Dark Matter and Dark Energy

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  • 1. 1) ( Dark Matter and Dark Energy Lectures - Video of: Dr. SEAN CARROLL of California Institute of Technology /
  • 2. 1- 25% , 5% - 70% , (Dark Matter) (Dark energy) -
  • 3. – • – • (Particle • Physics)
  • 4. ) ( – – – (Quarks) . (Up & down)
  • 5. – . .
  • 6. – . . – .
  • 7. – . . – (basic Science) .
  • 8. Questions to Consider (1) • Why is it interesting to study the structure of the whole universe? How would you explain that interest to someone else? • Should it be surprising that cosmology, the study of the very largest things, is intimately connected to particle physics, the study of the very smallest? • Cosmologists believe that most of the universe is made of substances utterly different than the atoms and particles with which we are familiar. How do you feel about that? Again, should we
  • 9. The Smooth, Expanding Universe , , 72 “ ” H . = H* ” 3262000 ((72 Km/S/migaparsec . (red shift)
  • 10. Questions to Consider astronomer, looking 1. Imagine that you are an ancient (2) at the night sky without any instruments. How would you estimate the distance to the planets and stars? 1. Think about how analogies and metaphors are useful or misleading when it comes to the whole universe. Can you think of any good analogies? 3. How does the cosmological principle compare to Copernicus’s original insight that the earth is not at the center of the solar system? Can you speculate this Copernican philosophy to other questions?
  • 11. Space, Time and Gravity (3) (special relativity) (spacetime) (Absolute space and absolute time) (spacetime is the force of gravity)
  • 12. Questions to Consider (3) • What does it mean for two distant events, to happen at the same time? Is this a concept that we can really afford to do away with? • Imagine a careful experiment showing that two objects fell at slightly different rates in a gravitational field. How would you interpret that result? • Einstein was a popular icon, as well as a leading scientist. Do you think that he deserved his special status in the popular imagination?
  • 13. 4 - Cosmology in Einstein’s Universe • ) ( • • ( • ) • (E = m c2 ) , ,
  • 14. Dark energy is expanding the Universe • , ) ( , • (K (p ) H) ( p), Friedmann (8 pi G / 3) p = H2 + K •
  • 15. 4 – Questions to Consider • Is there a difference between light being red shifted by the Doppler effect or by expansion of space? Can you think of examples to illustrate whether such a difference really exists? • Adding up the angles inside a triangle is one way to measure the curvature of space. Can you think of others? • How would you test the Friedmann equation experimentally?
  • 16. 5 – Galaxies and Clusters . • , , . (Dark Matter ) - -
  • 17. Cosmic Microwave Background CMB , • , , • •
  • 18. 5 - Questions to Consider • How could we, in principle at least, be sure that dark matter cannot possibly be ordinary matter that is simply not visible for some reason. • It is possible to prove that dark matter exists, at least beyond any reasonable doubt? • Can you think of hypothetical examples where we could detect dark matter or at least infer its existence without observing it directly? Do you always need to see something to know that it is there?
  • 19. 6 – Gravitational Lensing • • Questions to Consider • Ordinary lenses can be convex or concaved. What would be the analogous property of gravitational lenses? What would that imply about the matter that was creating gravitational field?
  • 20. 7 – Atoms and Particles • , ( • “ NUCLEUNS ” • UP-QUARKS and DOWN-QUARKS
  • 21. (-1) • (+3/2) • (-3/1) • ) ( •
  • 22. (Photons) • (Gluons) • .