2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/206600We present an exact solution of superstring theory that interpolates in time between an initial type 0 phase and a final phase whose physics is exactly that of the bosonic string. The initial theory is deformed by closed-string tachyon condensation along a lightlike direction. In the limit of large tachyon vev, the worldsheet conformal field theory precisely realizes the Berkovits-Vafa embedding of bosonic string theory into superstring theory. Our solution therefore connects the bosonic string dynamically with the superstring, settling a longstanding question about the relationship between the two theories.v2: references added, typos fixed; v3: new sections added; 62 pages, 5 figuresHigh Energy Physics - Theorytext