Astronomy chapter 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
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 telescope on board
which of the following statements about dark matter is FALSE
Astronauts have a petty good idea but doesn't really know
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
The first satellite (spacecraft with instruments) to measure and confirm the cosmic microwave background was the:
COBE (COsmic Background Explorer)
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
Why did Einstein introduce the cosmological constant into the equations of his general theory of relativity when describing the universe?
Einstein's equations required the universe to expand or contract; he could not imagine or accept it doing either one, so he put a factor in to stop it from moving.
Where in space did the expansion of the universe begin?
Everywhere at once
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?
Few hundred thousand years
Which of the following is the Earth not located in?
Globular cluster M-13
Scientists looking at an overview of physics today understand that there are four forces that govern all actions in the universe. These four forces are the strong nuclear force, the weak nuclear force, electro-magnetism and
Gravity
If we include the effects of deceleration in our calculations of the age of the universe, the age we get is
Greater than the Hubble time
How does a period of extremely fast inflation very early in the history of the universe explain the observation that the geometry of the universe looks flat (not curved) to us?
Inflation increased he size of the universe so much that the resulting universe looks flat from any point of view
The first scientist to propose a specific model(the primeval atom model) for the big band was
Lemaitre
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.
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:
Neutrinos
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
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
What is the strongest known force in the universe?
Strong nuclear force
Which of the following is pretty good evidence that the universe began with a Big Bang?
The 3-degree cosmic microwave background radiation
Astronomers have measured that there is more helium in the universe than can be explained by the fusion in stars over the last 13 billion years. How do they think the extra helium got into the universe?
The extra helium was made during the first few minutes of the Big Bang, when the entire universe was hot enough for fusion to occur briefly
According to our modern theories, the geometry of the entire universe (all of spacetime) may be curved or warped. This is a pretty bizarre notion; what other discovery in astronomy has helped us believe that space may be able to curve or warp?
The properties of black holes
The standard bulbs (standard candles) that made it possible for astronomers to discover the acceleration in the expansion of the universe were
Type Ia supernova
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 billions years
The reciprocal of the Hubble constant (1/H) is a rough measure of the:
age of the the universe
In the very distant future, given our best model of the accelerating universe, what will the universe look like?
all the stars will die and the galaxies will be dark
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.
In our modern view of the expansion of the universe, we understand that it is space that id 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.
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 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 or slowing down.
Scientists speculate that the properties (laws) of the universe must be the way they are because if they were significantly different, we would not be here to think about them. This idea is called
the anthropic principle
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
After the Big Bang, in order for the universe to become transparent to light and other electro-magnetic radiation, what had to happen?
the density of the universe had to decrease ( to 1000 nuclei per cubic centimeter or less)
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 measure meant of galaxies using Type 1a supernova.
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
One of the things that our current "standard Model" of the big bang theory doesn't explain is
why the temperature of the cosmic microwave background is so uniform throughout all of space