1. dark matter
    matter that has mass but doesn't emit light
  2. what is rotation curves
    plot of orbital velocity of the stars and gas moving around it at each distance from its center
  3. gravitational lens
    focuses light from behind it, making background objects look brighter
  4. MACHO stands for
    massive compact halo object
  5. WIMPS
    weakly interacting massive particles
  6. cosmology
    study of structure and evolution of universe as a whole
    when the universe was created through a hot dense violent state of matter and energy
  8. cosmological principle
    universe looks the same to all observers, no matter where they are located in.
  9. redshift caused by
  10. objects in space can move toward each other despite...
    expansion of space, gathering into clusters, galaxies, and solar systems.
  11. the loaf of the raisin bread bough rises, raisins move farther apart at what rate?
    rate proportional to their separation.
  12. age of the universe
    13.7 billion years ago
  13. how do we calcutlate age of universe
    recession of one galaxy from another galaxy
  14. olber's paradox
    argument that sky should be a bright night because a combined light from all distant stars and galaxies
  15. cosmic horizon
    the max distance light can travel in the universe's age
  16. visible horizon
    the space between the cosmic horizon
  17. cosmic microwave background
    radiation created during the big bang that permeates space
  18. temp of the CMB
  19. positive curvature
    bending of space leading to finite volume
  20. closed universe
    with positive curvature is analogous to surface of a sphere
  21. negative curvature
    form of curved space described as being open because it has no boundary.
  22. flat universe
    universe that extends forever with no curvature. total energy is zero
  23. early universe
    time when matter and radiation behaved almost as a single entity
  24. antimatter
    type of matter that brought into contact with ordinary matter annihilates it leaving nothing but energy
  25. positron
    antimatter partner of the electron
  26. antiproton
    the antimatter partner of the electron
  27. planck time
    when the universe would have been packed into volume far smaller than a proton and the temp greater than 10^33 Kelvin
  28. quantum fluctuations
    where particles flash in and out of existence and changes occur according to probablities
  29. inlfation
    an enormous expansion of early universe
  30. bubbles became??
    seperate universes
  31. is universe going to expand or collapse? what determines this?
    the strength of gravity and the upward impulse given to it
  32. if the expansion energy dominates than?
    the universe will expand forever
  33. to determine whether the universe will expand or recollapse calculate
    critical density or rho as pc
  34. Omega
    quanitity indicitaing how close the observed density is to the critical density.
  35. if omega is > 1
    universe recollapse
  36. omega<1
    universe expands forever
  37. omega=1
    universe at critical density.
  38. big crunch
    a crushing existing from an overwhelming force of gravity that all objects and atoms with be compressed to higher densities.
  39. cosmological constant
    a term in equations describes effects of gravity on the entire universe, a repulsive force opposing gravity
  40. descriptive name for cosmological constant
    dark energy
  41. dark energy
    energy detected by effect on expansion of the universe
  42. dark energy causes
    expansion to speed up
  43. fate of the universe
    the universe expands so fast that every part of the universe is pulled away from other parts at high speeds they disappear from each other
  44. gallilean relativity
    speed of a thrown object depends on how fast and in what direction thrower is moving
  45. light doesn't behave....
  46. time dilation
    when time stretches, length
  47. contraction
    contracts in the direction of motion
  48. lorentz factor
    matter contracts while it moves, reducing length in direction while it moves, reducing length in direction of motion
  49. escape velocity
    velocity necessary to avoid being gravitationally pulled back to an object
  50. general relativity
    theory of gravitation that shows space and time communicate the gravitational force through their curvature
  51. equivalence principle
    being stationary in a gravitational field is equivalent to being accelerated field is equivalent to being accelerated in a constant acceleration frame of reference.
  52. singularity
    compressed single point in a black hole
  53. event horizon
    boundary around black hole that light nor radiation can escape
  54. schwarzchild radius
    a compressed stellar core with a small radius where nothing can escape
  55. when it becomes a neutron star,
    it will not stop collapsing
  56. if you cross the event horizon,
    escape is impossible
  57. gravitational redshift
    photons traveling away from a massive object. light moving away loses energy
  58. gravitational tidal forces
    stretch matter out into longer and thinner strands
  59. MIlky way's rotation
    not like a solid disk, inner rotates faster then outer.
  60. law of intertia
    tendency of an object to stay in a constant state of rest or uniform motion
  61. T OR F: in our solar system, the terrestial planets are much larger than the jovian planets
  62. as one moves towards some object, objects angular size will....
  63. our solar system is primarily made of
  64. moon in its orbit about the earth is said to be in tidal lock what does this mean?
    same side of the moon always faces the earth
  65. when the Earth is lined between the SUn and mars, we say that mars is in
  66. planet means
  67. the average density of the outer planets is
    less than the average density of the inner planets
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