Chapter 16 Dark Matter Dark Energy and the Fate of the Universe Copyright 2009 Pearson Education Inc Mysteries Why no antimatter Where do the high energy cosmic rays come from What is the field producing the initial inflation and later dark energy What is dark energy What was the initial fluctuation What is time Copyright 2009 Pearson Education Inc The Ultimate Fate of the Universe Exponential acceleration The disapperance of the CMB The disapperance of the galaxies The Big Rip or the GNAB GIB and why Copyright 2009 Pearson Education Inc The Ultimate Question Can science ever understand the moment of Creation Should it try Copyright 2009 Pearson Education Inc 16 4 The Fate of the Universe Our goals for learning Will the universe continue expanding forever Is the expansion of the universe accelerating Copyright 2009 Pearson Education Inc Will the universe continue expanding forever Copyright 2009 Pearson Education Inc Does the universe have enough kinetic energy to escape its own gravitational pull Fate of a Launched Cannonball Copyright 2009 Pearson Education Inc Fate of universe depends on the amount of dark matter Lots of dark matter Copyright 2009 Pearson Education Inc Critical density of matter Not enough dark matter Amount of matter is 25 of the critical density suggesting fate is eternal expansion Not enough dark matter Copyright 2009 Pearson Education Inc But expansion appears to be speeding up Dark energy Copyright 2009 Pearson Education Inc Not enough dark matter old older oldest Estimated age depends on both dark matter and dark energy Copyright 2009 Pearson Education Inc Thought Question Suppose that the universe has more dark matter than we think there is today How would that change the age we estimate from the expansion rate A Estimated age would be older B Estimated age would be the same C Estimated age would be younger Copyright 2009 Pearson Education Inc Thought Question Suppose that the universe has more dark matter than we think there is today How would that change the age we estimate from the expansion rate A Estimated age would be older B Estimated age would be the same C Estimated age would be younger Copyright 2009 Pearson Education Inc Is the expansion of the universe accelerating Copyright 2009 Pearson Education Inc The brightness of distant white dwarf supernovae tells us how much the universe has expanded since they exploded Copyright 2009 Pearson Education Inc An accelerating universe is the best fit to supernova data Copyright 2009 Pearson Education Inc What have we learned Will the universe continue expanding forever Current measurements indicate that there is not enough dark matter to prevent the universe from expanding forever Is the expansion of the universe accelerating An accelerating universe is the best explanation for the distances we measure when using white dwarf supernovae as standard candles Copyright 2009 Pearson Education Inc Chapter 17 The Beginning of Time Copyright 2009 Pearson Education Inc Copyright 2009 Pearson Education Inc 17 1 The Big Bang Our goals for learning What were conditions like in the early universe What is the history of the universe according to the Big Bang theory Copyright 2009 Pearson Education Inc What were conditions like in the early universe Copyright 2009 Pearson Education Inc The universe must have been much hotter and denser early in time Estimating the Age of the Universe Copyright 2009 Pearson Education Inc The early universe must have been extremely hot and dense Copyright 2009 Pearson Education Inc Photons converted into particle antiparticle pairs and vice versa E mc2 The early universe was full of particles and radiation because of its high temperature Copyright 2009 Pearson Education Inc What is the history of the universe according to the Big Bang theory Copyright 2009 Pearson Education Inc Defining Eras of the Universe The earliest eras are defined by the kinds of forces present in the universe Later eras are defined by the kinds of particles present in the universe Copyright 2009 Pearson Education Inc Four known forces in universe Strong Force Electromagnetism Weak Force Gravity Copyright 2009 Pearson Education Inc Thought Question Which of the four forces keeps you from sinking to the center of Earth A B C D Copyright 2009 Pearson Education Inc Gravity Electromagnetism Strong Force Weak Force Thought Question Which of the four forces keeps you from sinking to the center of Earth A B C D Copyright 2009 Pearson Education Inc Gravity Electromagnetism Strong Force Weak Force Do forces unify at high temperatures Four known forces in universe Strong Force Electromagnetism Weak Force Gravity Copyright 2009 Pearson Education Inc Do forces unify at high temperatures Four known forces in universe Strong Force Electromagnetism Weak Force Gravity Yes Electroweak Copyright 2009 Pearson Education Inc Do forces unify at high temperatures Four known forces in universe Strong Force Electromagnetism Weak Force Gravity Yes Electroweak Copyright 2009 Pearson Education Inc Maybe GUT Do forces unify at high temperatures Four known forces in universe Strong Force Electromagnetism Weak Force Gravity Yes Electroweak Copyright 2009 Pearson Education Inc Maybe Who knows GUT String Theory Planck Era Time 10 43 s Temp 1032 K No theory of quantum gravity All forces may have been unified Copyright 2009 Pearson Education Inc GUT Era Time 10 43 10 38 s Temp 1032 1029 K GUT era began when gravity became distinct from other forces GUT era ended when strong force became distinct from electroweak force Copyright 2009 Pearson Education Inc Electroweak Era Time 10 10 10 10 s Temp 1029 1015 K Gravity became distinct from other forces Strong weak and electromagnetic forces may have been unified into GUT force Copyright 2009 Pearson Education Inc Particle Era Time 10 10 0 001 s Temp 1015 1012 K Amounts of matter and antimatter are nearly equal Roughly one extra proton for every 109 proton antiproton pairs Copyright 2009 Pearson Education Inc Era of Nucleosynthesis Time 0 001 s 5 min Temp 1012 109 K Began when matter annihilates remaining antimatter at 0 001 s Nuclei began to fuse Copyright 2009 Pearson Education Inc Era of Nuclei Time 5 min 380 000 yrs Temp 109 3000 K Helium nuclei formed at age 3 minutes The universe became too cool to blast helium apart Copyright 2009 Pearson Education Inc Era of Atoms Time 380 000 years 1 billion years Temp 3000 20 K Atoms formed at age 380 000 years Background radiation is released Copyright 2009
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