Quantum Physics and Beyond

Transcription

1 Physics 120 Today Lesson 3: Problems with the Big Bang Cosmic Inflation Yale Physics 120 1/29/2018 John Harris 1

2 Physics 120 Now posted on homepage Announcements Homework 1-2 Solutions Homework 3 Reading and Questions Quiz in two weeks Monday Feb minutes, 6 8 questions similar to those in homework Questions require short answers (no more than 2-3 sentences unless noted) Discussion session on Wednesdays (here 4 5 PM) Reminder Class grade based on: reading/homework assignments (total 20% of grade) 2 in-class quizzes (total 20% of grade) mid-term examination (20% of grade) participation in class discussion (15% of grade) a final paper (total 25% of grade) Yale Physics 120 1/29/2018 John Harris 2

3 Today s Class After the Big Bang: Picking up the pieces! Problems with the Big Bang Big Bang and its Epochs/Eras Today s Remnants of Early Times What did WMAP see in the Cosmic Microwave Background? The Mass/Energy Problem More on Dark Matter and Dark Energy Inflation (quantum tunneling) & the Big Bang Review of the Big Bang and its Epochs/Eras Gravity - the Force We Think We Know Yale Physics 120 1/29/2018 John Harris 3

4 Physics 120 Reading for next class 1) Echoes from the Big Bang (link on webpage) 2) Pop Goes the Universe, Sci. Am. Feb. 2017, (link on webpage) alternative view of inflation! 3) Einstein's gravitational waves found at last, Nature News: 4) Gravitational Waves read the 3 subheadings What are gravitational waves?, Why detect them? and Sources and Types of Gravitational Waves in 5) LIGO - A Gravitational-Wave Interferometer read the 4 subheadings What is LIGO?, About LIGO, What is an interferometer?, LIGO interferometer but not the last on LIGO technology in 6) Look Deeper read only the lead page on Why gravitational waves? 7) LIGO Does It Again: A Second Robust Binary Black Hole Coalescence Observed 8) LIGO Detection of Colliding Neutron Stars 9) The First Monster Black Holes, Sci. Am. Feb Yale Physics 120 1/29/2018 John Harris 4

5 A Few Things to Discuss from the Reading Principle of Relativity Laws of physics are the same in all inertial frames Some Rules of the Game according to Trefil! Basic Rule 1 Laws of Nature are the same throughout time, and can be understood by theories tested by experiment. [counter to it s always possible to explain a fact by tailoring a theory to fit it! ] Basic Rule 2 No special conditions at the creation. Yale Physics 120 1/29/2018 John Harris 5

6 What Are the Problems with the Big Bang Theory Anti-Matter Problem Horizon Problem Flatness Problem Galaxy (Structure) Formation Problem Yale Physics 120 1/29/2018 John Harris 6

7 What Are Plausible Solutions to the Problems of the Big Bang Theory? Anti-Matter Problem Horizon Problem Flatness Problem Galaxy (Structure) Formation Problem Yale Physics 120 1/29/2018 John Harris 7

8 Anti-Matter Problem Anti-Matter Problem Why is matter dominant in our Universe? Anti-Matter Plausible Answer(s) from Trefil Big Bang started with an imbalance of matter over antimatter. Antimatter became segregated or -? Yale Physics 120 1/29/2018 John Harris 8

9 Horizon Problem Horizon Problem How can regions causally disconnected have the same temperature? Horizon Problem Plausible Answer(s) from Trefil Some process before particle era (unknown) that precludes our assumptions Universe created in thermal equilibrium Yale Physics 120 1/29/2018 John Harris 9

10 Galaxy Formation Problem Galaxy (Structure) Formation Problem How did the large scale structure of the Universe come about? Galaxy (Structure) Formation Problem Plausible Answer(s) from Trefil Some process (unknown as yet) that aggregated matter before atoms form. Universe created with matter clumped enough to allow galaxy formation. Yale Physics 120 1/29/2018 John Harris 10

11 Flatness Problem Flatness Problem Will Universe continue to expand or end in a collapse or? Flatness Problem Plausible Answer(s) from Trefil Requires deeper understanding and experimental guidance! Yale Physics 120 1/29/2018 John Harris 11

12 A Few Things to Discuss from the Reading Trefil states at the time of his book: There are problems that are presently unsolved, but should be solvable with our present knowledge. Horizon Problem Galaxy Problem Antimatter Problem There is a problem that requires a much deeper understanding of physics than at present. Flatness Problem Yale Physics 120 1/29/2018 John Harris 12

13 A Few More Things to Discuss about the CMB The Signal and what it means! Yale Physics 120 1/29/2018 John Harris 13

14 Overview of the WMAP Results Transformation (into spherical harmonics) gives Details of clumpiness on different size scales Yale Physics 120 1/29/2018 John Harris 14

15 More on the WMAP Results Yale Physics 120 1/22/2018 John Harris 15

16 MAP Results Like Sound Waves in a Pipe Yale Physics 120 1/29/2018 John Harris 16

17 WMAP Results Acoustical Oscillations in the Early Universe Yale Physics 120 1/29/2018 John Harris 17

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19 Conclusions from WMAP Observations WMAP harmonic analysis gives info on basic parameters of Big Bang density and composition of Universe baryonic vs non-baryonic matter Non-baryonic matter properties Interactions Amount WMAP Universe is ~ flat! Mean energy density equals critical energy density = 5.9 protons / m 3 Energy/Matter breakdown to right Universe today Universe 380,000 years old Yale Physics 120 1/29/2018 John Harris 19

20 Dark Matter and Dark Energy Questions What do you think dark energy is? What characteristics would you give to dark matter? When and how in the evolution of the Universe is dark matter important? When and how in the evolution of the Universe is dark energy important? What force(s) would you expect each of them to interact with/through? How do they appear to be distributed (e.g. smooth, lumpy,..?) in the Universe? Yale Physics 120 1/29/2018 John Harris 20

21 Quantum Tunneling & Inflation Yale Physics 120 1/29/2018 John Harris 21

22 Tunneling A Quantum Mechanical Phenomenon Particle in a potential well Seeks lowest energy state could be a vacuum state Classically will be at bottom of well Can be in higher states (excited) Quantum Mechanics Probability to be at different places Probability distribution shown Note can be outside well Origin of Tunneling Has been observed But probability extremely small Yale Physics 120 1/29/2018 John Harris 22

23 False Vacuum Real vacuum state in early Universe? Energy minimum False vacuum state? Local minimum Tunneling From false to real vacuum state Quantum probability Yale Physics 120 1/29/2018 John Harris 23

24 Symmetry Breaking Yale Physics 120 1/29/2018 John Harris 24

25 Inflation A Few Important Things to Know from the Reading Trefil s use of the Higgs Field read as Inflaton Field Not the Higgs as we now know it Similar properties creates mass in the Universe (more later when we study the Higgs that has been discovered at CERN!) Energy tied up in the Higgs Field meaning Inflaton Field Inflationary Universe Radius of curvature expands exponentially Inflationary Universe doubles size 70 times in seconds: 2 70 size expansion No inflation doubles size 8 times in seconds: 2 3 size expansion Most of the mass of the Universe is created after tunneling out of the False Vacuum! Yale Physics 120 1/29/2018 John Harris 25

26 Inflation Yale Physics 120 1/29/2018 John Harris 26

27 Now that We Know About the CMB & Inflation Go to cartoon on Cosmic Inflation Explained: Yale Physics 120 1/29/2018 John Harris 27

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32 Evolution of Universe Cosmic Dust to Galaxies Z ~ percent redshift Large Z early times Small Z most recent Z ~ 28 Beginning of Universe Cosmic dust Z ~ 0 Now Galaxies Yale Physics 120 1/29/2018 Quantum Physics and Beyond John Harris 32

33 Review Big Bang and its Epochs/Eras Time Temperature s s Which Force(s) Freeze? GUT Era Freezes Electroweak Era Planck Time Which particles? s Freeze Quark Era 10-5 s 3 minutes 380,000 yrs Freeze Particle Era Form Form Yale Physics 120 1/29/2018 John Harris 33