Astronomy, Astrophysics & Astrobiology

Dark Matter, Dark Energy, and Black Holes

During early 1990's scientists were sure about the expansion of the universe. Theoretically the expansion process had to slow down due to the gravitational force as time pass by, but by the findings of Hubble Space Telescope in 1998 which observed a distant supernova that the universe was expanding more than slowing down today. Scientists even though it’s a result of a long-discarded version of Einstein's theory of gravity, one that contained the "cosmological constant" but even that didn't give them the answer they were looking for. So they decided it to name it as Dark Energy.  Almost 68% of the entire universe is dark energy, 27% composes of Dark Matter and all the other normal matter comprises to 5%. 

Dark Matter is the little portion of that visible matter present in the universe which sums up to form a total of 27 % . The matter is made up of particles called baryons. Scientists found this discovery after observing the absorption of radiations passing through them. Baryonic matter could still make up the dark matter if it were all tied up in brown dwarfs or in small, dense chunks of heavy elements. These possibilities are known as massive compact halo objects, or "MACHOs. Days later they discovered that the Dark Matter is not baryonic at all but it is made up of other more exotic particles like axions or WIMPS (Weakly Interacting Massive Particles).

Black Holes are great amount of matter packed together in a very small area which then results in large gravitational force that even light could escape through it. The term was coined by Princeton physicist John Wheeler in 1967.

Black holes are formed after the supernova explosion of any star. Einstein’s theory of general relativity predicted that after any star dies, it leaves behind a small, dense remnant core. And if the mass of this core is almost three times the mass of sun then according to the equation the black hole is generated by overcoming all the gravitational forces. And if the remnant is small then it becomes a dense neutron star that is just incapable of trapping enough light into it.