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Cosmology- the study of the origin, evolution and composition of the universe

Cosmology- the study of the origin, evolution and composition of the universe. Big Bang Theory (1940s)- universe violently exploded into being about 13-15 billion years ago

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Cosmology- the study of the origin, evolution and composition of the universe

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  1. Cosmology- the study of the origin, evolution and composition of the universe

  2. Big Bang Theory (1940s)- universe violently exploded into being about 13-15 billion years ago • Was an expansion of space that brought matter along with it http://www.globalchange.umich.edu/globalchange1/current/lectures/universe/universe.html

  3. Evidence for the Big Bang • Red Shift- Measurements of the red shifts of virtually all galaxies (except a few) show that the visible universe is expanding in all directions. http://www.globalchange.umich.edu/globalchange1/current/lectures/universe/universe.html

  4. The Expanding Universe! • In 1929, Edwin Hubble (yes, that Hubble) measured red shifts and distances of galaxies • Found that the farther from Earth a galaxy is, the faster it is moving away from us • All points are moving away from all other points, and no one point is at the center • Hubble’s Law: v = Hd

  5. Hubble’s Law • Hubble’s Law: v = Hd • V = velocity (km/s) • H = Hubble constant • (usually 65-73 km/sec/Mpc) • D = distance from Earth (Mpc)

  6. Evidence for an expanding universe The spectrum of hydrogen gas is the unique fingerprint of that element Hydrogen lamp

  7. Evidence for an expanding universe When we see a repeat of the pattern we saw in the lab, we know hydrogen is present Orion Nebula

  8. Evidence for an expanding universe We see the same repeating pattern of lines in a galaxy, but displaced to the red Galaxy UGC 12915

  9. Evidence for an expanding universe The further the galaxy, the more the shift to the red Galaxy UGC 12508

  10. Evidence for an expanding universe The greater the red shift, the faster the galaxy is receding Galaxy KUG 1750

  11. Evidence for an expanding universe The red shift is caused by the expansion of space. Galaxy KUG 1217

  12. Evidence for an expanding universe The red shift is evidence for an expanding universe Galaxy IRAS F09159

  13. 2. Cosmic background radiation- -visible universe is permeated by "cosmic background" microwave radiation, coming from all directions -it’s the red-shifted remnant of the radiation left over from the original Big Bang -Initial Bang would have sent out strong shortwave radiation (up to trillions of degrees) in all directions

  14. More on cosmic background radiation -Over time, radiation would spread out and cool; filling the universe -Would now strike Earth as microwave radiation only a few degrees above absolute zero (-270°C, or 3K) -Radiation mapped by COBE and WMAP observatories

  15. COBE- Cosmic Background Explorer Mission

  16. WMAP- Wilkinson Microwave Anisotropy Probe

  17. 3. Universe is mostly H and He • Prediction: A hot, dense expanding universe, should be predominantly hydrogen, helium (lighter elements) • Observation: Universe is ~75% hydrogen and ~25% helium by mass

  18. 4. Galaxies look different over time • Prediction: An expanding universe is evolving over time. If we look at the early universe, it should appear different. • Observation: Distant galaxies less evolved, physically and chemically.

  19. What’s the Fate of the Universe? The outward momentum of the expanding universe is opposed by the inward pull of gravity- Which force is stronger??? 3 scenarios: • Open universe- continual, slowed expansion (“Big Chill”) or continual, sped up expansion (“Big Rip”) • Closed universe (“Big Crunch”)- expansion will turn into a contraction • Flat universe- expansion will slow down and eventually stop some cool info

  20. So… What will happen? • Answer depends on the total amount of matter in the universe (expressed as the averagedensity of matter) • Average density can be observed by astronomers • It includes light and dark matter • Compare average density to criticaldensity (the dividing point between open or closed universe; about 10-26 kg/m3)

  21. If average density = critical density, then the universe is flat • If average density < critical density, then the universe is open • If average density > critical density, then the universe is closed SO FAR- astronomers favor the open model ALSO- data suggests that rate of expansion is speeding up…is dark energy pushing the universe apart?

  22. What does our galaxy look like? • The Milky Way

  23. The Milky Way- a Spiral Galaxy! It takes our sun about 225-250 million years to complete one journey around the galactic center at a speed of 800,000 km/hr. This is called a “cosmic year”.

  24. Galaxy Shapes

  25. Galaxy Groups • Galaxies are often part of larger groups of galaxies • The Milky Way is one of about 40 galaxies in our Local Group

  26. And now for some weird galactic stuff • Quasars- quasi-stellar radio sources • Exist at the nuclei of very distant active galaxies; very high red shifts • emit visible light, radio waves, infrared, x-rays, even gamma rays • Most luminous objects in the universe • Formed by material that builds up on the accretion disk of a supermassive back hole

  27. http://starchild.gsfc.nasa.gov -quasars (QSOs) give off more energy than 100 galaxies combined! -the most distant objects in the universe -get energy from black holes at centers of their galaxies

  28. Active galaxy at center of Centaurus A

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