  We argue that there exists an operational way to establish the objective
reality of the notions of space and time. Specifically, we propose a
theory-independent protocol for a gedanken-experiment, whose outcome is a
signal establishing the observability of the spacetime manifold, without a
priori assuming its existence. The experimental signal contains the information
about the dimension and the topology of spacetime (with the currently
achievable precision), and establishes its manifold structure, while respecting
its underlying diffeomorphism symmetry. We also introduce and discuss
appropriate criteria for the concept of emergence of spacetime, which any
tentative theoretical model of physics must satisfy in order to claim that
spacetime does emerge from some more fundamental concepts.
