Spacetime Substantivalism VII: The Great Experiment of Nature— The Substantial Nature of Spacetime Revealed by Gravitational Waves

Abstract

The direct detection of gravitational waves marks a revolutionary leap in humanity’s capacity to observe the universe, an achievement widely regarded as successful verification of general relativity’s predictions. Through in-depth comparative analysis, this paper points out that while mainstream physics revels in the academic tradition of “verifying predictions,” it overlooks the deeper essence revealed by empirical data—spacetime is not an abstract geometric background but a physical entity with definite constitutive properties.

Based on the theoretical framework established in the published papers of this series, particularly the spacetime ontological speed Cs concept established in Substantial Spacetime Dynamics (I), this paper systematically extracts ten pieces of evidence from gravitational wave observational data that point to the substantial nature of spacetime. On this foundation, we further construct a covariant effective field theory framework that treats general relativity as its infrared limit, encoding the constitutive response of spacetime as an effective medium through the introduction of higher-order curvature terms. In the linearized limit, this framework predicts small but testable deviations from standard gravitational wave propagation, including weak dispersion, phase corrections, and possible additional polarization modes, providing a phenomenological pathway for probing the microstructure of spacetime through future precision gravitational wave measurements.

Through residue matching of propagator poles, we establish a direct analytic link between the constitutive modulus beta and black hole echo parameters, demonstrating that echoes are not free parameters but necessary dynamical manifestations of the spacetime entity’s rigidity modulus. Population stacking forecasts for third-generation detectors (Einstein Telescope, Cosmic Explorer) are presented, showing that decisive sensitivity thresholds will be reached in the coming decade.

中文版 (Chinese Version)

引力波的直接探测标志着人类观测宇宙能力的革命性飞跃,这一成就被广泛视为广义相对论预言的成功验证。通过深入的对比分析,本文指出,虽然主流物理学沉浸在“验证预言”的学术传统中,却忽略了实证数据揭示的更深层本质——时空并非抽象的几何背景,而是一个具有明确本构属性的物理实体。

基于本系列已发表论文建立的理论框架,特别是《时空实体动力学(I)》中确立的时空本体速度 Cs 概念,本文从引力波观测数据中系统地提取了十项指向时空实体性质的证据。在此基础上,我们进一步构建了一个协变有效场论框架,将广义相对论视为其红外极限,通过引入高阶曲率项,将时空的本构响应编码为有效介质。在线性化极限下,该框架预言了与标准引力波传播相比微小但可测试的偏离,包括弱色散、相位修正以及可能的额外极化模式,为通过未来的精密引力波测量探测时空微观结构提供了唯象路径。

通过传播子极点的留数匹配,我们建立了本构模量 beta 与黑洞回声参数之间的直接解析联系,证明了回声并非自由参数,而是时空实体刚性模量的必然动力学表现。本文还给出了针对第三代探测器(爱因斯坦望远镜、宇宙探险者)的群体叠加预测,表明在未来十年内将达到决定性的灵敏度阈值。