Exam 22: Modern Cosmology

What was the temperature of the universe when a typical CMB photon was no longer able to spontaneously create a proton and antiproton pair? Note that a photon has an energy equal to E hc/λ,the CBR at any point in time has a blackbody spectrum that peaks at λ_peak = (2,900 μm K)/T,and the mass of a single proton is 1.7 × 10⁻²⁷ kg.

Describe the four fundamental forces of nature by listing their names and describing what effect each force has on objects in the universe.

What are the names of the two particles that mediate the electromagnetic force in quantum electrodynamics (QED)and the strong force in quantum chromodynamics (QCD)?

Astronomers have confirmed the Grand Unified Theory by observing that protons decay in laboratory experiments.

To determine how the expansion rate of the universe has changed over time,astronomers directly measure the __________ for a sample of Type I supernovae in distant galaxies.

What is the "flatness problem" in cosmology?

Put the following types of objects in order,starting with the first one to form after the Big Bang and ending with the last one to form:

If you found a globular cluster that had an age of 20 billion years,what cosmological observations would conflict with this observation?

What two properties of the universe are determined by the values of Ω _mass and Ω _Λ?

What are two observations that,when combined,tell us that the universe has Ω_mass+ Ω_Λ = 1 and is flat?

At what stage in the universe's history do we think the asymmetry between matter and antimatter was created?

The four fundamental forces of nature are gravity,electromagnetism,the weak force,and the strong force.

The three fundamental forces of nature are gravity,electromagnetism,and the strong force.

What would the universe be like if there were complete symmetry between matter and antimatter?

What can solve the flatness and horizon problem in cosmology,and why?

The Big Rip could occur in a universe where the effect of __________ increases with time.

Which of the following are NOT considered carrier particles used to mediate forces between other particles?

Explain what the uncertainty principle means,and how it relates to the horizon problem.

Observations of Type I supernovae in distant galaxies confirm that the expansion of the universe is decreasing over time.

The weak force mediates the beta decay of neutrons into protons,electrons,and antineutrinos.