This paper is the first in a three-paper series developing the classical gravity pillar of foundational D1 field theory. The wider aim of the series is to show how General Relativity can arise from a deeper field-theoretic structure, how Newton’s gravitational constant G can be understood as a D1 normalisation, and how black holes can be described as transitions between unfolded spacetime and a pure D1 phase.
The starting point of D1 theory is the proposal that time is not merely a coordinate inside spacetime, but the first and foundational dimension. The scalar field Phi_D1 represents the local freedom of absolute movement. In this framework, ordinary space is not assumed to be fundamental. Instead, spacetime geometry is treated as an emergent, low-energy phase of the D1 field.
This paper focuses specifically on the emergence of spacetime geometry. It formulates an effective D1 action containing kinetic, potential, matter-coupling, and curvature-coupling terms. The central geometric term is the non-minimal coupling between Phi_D1 squared and the Ricci scalar R. In the unfolded-space regime, where Phi_D1 settles into a stable background value, this term reduces to the Einstein-Hilbert form of gravitational action. The metric, curvature, and Einstein-type field equations are therefore interpreted as macroscopic effective structures induced by the ordered D1 phase.
The paper does not attempt to complete the full quantum theory, derive the numerical value of Newton’s constant, or present the full black-hole phase-boundary model. Those tasks are reserved for later papers in the series. The aim here is to establish the geometric emergence route by which classical spacetime curvature can arise from the D1 field.