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UW ASTR 101 - LECTURE NOTES

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Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW1Questions of the Day•What is inflation, and what cosmological conundrums does it help to resolve?•What are the conditions in the early Universe?•What is the eventual fate of the Universe?Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW2Universe is Ionized!Universe is Neutral! Photons are too low energyPhotons can scatter off unbound electronsNo unbound “free” electrons, so nothing to scatter photonsAstronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW3Fluctuations in the CMB encode information about early structure•Slight “overdensities”, pulled matter towards and away from us.•Slight motions at z~1300 caused some regions to be slightly Doppler redshifted or blueshifted!Future ClustersAstronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW4The bumps in the CMB say that the Universe is flat (!=1)!! Real Data!Prediction for closed, flat, and open universes!Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW5•Low density !<1•Critical density !=1•High density !>1MASS MEASUREMENTSCMB FLUCTUATIONSAstronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW6CMB says the universe is flat, but all the normal matter+dark matter aren’t enough to make !=1 on their own. (!matter~0.3)•E=mc2, so the dark energy provides the extra mass to make ! = 1 (sort of…)Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW7Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW8Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW9Everything has to be juuuuust right to get flat universe!•A flat universe is “unstable”.•Change things just a bit, and the universe would be extremely closed or extremely open!Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW10Why so flat?•“Inflation”!•10-36 seconds after the Big Bang, for 10-34 seconds, the universe expanded in size by >1043 times! Increasing time "! Scale of Universe "Not to scale!!! "Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW11Inflation makes the Universe big!Same effect that dark energy (") is having now, but much, much more so (and only early on)!Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW12Inflation makes the Universe flat!•The “radius of curvature” is so large after inflation that the Universe is effectively flat on any scale we can measure it.(Kind of like how Earth seems flat to us…)Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW13Inflation also fixes a problem with the CMB!• Why is the CMB soooo smooth?Opposite sides of the Universe are exactly the same temperature (within 0.00003K)!Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UWXOpposite sides of the universe cannot “know” about each other if they are farther apart than light can travel during the age of the universe. •The speed of light is the fastest that information of any kind can travel!Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UWXBefore inflation, A & B were close enough that they could come to the same temperature…Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UWXAfter inflation, A & B have been pushed so far apart that they can no longer “communicate” with each other.Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW14•Inflation ends after ~10-34 seconds (or so).•Universe goes back to a normal pokey rate of expansion.•Temperature and energies are incredibly high!•Weird physics takes over, but gradually shuts down as the Universe expands and cools.Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW15Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW16Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW17 “We now know all the extraordinary changes the universe went through in it’s first second. After that, unfortunately, it turns out to be very monotonous.”Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW18And what about the future???•The expansion of the universe seems to be speeding up!•Space gets more and more empty.Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UWXAstronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW19The Future…Hierarchical merging continues to completion.Most matter winds up in clusters.Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW20The Future…1. Galaxies turn all available gas into stars (<1014 years: “Stelliferous Era”).Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW21The Future…2.All stars eventually die, and turn into white dwarfs, neutron stars, or black holes. (1015-1037 years: “Degenerate Era”)DARK!!!!Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW22The Future…2. Universe contains big lumps of dark, fading stars, planets, & black holes.3. After about 1030 years, protons start to decay! Stars & planets start dissolving…4. By 1040 years, all protons are gone.Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW23The Future…5.Most remaining mass is in black holes (1037-10100 years: “The Black Hole Era”).6.By 10100 years, all black holes will have evaporated.7. Universe consists of nothing but a diffuse mist of photons, neutrinos, positrons, & electrons.8. Oh well. That was fun.Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW24The Future…Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW25Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UW26Thanks, and good luck on the Final!• 100 multiple choice questions• Bring a scantron• Cumulative! (i.e. the whole course!)• It’s in this room on Monday morning!• See web page or MyUW for detailsSIZE SCALESFORCES GRAVITY ENERGY ATOMS STATES OF MATTER LIGHT THERMAL RADIATION EMISSION/ABSORPTION LINES MAGNITUDES & BRIGHTNESSESFUSIONNORMAL STARSHR DIAGRAMSTAR CLUSTERSSTELLAR DISTANCESSTELLAR EVOLUTIONWHITE DWARFS NEUTRON STARS & PULSARS BLACK HOLES Astronomy 101, Winter 2010Copyright@2010 Julianne Dalcanton, UWTopics Covered27STAR FORMATION ISM GALAXY MORPHOLOGY STELLAR POPULATIONS INTERPRETING SPECTRA GALAXY INTERACTIONS GALAXY EVOLUTION ROTATION CURVES DARK MATTER CURVED SPACETIME GRAVITATIONAL LENSING DISTANCE SCALE LARGE SCALE STRUCTURE EXPANSION OF THE UNIVERSE DARK ENERGY CMB EARLY


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UW ASTR 101 - LECTURE NOTES

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