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The Origin of the Universe Massimiliano Galeazzi MALS 601 Miami, 20 November 2002 Summary • The Scientific method • The view of the Universe before 1900: •The Greeks •The Heliocentric system • The view of the Universe after 1900: •Einstein Theory of relativity •Beyond the solar system •Hubble law • The Big Bang theory The Scientific Method Observations Theory Predictions Experimental verification Philosophy Observations Theory Observations • Sun Predictions Experimental verification Observations Theory Observations • Sun • Moon Predictions Experimental verification Observations Theory Observations • Sun • Moon • Stars Predictions Experimental verification Observations Theory Observations • Sun • Moon • Stars Predictions Experimental verification Observations Philosophy Theory Theory 1 Theory Predictions Experimental verification Theory 2 Observations Philosophy Geocentric theory Theory Predictions Experimental verification • Movement is not so simple • The movement is not perfectly periodic • There are monthly, annual, and longer term changes Observations Philosophy Predictions Geocentric theory • Movement is no so simple • Planets Theory Experimental verification Mars Observations Philosophy Geocentric theory • Movement is no so simple • Planets • Distance to the objects Theory Predictions Experimental verification Observations Philosophy Geocentric theory Theory Predictions Experimental verification Ptolemy, The Almagest, A.D. c.100-c.178 Observations Philosophy Geocentric theory Theory Predictions Experimental verification Observations Philosophy Geocentric theory SUN Venus EARTH Mercury Theory Predictions Experimental verification Simplicity Philosophy Geocentric theory SUN Venus EARTH Mercury Observations Theory Predictions Experimental verification Observations Theory “Simpler” theories Predictions Experimental verification Heliocentric system: the planets (including Earth) rotate around the Sun, and the Earth is also spinning around its axis Pythagoreans, Aristarchus of Samos, Plato (?), Copernicus “Hybrid” geocentric system: the Earth is not moving, the planets rotate around the Sun that rotates around the Earth Heraclides of Pontus, Tycho Brahe Observations Theory Heliocentric theory Predictions Experimental verification Nicolaus Copernicus, On the Revolutions of the Heavenly Spheres, 1473-1543 Johannes Kepler, Epitome of Copernican Astronomy, The Harmonies of the World, 1571-1630 Galileo Galilei, Sidereus Nuncius, 1564-1642 Observations Theory Heliocentric theory Predictions Experimental verification Observations Theory Predictions The phase of Venus Experimental verification Observations Theory Predictions The phase of Venus Galileo Galilei, c1610 Experimental verification Observations Theory Predictions Parallax Experimental verification Observations Theory Parallax Predictions Experimental verification winter Observations Theory Parallax Predictions Experimental verification summer Observations Theory Parallax Predictions Experimental verification summer 1832 Alpha Centauri (nearest star), Henderson Vega, Friedrich von Struve 61 Cygni, Friedrich Bessel Beyond the solar system 1) High concentration of stars along the milky way The stars are distributed more in a disk than in as sphere Beyond the solar system 2) The star distribution in the milky way is asymmetric, with respect to the Earth, but is rather symmetric with respect to a point in the constellation of Sagittarius (Shapley, 1915) The Sun is not at the center of the Galaxy Beyond the solar system 3) There are other galaxies in the Universe in addition to ours (Hubble) Beyond the solar system 4) There are billions of galaxies in the Universe Solar System Galaxy Universe COSMOLOGY Doppler effect Doppler effect Doppler Effect in Galaxies Movement Earth Fast toward us Slow toward us Not moving Slow away from us Fast away from us Observations Theory Hubble law (redshift) Predictions Experimental verification ALL DISTANT GALAXIES ARE RECEDING FROM US Edwin Hubble 1929 Speed = H · distance (H = Hubble constant) Consequences of Hubble Law If all the galaxies move away from us, does it mean that we are at the center of the Universe? What happens if we rewind the tape of the Universe? How old is the Universe? Expansion of the Universe If all the galaxies move away from us, does it mean that we are at the center of the Universe? Raisin Cake Balloon Expansion of the Universe What happens if we rewind the tape of the Universe? REWIND Age of the Universe speed = H · distance AGE OF THE UNIVERSE IS APRROXIMATELY THE INVERSE OF THE HUBBLE CONSTANT: T ~ 1/H T ~ 2 1010 years = 20,000,000,000 years Observations Theory Evolution of the Universe Predictions Experimental verification What happened at the beginning? What will happen in the future? • COLD BIG BANG • HOT BIG BANG Observations Theory The Big Bang Theory Predictions Experimental verification Observations Theory The Big Bang Theory Predictions Experimental verification Observations Theory The Big Bang Theory Predictions Experimental verification Can we try to “see” the explosion? YES!!! Speed of light: 300,000 Km/s ~ 675,000,000 Miles/h distance = 20,000,000,000 light years ~100,000,000,000,000,000,000,000 Miles Observations The cosmic microwave background Theory Predictions Experimental verification Arno Penzias and Robert Wilson, 1965 (Nobel Prize in 1978) What will happed in the future? What happened before the Big Bang? ? Philosophy