This work investigates the presence of Thought Experiments (TEs) which refer to the theory of relativity and to quantum mechanics in physics textbooks and in books popularizing physics theories. A further point of investigation is whether TEs--as presented in popular physics books--can be used as an introduction to familiarize secondary school students with physics theories of the 20th century. The study of textbooks and popular physics books showed that authors of both types of books consider TEs as an important tool when presenting the theory of relativity and quantum mechanics. Furthermore, a qualitative research conducted in secondary education revealed that the historical TEs which were transformed into forms accessible to the public could trigger students' interest and act as educational material to familiarize them with concepts and principles of the 20th century physics.