Astronomy (part 11) for my love

Based on our current understanding of physics, we can understand the conditions that prevailed in the early universe as far back in time as about

• 380,000 years after the Big Bang.

• one ten-billionth of a second after the Big Bang

• 10-45 seconds after the Big Bang

• 10 billion years ago

What happens when a particle of matter meets its corresponding antiparticle of antimatter?

• They can form a complete atom.

• The combined mass of the two particles is completely transformed into energy (photons)

• They fuse to make a heavier particle

• The question makes no sense, since antimatter does not really exist

What is the significance of the Planck time?

• It is the time at which inflation is thought to have occurred

• Before it, conditions were so extreme that our current understanding of physics is insufficient to predict what might have occurred

• It is the time when the cosmic microwave background was released

• It is the amount of time required for two protons to fuse to make deuterium

The four fundamental forces that operate in the universe today are

• strong force, weak force, electromagnetic force, gravity.

• strong force, weak force, electric force, magnetic force

• nuclear force, electromagnetic force, gravity, tidal force.

• nuclear force, gravity, electric force, magnetic force

A "GUT" (grand unified theory) refers to theories that

• unify gravity with the strong and weak forces.

• unify the electromagnetic and weak forces

• unify all four forces together

• unify the strong force with the electromagnetic and weak forces

What do we mean by inflation?

• the expansion of the universe that we still observe today

• the sudden release of photons when a particle and antiparticle annihilate one another

• 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

• quantum fluctuations by high speed, relativistic particles in a state of false vacuum that caused disturbances in the space-time continuum leading to the process described in the question to which this answer refers

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

• 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.

• An episode of what we call inflation initiated the event of the Big Bang. Once the Big Bang got underway, particles and forces began to appear one by one. The forces produced protons, which fused to make hydrogen and helium until the universe was about 380,000 years old. Then gravity began to act, turning the hydrogen and helium into galaxies.

• Forces and various subatomic particles began to appear during the first second after the Big Bang. For reasons not understood, the particles were all made of ordinary matter and none were made of antimatter, thus explaining why we live in a universe made of matter. The particles underwent some fusion for the first 380,000 years after the Big Bang, at which time the first stars were born.

• The Big Bang began with the initiation of what we call inflation, which gradually slowed to the current expansion rate of the universe. Forces came to exist for a different reason, having to do with quantum fluctuations in the space-time continuum. Particles came to exist as a result of cracks made when forces froze. Once there were particles, gravity brought them together to make stars, and the stars then turned the particles into hydrogen, helium, and other elements.

Which statement about the cosmic microwave background is not true?

• Its spectrum corresponds to a temperature of just under 3 degrees above absolute zero

• With the exception of very small variations, it appears essentially the same in all directions in which we look into space

• It is the result of a mixture of radiation from many independent sources, such as stars and galaxies.

• It is thought to be radiation that began its journey to our telescopes when the universe was about 380,000 years old.

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 correctly predicts that the universe should be expanding; (2) the theory predicts the existence of and the specific characteristics of the observed cosmic microwave background.

• (1) the theory predicts the episode of inflation that we think occurred in the early universe; (2) the theory predicts the existence of large quantities of dark matter

• (1) the theory correctly predicts that the universe should be expanding; (2) the theory correctly predicts the observed ratio of spiral to elliptical galaxies in the universe.

• (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 universe.

Measuring the amount of deuterium in the universe allows us to set a limit on

• the total amount of mass in the universe

• the density of ordinary (baryonic) matter in the universe

• the acceleration of the universe

• the current age of the universe.