Cosmic Microwave Background Radiation

    13.7 billion years ago an enormous exlposion started the begining of the Universe.  The Big Bang started in motion what some say can ever be reversed, and that is the Universe, as we know of it today.  For thousands of years a "primeval atom", which contained everything that we know of inside of it, was the only that to occupy the Universe.  During that period all of the baryonic material was compressed so tightly that sound waves that propagated through this mass were able to travel at the same speed as light or electromagnetic radiation.    

   
    370,000 years after the Big Bang there was an instant of decoupling of electromagnetic radiation from the baryonic material.  The baryonic substance would thus have been able to slow down and during recombination begin to create the basic material for the structure of electrons, protons, and neutrons.  At the same instant of decoupling the electromagnetic radiation would have been able to travel throughout the Universe, "If we'd been around to see it, we'd have been blinded by a yellow-white brilliance bombarding us from all directions at once." (Lemonick Pg. 9).

    The Cosmic Microwave Background Radiation was detected far before it was theorized.  During the late 1930's a gentlemen, S.W. Adams, was making precise measurements of the spectra of individual stars and noted the star Rho Ophiuchi.  A certain wavelength of Rho Ophiuchi's spectrum was being absorbed by surrounding interstellar cyanogen gas and Adams noticed that some of the gas was in a certain swirling motion, which only happens when fluids are being heated.  Adams collaborated with another gentlemen, Andrew Keller, and the two of them compared as many spinning molecules to non-spinning molecules as possible and determined that the Universe was being showered by this "stuff" with a temperature that they determined to be equivalent t o 2.3 K (0ºC = 273K).

    The first theoretical predictions came from another pair of physicists by the names of Ralph Alpher and Robert Herman, but their predictions came as a byproduct of determining whether a certain theory about cosmic evolution was true or not.  George Gamow was thinking that if the Universe were expanding, then if one were to go back a long time ago then everything in the Universe would be extremely dense and extremely hot and he thought that at certain temperatures certain types of elements would be created.  Alpher was order by his Professor (Gamow) to determine if his prediction was right so he collaborated with Herman and they concluded that Gamow's predictions would work for the very simpleist elements but does not stand hold for any of the heavier ones.  The team of two determined that once the primeval atom cooled to about 6000 K there would be a decoupling of electromagnetic radiation and baryonic material.  With nothing in the electromagnetic radiations way it would have the ability to shine freely throughout the Universe and that light would still be shinning today. They calculated that the electromagnetic wave would have been stretched from a high intensity gamma ray to a length longer then infrared radiation and estimated a temperature of 5 K.  This light that is still shinning is what we call today the Cosmic Microwave Background Radiation (CMB) and can be detected everywhere.

    There have been many trials to measure the CMB but two stand out above all of them, COBE and WMAP.
   
    With deep study of the CMB five major questions have been answered.

    Glossary Page

    References