CP 22 The Birth of the Universe Flashcards
What was the significance of the end of the era of nucleosynthesis, when the universe was about 5 minutes old?
The basic chemical composition of the universe had been determined.
In terms of the “eras” that scientists use to describe different times in the history of the universe, we live in the __________.
era of galaxies
TF In the distant past, the temperature of the universe was colder than it is today
F
TF the cosmic microwave background is the result of a mixture of radiation from many independent sources, such as stars and galaxies
F (It is thought to be radiation from the temperature of the universe itself, not from independent objects.)
Why do scientists assume that the early universe was much hotter and denser than the universe of today?
The fact that the universe is expanding implies that objects were closer together in the past, and compressing material makes it hotter and denser.
What do we mean by the term inflation?
a sudden and extremely rapid expansion of the universe that occurred in a tiny fraction of a second during the universe’s first second of existence
Statement
The universe began with the forces unified. During the first fraction of a second, the forces separated and there was a brief but important episode of inflation. Subatomic particles of both matter and antimatter then began to appear from the energy present in the universe. Most of the particles annihilated to make photons, but some became protons, neutrons, electrons, and neutrinos. The protons and neutrons underwent some fusion during the first three minutes, thereby determining the basic chemical composition of the universe.
If observations had shown that the cosmic microwave background was perfectly smooth (rather than having slight variations in temperature), then we would have no way to account for _________.
how galaxies came to exist
What is the approximate temperature of the universe (as a whole) today?
3K
In principle, if we could see all the way to the cosmological horizon we could see the Big Bang taking place. However, our view is blocked for times before about 380,000 years after the Big Bang. Why?
Before that time, the gas in the universe was dense and ionized and therefore did not allow light to travel freely.
Olbers’s paradox is an apparently simple question, but its resolution suggests that the universe is finite in age. What is the question?
Why is the sky dark at night?
What does inflation help to explain?
the uniformity of the cosmic microwave background
Models of the Big Bang that include inflation predict that the overall geometry of the universe should be “flat” (in spacetime). This prediction __________.
agrees with data found by studying the cosmic microwave background
How did the “seeds of structure” come to be
Inflation would have caused random, microscopic quantum fluctuations to grow so large in size that they became the seeds of structure.
