Angels were created by God and they were present with God when He laid the foundation of the earth and they were present at Creation.

Col 1:16 For by him were all things created, that are in heaven, and that are in earth, visible and invisible, KJV

Job 38:4-7 Where wast thou when I laid the foundations of the earth? declare, if thou hast understanding.5 Who hath laid the measures thereof, if thou knowest? or who hath stretched the line upon it?6 Whereupon are the foundations thereof fastened? or who laid the corner stone thereof;7 When the morning stars sang together, and all the sons of God shouted for joy? KJV

I believe that was “the big bang”.  That was when the music of heaven exploded and it can still be heard, the echoes of that can be heard today.  Angels shouted as God spoke creation into being.  So angels possess wisdom and understand that stretches back beyond the creation of this world. 

Angels were there when Adam and Eve fled the Garden, when Noah built the ark, when Moses appeared before the court of Pharaoh.  Angels have seen every birth, marriage, death, and war on planet earth.