The ontological status of spacetime. Relativity brilliantly describes gravity as the curvature of a 4D spacetime continuum. The hard problem: Is this mathematical model—a static, geometric "block universe" where past, present, and future equally exist—a true picture of reality? If so, it obliterates free will and the passage of time as illusions. Or is it just a fantastically useful computational tool for predicting how things move and age relative to each other? We're forced to choose: either accept a frozen, deterministic cosmos that feels nothing like our lived experience, or admit our best theory of gravity describes relationships, not fundamental reality.
Example: According to relativity, from a god's-eye view, your birth, you reading this, and your death are all just fixed points in the spacetime block, like cities on a map. The hard problem: Your undeniable, visceral experience is of a flowing "now." Is that feeling a complete fiction generated by your brain? If spacetime is real, then the future is already "out there," waiting. This makes physics philosophically intolerable for most people, suggesting the theory may be a powerful instrumental description, not a literal metaphysical truth. But what, then, is gravity actually doing? Hard Problem of Relativity.
by Enkigal January 24, 2026
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