ASTR/PHYS 109 Dr. David Toback Lecture 26 & 27 Early Times & Fate of the Universe Topic 1: Possibilities 1
Was due Today L27 Last day of Class Reading: (Unit 6) Pre-Lecture Reading Questions (PLRQ) Unit 6, Stage 1: Was due today before class Unit 6, Stage 2: Due before usual class time Wednesday, May 3rd End-of-Chapter Quizzes: Chapter 17 Papers: Paper 3 Revision (if desired), Stage 2: Was due today before class Turn in to both CPR and turnitin on ecampus even if the text is the same (that way we know that it s the same) Paper 4, Stage 1: Due before the usual class time on Wednesday, May 3 rd Paper 4, Stage 2: Due Tuesday May 9 th by 11:55PM Honors Paper: Due tonight at 11:55PM in turnitin. Let me know if you need an extension General: CPR: Mis-graded on any Assignment? Let us know Extra credit for students who do PLRQ Unit 6 and/or Paper 4 stuff in Peerceptiv Early Times & Fate of the Universe Topic 1: Possibilities 3
Course Evaluations Course evaluations will be done online: I believe you should have gotten an email about this already The Spring 2018 evaluation period: Already Begun (http://evaluation.tamu.edu/) Ends Fri May 19 th, 5PM Please do them won t take long Early Times & Fate of the Universe Topic 1: Possibilities 4
Unit 6 Going back in time and going forward in time Before the first millionth of a second and the Fate of the Universe Early Times & Fate of the Universe Topic 1: Possibilities 6
Outline of Unit 6 1.Possible Fates of the Today Universe, Dark Matter and Dark Energy 2.Particle Physics, Dark Matter and the Very Early Universe 3.Inflation Early Times & Fate of the Universe Topic 1: Possibilities 7
The Accelerating Universe Big 28 Bang, Black Early Times & Fate of The
The Evolution and Fate of the Universe Dark Energy overcomes the deceleration of Gravity about 6 billion years ago, Universe starts accelerating Deceleration due to Gravity for the first 6 billion years 33 Dark Energy Makes the Universe Accelerate (keep expanding Faster and faster) Topic 5: Dar Energy We don t know the nature of Dark Energy Lots of possible Fates but it looks like we ll expand forever and it could get REALLY cold!
Lots of Questions How will we figure out the fate of the Universe? Need to know the Nature of Dark Energy What is Dark Energy? We don t know yet Just starting to have ideas.. This result was so important that it was Early Times & Fate awarded of the Universe Nobel Prize for 2012 34 Topic 1: Possibilities
Lecture on Chapter 18 now complete Big 35 Bang, Black
Interaction: The Weak Force Responsible for radioactivity, the decay of atomic nuclei The Particles that mediate this interaction are known as the W and Z particles These particles were predicted in the late 1960 s and discovered in the 80 s Einstein didn t know about them Topic 2: Particle Physics 14
The Weak Force A Down Quark can change into an up quark by emitting a W u W A W can decay into an electron and a neutrino e d W Lives 10-24 Seconds Topic 2: Particle Physics 15
Neutron Decay Neutron Proton + W Proton + Electron + Neutrino W Electron Neutrino Down Quark Down Quark Up Quark Up Quark Neutron Topic 2: Particle Physics Proton 16
Creating Neutron Stars Proton + Electron Neutron + Neutrino Electron W Neutrino (leaves the star) Up Quark Down Quark Up Quark Proton Down Quark Topic 2: Particle Physics Neutron 17
Other Weak Force Interactions Electron+Positron Z muon + antimuon Electron+Positron Z quark + antiquark e + quark + e - Z Can create lots of different types of particles this way in collisions Topic 2: Particle Physics Antiquark - 18
Some fun evidence that Dark Matter is Made of Particles Colliding Clusters of Galaxies Topic 2: Particle Physics 25
Look at Colliding Clusters of Galaxies Atoms in the Galaxies interact and slow down as they pass through each other Atoms Atoms Dark Matter doesn t interact much so it isn t slowed down much Dark Matter Dark Matter Topic 2: Particle Physics 26
Colliding Galaxy Clusters The atom part and the Dark Matter part of Galaxies interact differently as they pass through each other Atoms and Dark Matter Atoms and Dark Matter Topic 2: Particle Physics 27
Colliding Galaxy Clusters Galaxy Galaxy Galaxy Atoms and Dark Matter Light from a Galaxy Atoms and Dark Matter Topic 2: Particle Physics 28
Evidence for This in Nature? Colliding Clusters of Galaxies Blue is the part from lensing only Fast Dark Matter Red part from observing the light Slow Atoms Topic 2: Particle Physics 29
http://bigbang.physics.tamu.edu/figures/stolenanimations/bullett_anim_lg.mpg Topic 2: Particle Physics 30
Outline of Unit 6 1.Possible Fates of the Universe, Dark Matter and Dark Energy 2.Particle Physics, Dark Matter and the Very Early Universe 3.Inflation 4 Last Topic
Overview Example Brief History of Time 1. Universe grows slowly for awhile 2. Then grows really quickly for awhile 3. Then grows at the rate we see now Our Universe Now Our Universe right after the bang Topic 4: Inflation 17
An Inflationary Version of History 1.The Big Bang occurs, the universe expands and cools much more slowly than it does today For the first 10-35 seconds the expansion is SO SLOW that the Universe comes into thermal equilibrium 2.The Universe starts expanding VERY RAPIDLY for a really short time Call this time period Inflation Grows by between 10 20 and 10 30 times 3.After inflation is done, the Universe grows with the rate consistent with what we observe today Topic 4: Inflation 18
Put this in Perspective Before Inflation: The visible Universe was about the size of an atom During Inflation: It grew to about the size of a cherry pit After Inflation: Continued with a slower expansion to its current size Topic 4: Inflation 19
Aside on Relativity Remember: No THING can travel THROUGH SPACE faster than the speed of light However: General Relativity doesn t place a limit on the speed at which Space-Time can stretch Topic 4: Inflation 20
How does this make the Universe look like it s in Thermal Equilibrium? Before inflation the Universe was really small The stuff in it had plenty of time to come into Thermal Equilibrium After inflation all that occurs is the expansion of a Universe that at one point was in thermal equilibrium Thus, you live in an observable universe with the same temperature in all directions Topic 4: Inflation 21
Quantum Fluctuations and Inflation The quantum fluctuations in the early universe are what provided the seeds for galaxy formation Fluctuations occurred in the universe BEFORE inflation (when universe was small enough for quantum mechanics to be important) Just stayed in place during the rapid expansion Same temperature everywhere, even though not in thermal equilibrium today Topic 4: Inflation 22
Now we are able to explain all the major stages of the the Evolution of The Universe Topic 4: Inflation 23
Inflation The problem with the model Topic 4: Inflation 24
What Caused Inflation? Don t really know SHU Chapters 12 and 13 present some ideas, but its not clear they re right The reading Cosmology in the 21 st Century is closer to our current guess Scientists are still working on this Topic 4: Inflation 25
Lecture on Chapter 20 now complete Topic 3: Inflation 26
End of the Semester Pre-Lecture Reading Questions (PLRQ) Unit 6, Stage 2: Due before usual class time Wednesday, May 3 rd Unit 6 Revision (if desired), only by request (send me an email if you are interested) End-of-Chapter Quizzes: All chapters due by Monday May 8 th at 11:55PM (Final download of EOC quizzes) Will need to do AMS 2 before you can get to Chapter 20 Papers: Paper 4, Stage 1: Due before the usual class time on Wednesday, May 3 rd Paper 4, Stage 2: Due Tuesday May 9 th by 11:55PM Paper 4 Revision (if desired), only by request (send me an email if you are interested) Honors Paper: Due tonight at 11:55PM in turnitin. Let me know if you need an extension Other notes: Won t start calculating grades until after Wednesday May 10 th Please do the Course Evaluations CPR: Mis-graded on any Assignment? Let us know All paper and PLRQ grades are in CPR and won t get ported to ecampus Make sure you have turned in all papers (including Revisions) into turnitin. You will lose points if you don t. Extra credit for students who do PLRQ Unit 6 and/or Paper 4 stuff in Peerceptiv Topic 3: Inflation 27
That s it! Best of luck finishing all the papers and quizzes Best of luck on finals! Thanks for listening! Topic 4: Inflation 29