A theoretical team proposes an operational resolution of the initial cosmological singularity: quantum probes obeying a curvature-coupled Klein-Gordon equation never reach the Big Bang surface in finite proper time. The work, posted on arXiv, does not remove the singularity of the background spacetime, but renders it inaccessible to this class of quantum observers.

The starting point is a classical FLRW background near the initial singularity, on which a quantum scalar field acts. Applying the Madelung-Bohm decomposition to the Klein-Gordon equation, the authors show that the conformal geometry induced by the quantum field regularizes curvature invariants: quantities that diverge in classical theory remain finite from the probe's perspective.

The geometric consequence is that past-directed causal geodesics become complete in this effective geometry. In other words, a quantum probe travelling backward in time never arrives at the Big Bang surface in finite effective proper time, even though the underlying FLRW spacetime remains singular. The classical singularity is thus hidden behind an operational horizon for these observers.

The result offers a route distinct from the usual approaches to quantum regularization of the cosmological singularity: it does not modify Einstein's equations nor introduce full quantum gravity, but explores how the quantum structure of the probe, coupled to curvature, changes the causal accessibility of the singularity. It remains open whether the mechanism extends to other field classes, more general backgrounds, or probes with different couplings, and whether it can be tested in any observable regime.