Cosmic Microwave Background Radiation

What I have to say today is what I have learned about CMB or Cosmic Microwave Background Radiation, however there is a lot I don't know and so can only link you to the information that I got it from, reliable or not, Wikipedia. I have looked into this from a few other sources such as NASA's website, but I like to use wikipedia so there might be mistakes in my information.

Without further ado, CMB stands for as I said Cosmic Microwave Background Radiation, which is what is observed in the microwave spectrum as the name suggests. The observation was first seen in 1965 with a Dicke radiometer which caught a discrepancy in their temperature that was credited to CMB. It was predicted about 20 years earlier to exist, and since then many experiments were made to get more information about it. Currently they know the color temperature of CMB to be 2.72548 ± 0.00057 K which is of course very small from it's initial temperature of approximately 3000 K.

So what is CMB exactly? well it comes from the beginning of the Universe, or near it at least. After the big bang the Universe was expanding and was filled with very hot plasma made up of electrons and protons, as it continued to expand the temperature of this plasma dropped due to thermodynamic physics (not explained here). When this temperature hit a certain point, around 3000 K, the electrons and protons coupled to make elements like hydrogen, which of course released photons. These photons went out into the Universe as it continued to expand, and fast forward to today these photons are still traveling. However, over the course of time and distance they have been red shifted deep into the microwave and cooling down to the aforementioned temperature. When they first noticed it the photons seemed to come from everywhere and was isotropic in energy emission (which is saying it was the same everywhere from no matter which location you viewed it from), which told astrophysicists that it had to originate from near the beginning of the Universe, hence we now call it CMB.

Why is this important? well CMB gives us answers about the beginning of the Universe or what's called "The Big Bang" and is the best evidence of what happened then. It also gave evidence to the acceleration of the expansion of the Universe backing up the calculations done using supernovae. Astrophysicists continue to gather information about CMB in hopes it can reveal more information about the Universe and help answer some questions.

There is a lot I did not mention, some I could not understand, and if interested you could check the link I have in the beginning or NASA's website for more info.