HW - Ch 29

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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


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