The physics of inflation and dark energy 1.3 Dark energy: some evidence (short list) Ages of glob. clusters/galaxies at z~2-3:  m 0.6 SN Ia:   -  m  0.3 CMB:   +  m  1.0 Large scale motions: 0.15   m 0.4 Cluster mass function:  m 0.3 Bottom line: many indep. hints that  m 0.35   0.65    0.0)

The physics of inflation and dark energy + 2. How to achieve acceleration Newtonian physics ? DENIED...only mass is a source for gravity in Newtonian physics Einstein’s theory ? APPROVED...energy density and pressure are components of a tensor (the stress-energy tensor T ab ) and both are sources for gravity 2.1 Physical basis => gravity is always attractive... => gravity can be “repulsive” (cosmologically) if pressure is sufficiently negative !

The physics of inflation and dark energy 2.2 Einstein, Friedman, de Sitter... FRW geometry: p<-  /3: acceleration p>-  /3: decceleration Friedman equations:

The physics of inflation and dark energy 2.3 Can pressure ever be negative? General equation of state : p X = w X  X  w X  w X  t 

The physics of inflation and dark energy 2.4 Pressure and energy density conservation Energy conservation law in FRW: w X constant: If X is dominant: w Rad = 1/3 w Dust = 0 w  = -1 w X =...

The physics of inflation and dark energy 2.5 Life in an accelerating spacetime v = c Horizon: R horizon = H -1