The Big Bang Theory: How the Universe Began

  1. The Big Bang Theory says the universe began as a hot, dense point about 13.8 billion years ago.
  2. Space itself has been expanding ever since, carrying galaxies farther apart.
  3. Evidence comes from Edwin Hubble’s 1929 discovery that galaxies are moving away from us.
  4. The cosmic microwave background is the faint afterglow of the Big Bang, still visible today.
  5. In the first few minutes, the universe forged the lightest elements—hydrogen and helium.
  6. Tiny fluctuations in the early universe grew into stars, galaxies, and cosmic structures.
  7. The theory does not explain what caused the Big Bang, only what followed.
  8. Cosmic inflation suggests the universe expanded faster than light in its earliest fraction of a second.
  9. Dark matter and dark energy remain mysteries within the Big Bang framework.
  10. The Big Bang is the most widely accepted model, but scientists continue testing its limits.