Understanding Fast Radio Bursts and Cosmic Microwave Background

What are fast radio bursts (FRBs) characterized by?

• Infrared emissions

• Visible light emissions

• Quick flashes of broad frequency radio emissions

• Long-lasting radio emissions

What was the significant discovery about fast radio bursts in March 2016?

• They are visible to the naked eye

• They originate from the Milky Way

• They are caused by supernovae

• A fast radio burst repeated itself

How far did the cosmic microwave background photons travel to reach us?

• 10 billion light years

• 13.7 billion light years

• 5 billion light years

• 20 billion light years

What was the universe filled with before the moment of recombination?

• Only hydrogen gas

• Dark matter

• Plasma, atomic nuclei, and free electrons

• Solid matter

What is the Thomson scattering cross-section?

• A measure of the size of protons

• A measure of the size of electrons

• A measure of the interaction region for electrons

• A measure of the interaction region for protons

What is the mean free path in the context of photon travel?

• The average distance between stars

• The distance between two galaxies

• The distance light travels in a year

• The average distance a photon travels before hitting an electron

What was the estimated electron density at the moment of recombination?

• 0.2 electrons per cubic meter

• 200 million electrons per cubic meter

• 10 electrons per cubic meter

• 1 billion electrons per cubic meter

What is the significance of the redshift of the CMB being 1,089?

• It shows how much smaller the universe was at recombination

• It determines the age of the universe

• It measures the speed of light

• It indicates the universe is expanding

What is the main reason photons had difficulty traveling through the early universe?

• Lack of light sources

• Presence of dark matter

• Strong gravitational fields

• High density of free electrons

What should winners of the contest do to claim their prize?

• Submit a video response

• Visit the PBS Space Time website

• Email their mailing address and T-shirt size

• Call the PBS Space Time hotline