 Having constructed shape space in the relativistic case, one may then best match in order to construct one’s relational theory implementing Mach-heavy (the metric on configuration space is defined from the 3+1 dynamics of GTR): conceptually, the approach here is the same as that presented in the previous section. Moreover, one can again apply Jacobi’s principle, in order to eliminate a commitment to primitive temporal structure. In this case, the resulting theory is known as ‘shape dynamics’, which involves a commitment only to primitive conformal structure (i.e., facts about angles between objects) on the 3-geometries: all other absolute quantities, the claim goes, have been excised. One way to understand the relationship between GTR and shape dynamics is that one trades the relativity of simultaneity but absoluteness of scales in the former theory, for absolute simultaneity but the relativity of scales in the latter.