Following the explosive Big Bang experience, visitors exit onto the Harriet and Robert Heilbrunn Cosmic Pathway, a dramatic, spiraling ramp that ushers them through 13 billion years of cosmic evolution. At the start of the walkway, visitors can measure the length of their stride and determine how many millions of years pass with each step. Thirteen markers along the way denote the passage of each billion years and, at eight landings, computer interactives help visitors understand the nature and size of the universe at that point in time. Artifacts are also on display, including evidence of the earliest bacterial life on Earth and the fossilized tooth of a giant carnivorous dinosaur. At the end of the 360-foot circular pathway, the thickness of a human hair illustrates the relative duration of human history, from cave paintings to the present day. The Heilbrunn Cosmic Pathway was specially designed to allow for adjustments and updates to the exhibitry, as research in astrophysics reveals new information about the age and nature of the universe.