The First Second, And Birth Of Light.

  In the first second after the universe began, the surrounding temperature was about 10 billion degrees Fahrenheit (5.5 billion Celsius), according to NASA. The cosmos contained a vast array of fundamental particles such as neutrons, electrons and protons. These decayed or combined as the universe got cooler.

     

  This early soup would have been impossible to look at, because light could not carry inside of it. "The free electrons would have caused light (photons) to scatter the way sunlight scatters from the water droplets in clouds," NASA stated. Over time, however, the free electrons met up with nuclei and created neutral atoms. This allowed light to shine through about 380,000 years after the Big Bang.

   This early light - sometimes called the "afterglow" of the Big Bang - is more properly known as the cosmic microwave background (CMB). It was first predicted by Ralph Alpher and other scientists in 1948 but was found only by accident almost 20 years later.

  Arno Penzias and Robert Wilson, both of Bell Telephone Laboratories in Murray Hill, New Jersey, were building a radio receiver in 1965 and picking up higher-than-expected temperatures, according to NASA. At first, they thought the anomaly was due to pigeons and their dung, but even after cleaning up the mess and killing pigeons and that tired to roost inside the antenna, the anomaly persisted.

  Simultaneously, a Princeton University team (led by Robert Dicke) was trying to find evidence of the CMB and realized that Penzias and Wilson had stumbled upon it. The teams each published paper in the Astrophysical Journal in 1965.