In Amsterdam, he married Rosette Dasberg, and after some academic stops in Berkeley, Seattle, Boston and Paris, he joined the physics faculty at Tel Aviv University (TAU) in 1968, following an invitation by Yuval Ne'eman and Avivi Yavin. Rosette and Jonas have five children. Along his scientific career Jonas, continued to observe the Jewish faith, study the Talmud, and actively participate in Jewish history courses at TAU. Jonas has high level language skills, speaking fluently English, Hebrew, German, Dutch, French, and Yiddish.