principle. ``Inextricably-linked modern physics''? In many/almost all modern physics branches, the well established results of other branches are used as givens. It's logically like a house of cards or nearly. Caption: A house of cards. Credit: User:Mybluehair , but the link is dead and the user is unknown. Linked source: Wikipedia image http://en.wikipedia.org/wiki/File:DSC00990.JPG