Nearly, 13.8 billion years ago, our universe came into existence and big bang is the undeniable reason, atleast for me. The cosmic microwave background (CMB) is nothing but the leftover electromagnetic radiation from the big bang. This is the oldest light visible till date. As the theory states, the moment this universe took birth, it underwent an accelerated inflation and expansion. This CMB epitomizes the heat residues from the big bang. It is present everywhere in the universe but in microscopic form.
This CMB predates to around 400,000 years after the big bang. at that time the universe around hundred millionth the size of what it is today and it had skyrocketing temperatures. Due to the tremendous heat atoms were easily able to break off into smaller particles like electrons and protons snf sll thst existed was plasma. the light from this plasma state is what we call the Cosmic Microwave Background.
why is the CMB in the microwave spectrum and not in the visible spectrum? this is because the light coming from the CMB is very distant and it gets redshifted into the microwave spectrum.
The CMB was first theorised by George Gamow andRobert Wilson and Arno Penzias, two radio astronomers, discovered the CMB by accident in 1964. Robert and Arno’s radio sensors where picking up some buzzing noise from all points in the sky. first they thought that this interference was caused by disturbances in the surroundings. but after ruling out all possibilities , they realised that they discovered somehing big. The two astronomers were awarded the 1978 Nobel Prize in Physics for their work.
At present, the CMB radiation is extremely cold, around 2 degrees above the absolute zero, thus shining brightly in the microwave portion (wavelengths ranging from 1mm to 1m) of electromagnetic spectrum. Had we been capable of viewing microwaves then we would have seen the sky with uniform brightness.
Beyond the CMB
Well, don’t call yourself an astrophile, if you didn’t think of what is beyond this cosmic microwave background, well just kidding. According to NASA GODDARD Space flight centre, something way beyond the edge of our universe tending to pull the galaxies generally called dark flow exists. It further theorizes that this unseen stuff could be at least a thousand times farther than the horizon, and may become the cause of the slight tilt in our galaxy.
This CMB has helped scientist in studying the formation of this universe. The fluctuation in the CMB is serving a key to answering questions about the origin of galaxies and their massive structures.