The Sun is bright
Flux
Luminosity
Counting photons
Double the size of the sphere?
Change the distance?
Distance Luminosity relation
Standard candles
Supernova
Good standard candles
Supernova Type Ia
Hubble's Law (again)
Expansion
Not a constant
Gravitational attraction
Energy density
Measuring deceleration of universal expansion
Distance and redshift
Supernova Type Ia at high redshifts
Expansion rates
Explanations?
Perhaps they are not standard candles
Dust and grey dust
The Cosmological constant
