Figure 15-3 The Expanding Chocolate Chip Cake Analogy The expanding universe can be compared to what happens inside a chocolate chip cake as the cake expands during baking. (The cake is floating weightlessly inside the oven of an orbiting spacecraft crewed by hungry astronauts.) All of the chocolate chips in the cake recede from one another as the cake expands, just as all the galaxies recede from one another as the universe expands.