Are computer simulations theory, experiment, or something in between? Anne Dippel and Martin Warnke explore the epistemological status of computer simulations. By examining the erosion of concept-based truth in the digital age in combination with pathways of knowledge in physics, they offer a media ethnography of the famous quantum physics double-slit experiment and its simulation. Recognizing simulations as central to shaping reality and multiplying illusions, the authors propose "operational realism" as epistemic composure in the digital era. The work raises ethical questions about algorithmic world design, offering humor, revelations, and insights into new ontologies of knowledge.