Question 1

Which of the following is not consistent with observations of the cosmic microwave background?

Accepted Answer

The current age of the universe is estimated to be around 13.8 billion years based on observations of the cosmic microwave background, so option A is not consistent with those observations.

Question 2

Which of the following claims cannot be proved or disproved by science?

Accepted Answer

Claims about supernatural entities or events, such as the universe being created by God, cannot be proved or disproved by science because they are outside the realm of empirical investigation and rely on faith or belief systems.

Question 3

If observations had shown that the cosmic microwave background was perfectly smooth (rather than having very slight variations in temperature), then we would have no way to account for .

Accepted Answer

The slight variations in temperature in the cosmic microwave background are believed to be the gravitational imprint of initial density fluctuations that eventually led to the formation of galaxies. If the background was perfectly smooth, we would have no explanation for how galaxies came to exist. The other options are not directly related to the cosmic microwave background.

Question 4

Why did the Big Bang not produce heavier elements?

Accepted Answer

By the time helium could survive, the temperature had become too low for heavier elements to form. The Big Bang produced only helium, hydrogen, and a small amount of lithium because the heavier elements require higher temperatures and pressures to form. As the universe expanded and cooled, the temperature became too low for heavier elements to form.

Question 5

Why does the Big Bang theory predict that the cosmic background radiation should have a perfect thermal radiation spectrum?

Accepted Answer

According to the Big Bang theory, the universe was once very hot and dense. As it expanded and cooled, it emitted radiation in the form of photons, which eventually became the cosmic microwave background radiation. This background radiation should therefore have a thermal radiation spectrum with a peak corresponding to the temperature of the universe at that time, which is predicted by the theory.

Question 6

According to the Big Bang theory, why do we live in a universe that is made of almost entirely of matter rather than antimatter?

Accepted Answer

According to the Big Bang theory, during the first 0.001 second after the Big Bang, particles and antiparticles were made in almost but not perfectly equal numbers. Everything annihilated except the very slight excess of matter particles. This slight excess of matter particles is why we live in a universe made of almost entirely of matter, rather than antimatter.

Question 7

Which of the following statements cannot be tested by science today?

Accepted Answer

While there are theories about the origins of our universe, there is currently no scientific method available to test for the existence or properties of another universe prior to the Planck time.

Question 8

The Big Bang theory seems to explain how elements were formed during the first few minutes after the Big Bang. Which hypothetical observation below (these are not real observations)would call our current theory into question?

Accepted Answer

The answer of The Big Bang theory seems to explain...

Question 9

Which of the following statements correctly summarizes the events in the early universe according to the Big Bang theory?

Accepted Answer

Choice D correctly summarizes the events in the early universe according to the Big Bang theory. The forces did begin unified, and then separated during a brief episode of inflation. Particles of both matter and antimatter then appeared, with most annihilating to make photons. Protons, neutrons, electrons, and neutrinos were created from remaining particles. The protons and neutrons then underwent fusion, determining the basic chemical composition of the universe.

Question 10

According to the Big Bang theory, how many forces-and which ones-operated in the universe during the GUT era?

Accepted Answer

During the GUT (Grand Unified Theory) era, there were two forces: gravity and a single force that later split into the strong, weak, and electromagnetic forces.

Question 11

What is the temperature of the universe (as a whole)today?

Accepted Answer

The temperature of the universe as a whole today is approximately 3 K. This is the result of the cosmic microwave background radiation left over from the Big Bang, which has cooled as the universe has expanded. However, it should be noted that certain regions of the universe can have significantly different temperatures due to the presence of stars, galaxies, and other sources of radiation.

Question 12

What is postulated to have caused a sudden inflation of the early universe?

Accepted Answer

The sudden inflation of the early universe is postulated to have been caused by the energy released from the "freezing out" of the strong force from the GUT (Grand Unified Theory) force. This phase transition caused a sudden expansion of the universe, leading to the smooth and homogeneous distribution of matter that is observed today.

Question 13

Why might inflation have occurred at the end of the GUT era?

Accepted Answer

During the GUT era, the strong and electroweak forces were unified into a single force. As the universe expanded and cooled, the force split into two separate forces, releasing an enormous amount of energy. This energy caused the universe to undergo a period of rapid expansion, known as inflation, which resulted in a temporary increase in the rate of inflation.

Question 14

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 prior to about 380,000 years after the Big Bang. Why?

Accepted Answer

Before about 380,000 years after the Big Bang, the universe was filled with a dense and ionized gas which scattered photons, preventing light from traveling freely. This period is known as the Era of Recombination, and it was not until the gas cooled and neutral atoms formed that light could travel through the universe unimpeded. Therefore, our view is blocked for times prior to about 380,000 years after the Big Bang.

Question 15

The four fundamental forces that operate in the universe today are _ .

Accepted Answer

The four fundamental forces are strong force, weak force, electromagnetic force, and gravity. The strong force and weak force are nuclear forces, while the electromagnetic force includes both electric and magnetic forces. Tidal force is not considered a fundamental force. Option D includes all four fundamental forces.

Question 16

The cosmic microwave background gives us a view of the universe when it was

Accepted Answer

The cosmic microwave background radiation was emitted when the universe was about 380,000 years old, after a period known as the "recombination era." This radiation has been traveling through space ever since, making it a valuable tool for studying the early universe.

Question 17

What happened to all of the quarks that existed freely during the particle era?

Accepted Answer

During the particle era, quarks existed freely as a soup of particles called quark-gluon plasma. However, as the universe expanded and cooled, the quarks combined in groups of two or three to form protons, neutrons, and their antiparticles. This process is called hadronization, and it is believed to have occurred about one microsecond after the Big Bang. Therefore, the quarks did not disappear but rather transformed into other particles during the formation of matter in the early universe.

Question 18

What are the two possible explanations for not seeing something glowing brightly along every line- of- sight? I)The universe is infinite in size and infinitely old, but dust absorbs starlight from far away stars.
II)The universe has a finite number of stars.
III)The universe is changing in some way as to prevent us from seeing an infinite number of stars.

Accepted Answer

Explanation: II suggests a finite number of stars, limiting the light we see, and III suggests a dynamic universe, both explaining why we don't see infinite starlight.

Question 19

Which event in the history of the universe happened last?

Accepted Answer

Neutral atoms formed last, as this was the point at which the universe became transparent to light, allowing it to travel through space without being scattered by charged particles. This event occurred about 380,000 years after the Big Bang.

Question 20

What was the significance of the end of the era of nucleosynthesis, when the universe was about 5 minutes old?

Accepted Answer

At the end of the era of nucleosynthesis, about 5 minutes after the Big Bang, the basic chemical composition of the universe had been determined. This is because the fusion of protons and neutrons to form the nuclei of simple elements like hydrogen, helium, and lithium had occurred during this era, and their proportions had been set. This early composition has persisted throughout the universe's history, with later processes like supernova explosions and stellar evolution modifying it only slightly.

Quiz 17: The Birth of the Universe