State two characteristics of the cosmic microwave background (CMB) radiation.

Outline how Hubble measured the recessional velocities of galaxies.

Estimate the age of the universe in seconds using the Hubble constant H₀ = 70 km s^–1Mpc^–1.

Describe how the CMB provides evidence for the Hot Big Bang model of the universe.

Describe what is meant by the Big Bang model of the universe.

Explain how international collaboration has helped to refine this value.

On the graph, one galaxy is labelled A. Determine the size of the universe, relative to its present size, when light from the galaxy labelled A was emitted.

Outline why the estimate made in (b)(i) is unlikely to be the actual age of the universe.

State two features of the cosmic microwave background (CMB) radiation which are consistent with the Big Bang model.

Outline how Hubble measured the recessional velocities of galaxies.

Using the graph, determine in s, the age of the universe.

Light from a hydrogen source in a laboratory on Earth contains a spectral line of wavelength 122 nm. Light from the same spectral line reaching Earth from a distant galaxy has a wavelength of 392 nm. Determine the ratio of the present size of the universe to the size of the universe when the light was emitted by the galaxy.

Outline how Hubble’s law is related to $z$.

The light from a distant galaxy shows that $z=0.11$.

Calculate the ratio $\frac{\mathrm{size} \mathrm{of} \mathrm{the} \mathrm{universe} \mathrm{when} \mathrm{the} \mathrm{light} \mathrm{was} \mathrm{emitted}}{\mathrm{size} \mathrm{of} \mathrm{the} \mathrm{universe} \mathrm{at} \mathrm{present}}$.

Use the graph to determine the age of the universe in s.

Outline how Hubble’s law is related to $z$.

The light from a distant galaxy shows that $z=0.11$.

Calculate the ratio $\frac{\mathrm{size} \mathrm{of} \mathrm{the} \mathrm{universe} \mathrm{when} \mathrm{the} \mathrm{light} \mathrm{was} \mathrm{emitted}}{\mathrm{size} \mathrm{of} \mathrm{the} \mathrm{universe} \mathrm{at} \mathrm{present}}$.

Light from a hydrogen source in a laboratory on Earth contains a spectral line of wavelength 122 nm. Light from the same spectral line reaching Earth from a distant galaxy has a wavelength of 392 nm. Determine the ratio of the present size of the universe to the size of the universe when the light was emitted by the galaxy.

Estimate the size of the Universe relative to its present size when the light was emitted by the galaxy in (c).

Estimate, using the data, the age of the universe. Give your answer in seconds.

Identify the assumption that you made in your answer to (a).

Determine the distance to this galaxy using a value for the Hubble constant of H₀ = 68 km s^–1$$Mpc^–1.

Determine the distance to the galaxy in Mpc.

Estimate, in Mpc, the distance between the galaxy and the Earth.

A line in the hydrogen spectrum when measured on Earth has a wavelength of 486 nm. Calculate, in nm, the wavelength of the same hydrogen line when observed in the galaxy’s emission spectrum.