[youtube=http://www.youtube.com/watch?feature=player_embedded&v=8eZqQUdWURs]

[youtube=http://www.youtube.com/watch?feature=player_embedded&v=wy9gXKwRpXc]

[youtube=http://www.youtube.com/watch?feature=player_embedded&v=Rp3_cPRQSh0]

«El tejido del cosmos» con Brian Greene como presentador