(209) Astronomy: The Big Bang (24 of 30) Radiation Era (Dark Ages) 1st Stars and Galaxies Appears

The Radiation Era

• The Radiation Era follows the Big Bang and marks a significant phase in the universe's evolution.

• This era began after an important event known as decoupling.

Decoupling

• Decoupling refers to the moment when radiation was able to move freely throughout the universe.

• This event occurred approximately 380,000 years after the Big Bang.

Conditions Leading to Decoupling

• During this time, the universe had cooled to about 3000 Kelvin.

• At this temperature, electrons could recombine with protons, forming atomic hydrogen.

• Radiation, now free from interaction with matter, began its journey through the universe as cosmic microwave background radiation (CMB).

Effects of Decoupling

• The separation of matter and radiation occurred as a result of the cooling and recombination process, a pivotal transition known as decoupling.

• Once decoupled, the CMB could propagate largely undisturbed by matter, paving the way for subsequent developments in the universe's structure and evolution.