State Hubble's law.

What does redshift mean for light from a distant galaxy?

Write the redshift definition using emitted and observed wavelengths.

Using \(H_0=70\,\mathrm{km\,s^{-1}\,Mpc^{-1}}\), find \(v\) for \(d=10\,\mathrm{Mpc}\).

A line emitted at \(400\,\mathrm{nm}\) is observed at \(440\,\mathrm{nm}\). Find \(z\).

What is the relation between redshift and scale factor?

If \(z=3\), what was the scale factor at emission relative to today?

For small redshift, estimate recessional speed when \(z=0.020\).

Explain why the expansion of the universe does not noticeably expand atoms or the Solar System.

Using \(H_0=70\,\mathrm{km\,s^{-1}\,Mpc^{-1}}\), estimate the distance of a galaxy with \(v=2100\,\mathrm{km\,s^{-1}}\).

Why is \(1/H_0\) an age scale for the universe?

A galaxy has \(z=0.10\). Estimate its distance using \(H_0=70\,\mathrm{km\,s^{-1}\,Mpc^{-1}}\) and \(c=3.0\times10^5\,\mathrm{km\,s^{-1}}\).

Explain the difference between Doppler redshift and cosmological redshift.

Why does observing distant galaxies also mean observing the past?

What does a larger redshift imply about the scale factor when the light was emitted?

Derive \(d\approx cz/H_0\) for small redshift.

A spectral line has \(z=2\). By what factor has its wavelength stretched?

Why can recession speeds from Hubble's law exceed \(c\) at very large distances without violating special relativity locally?

Explain why Hubble's law is statistical rather than exact for every galaxy.

A galaxy's measured redshift includes both cosmic expansion and local motion. Why can that complicate distance estimates?