Trace the universe's expansion backward using ordinary general relativity, and the equations collapse into a singularity — a point of infinite density where the theory itself stops making sense. Loop Quantum Cosmology offers a different ending. As the universe contracts toward that point, the discreteness of quantum geometry generates an intense repulsion that no classical force can produce, halting the collapse just short of infinity and rebounding it outward again. In this picture, the Big Bang was not the beginning of everything, but a bounce: the visible edge of a universe that may have existed before it.
Sit for a moment with the possibility that the beginning you can trace backward may not have been a beginning at all.
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Quantum Gravity