Introduction
Dark matter is one of the biggest unsolved mysteries in the universe. It has captivated the attention of astronomers and stargazers for decades. Dark matter is invisible and can be only detected due to its gravitational effects.
According to latest studies universe contains 5% normal matter, 26.8 % dark matter and 68.2 % dark energy, yet we know very little about this. In this post we will dive deep into the fascinating world of dark matter, we will explore what it is, its history, its properties and what scientists are doing to uncover its secrets. So let’s dive right in.
What is Dark matter ?
Dark matter is a form of matter that is yet undiscovered and we do not know much about it. Dark matter does not interact with light or electromagnetic radiation causing it to be invisible for our telescope. Dark can be only detected due to its Gravitational effects.
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| Dark matter |
Dark matter is thought to make 27% of total matter in the universe, it is detected due its gravitational effects on stars and galaxies. Scientists are actively searching what dark matter is and according to some scientists dark matter could be Weakly interacting massive particles (WIMP’s), but the problem is that no such particles are found till date.
Dark matter is still a huge mystery which is not solved yet, dark matter is thought to be present at the outskirts of galaxies, and in empty space. According to the latest research’s space is not empty, but something is present inside space, it could be anything like virtual particles or pure energy but the main belief of scientist’s is that empty space is filled with dark matter.
Discovery of Dark matter
The concept of dark matter was first proposed in the 1930's by a swiss astronomer Fritz Zwicky, using the formulae he calculated the mass of the galaxy cluster and the gravitational force of the cluster. He found that the cluster's mass was not enough to provide gravitational force of that strength.
After many calculations he found more such results due to which he said that much of the mass present inside the cluster was not visible, and named the mass “Dunkle Materie”(dark matter in German). Over the next several decades astronomers and astrologers confirmed Zwicky’s observation by calculating individual masses of galaxies.
1970s and 1980s with computer simulation and advanced telescopes it was found that dark matter played a crucial role in the universe, and further with advancement in technology various effects of dark matter were discovered. But till date no concrete proof regarding dark matter is found.
Proof of presence Dark matter
Galaxy rotation curves
Astronomers using Newton's formula calculated that in a rotating galaxy, stars near the centre of the galaxy should rotate faster than the star present at the outskirts of galaxies. But, when observed it was found that star’s at the centre and the star’s at the outskirts of the galaxy both were rotating at the same speed.
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| Galaxy, Image source : Minuteschool |
After much research and development in computer simulation, it was found that such a phenomenon can only occur when the galaxy had additional mass which provided the galaxy additional gravitational force. This additional mass is considered as Dark matter. It is thought that dark matter provides the extra gravitational force and also forces stars to be present in clumps as they are seen today.
CMB radiation
Cosmic microwave background (CMB) radiation is the afterglow of the Big Bang, and it provides valuable information about the early universe. The CMB is not directly related to the presence of dark matter, but the distribution of matter in the early universe has an impact on the patterns in the CMB.
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| CBM radiation, Image source : Semantic scholar |
Using CMB the distribution of matter around the entire universe was calculated, but when actually observed the results were totally different. Patterns we observe today in our universe are only possible if there is the presence of an additional mass of dark matter. This shows that formation and distribution of matter around the universe is under the influence of dark matter.
Cluster of Galaxy
When scientists observe a cluster of galaxies, they measure the total mass of the cluster through various techniques, such as observing the motions of the member galaxies or studying the distribution of hot gas in the cluster.
These measurements showed that there is much more mass in the cluster than what is visible in the form of galaxies, gas, and other baryonic matter. Such a phenomenon also occurs due to the presence of dark matter. The gravitational pull of the dark matter holds the cluster together and shapes the distribution of visible matter, causing it to clump into the structures we observe today.
Properties of Dark matter
Weakly interacting Massive particle (WIMP)
WIMPs (Weakly Interacting Massive Particles) are a theoretical class of particles that are candidates for dark matter. WIMPs are called "weakly interacting" because they only interact with normal matter through gravity and through the weak force.
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| WIMP, image source : Nasa |
The idea of WIMPs as dark matter is explainable because it provides a simple explanation for the missing mass in the universe. If WIMPs make up dark matter, they could be the solution to the long-standing problem of explaining the discrepancy between the observed mass of the universe and the amount of visible matter.
WIMPs are thought to be dark matter, but still there is no direct evidence for their existence. Numerous experiments are carried out to detect the presence of WIMPs, but so far, all searches have been unsuccessful. Scientists are still trying to search for the presence of WIMPs, but all this still remains a possibility and no direct evidence is available.
Interaction with matter
Dark matter is thought to interact very weakly with normal matter. This is why it is often referred to as "dark" matter, as it does not emit, absorb, reflect or interact with light or any other electromagnetic waves and is therefore invisible to telescopes. Dark matter only interacts with normal matter through gravity, which is the dominant force affecting its behaviour.
Dark matter is also thought to interact weakly with normal matter through the weak force, which is one of the four fundamental forces of nature. But such interactions of normal matter with dark matter are very rare and still no such observations are done.
This weak interaction with normal matter makes dark matter difficult to detect. But still scientists are trying to search for dark matter through studying their gravitational effects on normal matter. Along with this scientist are also trying to find out its other properties of dark matter.
Theories related to Dark matter
Modified Newtonian Dynamics (MOND)
Modified Newtonian dynamics (MOND) is a theory that proposes an alternative to dark matter. According to the MOND theory the laws of gravitation need to be modified instead of assuming the existence of Dark matter. The MOND theory acts as an alternative to dark matter, explaining observed behaviour of galaxies and explaining other astrophysical systems.
According to the MOND, the gravitational force between two objects depends not only on their masses and the distance between them, but also on the acceleration produced by the force. At very low accelerations, the MOND theory predicts that the gravitational force will be stronger than what would be expected from the standard laws of gravity.
The MOND theory was proposed in the 1980s to explain the phenomenon Galaxy rotation curves. However, MOND is not widely accepted as a complete explanation for the observations. The main reason is that MOND has difficulty explaining the observed distribution of matter on larger scales, such as galaxy clusters and the cosmic web.
Additionally, the MOND theory has not yet been successfully incorporated into a comprehensive theory of gravity that is consistent with the other known laws of physics.
Gravitationally entangled Dark matter (GET)
GET (Gravitationally Entangled Dark Matter) theory is a new and relatively little-known proposal for what dark matter might be. According to GET, dark matter is made up of gravitationally entangled particles that are connected by a yet-undetected force. This force would be much stronger than the electromagnetic force, but much weaker than the strong force.
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| Dark matter, Image source: Live science |
In GET, the entangled dark matter particles would interact with each other through this new force, creating a network of interconnected "strings" that would act as a single entity. The combined effect of the strings would then produce the observed gravitational effects of dark matter.
One of the key predictions of GET is that the dark matter strings would form knots, which would then act as a new type of particle. These knots would have mass and would interact with normal matter through gravity.
However, GET is still a very speculative theory, and there is no experimental evidence to support it. The idea of dark matter as entangled particles is not widely accepted by the scientific community.
Future Implication
Further search
In the near future, a number of new and ongoing experiments are expected to provide new insights into the nature of dark matter. Main goals of current and future experiments is to directly detect dark matter particles, which would provide strong evidence for the existence of dark matter and allow us to determine its properties.
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| Largest telescope, Image source : Ars electronica |
Direct detection experiments use a variety of technique of target nuclei, along with this many more methods are in work to find the presence of dark matter.
Another area of active research is indirect detection, which involves looking for the products of dark matter annihilations, such as gamma rays, neutrinos, and cosmic rays. These experiments use telescopes, detectors, and particle accelerators to search for signals released by dark matter.Advancement in technology
Currently, dark matter has not been directly detected, and its properties and behaviour are still not well understood. And there are no concrete plans for using dark matter with advanced technology. However, some scientists and researchers have proposed various applications of dark matter in the future. If dark matter particles can be captured and controlled, they could potentially be used as a source of energy.
In addition, if dark matter particles interact with normal matter through a new force, this interaction could be harnessed for new technologies, such as communication or sensing. It's important to note that these are still purely speculative ideas and that much more research is needed before any practical applications of dark matter can be developed.
Conclusion
In Conclusion, Dark matter is still an unsolved mystery, despite our years of research, we have not directly detected any traces of matter. And we don’t have a complete understanding of what dark matter is and what its properties are. Dark matter is detected due to gravitational effects on normal matter.
There are various proofs of the presence of dark matter like galaxy rotation curves, CMB radiation, Cluster of galaxies, all this proof points towards the presence of dark matter. Dark matter does not interact with normal matter or electromagnetic radiation thus it is invisible to us. Dark matter is thought to be made up of WIMP.
There are many theories put forward to understand behaviour or presence of dark matter, but none of them have been proved. Still scientists are trying their best to detect dark matter through direct and indirect methods. If we understand the properties of dark matter it could be used as a source of energy.
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