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Cosmic Acceleration and Dark Energy For Phy 262 Andreas Albrecht

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  1. Cosmic Acceleration and Dark Energy For Phy 262 Andreas Albrecht (based on various seminars and colloquia) PHY 262 Dark Energy; A. Albrecht

  2. Slides with a large blue box like this are outlines slides that still need to be updated (due to this slides set being combined from different talks) PHY 262 Dark Energy; A. Albrecht

  3. CONCLUSIONS • Cosmic acceleration has made life really exciting for the theorist • Hardly a closed case PHY 262 Dark Energy; A. Albrecht

  4. CONCLUSIONS • Cosmic acceleration has made life really exciting for the theorist • Hardly a closed case PHY 262 Dark Energy; A. Albrecht

  5. OUTLINE needs updating • The Basics: Data, Directions and Issues • Anthropics, Landscape & Critique • Alternative Viewpoints • Conclusions PHY 262 Dark Energy; A. Albrecht

  6. OUTLINE • The Basics: Data, Directions and Issues • Anthropics, Landscape & Critique • Alternative Viewpoints • Conclusions  PHY 262 Dark Energy; A. Albrecht

  7. Cosmic acceleration Accelerating matter is required to fit current data Preferred by data c. 2003  Amount of w=-1 matter (“Dark energy”) “Ordinary” non accelerating matter Supernova  Amount of “ordinary” gravitating matter PHY 262 Dark Energy; A. Albrecht (Includes Dark Matter)

  8. Cosmic acceleration Accelerating matter is required to fit current data Kowalski, et al., Ap.J.. (2008) Preferred by data c. 2008  Amount of w=-1 matter (“Dark energy”) “Ordinary” non accelerating matter BAO  Amount of “ordinary” gravitating matter PHY 262 Dark Energy; A. Albrecht (Includes Dark Matter)

  9. Cosmic acceleration Accelerating matter is required to fit current data Suzuki, et al., Ap.J.. (2011) Preferred by data c. 2011  Amount of w=-1 matter (“Dark energy”) “Ordinary” non accelerating matter BAO  Amount of “ordinary” gravitating matter PHY 262 Dark Energy; A. Albrecht (Includes Dark Matter)

  10. Cosmic acceleration Accelerating matter is required to fit current data Preferred by data c. 2003 “Ordinary” non accelerating matter Supernova PHY 262 Dark Energy; A. Albrecht (Includes Dark Matter)

  11. Friedmann Eqn. PHY 262 Dark Energy; A. Albrecht

  12. Friedmann Eqn. Scale factor Dark Energy Curvature Non-relativistic Matter Relativistic Matter PHY 262 Dark Energy; A. Albrecht

  13. Friedmann Eqn. Scale factor Dark Energy Curvature Non-relativistic Matter Relativistic Matter PHY 262 Dark Energy; A. Albrecht

  14. Friedmann Eqn. PHY 262 Dark Energy; A. Albrecht

  15. Friedmann Eqn. PHY 262 Dark Energy; A. Albrecht

  16. Positive acceleration requires • (unlike any known constituent of the Universe) or • a non-zero cosmological constant or • an alteration to General Relativity. PHY 262 Dark Energy; A. Albrecht

  17. Positive acceleration requires • (unlike any known constituent of the Universe) or • a non-zero cosmological constant or • an alteration to General Relativity.  PHY 262 Dark Energy; A. Albrecht

  18. Positive acceleration requires • (unlike any known constituent of the Universe) or • a non-zero cosmological constant or • an alteration to General Relativity.  PHY 262 Dark Energy; A. Albrecht

  19. Positive acceleration requires • (unlike any known constituent of the Universe) or • a non-zero cosmological constant or • an alteration to General Relativity.  PHY 262 Dark Energy; A. Albrecht

  20. Two “familiar” ways to achieve acceleration: 1) Einstein’s cosmological constant and relatives 2) Whatever drove inflation: Dynamical, Scalar field? Positive acceleration requires • (unlike any known constituent of the Universe) or • a non-zero cosmological constant or • an alteration to General Relativity. PHY 262 Dark Energy; A. Albrecht

  21. Two “familiar” ways to achieve acceleration: 1) Einstein’s cosmological constant and relatives 2) Whatever drove inflation: Dynamical, Scalar field? Positive acceleration requires • (unlike any known constituent of the Universe) or • a non-zero cosmological constant or • an alteration to General Relativity. PHY 262 Dark Energy; A. Albrecht

  22. Some general issues: Numbers: • Today, • Field models typically require a particle mass of from PHY 262 Dark Energy; A. Albrecht

  23. Some general issues: Numbers: • Today, • Field models typically require a particle mass of from Where do these come from and how are they protected from quantum corrections? PHY 262 Dark Energy; A. Albrecht

  24. Some general issues: Numbers: • Today, • Field models typically require a particle mass of from Where do these come from and how are they protected from quantum corrections? PHY 262 Dark Energy; A. Albrecht

  25. Some general issues A cosmological constant • Nice “textbook” solutions BUT • Deep problems/impacts re fundamental physics • Vacuum energy problem  = 10120 Vacuum Fluctuations   0 ? PHY 262 Dark Energy; A. Albrecht

  26. Some general issues A cosmological constant • Nice “textbook” solutions BUT • Deep problems/impacts re fundamental physics • Vacuum energy problem (not resolved by scalar field models)  = 10120 Vacuum Fluctuations   0 ? PHY 262 Dark Energy; A. Albrecht

  27. OUTLINE • The Basics: Data, Directions and Issues • Anthropics, Landscape & Critique • Alternative Viewpoints • Conclusions  PHY 262 Dark Energy; A. Albrecht

  28. OUTLINE • The Basics: Data, Directions and Issues • Anthropics, Landscape & Critique • Alternative Viewpoints • Conclusions  PHY 262 Dark Energy; A. Albrecht

  29. Anthropics and the value of Λ • Basic idea: • When Λ or radiation dominates the universe structure (i.e. galaxies) cannot form PHY 262 Dark Energy; A. Albrecht

  30. Anthropics and the value of Λ • Basic idea: • When Λ or radiation dominates the universe structure (i.e. galaxies) cannot form Density Structure forming zone Time  PHY 262 Dark Energy; A. Albrecht

  31. Anthropics and the value of Λ • Basic idea: • When Λ or radiation dominates the universe structure (i.e. galaxies) cannot form Density Structure forming zone Time  PHY 262 Dark Energy; A. Albrecht

  32. Anthropics and the value of Λ • Basic idea: • When Λ or radiation dominates the universe structure (i.e. galaxies) cannot form Density Structure forming zone Time  PHY 262 Dark Energy; A. Albrecht

  33. Anthropics and the value of Λ • Basic idea: • When Λ or radiation dominates the universe structure (i.e. galaxies) cannot form • Can we input that data that we have cosmic structure and predict the (very small) value of Λ? (Life?!) • To do this one requires: • A theory with an ensemble of values of Λ • A way to quantify “having structure” sufficiently PHY 262 Dark Energy; A. Albrecht

  34. Anthropics and the value of Λ • Basic idea: • When Λ or radiation dominates the universe structure (i.e. galaxies) cannot form • Can we input that data that we have cosmic structure and predict the (very small) value of Λ? (Life?!) • To do this one requires: • A theory with an ensemble of values of Λ • A way to quantify “having structure” sufficiently • Weinberg used some simple choices for 1) and 2) and “predicted” a value of Λ in 1987 similar to the value discovered ~10 years later. • Since then string theorists have argued that the string theory landscape delivers a suitable ensemble of Λ’s (Bousso & Polchinski) PHY 262 Dark Energy; A. Albrecht

  35. LAB LAB LAB LAB LAB LAB Comment on how we use knowledge (“A” word!) Total knowledge about the universe Input Theory Output PHY 262 Dark Energy; A. Albrecht

  36. LAB LAB LAB LAB LAB LAB Comment on the “A” word: Total knowledge about the universe Input Theory Output PHY 262 Dark Energy; A. Albrecht

  37. LAB LAB LAB LAB LAB LAB Comment on the “A” word: Total knowledge about the universe Input Theory Output PHY 262 Dark Energy; A. Albrecht

  38. LAB LAB LAB LAB LAB LAB Comment on the “A” word: Total knowledge about the universe Input Theory Output PHY 262 Dark Energy; A. Albrecht

  39. LAB LAB LAB LAB LAB LAB LAB PREDICTIONS Comment on the “A” word: Total knowledge about the universe Input Theory Output PHY 262 Dark Energy; A. Albrecht

  40. PRED LAB LAB LAB LAB LAB LAB LAB The best science will use up less here and produce more here Input Theory Output PHY 262 Dark Energy; A. Albrecht

  41. Further comments on anthropics: • Replace “life” with more humble “correlations” and one has a commonplace part of physics (non-controversial) PHY 262 Dark Energy; A. Albrecht

  42. Further comments on anthropics: • Replace “life” with more humble “correlations” and one has a commonplace part of physics (non-controversial) • In my view 2nd law is most robust candidate for anthropic analysis PHY 262 Dark Energy; A. Albrecht

  43. Further comments on anthropics: • Replace “life” with more humble “correlations” and one has a commonplace part of physics (non-controversial) • In my view 2nd law is most robust candidate for anthropic analysis • These ingredients still not well developed in case of Λ anthropics: • A theory with an ensemble of values of Λ • A way to quantify “having structure” (or alternative condition) sufficiently PHY 262 Dark Energy; A. Albrecht

  44. Further comments on anthropics: • Replace “life” with more humble “correlations” and one has a commonplace part of physics (non-controversial) • In my view 2nd law is most robust candidate for anthropic analysis • These ingredients still not well developed in case of Λ anthropics: • A theory with an ensemble of values of Λ • A way to quantify “having structure” (or alternative condition) sufficiently Can get very different answers depending on how these ingredients are realized Banks, Dine & Motl PHY 262 Dark Energy; A. Albrecht

  45. Can get very different answers depending on how these ingredients are realized • Use "entropy production weighting” (Causal Entropic Principle, Bousso et al) • Include variability of world lines due to cosmic structure • Two different behaviors for late time entropy production in halos Un-normalized probability density Phillips & Albrecht 2011 PHY 262 Dark Energy; A. Albrecht

  46. Further comments on anthropics: • Replace “life” with more humble “correlations” and one has a commonplace part of physics (non-controversial) • In my view 2nd law is most robust candidate for anthropic analysis • These ingredients still not well developed in case of Λ anthropics: • A theory with an ensemble of values of Λ • A way to quantify “having structure” (or alternative condition) sufficiently Can get very different answers depending on how these ingredients are realized Banks, Dine & Motl PHY 262 Dark Energy; A. Albrecht

  47. Further comments on anthropics: • Replace “life” with more humble “correlations” and one has a commonplace part of physics (non-controversial) • In my view 2nd law is most robust candidate for anthropic analysis • These ingredients still not well developed in case of Λ anthropics: • A theory with an ensemble of values of Λ • A way to quantify “having structure” (or alternative condition) sufficiently Can get very different answers depending on how these ingredients are realized Banks, Dine & Motl PHY 262 Dark Energy; A. Albrecht

  48. Further comments on anthropics: • Replace “life” with more humble “correlations” and one has a commonplace part of physics (non-controversial) • In my view 2nd law is most robust candidate for anthropic analysis • These ingredients still not well developed in case of Λ anthropics: • A theory with an ensemble of values of Λ • A way to quantify “having structure” (or alternative condition) sufficiently PHY 262 Dark Energy; A. Albrecht

  49. Further comments on anthropics: • Replace “life” with more humble “correlations” and one has a commonplace part of physics (non-controversial) • In my view 2nd law is most robust candidate for anthropic analysis • These ingredients still not well developed in case of Λ anthropics: • A theory with an ensemble of values of Λ • A way to quantify “having structure” (or alternative condition) sufficiently • In my view the string theory landscape is unlikely to survive as a compelling example of 1) PHY 262 Dark Energy; A. Albrecht

  50. Further comments on anthropics: • Replace “life” with more humble “correlations” and one has a commonplace part of physics (non-controversial) • In my view 2nd law is most robust candidate for anthropic analysis • These ingredients still not well developed in case of Λ anthropics: • A theory with an ensemble of values of Λ • A way to quantify “having structure” (or alternative condition) sufficiently • In my view the string theory landscape is unlikely to survive as a compelling example of 1) Eternal inflation PHY 262 Dark Energy; A. Albrecht