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Todays Comments Graded papers see Raquel to get old papers or tests. Grades updated Lab Students: optional Test 2 in lab Tuesday or Thursday Please let me know if you plan to take it Test 3: Tuesday, May 5, 50-60 multiple choice questions D2L Quizzes 9-12 available; do them to prepare for test 3 Group study session with tutor Daniel Observations check due dates on calendar Binoculars available for Moon Craters on your own. Fill out loan form. RETURN BINOCULARS BY RETURN DATE Sunset Part 2. Work on this. Due Apr. 28: Today by midnight Telescopes, Star Gazing & Moon Craters available at UMN or Macalester see dates on calendar Apr. 28 & May 1 Space Exhibit at Science Museum of MN on 5:30-9pm, Thursday, May 7; Answer EVITE Respond by midnight Tuesday, Apr. 28

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Big Bang In the beginning??? How the universe evolved after it started Rough timeline of events Evidence

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*Very Rough Cosmic timeline Big Bang Now Stuff Happens t > 0 14 billion years later Milky Way Solar system and Earth H, He First stars First humans Massive Element factories Galaxies collide and grow First galaxies

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Cosmic Calendar (From The Dragons of Eden - Carl Sagan) Play Video. Cosmos: a Space-Time Odyssey with Neil deGrasse Tyson, Episode 1 Jan Big Bang H and He, First stars, First galaxies Feb Milky Way Galaxy Mar AprMay Milky Way Galaxy Jun JulAugSep Solar system, Earth Life on Earth Oct Oldest fossils NovDec First cells with nuclei

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1 O 2 2345 Mars channels 67 891011121314 1516 Worms 1718 Plankton 19 Fish 2021 Insects 22 Amphibians 23 Trees 24 Dinosaurs 2526 Mammals 27 Birds 28 Flowers 29 Primates 30 Hominids 31 Humans December

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December 31 11:59:37 p.m. Agriculture 11:59:45 p.m. The Wheel 11:59:56 p.m. Ptolemy astronomy 11:59:58 p.m. Mayan civilization; Byzantine empire 11:59:59 p.m. Renaissance; experimental method in science; the telescope Now http://www.astrosociety.org/edu/astro/act2/H2_Cosmic_Calendar.pdf

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Big Bang (slightly revised model) Universe (space and time) Springs into existence (tiny) About 14 billion years ago Expanding, cooling ever since Rate of expansion slowing due to gravity *Makes specific, testable predictions BIG BANG Universe expands and cools Stuff happens 14 billion years later Rate of expansion slows

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Big Bang Model *The Big Bang Model or Theory describes the evolution of the universe from a tiny fraction of a second (10 -43 s) on. *Makes specific, testable predictions. *It does not tell you how it all started. At t = 0 ? (speculations next time) From t = 0 to t = 10 -43 s (Planck time) Conditions too extreme: our physics cant handle it

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Big Bang Timeline Examples of specific, testable predictions (dont need these for exam) By 10 -5 s: universe filled with gamma ray photons, sea of energy and particles By 0.0001 s: slight excess of matter over anti-matter Tested in particle accelerators

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Big Bang Timeline More examples of specific, testable predictions (dont need these for exam) By 4 s: protons, neutrons, electrons of today produced By 3 min: He produced Tested in particle accelerators

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Big Bang Timeline *More specific, testable predictions (LEARN!) By 30 min: Universe cooled enough so nuclear production stopped 75% H & 25% He By 380 000 yrs: Universe cooled to 3000K, became transparent By 200-400 Myrs: first stars appeared (H rich), made heavy elements, blasted those elements back into space, continuing today

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Big Bang Timeline *More specific, testable predictions (LEARN!) 1-14 Byrs: Galaxies grow (merge, collide). Milky Way takes shape (13 Byrs old) Successive generations of stars enrich the next generation with heavier elements (massive stars) By 10 Byrs: Our solar system has formed About 14 Bys: We think about the Universe

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BIG BANG plus 380 000 years BIG BANG BIG BANG plus 10 -43 s INFLATION Universe transparent Light from first stars Today BIG BANG plus ~200-400 million years Understand from here on Inflation BIG BANG plus 14 billion years After 10 -43 s, the Big Bang model makes specific, testable predictions about the current Universe Stars produce heavy elements

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About how old is our universe? 14 billion years

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About how old is our Milky Way Galaxy? 13 billion years

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About how old is our solar system? 5 billion years (same age as our Sun)

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Universe Timeline http://www.pbs.org/deepspace/timeline/

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*Evidence for BB 1a. Redshift Universe began small (Hubble)

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*Evidence for BB 1a. Redshift Universe began small 1b. Hubbles Law Space-time expanding expanding at a faster rate accelerating

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Universe Expansion Acceleration Due to Dark Energy http://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/ http://www.scientificamerican.com/article/expanding-universe-slows-then-speeds/

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*Evidence for BB 1a. Redshift Universe began small 1b. Hubbles Law Space-time expanding 2. Specific, testable predictions from the BB

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Evidence for BB 2.Specific, testable prediction from Big Bang model a. H and He found at predicted 75% to 25% ratio BB model predicts: H and He fused from protons and neutrons in the first few minutes AND at 75% to 25% ratio by mass Found : 9 H to every 1 He 75% of mass is H 25% of mass is He

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Evidence for BB 2.Specific, testable prediction from Big Bang model b. Early galaxies BB model predicts: First star light should appear ~200-400 Myears after BB So far : 13.4 Bly distant galaxy (~400Myears) http://hubblesite.org/newscenter/ archive/releases/2012/48/

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http://hubblesite.org/newscenter/archive/releases/2012/48/ 12 Dec 2012

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http://news.nationalgeographic.com/news/2014/01/140107-hubble-oldest- frontier-science-space-astronomy/ Jan 2014

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Evidence for BB 1a. Redshift Universe began small 1b. Hubbles Law space-time expanding 2.Specific, testable predictions from BB a. H and He found at predicted 75% to 25% ratio b. Early galaxies 3. Radiation from BB

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Evidence for BB 3. Radiation from BB predicted to be at ~3K! ???? Is 3K hot or cool? Cool

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*Evidence for BB 3. Radiation from BB predicted to be at 3K! ???? Why so cool if universe began hot? If Universe began hot, Look for ??? Microwave Gamma rays Electromagnetic spectrum? Wavelengths of red and violet? of red and violet?

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Microwave *Evidence for BB 3. Radiation from BB predicted to be at 3K! ???? Why so cool if universe began hot? Look for? Early universe composed of + and charges that trap radiation. Universe expands for ~ 380 000 years and cools to ~3000 K + and charges combine to form H. Matter and radiation decouple. Universe becomes transparent. IR!

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*Evidence for BB 3. Radiation from BB predicted to be at 3K! ???? Why so cool if universe began hot? Look for? After decoupling (380 000 years after BB), Universe continues expanding, stretching the waves. Microwave Microwaves

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*Evidence for BB 3. Radiation from BB predicted to be at 3K! Found Cosmic Microwave Background (CMB)

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Found by Penzias and Wilson in 1964 *Cosmic Microwave Background (CMB) *Universe is filled with radiation at 2.73 K

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*Evidence for BB 1a. Redshift Universe began small 1b. Hubbles Law space-time expanding 2. Specific, testable predictions from the BB 3. BB radiation found - CMB at 2.73 K 4. Tiny variations in CMB Planck spacecraft results! Radiation from the early universe is very smooth (2.73 K). Temperature of early universe does not vary by more than 0.01 K. Therefore density varies very little.

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*Planck results* ESA http://www.esa.int/Our_Activities/Space_Science/Planck/Planck_reveals_an_almost_perfect_Universe Tiny variations in CMB (+/- 0.0001K) Tiny density variations in early universe

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Planck results CMB shows tiny variations in wavelengths from early universe. Early universe varied slightly in temperature from one spot to next (+ or - ~0.0001 K) And early universe varied slightly in density from one spot to next. Seeds of galaxies.

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Evidence for BB 4. Planck results also show which BB model is correct. Different BB models predicted different sizes for these small variations and different ages for the universe.

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Evidence for BB *4. More Planck Results Universe began 13.8 billion years ago Radiation decouples from matter 380 000 yrs later First stars appear ~200-400 million years later Composition of universe ~5% (4.9%) normal matter (p, n, H, He, you) (called baryonic matter) ~1/4 (26.8%) dark matter ~2/3 (68.3%) something else (more in a bit)

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Evidence for BB 4. More Planck Results (not for test) Data fits the accepted BB model very nicely except Slight assymetry in temperature variation from one side of universe to the other Large cool spot Maybe some new physics?

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First stars ~200-400 million years 13.8

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Nicholas Gurewitch of www.thepbf.com

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***Evidence for BB*** 1a. Redshift Universe began small 1b. Hubbles Law space-time expanding 2. Specific, testable predictions from BB 3. BB radiation found CMB at 2.73 K 4. Slight variations in CMB Planck Results !!!!

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***Evidence for BB*** 1a. Redshift Universe began small 1b. Hubbles Law space-time expanding 2. Specific, testable predictions from BB 3. BB radiation found CMB at 2.73 K 4. Slight variations in CMB Planck Results !!!! 5. Many Others

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Evidence for BB 5. Galaxies grow with time

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http://antwrp.gsfc.nasa.gov/apod/ap051122.html

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http://antwrp.gsfc.nasa.gov/apod/ap060415.html

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Evidence for BB 5. Galaxies grow with time 6. Polarization of CMB BB model predicts again

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Evidence for BB 5.Galaxies grow with time 6.Polarization of CMB BB model predicts again Polarization Demo Video http://video.mit.edu/watch/mit-physics-demo-microwave- polarization-3073/

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Evidence for BB 5.Galaxies grow with time 6.Polarization of CMB 7.Computer models of universe include dark matter

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Summary - Some Evidence for BB 1a. Redshift Universe began small 1b. Hubbles Law space-time expanding 2.Specific testable results a. H to He is 75% to 25% - BB prediction works b. First stars/galaxies at ~300 million years 3.BB radiation found CMB at 2.73 K 4.CMB is slightly lumpy Planck Results !!!! 5. Galaxies grow with time 6. Polarization of CMB BB model wins again 7. Computer models of universe include dark matter

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More Big Bang next lecture

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Survey Notecard One side: What did you like about astronomy class? Turn over, Other side: What would you change or improve about astronomy class? Name is optional When finished, place in big envelope