Fine-Tuned Universe: The Rumour That the Numbers Were Set for Life

An atom does not choose the force holding its electrons. A star does not choose how quickly it burns fuel. A galaxy does not choose how strongly matter gathers instead of spreading apart. Those events depend on numbers present from the beginning: the strength of gravity, electromagnetism, strong and weak nuclear forces, particle masses, dark-energy density, the ratio of matter to radiation and the initial expansion rate. If the numbers were different, the universe might have no stable atoms, no long-lived stars, no carbon, no planets and no people asking why the numbers are so exact.