The Beginning

Hola Cosmoplorer! Let's start our journey from the very beginning. From a time when even "time" didn't exist. From a place where "space" held no significance. 13.77 billion years ago all the things (and energy) you see around, your favorite ice-cream, all the planets and stars, all the galaxies, and even the atoms you are composed of were concentrated in a volume of less than one-trillionth the size of a point you could ever think of ( *If you just wanna wrap your head around this try counting a trillion with one number per second.....OK don't try that , I already did and it took me 31000 years!! That's how big this number is and imagine one trillionth of this ........how tiny it would have been....even much much much tinnier than the smallest microorganism that ever lived on me!!! )

This tiny-tiny-tiny-tiny cosmos had no choice but to expand. This is what the humans came to call as the BIG BANG. For the time interval, t=0(from the big bang) to t=10^-43seconds and before the space had expanded to a size of 10^-35,the four fundamental forces that exist in the universe were unified. No known law of physics can describe that era because "The big was small ". This era came to be known as Planck's era after a human physicist MAX PLANCK (father of quantum mechanics).

After the end of Planck's era, the four fundamental forces unmingled from each other and an unnoticeable asymmetry arose in the ratio of number of matter and antimatter particles....One-billion-one to one-billion (1000000001 : 1000000000)

After trillionth of a second had passed ,the universe was hot enough to convert photon into matter-antimatter pairs which then annihilated to again form photon. However , as the time progressed and as the space expanded and started cooling down , the photons didn't had enough energy for spontaneous conversions. For every billion annihilations, one matter particle (more specifically hadron) survived. The asymmetry at the beginning resulted in the formation of every thing we see around (everything from just those extra particles! ) . And the photons resulting from the annihilations kept traveling in the cosmos as light. (Consider if the matter-antimatter ratio had been symmetric , the whole universe would have been made up of light only!!!!!! )

This light though first was in visible region (peaking in infrared ) but as the universe expanded the light also got stretched, and so first got converted to infrared waves and now this light is in microwave spectrum ,known as COSMIC MICROWAVE BACKGROUND which after some(by some I mean maaannnnyyyyy) years it will be known as COSMIC RADIOWAVE BACKGROUND.

Video credit: Physics Girl

But how do we KNOW that big bang happened at all? The hint to the big bang was given by the Hubble telescope launched in 1990 by the people living on me. Data from Hubble telescope showed that the universe was expanding at a rate much faster than was expected. Georges Lemaître , a Belgian cosmologist and a catholic priest thought , "So if the universe is rapidly expanding,........ it would have been smaller than the current state some years back......and if we look some MORE years back, it would have been EVEN smaller than this......sooooo iffffff weeeee gooooooo baaaccckkkk tooooo the very beginning, what it would have been?? A..VERY .. SMALL.. POINT.. Eureka!!!!! "