Khan Academy Static

What does it mean for the universe to expand? Was the "big bang" an explosion of some sort or a rapid expansion of space-time (it was the latter)? If the universe was/is expanding, what is "outside" it? How do we know how far/old things are? This tutorial addresses some of the oldest questions known to man.

10643_Cosmic_background_radiation.html

10644_Cosmic_background_radiation_2.html

10640_Radius_of_observable_universe.html

10639_Big_bang_introduction.html

10645_Hubble_s_law.html

10642_Red_shift.html

10646_A_universe_smaller_than_the_observable.html

10641_Radius_of_observable_universe_correction_.html