COSMIC MICROWAVE BACKGROUND RADIATION/CMB

Detailed map of CMB, from the data of Wilkinson Microwave Anisotropy Probe, the probe was launched in 2001 and it took 9 years to complete this map.this image is in public domain 

Cosmic microwave background radiation (CMB/CMBR), what is it? How it supports the big bang theory? Who discovered this?

In this post, I am going to give answers for all these questions.

But, first before understanding CMB, you have to know about few things,

1. Photons

Just keep in mind that – Light is made up of photons, photons are mass-less particles that travel in a wave-like pattern at the speed of light.

   Cartoonize image of photons, credit - 

NASA/Sonoma State University/Cruz deWilde/Aurore Simonnet

2. Electromagnetic radiation

They are also made up of photons, or we can just say that that they are the transmission of energy in form of Particles, and those particles are PHOTHONS.

 Electromagnetic radiations make up the electromagnetic spectrum.

In physics spectrum means range of frequencies, so it concludes that,  electromagnetic spectrum consists of all the electromagnetic radiations with different range of frequencies.

(and yes , visible light also come in electromagnetic spectrum).

you can take help of below two images to understand electromagnetic spectrum better.

Now let’s connect all of these-

According to big bang theory. After 380,000 years  from the beginning of big bang the universe expanded and cooled enough for the first atoms to form , and that’s the time when photons can finally start to emit,

because before that the universe was so dense that if a photon will emit than it will suddenly just get absorbed by something else, or maybe because of ultra-high temperature it hadn’t emit.

Now if this is true, then even after billions of years we still have to get some tiny fraction of that radiation produced by photons …

and Yes I know that I have to tell the reason behind this😓😓, so listen , because at that time the radiation, or I can say electro – magnetic radiations was emitted from every point of the universe ,

so the electro- magnetic radiations which was near us, reached to us immediately ,

But many of them went far away from us, because of universe expansion. means many of them got red shifted from us (they got very very very far away from us,)

 and the wavelength of those radiation got increased, and the frequency decreased, so they should be transformed into radio waves till the time they reach us, 

means these radiations spread throughout in billion of light years, and even today, we should be getting these all throughout the space. On May 20, 1964 Robert Wilson and Arno Penzias did discovered these radio waves/CMB.  

And in 1978 they even got noble prize for their discovery. and we got a strong pillar for our theory.

(note - the time when the cmb first emitted without getting transformed in radio waves , the frequency of that radiation can be sooo high , that it can't even be placed in electromagnetic spectrum)