HW - Ch 29
According to our textbook, roughly what percent of the mass and energy contents of the universe is made up of dark matter plus dark energy?
95 percent
The first scientist to propose a specific model (the primeval atom model) for the big bang was
Lemaitre
The two scientists who first discovered the cosmic microwave background radiation were:
Penzias and Wilson
The satellite that has given us the most precise measurements of the characteristics of the cosmic background radiation is:
Planck
The standard bulbs (standard candles) that made it possible for astronomers to discover the acceleration in the expansion of the universe were
Type Ia supernovae
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
Factoring in everything we currently know about the history of the universe, our best estimate for the age of the universe is
about 13.8 billion years
In our modern view of the expansion of the universe, we understand that it is space that is stretching; individual galaxies don't speed away from each other as if they were rockets. In that case, why do galaxies show a red-shift?
as space stretches, the waves of radiation in space also stretch and their wavelength increases
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
Where in space did the expansion of the universe begin?
everywhere at once
Based on many surveys of the average density of matter in the universe (regular matter and dark matter), astronomers now conclude that the average density of the universe is
less than the critical density
When do astronomers now think that the "dark energy" began to accelerate the expansion of the universe?
several billion years after the Big Bang
Which of the following did Not happen during the first few minutes after the Big Bang?
some very massive early stars formed
When we determine the age of the universe using the Hubble Time, what important simplifying assumption goes into our calculations?
that the expansion of the universe has been happening at the same rate - neither speeding up or slowing down
Which of the following is pretty good evidence that the universe began with a Big Bang?
the 3-degree cosmic microwave background radiation
The reciprocal of the Hubble constant (1/H) is a rough measure of the:
the age 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 just a little less than 70% of the density of the universe, making it the most significant constituent of the mass-energy
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
Some scientists speculate that our universe is not the only universe that exists, but the only one we can gather evidence about. This idea is called
the multiverse theory
