Abstract

A phenomenological two-component pressure model is presented for the Casimir effect and its extension to dark energy and the cosmological constant. The interaction between closely spaced plates is described as a balance between an effective background compressive pressure associated with underlying oscillatory dynamics and a short-range repulsive contribution arising from matter-induced effects. Within this formulation, the characteristic inverse fourth-power dependence of the Casimir force is reproduced, with consistency achieved with experimentally observed trends. The framework is extended to larger scales by treating the compressive component as a uniform background pressure and by introducing a matter-induced dark-energy contribution within the intervening region. In this context, the cosmological constant is interpreted as the net pressure arising from the difference between the background compressive contribution and the repulsive component and is associated with an effective large-scale energy density. Numerical analysis and illustrative plots demonstrate that the evolution of the scale factor is governed by the sign of the net pressure. A critical density is identified that separates expanding and contracting regimes: negative net pressure leads to accelerated expansion, whereas positive net pressure results in contraction. Although the formulation is phenomenological and not intended as a first-principles derivation, it provides a consistent pressure-based framework linking confined interactions with large-scale dynamical behavior.

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