A speculative framework proposing that our observable spacetime is not the only one—that there may be "outer" spacetime beyond or outside our cosmological horizon. Outer Spacetime Theory suggests that the universe we observe is a bubble, a membrane, or a region within a larger multiverse of spacetime manifolds. This outer spacetime might have different dimensions, different physical constants, or different laws entirely. The theory extends relativity beyond the observable, asking what lies outside—not just in space, but in the fabric of reality itself. It's cosmology's frontier: what's beyond the cosmic horizon?
"Our universe is 13.8 billion years old, but Outer Spacetime Theory asks: old relative to what? Our spacetime might be a bubble in a vast cosmic ocean of other spacetimes. The question isn't just what's in the universe; it's what's outside the universe. Outer Spacetime: the ultimate beyond."
by Dumu The Void March 5, 2026
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