<p>In this essay, we explore how empty space can create possibilities for change in mathematics teacher education. We draw on ideas from physics, theater, architecture, and graphic design to understand emptiness as a space where meaning, relationships, and creativity can emerge. We suggest that intentionally leaving spaces within teacher education programs open (i.e., spaces in which the content remains undefined, and the trajectory remains flexible) can invite processes of co-creation, critical reflection, and pedagogical imagination. To develop this argument, we turn to Mikhail Bakhtin’s notion of the carnivalesque together with speculative design, using these perspectives to understand such spaces as dialogic arenas through which established hierarchies loosen and new meanings emerge. From this viewpoint, emptiness can be conceptualized as productive through the creation of conditions for interaction, experimentation, and evolving roles of teaching and learning. Building on this understanding, we also propose that such forms of openness invite a reconsideration of academic rigor in mathematics teacher education, suggesting that rigor may be understood through ethical responsiveness, relational depth, and the capacity to imagine alternative possibilities for teaching and learning. To illustrate these ideas, we present two speculative examples that show how such open spaces may unfold in practice and that offer provocations for more reflective, responsive, and creatively oriented forms of mathematics education.</p>