Gravity And Orbits - PhET Interactive Simulations The Dynamic Theory of Gravity of Directory:Nikola Tesla explains the relation between gravitation and electromagnetic force as a unified field theory (a model over matter, the aether, and energy). It is a unified field theory to unify all the fundamental forces (such as the force between all masses) and particle responses into a single ... between the two countries is greater (smaller) than the expected level based on the gravity model estimations, (i.e. the strength of trade relationship between the two economies cannot be completely explained by their economic, geographic and cultural characteristics described in the gravity model). Chaney (2008) extends the Melitz (2003) model to derive a similar gravity equation in a model with heterogeneous ﬁrms. Arkolakis, Costinot and Rodriguez-Clare (forthcoming) show that the same gravity equation can be derived in many settings with or without heterogeneous ﬁrms. The original form of the gravity model gives a close t to observed ows: a scatter plot of X^ on observed Xshows most points clustered close to a 45 degree line, much closer than most estimated economic relationships. Estimated band ctend to be close to 1 and estimated close to 1 in many di erent applications. Nov 04, 2016 · If gravity atoms are distinct from mass, as the Capacitor Model implies, we get that gravity atoms may always attract mass, regardless of which poles are used. Only when gravity atoms interact with other gravity atoms will there be a dipole effect for sure. Dual Behaviour of Dipoles The gravity equation in international trade is one of the most robust empirical finding in economics: bilateral trade between two countries is proportional to size, measured by GDP, and inversely proportional to the geographic distance between them. While the role of size is well understood, the role of distance remains a mystery.