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dark matter
matter that has mass but doesn't emit light
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what is rotation curves
plot of orbital velocity of the stars and gas moving around it at each distance from its center
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gravitational lens
focuses light from behind it, making background objects look brighter
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MACHO stands for
massive compact halo object
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WIMPS
weakly interacting massive particles
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cosmology
study of structure and evolution of universe as a whole
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BIG BANG
when the universe was created through a hot dense violent state of matter and energy
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cosmological principle
universe looks the same to all observers, no matter where they are located in.
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redshift caused by
stretching
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objects in space can move toward each other despite...
expansion of space, gathering into clusters, galaxies, and solar systems.
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the loaf of the raisin bread bough rises, raisins move farther apart at what rate?
rate proportional to their separation.
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age of the universe
13.7 billion years ago
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how do we calcutlate age of universe
recession of one galaxy from another galaxy
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olber's paradox
argument that sky should be a bright night because a combined light from all distant stars and galaxies
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cosmic horizon
the max distance light can travel in the universe's age
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visible horizon
the space between the cosmic horizon
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cosmic microwave background
radiation created during the big bang that permeates space
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positive curvature
bending of space leading to finite volume
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closed universe
with positive curvature is analogous to surface of a sphere
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negative curvature
form of curved space described as being open because it has no boundary.
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flat universe
universe that extends forever with no curvature. total energy is zero
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early universe
time when matter and radiation behaved almost as a single entity
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antimatter
type of matter that brought into contact with ordinary matter annihilates it leaving nothing but energy
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positron
antimatter partner of the electron
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antiproton
the antimatter partner of the electron
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planck time
when the universe would have been packed into volume far smaller than a proton and the temp greater than 10^33 Kelvin
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quantum fluctuations
where particles flash in and out of existence and changes occur according to probablities
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inlfation
an enormous expansion of early universe
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bubbles became??
seperate universes
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is universe going to expand or collapse? what determines this?
the strength of gravity and the upward impulse given to it
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if the expansion energy dominates than?
the universe will expand forever
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to determine whether the universe will expand or recollapse calculate
critical density or rho as pc
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Omega
quanitity indicitaing how close the observed density is to the critical density.
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if omega is > 1
universe recollapse
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omega<1
universe expands forever
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omega=1
universe at critical density.
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big crunch
a crushing existing from an overwhelming force of gravity that all objects and atoms with be compressed to higher densities.
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cosmological constant
a term in equations describes effects of gravity on the entire universe, a repulsive force opposing gravity
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descriptive name for cosmological constant
dark energy
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dark energy
energy detected by effect on expansion of the universe
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dark energy causes
expansion to speed up
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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
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gallilean relativity
speed of a thrown object depends on how fast and in what direction thrower is moving
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light doesn't behave....
classically
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time dilation
when time stretches, length
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contraction
contracts in the direction of motion
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lorentz factor
matter contracts while it moves, reducing length in direction while it moves, reducing length in direction of motion
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escape velocity
velocity necessary to avoid being gravitationally pulled back to an object
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general relativity
theory of gravitation that shows space and time communicate the gravitational force through their curvature
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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.
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singularity
compressed single point in a black hole
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event horizon
boundary around black hole that light nor radiation can escape
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schwarzchild radius
a compressed stellar core with a small radius where nothing can escape
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when it becomes a neutron star,
it will not stop collapsing
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if you cross the event horizon,
escape is impossible
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gravitational redshift
photons traveling away from a massive object. light moving away loses energy
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gravitational tidal forces
stretch matter out into longer and thinner strands
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MIlky way's rotation
not like a solid disk, inner rotates faster then outer.
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law of intertia
tendency of an object to stay in a constant state of rest or uniform motion
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T OR F: in our solar system, the terrestial planets are much larger than the jovian planets
False
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as one moves towards some object, objects angular size will....
Increase
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our solar system is primarily made of
hydrogen
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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
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when the Earth is lined between the SUn and mars, we say that mars is in
opposition
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the average density of the outer planets is
less than the average density of the inner planets
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