nature of Sun
- Inward (gravity) and outward (pressure) forces must exactly balance
- so the net force is zero
- otherwise sun would collapse or explode
- the sun has been stable for billions of years
- first life on Earth 3-4 billion years ago
- life requires liquid water (H2O)
- Prodigous energy output (4 x 1026 W)
- from energy flux at earth (1 kW/m2) and inverse square law
- Nuclear fusion reactions (E=mc2) deep in the interior
- 4 H atoms are fused to 1 He atom
- difference in mass is converted to energy
- Same principle as H-bombs
- UR’s Laboratory for Laser Energetics is attempting to do this in the lab using lasers to compress and heat H gas
- enormous temperature and pressure for fusion
- exactly that which is needed to balance gravity above