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fine-tuned, or just here

Several of the universe's basic constants sit in a surprisingly narrow range that allows stars, atoms, and chemistry to exist at all. The most extreme case: the cosmological constant's "natural" value should be roughly 10 followed by 120 zeros larger than what's actually observed. Nudge it by a small fraction, and the equations predict a universe with no galaxies, no stars, no atoms heavier than hydrogen. This is real, established physics, not speculation. What it doesn't settle is why: a multiverse of differently-tuned universes, a selection effect built into the question itself — we could only ever find ourselves somewhere life is possible — or something else entirely. Physicists and philosophers still argue over which, and none of the answers has earned the right to call itself settled.