to describe the unseen matter that should dominate a feature of the universe, the Coma Cluster of Galaxies, the densest cluster of galaxies in the universe. The galaxies in the Coma Cluster were moving too fast to have as much mass as they appeared, and dark matter seemed a plausible explanation. In the 1970s, Vera Rubin, a scientist at the Carnegie Institution, found evidence for dark matter in her research on the rotation of galaxies. However, the nature of dark matter remains a mystery because it cannot be observed directly.

How to Observe Dark Matter?

The existence of dark matter has been indirectly proven by its effect on the gravitational behavior of galaxies and galaxy clusters. Because it does not interact with light or electromagnetic waves, it is impossible to observe dark matter with telescopes or other traditional astronomical instruments. While this has raised doubts among some scientists, the indirect evidence is quite convincing, and the findings of dark matter are helping us understand many secrets about the universe. Our current theories about the matter are based on the existence of dark matter. Clusters of galaxies can contain hundreds or thousands of galaxies, each with its own dark matter halo. However, the fact that these clusters have their own dark matter can explain their total mass. This dark matter also affects how the galaxies and hot gas move within the cluster. Just as with galaxies, astronomers can measure how much invisible mass is inside a cluster by the motion of the visible material. Researchers can also determine the amount of dark matter in a cluster by the way gravity affects light. This effect is called gravitational lensing, and it provides an independent measure of how much mass is in a cluster and where it is located.

One particular cluster of galaxies, known as the Bullet Cluster, provides some of the best evidence we have for the existence of dark matter. This cluster consists of two smaller clusters that collided at some point in the past. During this collision, hot plasma is thought to have interacted to create a shock wave similar to that created by a bullet. However, gravitational lensing shows that most of the mass of the combined cluster is concentrated around the galaxies, not at the center where the gas is. This provides the first independent measurement of how much gas and dark matter are in a galaxy cluster, with plasma and dark matter occupying the same areas in most clusters.

The Formation of Dark Matter

There is no definitive information about how dark matter was formed. Scientists have developed different theories about whether dark matter was formed in the early moments of the Big Bang or later.
• Formation After the Big Bang: According to this theory, dark matter is made up of exotic particles that formed as the universe cooled and expanded after the Big Bang. These particles may have formed a separate entity from normal matter by interacting with the weak nuclear force.
• Formation Before the Big Bang: According to this theory, dark matter is a type of matter that existed before the Big Bang and played a role in the formation of the universe. Some versions of this theory suggest that dark matter is a fundamental component of the universe and is derived from quantum fields that existed before the Big Bang.
Methods for Detecting the Existence of Dark Matter:
There are three main types of observational evidence that prove the existence of dark matter:
• Rotation Curves of Galaxies: The rotation speed of galaxies should increase in proportion to their distance from the center. However, observations show that even in the outer regions of galaxies, stars are spinning faster than expected. This suggests that the gravitational pull of the visible matter of the galaxies is not spinning the galaxies fast enough and that there must be a halo of dark matter around the galaxies.
• Hot Gas in Galaxy Clusters: The hot gas in galaxy clusters is held together by gravity. Observations show that the gravitational pull of this gas is stronger than expected from the cluster. This suggests that there must be much more dark matter in galaxy clusters than visible matter.
• Structural Formation of the Universe: When the distribution of the universe on a large scale is simulated with computer models, an image that does not match the observations emerges. This situation can be corrected by adding dark matter to the models.

Importance of Dark Matter:

Dark matter plays a critical role in the formation and evolution of the universe. It enables the formation and shaping of galaxies and galaxy clusters, regulates the expansion of the universe and creates the large-scale universal structure. Understanding the nature of dark matter will allow us to significantly improve our knowledge of the functioning of the universe.

Dark Matter Research

Scientists conduct various experiments and observations to understand the nature of dark matter. Some of the methods used in these studies are as follows:
• Underground Experiments: These experiments are carried out in underground laboratories to directly detect dark matter particles or search for their interactions.
• Space Observations: Space telescopes and other spacecraft are used to study the distribution and effects of dark matter in the universe.
• Computer Models: Computer models are used to simulate how dark matter behaves in the formation and evolution of the universe. Dark matter continues to be one of the greatest mysteries of the universe. Scientists are conducting intensive research to understand this mysterious substance. Understanding the nature of dark matter also means understanding the nature of the universe. Some scientists even think that dark matter may have its own special atomic element table. In this case, there may even be elements specific to dark matter, and in this case, there may be many different properties and structures in the universe that we cannot observe. However, this will be understood with the studies carried out in time and until then both dark matter and dark energy remain a mystery.