* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Galaxies and the Universe
Wilkinson Microwave Anisotropy Probe wikipedia , lookup
International Ultraviolet Explorer wikipedia , lookup
Gamma-ray burst wikipedia , lookup
Anthropic principle wikipedia , lookup
Modified Newtonian dynamics wikipedia , lookup
Observational astronomy wikipedia , lookup
High-velocity cloud wikipedia , lookup
Timeline of astronomy wikipedia , lookup
H II region wikipedia , lookup
Hubble's law wikipedia , lookup
Dark energy wikipedia , lookup
Shape of the universe wikipedia , lookup
Star formation wikipedia , lookup
Expansion of the universe wikipedia , lookup
Ultimate fate of the universe wikipedia , lookup
Flatness problem wikipedia , lookup
Lambda-CDM model wikipedia , lookup
Hubble Deep Field wikipedia , lookup
Fine-tuned Universe wikipedia , lookup
Galaxies and the Universe What Are Galaxies? • Greek galax = milk • William Herschel, 1783: A disk with the Sun slightly off-center What Are Galaxies? • • • • • 19th Century: “Spiral Nebulae” Nearby? Maybe Solar Systems in Formation? 1920: Galaxies are Stars 1920’s: Galaxies are like the Milky Way Biggest single increase in our mental picture of the Universe in human history Where Are We in our Galaxy? • The visible Milky Way suggests our galaxy is a flat disk • Surrounding other galaxies is a spherical halo of Globular Star Clusters Galaxies and Globular Clusters The Milky Way’s Globular Clusters The Milky Way As We See It Anatomy of a Galaxy Spiral Arms In Microwaves, We Can See the Hub of the Galaxy Mapping the Neighborhood Mapping the Neighborhood Mapping the Galaxy: Not There Yet Mapping the Galaxy: Not There Yet The Local Group Downtown: The Virgo Cluster: 50 m.l.y The Local Supercluster The Coma Cluster 350 m.l.y. Large-Scale Structure of the Universe to 500 m.l.y. Travel to the Stars? • Kinetic Energy = 1/2 Mv2 • What does it take to get a 1000-ton spaceship to 10% of the speed of light? (43 years to Alpha Centauri) • M=106 kg, v = 3 x 107 m/sec • KE = 1/2 x 106 x 9 x 1014 = 4.5 x 1020 joules • Equals U.S. Energy Production for 4.5 years • Once you get there, you have to stop. Relativity • Speed of Light is Independent of Source • Michelson and Morley, 1887 - Speed of Light Independent of Observer • “One of the Most Unexpected Results in the History of Science” - Isaac Asimov • Conclusion: Speed of Light is the Same for All Observers • Implication: Space and Time Must Change to Keep Speed of Light Constant Why the Speed of Light is a Speed Limit • Energy of a Moving Object in Relativity: E = mc2 1 - v2/c2 ------------------------------------------------------------------------------- • One consequence: as v approaches c, Energy goes to infinity • Also, as we approach c, Energy goes up very fast Fuel Economy of a Starship • At 0.1 c, energy is 0.7% greater than Newtonian formula • At 0.5 c, 24% greater • At 0.9 c, 3 x greater • At 0.99 c, 12 x greater • At 0.999 c, 43 x greater • Each extra 9 more than triples the energy • Getting our 1000 ton ship to 0.9 c takes 1.1 x 1023 joules = U.S. energy use for 1100 years Another Consequence of RelativityGravitational Lenses What Does The Universe Look Like? What Does The Universe Look Like? “The Big Bang” • • • • • Edwin Hubble, Recession of Galaxies, 1929 Red-shift increases with distance Cosmic Microwave Background, 1965 Estimated Age of Universe: 12-15 b.y. “Big Bang” originally a derisive term, coined by Fred Hoyle As Far Out as We Can See - Ten Days With the Hubble Telescope A New Name for the “Big Bang?” (Sky and Telescope, 1995) • The Big Boot • God’s Log-On • Fred Withair Day (“Nobody ever named anything else after me, so why not?”) • What Happens If I Push This Button? • You’re Never Going To Get It All Back In There Again 90% of the Universe is “Missing” • Outer Stars in Galaxies revolve faster than expected • What holds clusters of galaxies together? • Conclusion: There must be a lot of invisible mass in the Universe • Not really “missing”, just non-luminous Astronomers Are Not As Upset As One Might Expect • MACHO’s (Massive Compact Halo Objects): faint stars, brown dwarfs, planets • Cool non-luminous gas • Massive Neutrinos? • WIMP’s (Weakly Interacting Massive Particles) • Magnetic monopoles • Exotic objects: strings, mini-black holes Fine Tuning the Universe • Density – Much greater and the Universe would already have collapsed in on itself – Much less and stars could not have formed • Nuclear Forces – Fusion impossible – Fusion too easy • Anthropic Principle – Cosmology has to be able to explain why we exist Fine Tuning the Universe • It just came out that way • It has to be that way for reasons we haven’t yet discovered • Maybe there are an infinity of universes but only those with certain parameters develop intelligent life (Multiverse) • Engineered or designed Fine Tuning the Universe • Designer? • Doesn’t Explain Anything • If the Designer can create a Universe, why is c = 300,000 km/sec instead of 400,000? • If Designer had to have c = 300,000 km/sec, why? What (who?) dictated that, and why? • Who says Designer is anything pictured by any religion? Misinterpreting Relativity • There are no absolutes – Speed of light is absolute – It may not be possible to be absolutely right but it is very easy to be absolutely wrong Where Will It All End? • • • • • • • Trillions of years: Star formation ends 10-100 trillion years: Stars stop radiating 1015 – 1020 years: Planetary orbits decay 1032 – 1041 years: Protons decay? Heat Death? Big Crunch? Big Bounce? What Does Cosmology Imply for Philosophy? • Nothing • At Least, Not Yet • It Is Hopelessly Premature To Try To Create A Philosophy Based on Cosmology – We can say what the fate of the Universe will be based on specific assumptions – We are a long way from knowing the assumptions are complete or correct • If you support your philosophy with science, be prepared for science to prove it wrong