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Fermi Problems and Scale of the Universe

Fermi Problems and Scale of the Universe. Advanced Introduction to Astronomy Spring 2014 Pomona College. by Dr. Bryan E. Penprase. An Example of a “ Flipped ” Class!!. Enrico Fermi, U. of Chicago Physics professor (and pioneer of nuclear physics) at the chalkboard. Fermi Problems.

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Fermi Problems and Scale of the Universe

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  1. Fermi Problems and Scale of the Universe Advanced Introduction to Astronomy Spring 2014 Pomona College by Dr. Bryan E. Penprase An Example of a “Flipped” Class!!

  2. Enrico Fermi, U. of Chicago Physics professor (and pioneer of nuclear physics) at the chalkboard Fermi Problems

  3. Best Guess: a). 15,000 b). 20,000 c). 35,000 d) 50,000 e). 60,000 How many cars are in Claremont? 35,000 = Population of Claremont 2.28 = average cars / household in the US 2.5 = average household size in US Fermi Problem

  4. How many cars are in Claremont? Best Guess: a). 15,000 b). 20,000 c). 35,000 d) 50,000 e). 60,000 Fermi Problem

  5. How Many Piano Tuners are there in Chicago? Population of Chicago = 2.7 million (2013) Number of families - 1 million (using 2.7 = avg family size) Number of pianos? Classic Fermi Problem ~7% would be at income level with kids -> 75,000 pianos

  6. each piano tuned every 3 years -> 25,000 tuned per year tuner can do about 5 per day -> 5*360 days = 1800 per year need 25,000 / 1800 = 14 full-time tuners in Chicago Fermi Calculations

  7. Best Guess: a). 1011 b). 2x1011 c). 1022 d) 2x1022 e). 4x1023 How many planets are in the universe? 1011 = Average Stars per galaxy 1011 = number of galaxies (estimated) 2.3 = average number of planets per star (based on current research) Fermi Problem

  8. How many planets are in the universe? Best Guess: a). 1011 b). 2x1011 c). 1022 d) 2x1022 e). 4x1023 1011 = Average Stars per galaxy 1011 = number of galaxies (estimated) 2.3 = average number of planets per star (based on current research) Fermi Problem

  9. The Size of Things Moving Through Space to the Edge of the Universe by Dr. Bryan E. Penprase

  10. Limit of Human Travel (1.25 light seconds) Geosynchronous Orbit • Near Earth Environment

  11. unexplored Limit of Human Spacecraft (Voyager 1: 125 AU; Voyager 2: 102 AU) 1 AU = 8 light minutes • Solar System

  12. Next Spiral Arm (500 pc) Nearest star (3 light years) • Nearby Stars (with parallax)

  13. Virgo Cluster of Galaxies (10 Mpc) Andromeda Galaxy (0.9 Mpc) LMC and SMC (50kpc) Galactic Center (8.5 kpc) • Nearby Galaxies

  14. First “free” photons (13.7 billion lyrs-300klyrs) “Dark Ages” (unexplored) Most distant quasars Half way back to origin of time and space (z=1) Distant Galaxies Large Scale Structure (100 Mpc) • Edge of the Universe

  15. Our Place in the Universe

  16. Our Place in the Universe (continued)

  17. This part will include history of transit expeditions; especially poor French dude Voyager exercise to recreate parallax; Retrograde loops and order of mag calculations; definition of parsec; intro to proper motion History of telescopes and first proper motion and parallax measurements Modern techniques -- Hipparcos sattelite and upcoming Kepler and SIM missions If time allows -- do simulation with the Partiview program where one sees stars moving. Ask David Haley to be sure “Digital Universe” is installed on laptops; can do 3D imageing and proper motions both. • Parallax • Venus Transit - measure of AU • Stellar Parallax • Early studies • Modern techniques (Hipparcos + SIM) • Distance Ranging • Radar studies of planets • Laser lunar ranging • Timing of Spacecraft signals • Secondary Techniques • Standard Candles • Cepheids + Spectroscopic Parallax This part will include some interesting information on early radar studies; some calculations for distances to different planets. Try to find some good footage of lunar ranging (email our friend teaching with us - ask for talk slides or movie) Include information on spacecraft and alternate theories of gravity Include basic concept of standard candle. Give some information on number of photons from different sources. Sun for example - kw + photons per square cm per second. Then scale for sun at distance of 1 pc. Include idea of flux units and basis for inverse square law This will set us up for discussion of light on next class (Tuesday). • The Cosmic Distance Ladder - The first rungs (to Milky Way Center)

  18. Flying through the Big Dipper

  19. Flying through Orion

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