"Wielki projekt" Autor: Leonard Mlodinow, Stephen William Hawking

Easy
http://www.youtube.com/watch?feature=player_detailpage&v=DfPeprQ7oGc
http://www.youtube.com/watch?feature=player_detailpage&v=6LKjJT7gh9s
http://www.youtube.com/watch?feature=player_detailpage&v=BWyTxCsIXE4


Hard
http://www.youtube.com/watch?feature=player_detailpage&v=6rgYz_BU2Ew
http://www.youtube.com/watch?v=dbh5l0b2-0o