The Wow signal (1420.405 MHz, Big Ear Observatory, 15 August 1977) remains unexplained after 47 years. BCT offers two complementary interpretations. (1) Natural OHC maser: interstellar hydrogen clouds acting as OHC Bessel resonance cavities can produce coherent amplification at exactly 1420 MHz — the Hopf charge spin-flip transition of hydrogen. (2) Intentional broadcast: any technological civilisation that discovers the OHC condensate structure of the vacuum would identify 1420 MHz as the universal first-contact frequency. The hydrogen line is not arbitrary. It encodes Hopf charge geometry at the atomic scale. They found the same √2. Zero free parameters.
Michel Robert Cabrié (2026) studied this question.