Please answer the following questions below. Don’t skip any, do all. Pick from t
ID: 115003 • Letter: P
Question
Please answer the following questions below. Don’t skip any, do all. Pick from the following anwers that are below the question
A star’s life can be described as a battle between what two things
Electric forces trying to pull everything together and atomic forces opposing gravity
Gravity trying to crush down everything and nuclear interactions speeding in the atoms
Gravity and quantum mechanics because they are the two most important forces in stars.
What option best represents the first time there existed lots of stars and galaxies in the universe?
A microsecond after the bang
A second after the bang
Ten seconds after the bang
Three minutes after the bang
One hour after the bang
A thousand years of the bang
A few hundred thousand years after the bang
A half a billion of years after the bang.
What is the evidence that there were quantum fluctuations in the early universe?
Differences in the number of hydrogen and helium atoms in the early universe
Temperature differences of the cosmic background radiation in different directions
The difference in the temperature in the universe now and in the early universe
The fact that galaxies started so early.
What is one problem with the simple story of the universe being exactly the same in all directions?
If the universe were perfectly smooth, galaxy formation could never occur
If the universe were perfectly smooth, galaxy formation can occur, but no stars
If the universe were perfectly smooth, galaxy formation could occur, but not on the lifetime of the universe
What is significant about the fact that after electrons and nuclei combine, the universe becomes electrically neutral
Without the universe being neutral we couldn’t have had quantum fluctuations
The electromagnetic force roughly cancels out on scales larger than that of an atom leaving gravity to be the dominant force
Once the universe becomes neutral, it stops fighting against gravity
Explanation / Answer
Question 1: A star's life can be described as a battle between what two things?
Answer: B. Gravity trying to crush down everything and nuclear interactions speeding in the atoms.
Explanation: Generally throughout their lives, stars fight the inward pull of the force of gravity. Interestingly most of their lifetime the interior heat and radiation is provided by nuclear reactions.
Question 2: What option best representthe first time there existed lots of stars and galaxies in the universe?
Answer: A few hundred thousand years after the bang.
Explanation: The universe is currently about 13.7 billion years old and it was very early in the time after the big bang explosion that stars formed.
Question 3: What is the evidence that there were Quantum fluctuations in the early universe?
Answer: B. Temperature differences of the cosmic background radiation in different directions.
Explanation: Quantum fluctuations were created at the beginning of inflation and the expansion of universe during inflationary leaves imprints in the cosmic microwave background.
Question 4: What is one problem with the simple story of the universe bring exactly the same in all directions?
Answer: A. If the universe were perfectly smooth , galaxy formation could never occur.
Explanation: The big-bang theory is modified by the inflation theory which states that the universe expanded rapidly shortly after it was created.
Question 5: What is the significant fact about the fact that after electron and nuclei combine, the universe becomes electrically neutral?
Answer: With the universe being neutral we couldn't have Quantum fluctuations.
Answer: By the definition itself atom is electrically neutral. When an atom has the same number of electrons and protons, charges balance and the atom is neutral. Because the universe is filled with electrons and anti-electrons, but the fact is that protons are lighter than neutrons. So it becomes energetically favorable to have more protons and neutrons in the universe. But the universe is filled with over a billion photons for every proton and neutron in it.