Transcript Document
Our Cosmic History Saturday Symposia Lecture #2: “Our Cosmic Context - A Brief Tour of the Universe” Dr. Todd Duncan Center for Science Education, Portland State University October 18, 2008, 10 a.m. Goals of the series… 1. Big picture view of science to give the details a meaningful context. (In this case, the story of our own origins, relevant to our perspective on who we are and where we are headed.) 2. Help weaving big picture motivation provided by the series into the details of science curricula (complement broad-brush view with nitty-gritty details) 3. Building a community of people curious about the universe and our place within it (regardless of professional role: teacher, student, researcher, or other member of the public) After the lecture: Roundtable discussion for teachers 11:30 am - 12:30 pm in the entryway of Hoffman Wiki Site for resources & continuing discussion: http://oregonteacherscholars.pbwiki.com/Our-Cosmic-History (or link from www.scienceintegration.org) Upcoming… l Lecture #3: “The Early Universe big bang to stars & galaxies” Dr. Aparna Venkatesan Dept. of Physics & Astronomy, University of San Francisco Oct. 25, 2008 10 a.m. Hoffman Hall, PSU Warm-up Questions 1. The radius of Earth is about… a. 64 km b. 640 km c. 6,400 km d. 64,000 km 2. About how far away from us is the closest star other than our Sun? a. About the same distance as the Sun. b. Ten times farther than the Sun. c. One hundred times farther. d. One thousand times farther. e. More than a thousand times farther. 3. Which answer shows the most accurate arrangement of the three objects in order from closest object to Earth to farthest from Earth? a. center of Milky Way --> Andromeda galaxy --> North Star b. center of Milky Way --> North Star --> Andromeda galaxy c. Andromeda galaxy --> North Star --> center of Milky Way d. North Star --> Andromeda galaxy --> center of Milky Way e. North Star --> center of Milky Way --> Andromeda galaxy Today – A quick tour of the universe… The series overall presents the history of the universe as a framework for how that history made our existence possible. So first we need to know something of the structure and arrangement of this universe whose history we want to describe. Theme - Gaining perspective on how we connect to the universe: we are products of the whole universe, not just our immediate surroundings “In human affairs an idea is a greater moving force than any physical influence... So the shape of our future will depend to a large extent on our understanding of our role in the cosmic process.” – Louise B. Young (The Unfinished Universe) Your Self-image within the Universe • I am one cog in a giant machine. • I am the “eyes of the Milky Way” – a way for the universe to notice and appreciate itself. • I am a cosmic artist – a contributor to a universal creative process. • I am a participant in a definite cosmic plan or purpose, with some assigned role to play in carrying out that purpose. • I am a random speck in a vast uncaring universe. “On the maps provided by science, we find everything except ourselves.” – Bryan Appleyard (Understanding the Present: Science and the Soul of Modern Man) “Small as we are, minute as is the point by which the cosmos impinges upon each one of us, each one desires to feel that his reaction at that point is congruous with the demands of the vast whole…” – William James (The Sentiment of Rationality) A healthy consciousness is like a spider’s web, and you are the spider in the centre. The centre of the web is the present moment. But the meaning of your life depends on those fine threads which stretch away to other times, other places, and the vibrations that come to you along the web…Normally, your consciousness is like a very small spider’s web; its threads don’t stretch very far. Other times, other places, are not very real to you…And our lives are turbulent, like living in a strong wind, so the web gets broken pretty frequently. But sometimes the wind drops, and you manage to create an enormous web. And suddenly, distant times and distant places become realities, as real as the present moment, sending their vibrations down into your mind. — Colin Wilson (The Philosopher’s Stone) Cassini-Saturn-Earth Sun From Earth About 109 Earths fit across the face of the Sun Distance from Earth to Sun (1 Astronomical Unit) is about 150 million km Astronomical Distances • To make the numbers somewhat manageable, take the fastest thing we know of (light: 300,000 km/s), and express distances in terms of how far light would get in a certain amount of time. 1 light year = the distance light travels in 1 year = about 10 trillion km (1013 km) To convince yourself that this really is a distance, think of looking at a car speedometer. If you ride in a car at 50 miles/hour, for 1 hour, you will go 50 miles. If you travel at that speed for 2 hours, you go 100 miles. Most people would just call that 100 miles, but you could also call it “2 car hours.” A light year is the same sort of unit. Solar system scale 40 AU (about 5 light hours) to Pluto How far away are the stars? The closest star, Proxima Centauri, is 4.2 light years away That’s almost 7,000 times the Sun – Pluto distance!! We reside in a galaxy of ~ 300 billion stars. On this image of our Milky Way Galaxy, diameter of green circle is 1000 times bigger than the distance from our solar system to Proxima Centauri !!! Red dot is still 100 times too big! Andromeda Galaxy (M31) Whirlpool Galaxy (M51) Image Credit: S. Beckwith (STScI), Hubble Heritage Team http://astro.uchicago.edu/cosmus/projects/sloangalaxies/animations.html QuickTime™ and a Cinepak decompressor are needed to see this picture. Summary of Distance Scale • Portland to Eugene -------------- about 150 km • Earth (circumference) ------------ ~40,000 km • Distance to Moon ----------- ~384,000 km (~ 1 light second) • Distance to Sun --------------------- ~ 8 light-minutes • Distance to nearest star (beyond sun) --- ~ 4 light years • Milky Way Galaxy (diameter) ---- ~ 100,000 light years • Distance to nearby galaxy ------ ~ 2 million light years • Most distant visible galaxies ----- ~ billions of light years Cassini-Saturn-Earth “Precisely when we grasp the vastness of the universe we also grasp an equally vast interior, the enormous geography of the soul, so to speak. Words may fail afterward, forcing us to rely on hackneyed descriptions that emphasize our insignificance, but what we actually sense, if only for an instant, is largeness of spirit.” – Edwin Dobb (Harpers, Feb. 1995, p.40) “The most beautiful experience we can have is a sense of the mysterious.…A knowledge of the existence of something we cannot penetrate…I am satisfied with the mystery of life's eternity and with a knowledge, a sense, of the marvelous structure of existence – as well as the humble attempt to understand even a tiny portion of the Reason that manifests itself in nature.” – Albert Einstein “What is demanded…is not…to endure the meaninglessness, of life, but rather to bear [our] incapacity to grasp its…meangfulness.” – Viktor Frankl Composition of the Universe • The stuff we’re made of (baryonic matter, e.g. protons and neutrons) only comprises ~ 4% of the energy content of the universe • ~4% of energy is baryonic matter, ~23% exotic dark matter, and ~73% dark energy Bullet Cluster Dark Matter Survey Large Hadron Collider • Search for dark matter “WIMP” particles • LHC rap - http://www.youtube.com/watch?v=j50ZssEojtM Sun From Earth “The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the Universe to do.” –Galileo Galilei QuickTime™ and a YUV420 codec decompressor are needed to see this picture. “There are more things in heaven and Earth…than are dreamt of in your philosophy.” –Shakespeare (Hamlet) Seal Cosmic History in a Nutshell Adapted from Girl Meets Boy: A Comedy about the Universe, by Melinda Lopez (http://cfa-www.harvard.edu/seuforum/exhibit/resources/GMB_CUESCRIPT.pdf) Thanks to… • Oregon Dept. of Education Math/Science Partners Grant (primary funding for this lecture series) • Portland State University Center for Science Education • Beaverton and Hillsboro School Districts • Pacific University • Science Integration Institute References • Duncan & Tyler, Your Cosmic Context: An Introduction to Modern Cosmology (Addison-Wesley, 2009) • Poitier, The Measure of a Man: A spiritual autobiography (HarperCollins, 2000) • Cosmus education web site (tour of the universe, etc.): http://astro.uchicago.edu/cosmus/ • Sloan Digital Sky Survey: http://www.sdss.org/ • Science Integration Institute http://www.scienceintegration.org