3.1 Worlds and the Universe

      3.1.1 Basics

      3.1.2 Simple Simulations

      3.1.3 Interactions

      3.1.4 Scenes and Images

      3.1.5 A First Sample World

        3.1.5.1 Understanding a Door

        3.1.5.2 Hints on Designing Worlds

        3.1.5.3 Simulating a Door: Data

        3.1.5.4 Simulating a Door: Functions

      3.1.6 The World is not Enough

        3.1.6.1 Messages

        3.1.6.2 Sending Messages

        3.1.6.3 Connecting with the Universe

        3.1.6.4 Receiving Messages

      3.1.7 The Universe Server

        3.1.7.1 Worlds and Messages

        3.1.7.2 Universe Descriptions

      3.1.8 A First Sample Universe

        3.1.8.1 Two Ball Tossing Worlds

        3.1.8.2 Hints on Designing Universes

        3.1.8.3 Designing the Ball Universe

        3.1.8.4 Designing the Ball Server

        3.1.8.5 Designing the Ball World