In 1937, Paul Dirac noticed that very different quantities in physics land near the same giant number. The electric force between a proton and an electron is about 10³⁹ times stronger than their gravitational pull.
The age of the universe, counted in the time light needs to cross an atom, is close to 10⁴⁰.
Why did physicists take this seriously? Dirac was no numerologist. He was a founder of quantum mechanics, and he argued that matches this neat should not be accidents.
His bold step was a testable claim. If these numbers stay linked as the universe ages, gravity must weaken with time. That turned a curiosity into a prediction.
Measurements since, from lunar laser ranging and planetary orbits, show no change anywhere near that size. Robert Dicke later argued that observers can only exist in a limited era of cosmic history, so the match is expected. Dirac's idea remains speculative, not established physics.
Even so, it still asks how deeply atoms and the cosmos may be tied together.
Reference :Dirac, P. A. M. (1937). The Cosmological Constants. Nature, 139(3512), 323.
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