Astronomy & Cosmology Chapter 29

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 billion years 10-43 seconds a few hundred thousand years only last Thursday 3 minutes

Correct answer: a few hundred thousand years

Factoring in everything we currently know about the history of the universe, our best estimate for the age of the universe is 4.6 billion years the age of the universe is infinite; there was no beginning roughly 2 million years about 100 billion years about 13.8 billion years

Correct answer: 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 galaxies will start showing blue-shifts galaxies will shine even more brightly than today from all the dark energy all the stars will die and the galaxies will be dark the entire universe will become one huge black hole the universe will look pretty much the same as it does today

Correct answer: all the stars will die and the galaxies will be dark

Which of the following statements about dark matter is FALSE: it may make up even more of the universe that the matter we cansee it is observed to be a major part of the Milky Way we can detect its gravity, even though we can't see it it is observed to be present in other groups of galaxies astronomers have a pretty good idea what the dark matter is made of

Correct answer: astronomers have a pretty good idea what the dark matter is made of

Where in space did the expansion of the universe begin? nowhere at all; new observations show that the universe is not expanding after all at a point so far away that only our largest telescopes can show us glimpses of it at the center of the Milky Way Galaxy; that's why all the other galaxies are moving away from us near the center of the Virgo Supercluster of Galaxies everywhere at once

Correct answer: everywhere at once

Which of the following did NOT happen during the first few minutes after the Big Bang? two or three of the simplest elements fused together matter and antimatter collided and turned into energy temperatures throughout the universe were hotter than the cores of stars are today some very massive early stars formed energy was converted to matter

Correct answer: some very massive early stars formed

Which of the following is pretty good evidence that the universe began with a Big Bang? the fact that all the galaxies are moving toward us the fact that galaxies collide the fact that stars explode the 3-degree cosmic microwave background radiation the existence of a double star system like Cygnus X-1

Correct answer: the 3-degree cosmic microwave background radiation

According to the most recent data from satellites making precise measurements of the properties of the cosmic background radiation (CBR), the universe is only about 6,000 years old dark matter makes up less than 5% of the total mass-energy of the universe; it's only a minor contributor to what makes up the cosmos normal matter (like the atoms in our bodies) makes up 99% of the total mass-energy of the universe 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 normal matter, dark matter, and dark energy each contribute about 1/3 of the total density of the universe - their contributions are almost exactly equal

Correct answer: 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

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 idea that there is extra helium has been shown to be in error; we were confused by the high red shifts of distant galaxies distorting their spectra the extra helium was produced by the interaction of dark matter with the material at the edges of all galaxies 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 extra helium was produced recently during Type Ia supernova explosions the extra helium was produced in the accretion disks of supermassive black holes

Correct answer: 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

Which of the following is the Earth not located in? the Milky Way Galaxy the Earth is located in all of these the universe the globular cluster M-13 the solar system

Correct answer: the globular cluster M-13