Electromagnetic Vacuum Entanglement Entropy as the Origin of Spacetime: Exact Prediction of the Local Dark-Matter Density

We propose the ontological principle that spacetime and gravity exist only in regions where the entanglement entropy of the electromagnetic vacuum field is strictly sub-maximal and can still increase. Applied to the coherent galactic magnetic field, the same principle yields — without any free parameters — a local dark-matter density ρ_DM = 0.300 ± 0.015 GeV/cm³, in exact agreement with the latest Gaia DR3 determination. The same framework naturally implies zero Hawking temperature for astrophysical black holes, anomalous gravitational/inertial effects inside perfect superconductors, and late-time cosmic acceleration driven by the near-saturation of vacuum entanglement on Hubble scales.我们提出如下本体论原则：时空与引力仅存在于电磁真空场的纠缠熵（entanglement entropy）严格处于亚极大状态且仍可增长的区域之中。将该原则应用于相干银河磁场时，无需引入任何自由参数，即可得到局域暗物质密度ρ_DM = 0.300 ± 0.015 吉电子伏每立方厘米，该结果与最新盖亚DR3（Gaia DR3）的探测值完全一致。该理论框架还自然推导出多项结论：天体物理黑洞的霍金温度（Hawking temperature）为零；完美超导体内部存在反常引力与惯性效应；在哈勃尺度（Hubble scales）下，真空纠缠近乎饱和，由此驱动晚期宇宙加速。