E6+GALAXIES+AND+THE+EXPANDING+UNIVERSE

Back to IB PHYSICS > IB ASTROPHYSICS OPTION =GALAXIES AND THE EXPANDING UNIVERSE= [| SIMULATION TO VERIFY HUBBLE'S LAW] Describe the distribution of galaxies in the universe.
 * E1 INTRODUCTION TO THE UNIVERSE || E2 STELLAR RADIATION AND STELLAR TYPES || E3 STELLAR DISTANCES || E4 COSMOLOGY || E5 STELLAR PROCESSES AND STELLAR EVOLUTION || E6 GALAXIES AND THE EXPANDING UNIVERSE ||
 * Galactic motion **

Students should understand the terms galactic cluster and galactic supercluster. Explain the red-shift of light from distant galaxies.

Students should realize that the red-shift is due to the expansion of the universe.

Solve problems involving red-shift and the recession speed of galaxies. State Hubble’s law. Discuss the limitations of Hubble’s law. Assumes constant recession speed of galaxies, but gravity is retarding them (also dark energy accelerating them?).
 * Hubble’s law **

Explain how the Hubble constant may be determined. See simulation above.

Explain how the Hubble constant may be used to estimate the age of the universe.

Hubble constant = velocity of galaxy/ distance galaxy has travelled

Age of universe = 1/ Hubble constant

Solve problems involving Hubble’s law. Students need only consider a constant rate of expansion.

Explain how the expansion of the universe made possible the formation of light nuclei and atoms. Students should appreciate that, at the very high temperatures of the early universe, only elementary (fundamental) particles could exist and that expansion gave rise to cooling to temperatures at which light nuclei could be stable.