CH29

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 satellite (spacecraft with instruments) to measure and confirm the cosmic microwave background was the:

COBE (COsmic Background Explorer)

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

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

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?

a few hundred thousand years

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 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 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

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

Where in space did the expansion of the universe begin?

everywhere at once

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 action in the universe. These four forces are the strong nuclear force, the weak nuclear force, electro-magnetism and

gravity

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 the size of the universe so much that the resulting universe looks flat from any point of view

If we include the effects of deceleration in our calculations of the age of the universe, the age we get is:

less than the Hubble time

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

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

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

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)

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

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

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

According to our modern theories, the geometry of the entire universe (all of space-time) 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

What is the strongest known force in the universe?

the strong nuclear force

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