Big Bang Cosmology Flashcards
what does the cosmological principle state?
on sufficiently large scale, the properties of the Universe are the same for all observers
what causes the expansion of the Universe?
the expansion of SPACE
what is one proof that the expansion of universe has no center
no matter where you are in the universe you will measure the same Hubble Law
what measurement should we talk about rather than the SIZE of the universe?
the scale factor of the universe
what does the scale factor describe?
how the separation of galaxies change with time
what does the amount of stretching depend on?
the change in scale factor
redshift is equal to (z + 1 =)
scale factor of the universe today/scale factor when light was emitted
what does cosmological expansion imply?
that in the past galaxies were closer together
the cosmological principle does not state that the universe is ____ at all times
constant
what are two things that can help us determine the age of the universe?
1) separation of two galaxies
2) we know how fast these galaxies are moving apart due to expansion of universe
the combined gravity of the mass to slow the expansion of the universe tells us that expansion cannot be ___
constant
the mass contained w/in the volume exerts a _____ force that slows down expansion
gravitational
what does the geometry of the universe depend on?
mass and energy density of the universe
closed universe (>1)
positive curvature, spherical geometry…finite in size
flat universe (=1)
no curvature, flat geometry…infinite in size
open universe (<1)
negative curvature…infinite in size…..saddle shaped
why is the sky dark at night?
the universe has a finite age, thus our view of the Universe is limited to the finite speed of light so we cannot see infinite number of stars
what is the cosmic horizon
marks a limit to the observable universe and is limited by time and not space
what did. Gamow, Alpher, and Herman predict in 1948?
the early universe was filled w/ visible radiation
when was the universe opaque to light?
when the universe was hot and ionized
when did the universe become transparent to light?
when it cooled below 3000 K…can now see microwave radiation
who discovered cosmic microwave background and when was it?
1965 by Penzias and Wilson
why are anisotropies important?
they represent the beginning of structure of the universe
