This – all in English – twenty-first volume of AutoRicerca is dedicated to physics and contains four articles addressing foundational topics of quantum mechanics and relativity theory. All of these four articles touch, in a more or less specific way, the so-called conceptuality interpretation of quantum (and relativity) theory, initially proposed by Diederik Aerts and currently investigated within his “Brussels group,” at the Center Leo Apostel for Interdisciplinary Studies (CLEA).