https://www.khanacademy.org/science/cosmology-and-astronomy/universe-scale-topic/big-bang-expansion-topic/v/big-bang-introduction 2021-04-04T12:52:27Z Big bang introduction Sal Khan video https://cdn.kastatic.org/googleusercontent/yS3isbJgQeGzBD2vA3nsZb49qvokvWETy54AlwE_N_Jhc0ZJJrs0Wk2zS2ltwo39kCvOIzaKRDsldX2D0Boyr7k Big bang introduction https://cdn.kastatic.org/ka-youtube-converted/eUF59jCFcyQ.mp4/eUF59jCFcyQ.mp4 663 The origin of universe https://www.khanacademy.org/humanities/oer-project-big-history/xc3079f0f2dd307e4:unit-2/xc3079f0f2dd307e4:big-bang-2-2/a/video-the-big-bang 2026-01-24T14:10:36.770864637Z The Big Bang We may not know everything about the Big Bang, but there’s a lot we do know. Our knowledge of the Universe begins just a fraction of a second after the Big Bang took place. article https://www.khanacademy.org/science/cosmology-and-astronomy/universe-scale-topic/big-bang-expansion-topic/v/radius-of-observable-universe 2021-04-04T12:52:27Z Radius of observable universe Radius of Observable Universe Sal Khan video https://cdn.kastatic.org/googleusercontent/sVQyaTNAayDXAxRdrP4S0vsEAHd8YND1HtlYds0SJa4I_eciVraSZazEKKEJ3KIyabi-5ctpy7n2K8nzdENu6VjHTg Radius of observable universe Radius of Observable Universe https://cdn.kastatic.org/ka-youtube-converted/6nVysrZQnOQ.mp4/6nVysrZQnOQ.mp4 999 The origin of universe