Spectral Causal Geometry: A Unified Framework for Quantum Gravity and Vacuum Engineering at the Planck Scale

<p>We propose Spectral Causal Geometry, a unified theoretical framework that integrates noncommutative geometry (NCG),<br>causal set theory (CST) and loop quantum gravity (LQG) to describe the quantum origin of spacetime. The framework posits<br>a spectral causal set-a partially ordered discrete structure equipped with a noncommutative algebra-as the fundamental entity,<br>from which classical spacetime emerges. We introduce vacuum engineering at the Planck scale as a novel method to probe<br>spacetime quantization and noncommutative geometry, manipulating quantum vacuum fluctuations via advanced materials<br>and fields. A spectral action principle yields modified Einstein field equations with a small positive cosmological constant,<br>suggesting emergent dark energy.</p>