A geometric origin of the Bohm potential from Einstein–Cartan spin–torsion coupling

A deterministic quantum-gravity framework is proposed that embeds Bohmian mechanics within the spin–torsion geometry of Einstein–Cartan–Kibble–Sciama theory. Starting from the Palatini form of the action for a Dirac field, a Gordon decomposition followed by a Foldy–Wouthuysen expansion shows that the familiar Bohm quantum potential, namely the term proportional to the Laplacian of the wave-function amplitude divided by that amplitude, coincides exactly with the axial-torsion contribution to the Ricci scalar. A covariant, spin-augmented guidance law then follows, and the algebraically determined torsion field, sourced by the global spin density of an entangled state, mediates non-local correlations without superluminal signalling. The same spin–torsion couplings produce an effective dark stress–energy tensor, for which observational tests are outlined across a wide range of scales: neutron-star magnetospheres, black-hole jets, gravitational-wave inspirals and spin-polarized interferometry. This geometric mechanism extends to spinless particles via torsion’s universal back-reaction on the connection, yielding a deterministic reformulation of quantum mechanics without metric quantization. A simple one-dimensional toy model reproduces the Tsirelson bound for Bell-inequality violations, underscoring the empirical and conceptual viability of this geometric route to quantum gravity, which dispenses with the need to quantize the metric.