GR Is Technically Indeterministic. Here's Why

Why It Matters

Understanding GR’s model‑dependent determinism shapes theoretical research and informs the reliability of predictions used in astrophysics and technology development.

Key Takeaways

• GR comprises many mathematically distinct model families.
• Determinism hinges on which GR models are admitted.
• Pathological solutions expose indeterministic behavior in GR.
• Removing “bad” models makes GR appear deterministic artificially.
• Pluralistic view accepts GR as a framework, not a single theory.

Summary

The discussion centers on whether General Relativity (GR) is fundamentally deterministic. The speaker emphasizes that GR is not a monolithic theory but a collection of varied mathematical models, each with its own assumptions and boundary conditions. Determinism, therefore, cannot be judged universally; it depends on the specific subset of models under consideration.

Key insights reveal that certain exotic solutions—such as those with closed timelike curves or singularities—introduce genuine indeterminism. Proponents who claim GR is deterministic often exclude these pathological cases, effectively redefining the theory to fit a desired outcome. This selective pruning raises philosophical questions about what counts as the “real” GR.

The conversation highlights a pluralistic stance: rather than seeking a single, definitive version of GR, researchers should acknowledge its diversity. As one participant notes, asking which model is the true one is misguided because empirical access to the full space of solutions is impossible. The debate thus shifts from a binary deterministic/indeterministic label to a nuanced understanding of model dependence.

Implications are clear for both theorists and policymakers. Recognizing GR’s model-dependent determinism influences how we interpret predictions about black holes, cosmology, and potential quantum gravity extensions. It also cautions against over‑reliance on idealized, deterministic simulations when planning high‑precision experiments or space missions.

Original Description

General Relativity (GR) isn't one single theory, but a collection of models. Whether GR is deterministic depends entirely on which model you examine. The 'real' GR remains an elusive question. #GeneralRelativity #Physics #ScienceExplained #Cosmology Full podcast with Prof. J.B. Manchak: https://youtu.be/iGOGxaZZHwE