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astro111n_ch17
| Question | Answer |
|---|---|
| What events occurred after the first five minutes in the history of the universe? | Galaxies formed,Carbon nuclei formed by fusion, Stars formed, photons of cosmic microwave background released |
| Rank the eras from based on the size, temp, and order that they occurred from smallest(first, hottest) to largest (last, coolest). | Planck era, GUT era, electroweak era, nucleosynthesis era, atoms era, galaxies era |
| What happens when a proton collides with an antiproton? | They convert into two photons. |
| the temperature of the universe ________. | fell very rapidly when the universe was young, but is changing very gradually today |
| What is the charge of an antiproton? | negative |
| Rank these times based on the average temperature of the universe at each time, from coolest to hottest. | Today-1.5 billion years after the big bang-100 million years after the big bang-1 million years after the big bang-500,000 years after the big bang |
| In the past, the temperature of the universe was _____ | hotter than it is today |
| Which of the following does not provide strong evidence for the Big Bang theory? | observations of the amount of hydrogen in the universe |
| Which statement about the cosmic microwave background is NOT true? | It is the result of a mixture of radiation from many independent sources, such as stars and galaxies. |
| If the current density of normal matter in the universe were 10 times as great as it is now, we would expect to observe | less deuterium. |
| Photons of the cosmic microwave background have traveled through space for almost 14 billion years. This statement follows from our model of the Big Bang, because the Big Bang model is based on the idea that | the universe began very hot and dense and has been cooling as it expands |
| Large-scale structure grew around density variations present in the early universe." Observational evidence that such density variations really existed comes from the fact that the cosmic microwave background exhibits | tiny temperature variations in different directions |
| The Big Bang theory is closely linked to Hubble's discovery that the universe is expanding, which seems to imply that there was a time in the past when the expansion first began. Big Bang theory did not gain widespread acceptance until the 1960s because | Although expansion seems to imply a Big Bang, no other specific predictions of the Big Bang theory were tested and confirmed until the 1960s. |
| Today, most scientists accept the Big Bang theory. But a scientific theory can always be revised or discarded if future observations do not agree with its predictions. Which hypothetical would be inconsistent with the Big Bang theory? | Astronomers discover distant protogalactic clouds with a helium abundance below 20%. |
| Today, most scientists accept the Big Bang theory. But a scientific theory can always be revised or discarded if future observations do not agree with its predictions. Which hypothetical would be inconsistent with the Big Bang theory? | Careful studies of quasar spectra show that, 12 billion years ago, the temperature of the cosmic microwave background was slightly lower than it is today. |
| observations do not agree with its predictions. Which hypothetical would be inconsistent with the Big Bang theory? | Over the next 10 years, the temperature of the cosmic microwave background falls to 1 K. |
| Which of these pieces of evidence supports the idea that inflation really happened? | observations of the cosmic microwave background that indicate a flat geometry for the universe |
| Which of the following statements can NOT be tested by science today? | Prior to the Planck time, our universe emerged from another universe |
| What is the earliest time in the universe that we can directly observe? | a few hundred thousand years after the Big Bang |
| Which of these options is the best explanation for why the night sky is dark? | The universe is not infinite in space. |
| Which of the following observations cannot be explained by the Big Bang theory unless we assume that an episode of inflation occurred? | the fact that the temperature of the cosmic microwave background is almost the same everywhere |
| The Big Bang theory is supported by two major lines of evidence that alternative models have not successfully explained. What are they? | (1) The theory predicts the existence of and the specific characteristics of the observed cosmic microwave background; (2) the theory correctly predicts the observed overall chemical composition of the primeval universe. |
| What is the current temperature of the universe? | a few degrees |
| Measuring the amount of deuterium in the universe allows us to set a limit on _________. | the density of ordinary (baryonic) matter in the universe |
Created by:
zemca
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