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Announcements

Announcements. Midterm III grades are online final projects due: today !!!! all extra credits due: Wednesday, May 2nd final: Friday, May 11th, 2pm - 4pm review session for final: Wednesday May 9th, 6pm. 1st peak. 2nd peak. 3rd peak. The Music of the Universe.

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Announcements

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  1. Announcements • Midterm III grades are online • final projects due: today !!!! • all extra credits due: Wednesday, May 2nd • final: Friday, May 11th, 2pm - 4pm • review session for final: Wednesday May 9th, 6pm Astronomy 201 Cosmology - Lecture 41

  2. 1st peak 2nd peak 3rd peak The Music of the Universe Astronomy 201 Cosmology - Lecture 41

  3. New results from Boomerang (April 29, 2001) Astronomy 201 Cosmology - Lecture 41

  4. News summary • 3 independent CMB experiments (BOOMERANG, MAXIMA, DASI) obtain consistent results • clear measurement of 2nd peak, strong indication for 3rd peak • data analysis • universe is flat 0+ = 1.03±0.06 • bary = 0.04 ±0.01, consistent with big bang nucleosynthesis • strong indication for >0. Astronomy 201 Cosmology - Lecture 41

  5. Lecture 41:Frontiers in cosmology I: Inflation stockbrokers are not afraid of Astronomy 201 Cosmology - Lecture 41

  6. Unsolved issues in the standard model • Horizon problem: • Why is the CMB so smooth? • The flatness problem: • Why is ~~1 ? Why is the universe flat ? • The structure problem: • Where do the fluctuation in the CMB come from? • The relic problem • Why aren’t there magnetic monopoles, why is there more matter than antimatter? Astronomy 201 Cosmology - Lecture 41

  7. Problem I: The horizon problem • CMB: light emitted when the universe became transparent. • Age of the Universe at that epoch: 100 000 yr • The size of patches that can have influenced each other: < 100 000 lyr • Those patches appear today under an angle of less than 1º • Why is the CMB so smooth on scales larger 1º if those region never knew about each other? Astronomy 201 Cosmology - Lecture 41

  8. Problem II: The flatness problem • =0: for most of its age, the universe looks either to be flat or to be empty • >0: for most of its age, the universe looks either to be flat or to be exponentially expanding • Isn’t it strange that we appear to live in that short period between those two extremes? • Should we be surprised that the universe appears to be flat? Astronomy 201 Cosmology - Lecture 41

  9. Problem III: Large scale structure • Models like CDM nicely explain how the fluctuations we can observe in the CMB grew to form galaxies. • They also can reproduce the observed large scale distribution of galaxies and clusters of galaxies. • But why are there fluctuations in the first place? Astronomy 201 Cosmology - Lecture 41

  10. Problem IV: The relic problem • Modern cosmology is a very successful synergy of astrophysics and particle physics. • Why are there so many photons in the universe (a billions times more than baryons) • Why is there more matter than anti-matter ? • Why aren’t there magnetic monopoles or any other relic particles? Astronomy 201 Cosmology - Lecture 41

  11. Timeline of the Universe ??? Backed by experiment Astronomy 201 Cosmology - Lecture 41

  12. The concept of inflation • The idea (A. Guth 1980): Shortly after the big bang, the universe went through a phase of rapid (exponential) expansion. In this phase the energy and thus the dynamics of the Universe was determined by term similar to the cosmological constant (vacuum energy). • Why should the Universe do that? • Why does it help? Astronomy 201 Cosmology - Lecture 41

  13. The model of inflation Astronomy 201 Cosmology - Lecture 41

  14. steam Phase transition: water  steam water ice Phase transition: ice  water Phase transitions • Example: ice  water  steam Temperature Invested energy Astronomy 201 Cosmology - Lecture 41

  15. Phase transitions in the early Universe • Electroweak phase transition:As the temperature drops below ~ 1015K, the electroweak force separates into electromagnetism and the weak nuclear force • T > 1015K: electroweak force • T < 1015K: electromagnetism, weak nuclear force • but to moderate a phase transition to trigger inflation Astronomy 201 Cosmology - Lecture 41

  16. Phase transitions in the early Universe • GUT phase transition:As the temperature drops below ~ 1029K, GUT force separates into the strong nuclear force and the electroweak force • T > 1029K: GUT • T < 1029K: electroweak force, strong nuclear force • One of the candidates for inflation • Other candidates: specifically designed inflaton fields Astronomy 201 Cosmology - Lecture 41

  17. What happens in such a phase transition • Universe in the state of false vacuum • energy of Universe dominated by vacuum energy • vacuum energy acts like a cosmological constant • Universe expands exponentially • Problem: how to gracefully exit inflation? Astronomy 201 Cosmology - Lecture 41

  18. Manifestation of vacuum energy: the Casimir effect Astronomy 201 Cosmology - Lecture 41

  19. Inflation and the horizon problem Astronomy 201 Cosmology - Lecture 41

  20. Inflation and the flatness problem Astronomy 201 Cosmology - Lecture 41

  21. Inflation and the structure problem • Before inflation: quantum fluctuations • Inflation: amplifies quantum fluctuations to macroscopic scales • After inflation: macroscopic fluctuations (as can be observed in the CMB radiation) provide the seeds from which galaxies form Astronomy 201 Cosmology - Lecture 41

  22. Inflation starts, many irregularities present Extreme expansion … More expansion ... Inflation and the relic problem Astronomy 201 Cosmology - Lecture 41

  23. The orange area becomes more smooth The irregularities disperse Our Universe (orange spot) is now in a very smooth region Inflation and the relic problem Astronomy 201 Cosmology - Lecture 41

  24. How can we test inflation ? • With the CMB (again) • recall: 1st peak  universe resonates • 2nd and 3rd peak next overtones (harmonics) • but in order to “hear” the overtones, all “bells” have to be ringed in phase. • Inflation synchronizes the bells. • The recent measurement of the 2nd (and 3rd ?) peak is strongly in support of inflation Astronomy 201 Cosmology - Lecture 41

  25. New results from Boomerang (April 29, 2001) Astronomy 201 Cosmology - Lecture 41

  26. Announcements • Midterm III grades are online • final projects due: today !!!! • all extra credits due: Wednesday, May 2nd • final: Friday, May 11th, 2pm - 4pm • review session for final: Wednesday May 9th, 6pm Astronomy 201 Cosmology - Lecture 41

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