1. Salient Features of the Universe Homogeneity and isotropy for 6000 Mpc > x > 100 Mpc Universe expanding uniformly ordinary matter is more abundant than ordinary antimatter chemical composition is roughly 75% H, 25% He, + trace thermal background of radiation with T~3K nearly scale invariant, adiabatic CMB fluctuations hierarchy of lumpy structure from 1 kpc to 100 Mpc scales matter is a minority (1/4x) of all energy ordinary matter is a minority (1/6x) of all matter universe is spatially flat expansion rate is accelerating

3. Best evidence: we exist !

8. Case II: If clustered matter does not dominate: Case I: Flat, matter dominated Universe

9. a ~ 1/1000 a ~ 1/5  ~ a(t)  grows by only 200

12. Salient Features of the Universe Homogeneity and isotropy for 6000 Mpc > x > 100 Mpc Universe expanding uniformly ordinary matter is more abundant than ordinary antimatter chemical composition is roughly 75% H, 25% He, + trace thermal background of radiation with T~3K nearly scale invariant, adiabatic CMB fluctuations hierarchy of lumpy structure from 1 kpc to 100 Mpc scales matter is a minority (1/4x) of all energy ordinary matter is a minority (1/6x) of all matter universe is spatially flat expansion rate is accelerating

13. Best evidence: we exist !

14. Mass density/critical density Hubble constant (x 100 km/s/Mpc) J. Ostriker & PJS, Nature (1995): Compelling evidence for Low Matter Density

15. J. Ostriker & PJS, Nature (1995): Compelling evidence for Low Matter Density Fluctuations in the Cosmic Microwave Background Anisotropy Compelling case for a Flat Universe

16. J. Ostriker & PJS, Nature (1995): Compelling evidence for Low Matter Density Compelling case for a Flat Universe Only possible if there is Dark Energy

17. J. Ostriker & PJS, Nature (1995): Compelling evidence for Low Matter Density Compelling case for a Flat Universe Only possible if there is Dark Energy … but, then, the dark energy better have negative pressure

18. Positive pressure time energy density

19. Negative pressure Matter dominates time energy density

20. J. Ostriker & PJS, Nature (1995): Compelling evidence for Low Matter Density Compelling case for a Flat Universe Only possible if there is Dark Energy … but, then, the dark energy better have negative pressure … but, then, the universe must be accelerating

22. Type IA Supernovae

23. Cosmological Constant or Quintessence?

24. w < -1/3 means KE < V/2 scalar fields

25. Case II: If clustered matter does not dominate: Case I: Flat, matter dominated Universe

26. Steady expansion

27. Observed Features of the Universe Universe is homogeneous and isotropic on lengths > 100 Mpc Universe expanding uniformly ordinary matter is more abundant than ordinary antimatter chemical composition is roughly 75% H, 25% He, + trace thermal background of radiation with T~3K nearly scale invariant spectrum of CMB fluctuations hierarchy of structure from 1 kpc to 1 Mpc scales matter is a minority (1/4x) of all energy ordinary matter is a minority (1/6x) of all matter universe is spatially flat expansion rate accelerating

28. Observed Features of the Universe Universe is homogeneous and isotropic on lengths > 100 Mpc Universe expanding uniformly ordinary matter is more abundant than ordinary antimatter chemical composition is roughly 75% H, 25% He, + trace thermal background of radiation with T~3K nearly scale invariant spectrum of CMB fluctuations hierarchy of structure from 1 kpc to 1 Mpc scales matter is a minority (1/4x) of all energy ordinary matter is a minority (1/6x) of all matter universe is spatially flat expansion rate accelerating

29. Observed Features of the Universe Universe is homogeneous and isotropic on lengths > 100 Mpc Universe expanding uniformly ordinary matter is more abundant than ordinary antimatter chemical composition is roughly 75% H, 25% He, + trace thermal background of radiation with T~3K nearly scale invariant spectrum of CMB fluctuations hierarchy of structure from 1 kpc to 1 Mpc scales matter is a minority (1/4x) of all energy ordinary matter is a minority (1/6x) of all matter universe is spatially flat expansion rate accelerating

30. Observed Features of the Universe Universe is homogeneous and isotropic on lengths > 100 Mpc Universe expanding uniformly ordinary matter is more abundant than ordinary antimatter chemical composition is roughly 75% H, 25% He, + trace thermal background of radiation with T~3K nearly scale invariant spectrum of CMB fluctuations hierarchy of structure from 1 kpc to 1 Mpc scales matter is a minority (1/4x) of all energy ordinary matter is a minority (1/6x) of all matter universe is spatially flat expansion rate accelerating

31. Looking for some problems? What is the nature of dark matter? What is the nature of dark energy? What is origin of supermassive black holes? What role does dark energy and cosmic acceleration play? Why is the cosmological constant so small? What is the origin of matter-antimatter asymmetry? Is the inflationary theory correct? (or the cyclic?) What is the inflaton or cyclic field responsible? How far does space extend? Is the Big Bang a beginning of space and time? Why are there three large spatial dimensions?