nDominant force on astronomical size scale.
nNeed very close
balance of gravity and cosmic expansion for
stable universe.
uIf gravity weaker by 1 in 1060, universe expands too
quickly, no galaxies or stars formed.
uIf gravity stronger by 1 in 1060, universe collapses
without forming galaxies or stars.
nGravity is fine-tuned
to 1 part in 1060.