Dark matter - Mystery of the cosmos
The cosmos is yet to be uncovered fully, we only know what can be detected by us using our current technology. But as our technology increases we come across more questions, questions like what caused this flaw or is it really a flaw or is that something we missed. That something caused anomalies in the orbit of mercury some say it is due to our incomplete understanding of gravity but over observations we couldn’t say it is solely due to our incomplete understanding of gravity. When you see a photo of Dubai with its skyscrapers at night you will only see spots of light on the skyscrapers, you couldn’t see whole buildings but in the morning you would see the structure the same way we got to know something else is there in the cosmos which we couldn’t detect as in the night sky.
That something might be dark matter, dark energy. We say dark as we don’t know what it is but we yet know it was there and it is everywhere, it would even be just in front of your eyes while reading this.
Dark matter an overview.
Now here we will focus on this Dark matter which is also known as non baryonic matter. Baryonic matter is something which consists of protons and nuetrons, but dark matter is non baryonic which is the direct opposite of baryonic matter. Dark matter is the matter which doesn’t get detected or interact very weakly or not interact at all to EM waves like visible, UV, infrared, radio or even gamma rays, anything we know. Eventough having been inactive it makes up 30.1 percent of matter-energy composition of the universe while our normal matter is just about 5 percent. The rest is Dark energy.
Discovery of dark matter.
Fritz Zwicky, a Swiss American Astronomer in 1933 discovered that the mass of all stars in the coma cluster of galaxies provided only about 1 percent of the mass needed to keep the galaxies from escaping the cluster’s gravitational pull. He called it “missing mass” and later it came to be known as dark matter.
In the 1970s the American Astronomers Vera Rubin and W. Kent Ford confirmed its existence by observing similar phenomena. “To physicist such as myself, the huge amount of invisible dark matter needed to make Einstein’s theory fit the astrophysical data is reason enough for exploring modified gravity theories” – John Moffat.
Why dark matter???
We get to our question “why dark matter”. Some say that as dark matter interacts rarely and there isn’t much of a problem dealing with ordinary matter and energy (As compared to the unknown dark matter and energy). There is a saying “a known devil is better than unknown angel”, but dark matter might give us A better understanding of the universe and without it we cannot have “Theory of everything” which physicists and cosmologists are craving for. (as the theory wouldn’t be able explain dark matter and its influence in our universe). When capturing a gamma ray map of our galaxy. There were some places in the map having an excess of gamma ray emissions, theorists suggest that as dark matter annihilates with each other due to some phenomena gamma rays are produced.
Dark matter and the early universe.
Just after the big bang, before the formation of baryonic matter like hydrogen, helium and everything else we know today. There was just dark matter, this dark matter at first might have interacted with hydrogen but later might have detached from it. There should be some matter, which is responsible for some regions of universe to be denser while others less dense. Highly dense region might have had a large amount of dark matter. Stars and other objects of galaxies as they move away from thier galactic centre should spin fastly as it spins, the outer most stars should start falling of like water droplets fly off from a wet fastly spinning wheel, but it is not so. Hence we can say that dark matter is holding them from falling off.
Predicting dark matter.
Dark matter can be predicted through the phenomenon of gravitational lensing. That is based on the principle that matter acts as lens by distorting the passage of background light. The “missing matter” can also inferred from the motion and heat of gas which gives rise to x rays (observed). Dark matter detectors are usually kept underground or inside mountains as signals are faint and only 1 out of 1000000000 weakly interacts. The large haldron collider at CERN is also used to atleast detect the impacts of the dark matter as it is not possible to detect such weakly interactive particles, the large haldron collider isn’t sufficient enough to detect dark matter.
CDM and WDM
Cold dark matter (CDM) is a type of dark matter.Cold refers to the fact that the dark matter moves slowly compared to the speed of light, while dark indicates that it interacts very weakly with ordinary matter and electromagnetic radiation. Theorists suggest that most of dark matter is composed of Cold dark matter. Cold dark matter can be WIMPS (weakly interacting massive particles) and nuetralinos. Warm dark matter can behave like fast moving neutrinos, then there would be a question arising, is neutrinos dark matter, the answer is No. This is due to the fact that neutrinos decompose and it isn’t possible to be 30 percent of matter-energy composition. It is just thought to behave like it.
WIMPs
Weakly interacting massive particles (WIMPs) are hypothetical particles that are one of the proposed candidates for dark matter . There exists no clear definition of a WIMP, but a WIMP is a new type of particle which interacts through gravity and any other forces , which is as weak as or weaker than the weak nuclear force , but also non vanishing in its strength. WIMP particles are predicted by R-parity a concept in particle physics conserving supersymmetry, a popular type of extension to the Standard Model of particle physics, although none of the large number of new particles in supersymmetry have been observed.
Supersymmetry
The supersymmetry hypothesis introduces the symmetry between fermions and bosons, it states that for each boson there is a fermion, this hypothesis has been researched after discovering the Higgs boson. Supersymmetry can be able to provide a particle that might be a dark matter candidate. Supersymmetry can also help to unify the fundamental forces of nature. “If we find it, we will have proved the supersymmetry hypothesis, and if we find any of the supersymmetric particles at all, we will also in all probability have explained dark matter.”-Sara strandberg a associate professor of particle physics at the Stockholm University
Conclusion
Dark matter is a mystery which has to be solved to have a deeper understanding of our universe. We could be able to find dark matter in smaller galaxies as most of them are distorted to us but might actually not distorted, this distortion might be due to dark matter (concept of gravitational lensing again). The Dark energy survey mapped up about 1/8 of the sky showing about 100 million galaxies the map looked in a very unique and weird way, this cannot be like this but it is due to dark matter and dark energy.
This is just according to theorists,physicists on dark matter and my perspective and understanding of this Dark matter, this is not the complete story of dark matter, as it is still the very mysterious thing yet to be unveiled of the cosmos.
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