A Lightlike Membrane of the Hubble Horizon (Bilingual Edition)

A model of the Hubble volume bounded by the horizon is constructed as a lightlike relativistic membrane with tension and extended to an observationally testable dark energy model. All key properties are derived rather than postulated. Lightlikeness follows from a no-go theorem for timelike Nambu–Goto shells. The tension is obtained through several independent arguments, including a thermodynamic identity and junction condition consistency. The holographic entropy is carried by a Virasoro module and the Cardy formula reproduces the Bekenstein–Hawking entropy exactly. The equation of state of the layer is w = −2/3. Naive dynamical branches are rejected by DESI DR2 BAO, Pantheon+, and Planck 2018 distance priors. The only surviving route is the exchange term between vacuum and matter; its parameter is estimated independently and fitted to DESI data, with agreement within a few percent. The two-channel model improves the fit, but BIC still favours ΛCDM at the current sample size — this is stated explicitly. The membrane component is subdominant. A quantitative verification program is formulated.