This on-site splinter meeting will build on the outcomes of discussions arising from the PS division session PS8.1, as well as PS4.1, & PS4.2. We envision that this splinter meeting will feature lively debates and critical analyses of new models that tie together disparate viewpoints. This splinter session will also motivate participation in the poster sessions the following day (Thursday). After the splinter session, groups will gather for dinner to continue talking.