Astronomy
13.8 billion years
Hydrogen and Helium
Cosmology
Strong force, electromagnetic force, weak force, gravity
Big bang theory
George's Lemaitre
George Gamow
Albert Einstein
Edwin Hubble
Cosmological principle
Expansion
Flat, closed, open, accelerating universe
Flat universe
Open universe
Steady state theory
Fred Hoyle
Alan Guth
Solar system
Fission theory-George Darwin 1984