This lab activity will allow the students to examine the evidence for
an expanding universe and thereby calculate the approximate age of the
universe from an analysis of Hubble's Law.
Hubble's Law deals with examining the large scale structure of our
universe as well as it's age. One of the key principle's to understanding
Hubble's Law is to first understand and accept the Cosmological
Principle, which states:
Let us look at the Cosmological Principle in terms of viewing the universe as a balloon with a series of polka dots drawn onto it's outer surface. Each dot is to represent a galaxy or a cluster of galaxies. If we begin to blow the balloon up, then it's easy to see that the galaxies would all then appear to move away from not only the center of the balloon, but they would also appear to move away from each other as well!
The result of this basic analysis is that if we were to place an observer (i.e., ourselves) into any one of the galaxies in our balloon-universe, then no matter which galaxy they were in, they would see the rest of the galaxies in the universe moving away from them if the universe were expanding. Is this what we see in our observations of the universe? The answer is for the most part a resounding "yes".
The Hubble Law and Galactic Red Shifts
From the work of V. M. Slipher and Edwin Hubble, it was seen that numerous (that is, most) galaxies as seen from Earth exhibited a very noticable red shift due to the Doppler shifting of their emitted light (known as the "Galatic Red Shift"). This meant that these galaxies were moving away from the Earth's galaxy, the Milky Way. In addition, the data suggested that the further away that a galaxy was, the faster it was moving; this led to Hubble's Law:
From an analysis of these laws and principles, you will be using observational data to calculate the age of the known universe!