-Most of the helium in the universe formed during the ERA OF NUCLEOSYNTHESIS.
-The GUT ERA refers to a time period in which the strong, weak, and electromagnetic forces were all unified.
-The PLANCK ERA refers to a time period in which all four forces are thought to have been unified.
-The COSMIC MICROWAVE BACKGROUND is our name for the photons we see that were first released when the universe was about 380,000 years old.
-The BIG BANG is the name we give to the moment when the expansion of the universe began.
-A very short period of extremely rapid expansion, called INFLATION, is thought to have occurred when the universe was about 10^-38 second old.