Astronomy 1, Chapter 7
Which of two main predictions of the Big Bang theory turned out to be true?
-the oldest stars are made of hydrogen, helium, and lithium, in the proportions predicted -radiation has been found coming from all of space, just like predicted -Both of these factors
At the beginning of the universe
-the temperature was billions of degrees -the density was enormously high -matter could turn into energy and vice versa ALL OF THE ABOVE
How long after the Big Bang was the Planck time, before which our current theories are completely unable to describe conditions in the universe?
10 -43 second
The satellite that has given us the most precise measurements of the characteristics of the cosmic background radiation is
WMAP
What causes the expanding universe to decelerate in many of our cosmological models?
the mutual gravity of the galaxies pulls them together
At first, right after the Big Bang, the universe was too hot for nuclei and electrons to combine into the kinds of neutral atoms that are familiar to us today. How soon after the beginning did it become cool enough for neutral atoms to form?
3 minutes
Why might inflation have occurred at the end of the GUT era?
An enormous amount of energy was released when the strong force froze out from the GUT
The first scientist to propose a specific model (the primeval atom model) for the big bang was
Lemaitre
The period from about 100 seconds up to 15 minutes after the Big Bang is the
Nuclear Epoch
The two scientists who first discovered the cosmic background radiation were
Penzias and Wilson
Why can't current theories describe what happened during the Planck era?
We do not yet have a theory that links quantum mechanics and general relativity
What do we mean by inflation?
What happened the instant after the Big Bang
The Hubble Time is
a rough estimate of the age of the universe
If you want to check on what conditions were like in the universe a few hundred thousand years after the Big Bang, what sort of instrument would it be best to use?
a satellite with infrared and microwave telescopes on board
According to our studies of the ages of the oldest stars we know, the age of the universe must be
about 13 - 14 billion years
The crossover point from radiation to matter domination occurred
about 50,000 years after the Big Bang, at a temperature of about 16,000 K
The reciprocal of the Hubble constant (1/H) is a rough measure of the
age of the universe
Which of the following observations helps show that the universe is evolving with time?
all of the above help show that the universe evolves
According to the models of the universe we discussed in this course, why do the galaxies move apart (why do we have Hubble's law)?
as a result of the Big Bang, space itself is stretching, and this stretching carries the galaxies away from each other
Which of the following statements about dark matter is FALSE?
astronomers have a pretty good idea what the dark matter is made of
Which of the following statements about the early universe (as envisioned by the standard model of cosmology) is FALSE?
at the very beginning, the energies were so great that the universe was actually contracting for a while
According to our modern theories, the geometry of the universe (all of space-time) may be curved or warped. This is pretty bizarre notion; what other discovery in astronomy has helped us believe that space may be abel to curve or warp?
black holes
Today, we believe that only a small number of elements were actually formed during the Big Bang. Which of the following was NOT one of these?
carbon
In the closed universe model, the universe will end by
coming together in a "big crunch"
Einstein included a cosmological constant in his equations describing the universe, because he
could not bring himself to imagine a universe in motion
In the open universe model, the universe will
expand forever
In describing the universe using his equations of general relativity, Einstein assumed that it was isotropic (the same in all directions). What recent observations have confirmed that the universe is isotropic on the large scale?
measurements of the 3 - degree cosmic background radiation
Helium originates from
mostly from the Big Bang with a small contribution from stellar nucleosynthesis
At about 1 second after the beginning of the universe, one type of particle was able to start traveling freely through the universe. These particles are still with us, but they are extremely hard to detect. They are called
neurtinos
What did the Big Bang theory predict could be seen today?
radiation from the Big Bang might be detected. It was gamma rays 14 billion years ago, but today it is cooler and would look like weak microwaves coming from all of space
Which of the following is NOT an observation made by the COBE satellite?
that many new elements were being produced at the time that the cosmic background radiation was emitted
Which of the following is pretty good evidence that the universe began with a Big Bang?
the 3-degree background radiation
The universe appears flat; this is explained by
the Inflationary epoch
In which model (theory) of the universe will all the galaxies eventually show a blue shift in their spectrum instead of a redshift?
the closed universe (with positive curvature)
What are the two key observational facts that led to widespread acceptance of the Big Bang model?
the cosmic background radiation and the expansion of the universe
According to the most recent data from satellites making precise measurements of the properties of the cosmic background radiation (CBR)
the dark energy makes up more than 70% of the density of the universe, making it the most significant constituent of the mass-energy
The amount of deuterium we find in stars today can give astronomers an important clue about
the density of the universe just a few minutes after the Big Bang
Where do the photons in the cosmic background radiation originate?
the end of the era of nuclei
The model of the universe that involves an enormous increase of scale during a very short time in the early universe is called
the inflationary universe model
Recent observations indicate that the universe is expanding faster today than it was a few billion years ago (that, in other words, the expansion of the universe is accelerating). What kind of observations have led astronomers to this surprising conclusion?
the measurement of galaxy distances using Type Ia supernovae
What is the strongest force in the universe?
the strong nuclear force
If the Hubble constant turns out to be larger than we have thought in the past, it means that
the time that has passed since the Big Bang is less than we thought
What did the COBE observations tell cosmologists about the early universe?
there are tiny but important "ripples", temperature fluctuations that are perhaps the seeds of galaxies that form later
What happened to the quarks that existed freely during the particle era?
they combined in groups to make protons, neutrons, and their antiparticles
How many forces operated in the universe during the GUT era?
two, gravity and the GUT force
A GUT (Grand Unified Theory) refers to theories that
unify the strong force and the electromagnetic and weak forces
To measure whether the expansion of the universe is decelerating or accelerating, we need an independent way of measuring the distance to really remote galaxies. Which of the following holds promise as a way of measuring such very large distances?
using the brightness of type I supernovae as standard bulbs
The redshift of the universe at decoupling was about
z= 1,000,000
