Salient Features of the Universe

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

3. Best evidence: we exist !

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

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

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

13. Best evidence: we exist !

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

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

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. energy density Positive pressure time

19. Matter dominates energy density Negative pressure time

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

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

26. Steady expansion

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

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

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

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