For billions of years, small clumps of matter began to gravitationally clump into each other in slightly denser areas and attracted nearby matter. They thus grew even denser, forming new clouds, present-day stars, galaxies, and other astronomical structures observable today. The attribute of this process depended on the type and quantity of matter in the Universe. The 4 presently possible types of known matter are known as cold matter, warm dark matter, hot dark matter, and baryonic matter. Supercomputer simulations of the present-day Universe, from the data measurements at Wilkinson Microwave Anisotropy Probe, indicate that the data is well fit in Lambda -CDM model where dark matter is assumed to be cold, which is thought to make up about 23% of the mass in the Universe. Baryonic matter, on the other hand, makes up only 4.6% of the matter in the Universe.
Abell 2477 galaxy cluster
First Cosmology Results Using Type Ia Supernovae From the Dark Energy Survey
Extending the model further and including hot dark matter in the form of neutrinos, then if the physical baryon density is estimated to be at about 0.023, and the corresponding cold dark matter density at about 0.11, the corresponding neutrino density is found to be about lesser than 0.062.
Observations of different astronomical objects including Type Ia supernovae and an independent line of evidence from CMB radiation imply that the Universe is filled with an ever dominating permeable field known as dark energy. Modern day observations suggest that it takes up 73% of the total energy density in the Universe. At the time of Big Bang, the Universe was very young, and therefore everything was very close together. Dark energy was inside a very small space. But after billions of years of expansion, dark energy caused the expansion of the Universe to slowly accelerate and eventually become faster than the speed of light.
The only known form of Dark energy in the equations is of the form of Cosmological Constant term in Einstein’s field equations of theory of relativity. However, its true nature and composition and its mechanism are unknown. The most fundamental question as to what boggles the mind of physicists is the explanation of its relationship with the Standard model of particle physics continues to be observed even now both through observations and theoretically.
Written by- Sukhjit Singh
He is pursuing B.Sc in Mathematics Honours from SGTB Khalsa College, Delhi University. He often takes up multiple exciting projects and aims to develop multiple skills.