RT Journal Article T1 Time, clocks and parametric invariance A1 Fernández-Rañada, Antonio AB In the context of a parametric theory (with the time being a dynamical variable) we consider here the coupling between the quantum vacuum and the background gravitation that pervades the universe (unavoidable because of the universality and long range of gravity). We show that this coupling, combined with the fourth Heisenberg relation, would break the parametric invariance of the gravitational equations, introducing thus a difference between the marches of the atomic and the astronomical clocks. More precisely, they would be progressively and adiabatically desynchronized with respect to one another in such a way that the latter would lag behind the former. This would produce a discrepancy between gravitational theory and observations, which use astronomical and atomic time respectively. It turns out that this result, surprising at it might be, is fully compatible with current physics, since it does not conflict with any known physical law or principle. We argue that this phenomenon must be studied, since it could have cosmological consequences. PB Springer SN 0015-9018 YR 2008 FD 2008-05 LK https://hdl.handle.net/20.500.14352/50998 UL https://hdl.handle.net/20.500.14352/50998 LA eng NO © Springer Science+Business Media, LLC 2008. We are grateful to J.Martín and R. Tresguerres for discussions. This work has been partially supported by the Spanish Ministerio de Educación y Ciencia under grant BFM2003-05453. NO Spanish Ministerio de Educación y Ciencia DS Docta Complutense RD 7 abr 2025