What practical difficulties limit the use of Hubbles law for measuring distances?
” Hubble’s law says the velocity of a galaxy (the speed at which it’s moving away) divided by Hubble’s constant is equal to the galaxy’s distance from us. One of the difficulties with Hubble’s law is that Hubble’s constant hasn’t been precisely pinned down yet, per question eleven. Also, the law doesn’t take into account gravitational tugs that affect galaxies, such as the gravitational influences within our Local Group. “What makes white dwarf supernovae good standard candles? Briefly describe how we have learned the true luminosities of white dwarf supernovae.” White dwarf supernovae make good standard candles because a white dwarf supernova always takes place when the star reaches the 1.4 solar mass limit, so all white dwarf supernovae have about the same luminosity. This was confirmed by observing Cepheid variables in the same galaxies as the few known white dwarf supernovae. The Cepheid variables were used to determine the galaxy’s distance, which meant the luminosity-distance for
