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Exploring a Century of Cosmic Surprises

Exploring a Century of Cosmic Surprises. Jim Lochner (USRA/GSFC) Barb Mattson (Adnet/GSFC) March 7, 2009 Celebration of Teaching and Learning. The year is 1919…. What’s going on? What’s going on in science? What is your view of the Universe?. Infinite. Unchanging/static. Ageless.

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Exploring a Century of Cosmic Surprises

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  1. Exploring a Century of Cosmic Surprises Jim Lochner (USRA/GSFC) Barb Mattson (Adnet/GSFC) March 7, 2009 Celebration of Teaching and Learning

  2. The year is 1919… • What’s going on? • What’s going on in science? • What is your view of the Universe? • Infinite • Unchanging/static • Ageless

  3. Enter Einstein • What is Gravity? • Gravity is curved space-time. • Gravity bends light. • Amount of deflection differs from Newton’s prediction. • 1919 Solar Eclipse verified Einstein’s prediction

  4. Cosmic Times • Curriculum support materials that trace our changing understanding of the expanding Universe over the past century • Includes: • 6 posters resembling newspaper front pages • 2 newsletter versions for each poster, one at a differentiated reading level • 4-5 lesson plans for each poster exploring fundamental science, social context, and reading skills You will receive a DVD containing all of these materials at the end of this workshop

  5. Unchanging Universe? • Einstein’s theory of gravity implies universe is not static - it’s expanding or contracting. • Einstein was troubled by a non-static Universe. • Cosmological Constant keeps the Universe static.

  6. Skip ahead to 1929… • Hubble discovered that “spiral nebulae” are “island universes” • Hubble went on to study external galaxies.

  7. Let’s Take the Role of Hubble • Edwin Hubble measured the distance and redshift of many galaxies. (Much of the work done by Humason.) “Tedium & solitude are the inseparable companions of scholarship.” • You and your students can replicate their work with our “Determining the Universe” lesson.

  8. Determining Distance from a Picture • What information do we need to determine the distance to the galaxy in this picture? • Size of the galaxy • Magnification of the image, or the size of the area of the photograph • A bit of trig…or the Rule of 57

  9. Determining Distance from a Picture • Size of the galaxy? • Assume it is the same as our Milky Way 100,000 light years

  10. Determining Distance from a Picture • Area of the photograph? • Images from telescope w/standard optics • 0.9 degrees wide • 0.7 degrees high 0.7 degrees 0.9 degrees Images taken by Harvard-Smithsonian’s MicroObservatory

  11. Determining Distance from a Picture • Rule of 57 – connecting size and distance • An object that takes up 1 degree of a field of view is 57 times further away than it is big

  12. Determining Distance from a Picture • Putting it all together • Galaxy’s Angular size • Now, find the distance 6.5 cm 16.5 cm (0.9 degrees) • Your turn! Here are a couple of tips • keep the distances in terms of 106 light years • please do **all** of your galaxies – we’ll need them later

  13. Redshift • Next, find the redshift for each of your galaxies on the provided “information cards”. • In class w/Internet connection, could have students look up redshifts on the NASA Extragalactic Database. (http://nedwww.ipac.caltech.edu/)

  14. Put it all together… • We’re going to make a plot of distance versus redshift. • Off to Excel-land…

  15. Hubble’s Law • All galaxies are receding away. • The further a galaxy, the faster it appears to be moving. • Expanding Universe

  16. Hubble’s Law • All galaxies are receding away. • The further a galaxy, the faster it appears to be moving. • Expanding Universe

  17. Now it is 1955… • Scientists debate: Is Universe … • ageless and infinite? • finite, with hot “bang” beginning? • Both theories account for observations. • Deadlock!

  18. Breaking the Stalemate • A hot “bang” should leave left-over heat. • That heat should still be around. • Where to look in the EM spectrum? • Many looked. Some concluded it would be too faint to detect.

  19. In 1965, Enter Dumb Luck* • Penzias and Wilson were making radio observations of the Milky Way. • Effort to reduce noise in the detector left them with a mysterious 3 K residual. • Peebles and Dicke (Princeton) had just calculated an estimate for the temperature of the residual background in the microwave region. * Not to imply that the researchers were dumb – quite the opposite, in fact!

  20. In 1965, Enter Dumb Luck • The CMB was a predicted by Big Bang Theory while Steady State theory has no such prediction. • The signal peaks in the microwave, so is called the Cosmic Microwave Background radiation, or CMB for short.

  21. Let’s Explore the CMB • Turn the balloon to the side that looks like this image. • The “dots” represent galaxies. • The “wave” represents the wavelength of light emitted in the Big Bang.

  22. Characteristics of the CMB? • We’ve seen that the CMB is • isotropic – observed in all directions • smooth – similar in all directions • What does our Universe look like today? • Lumpy/structured, not smooth! • Problem!! We need *some* lumpiness – some “anisotropies”

  23. Jump Ahead to 1993… • NASA’s COBE mission finds “lumps” found in the CMB! • These “lumps” are tiny, consisting of changes on the order of 1 part in 105. • But they are enough to produce the structure we see.

  24. Explore CMB Anisotropy • Go back to your balloon, turn it to the other side. • Imagine that gray is one temperature, pink (or balloon color) another temperature. Region 1 Region 2

  25. Cosmology’s End? • By the mid-90s, cosmologists thought that they had only to “fill in the details”. • Remaining questions: • Will the expansion continue forever, or will Universe eventually collapse back on itself? • What is the mass-density of the Universe (which would answer the above)?

  26. Cosmology’s End? • Things may not be what they seem. • When we see odd behavior, we look more carefully at what’s going on.

  27. Not the End In 1997 … • Recall, we were looking to “fill in the details” of the Universe’s expansion. • Given that gravity is the longest-reaching force according to physics, the expansion of the Universe should be slowing down…

  28. Slowing Expansion? More distant galaxies recede from us more rapidly. Velocity These supernovae are more distant than expected. Space-time has expanded more than expected. Distance (via SN Ia)

  29. Expansion History of the Universe

  30. By 2006… • Dark energy is well-established, having been detected in many ways. • Still, the nature of DE is largely a mystery. • Stay tuned to this continuing science story…

  31. The year is 2009… • What’s going on? • What’s going on in science? • What is your view of the Universe? • Finite • Changing • 13.7 Billion Years Old

  32. Cosmic Times http://cosmictimes.gsfc.nasa.gov/ Posters, Newsletters, Teacher Guide, Lessons

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