The Past Hypothesis states that the universe began in a condition of extremely low thermodynamic entropy. The standard fine-tuning problem asks why the initial state occupies a vanishingly small region of a vast phase space. This paper argues that the question rests on an assumption that fails if spacetime is emergent: the assumption that the thermodynamic phase space is a fixed, time-independent arena from which the initial state was selected. If spacetime emerges from a pre-geometric substrate, as proposed in causal set theory, loop quantum gravity, and group field theory, then the thermodynamic phase space is not given in advance but grows with the emergent structure. The first configuration admitting a thermodynamic description has minimal entropy not because it was selected from an enormous space of alternatives, but because it is the configuration at which the space of alternatives begins. This reframes the fine-tuning problem without eliminating it: the question shifts from “why this point in a fixed phase space?” to “what determines the dynamics of structure formation, and why does the resulting arrangement generate a thermodynamic arrow?” The paper situates this argument relative to existing responses to the Past Hypothesis (Penrose, Carroll, Price, Callender, Chen, Wallace, Gryb), engages the Boltzmannian typicality programme of Goldstein, Lebowitz, Tumulka, and Zanghì, and identifies recent work on typicality in dynamically growing phase spaces (Hanel and Corominas-Murtra) as a mathematical framework within which the argument might in principle be formalised.
Sander Hollebrand (Sat,) studied this question.