plot of orbital velocity of the stars and gas moving around it at each distance from its center
gravitational lens
focuses light from behind it, making background objects look brighter
MACHO stands for
massive compact halo object
WIMPS
weakly interacting massive particles
cosmology
study of structure and evolution of universe as a whole
BIG BANG
when the universe was created through a hot dense violent state of matter and energy
cosmological principle
universe looks the same to all observers, no matter where they are located in.
redshift caused by
stretching
objects in space can move toward each other despite...
expansion of space, gathering into clusters, galaxies, and solar systems.
the loaf of the raisin bread bough rises, raisins move farther apart at what rate?
rate proportional to their separation.
age of the universe
13.7 billion years ago
how do we calcutlate age of universe
recession of one galaxy from another galaxy
olber's paradox
argument that sky should be a bright night because a combined light from all distant stars and galaxies
cosmic horizon
the max distance light can travel in the universe's age
visible horizon
the space between the cosmic horizon
cosmic microwave background
radiation created during the big bang that permeates space
temp of the CMB
2.73
positive curvature
bending of space leading to finite volume
closed universe
with positive curvature is analogous to surface of a sphere
negative curvature
form of curved space described as being open because it has no boundary.
flat universe
universe that extends forever with no curvature. total energy is zero
early universe
time when matter and radiation behaved almost as a single entity
antimatter
type of matter that brought into contact with ordinary matter annihilates it leaving nothing but energy
positron
antimatter partner of the electron
antiproton
the antimatter partner of the electron
planck time
when the universe would have been packed into volume far smaller than a proton and the temp greater than 10^33 Kelvin
quantum fluctuations
where particles flash in and out of existence and changes occur according to probablities
inlfation
an enormous expansion of early universe
bubbles became??
seperate universes
is universe going to expand or collapse? what determines this?
the strength of gravity and the upward impulse given to it
if the expansion energy dominates than?
the universe will expand forever
to determine whether the universe will expand or recollapse calculate
critical density or rho as pc
Omega
quanitity indicitaing how close the observed density is to the critical density.
if omega is > 1
universe recollapse
omega<1
universe expands forever
omega=1
universe at critical density.
big crunch
a crushing existing from an overwhelming force of gravity that all objects and atoms with be compressed to higher densities.
cosmological constant
a term in equations describes effects of gravity on the entire universe, a repulsive force opposing gravity
descriptive name for cosmological constant
dark energy
dark energy
energy detected by effect on expansion of the universe
dark energy causes
expansion to speed up
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
gallilean relativity
speed of a thrown object depends on how fast and in what direction thrower is moving
light doesn't behave....
classically
time dilation
when time stretches, length
contraction
contracts in the direction of motion
lorentz factor
matter contracts while it moves, reducing length in direction while it moves, reducing length in direction of motion
escape velocity
velocity necessary to avoid being gravitationally pulled back to an object
general relativity
theory of gravitation that shows space and time communicate the gravitational force through their curvature
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.
singularity
compressed single point in a black hole
event horizon
boundary around black hole that light nor radiation can escape
schwarzchild radius
a compressed stellar core with a small radius where nothing can escape
when it becomes a neutron star,
it will not stop collapsing
if you cross the event horizon,
escape is impossible
gravitational redshift
photons traveling away from a massive object. light moving away loses energy
gravitational tidal forces
stretch matter out into longer and thinner strands
MIlky way's rotation
not like a solid disk, inner rotates faster then outer.
law of intertia
tendency of an object to stay in a constant state of rest or uniform motion
T OR F: in our solar system, the terrestial planets are much larger than the jovian planets
False
as one moves towards some object, objects angular size will....
Increase
our solar system is primarily made of
hydrogen
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
when the Earth is lined between the SUn and mars, we say that mars is in
opposition
planet means
wanderer
the average density of the outer planets is
less than the average density of the inner planets