What does it mean that the universe is homogenous?
The universe looks the same from every perspective
Galaxies are generally distributed evenly throughout the universe
All stars in all galaxies have planetary systems just like ours
The universe has looked the same at all times in its history
What do astronomers mean when they say that the universe is isotropic?
More distant parts of the universe look just like nearby parts
Intergalactic gas has the same density everywhere in the universe
The laws of physics apply everywhere in the universe
The universe is the same in every direction
Cosmological redshifts are calculated from observations of spectral lines from
individual stars in different galaxies
clouds of dust and gas in different galaxies
spectra of entire galaxies
rotations of the disks of distant galaxies
Astronomers observe that all galaxies are moving away from the Milky Way. According to the cosmological principle, this observation suggests that
the Milky Way is at the center of the universe
the Milky Way must be at the center of the expansion
the Big Bang occurred at the current location of the Milky Way
an observer in a distant galaxy would make the same observation
Some galaxies have redshifts (z) that if equated to Vr/c correspond to velocities greater than the speed of light. Special relativity is not violated
because of relativistic beaming
because it's a trick of the measurement angle
because redshifts carry no information
because those velocities do not measure motion through space
The Big Bang theory predicted
the Hubble law
the cosmic microwave background radiation
the cosmological principle
the abundance of helium
the period-luminosity relationship of Cepheid variables
The simplest way to estimate the age of the universe is from
using the slope of Hubble's Law
the age of Moon rocks
models of stellar evolution
measurements of the abundances of elements
The CMB includes information about
the age of the universe
the temperature of the early universe
the density of the early universe
density fluctuations in the early universe
the motion of Earth around the center of the Milky Way
Repeated measurements showing that the current helium abundance is much less than the value predicted by the Big Bang would imply that
some part of the Big Bang theory is incorrect or incomplete
the current helium abundance is wrong
scientists don't know how to measure helium abundances
If the density of the universe is higher than the critical density, the universe will
expand forever
expand, but gradually slow down
eventually collapse
neither expand nor contract
Dark energy has been hypothesized to solve which problem?
the universe is expanding
the cosmic microwave background radiation is too smooth
the expansion of the universe is accelerating
stars orbit the centers of galaxies too fast
What problems of cosmology does inflation solve?
flatness
horizon
fluctuation
sphere
The first stars formed in the universe had fewer more( fewer, more ) heavy elements and higher lower( higher, lower ) mass than the stars formed today.
We expect the kinds of galaxies that we see at a redshift of z = 4 to be:
much like we see today
smaller and much more irregular looking than today
far more numerous but with more spiral galaxies
larger versions of what we see today
Place the following in order of size, from smallest to largest. ❌ ❌ ❌❌ ❌❌ ❌
The dominant force in the formation of galaxies is
gravity
angular momentum
the electromagnetic force
the strong nuclear force
Larger galaxies form from the merging of small protogalaxies. That process is similar to the formation of:
stars
planets
molecular clouds
asteroids
Which of the following is a characteristic difference between cold and hot dark matter?
temperature
ability to emit radiation
the way they clump under the influence of gravity
mass density
The dominant factor in the formation of galaxies is the distribution of in the early universe.
