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Cosmic Microwave Background Radiation




Have you ever thought of measuring the size of this whole universe? Our solar system is so vast that it would be silly to think about measuring its size let alone THE WHOLE UNIVERSE, of which our solar system, Milky Way, is a small part.
Most of us know that about the worldwide famous theory of Stephen Hawking, The Big Bang Theory. The whole universe was confined to a single point. ‘Big Bang’ happened and that single point started to expand and emit lights. This a story of 13.8 BILLION YEARS AGO! At that time, the whole universe was so dense and unstable that not a single object could form. All the protons, electrons and minute particles were moving and ricocheting off each other. We all know that every single thing in this universe radiates heat through electromagnetic waves. At that time, those particles were also emitting light and as the particles were very close, it looked like thousands of light bulbs are flashing together. As a result, there were too much light in the universe and it seemed like the whole universe was of ORANGE color. You may think how the black universe which we can observe now used to look orange Well this is the reason! ORANGE IS THE NEW BLACK!
380,000 years after the Big Bang, the universe cooled down a little due to expansion and the temperature became somewhere around 3000 K. Then the very first Hydrogen atom could form. Before that, due to a very dense environment, the waves emitted from the particles couldn’t travel a longer distance and get bumped off other particles. However, when the 1st H atom formed, the wave emitted from that atom could travel a longer path because of a low dense environment.
Now comes the most interesting part. The emitted waves started to scatter throughout the universe in all directions. Because of cosmological redshift, the wavelengths of those waves got stretched and eventually became MICROWAVE. Travelling the path of universe, these waves reached to the earth and thus we can measure the start of the observable universe. Those radiation of waves from the very 1st H atom is called COSMIC MICROWAVE BACKGROUND RADIATION or CMBR. 
It was first predicted in 1948 that these types of waves could exist. But later, in 1964, Arno Penzias and Robert Woodrow Wilson discovered Cosmic Microwave Background or CMB through the Holmdel Horn Antenna. Therefore, it is possible to know from where and when CMB was originated. It is considered that our solar system is at the middle of the universe and the Big Bang happened at one end of the universe. If we consider that CMB has travelled to us carrying the light of 13.8 billion years old, we can go way back to the very start of this universe and thus know how much way that light waves had travelled. After a vast research and complex mathematical explanations, scientists have found that those waves have travelled a way of 46 BILLION LIGHT YEARS which is indeed the radius of the observable universe. That means, the diameter of the observable universe is 92 BILLION LIGHT YEARS which is equal to 8.8×1026 meters!
Another interesting fact is that, CMBR is something that proves the Big Bang theory. The waves of CMBR is not confined to a specific direction, rather they can be found at any point in the universe. If we adjust an antenna in any direction of the sky, we will find bands of CMB. If CMB was emitted from something like stars or other astronomical objects, we couldn’t find them in every single point of the universe. This proposes the idea that CMB was emitted from a single point which upholds the existence of THE BIG BANG THEORY.
Now, LET’S THINK! This is the size of the observable universe which means light outside of the last horizon of this area can’t reach to us and we can’t see after that. It would take you 46 billion years if you travel at the speed of light which is nowhere near possible. The oldest man in the world lived 122 years and the tallest man measured n somewhere around 9 ft. Can you imagine what will be the size of the total universe, including the unobservable part? Is there any end? Will we ever be able to find it out? Can you really think how small you are in comparison to this universe? Just think…

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