The Big Bang can be modeled as a balloon with tiny dots drawn on it. As you inflate the balloon, it gets larger, and the dots spread apart. However, models are often limited because they cannot explain every aspect of a phenomenon. Which phenomenon caused by the Big Bang is best modeled by the dotted balloon?
Answer
A
We can observe galaxies moving farther away from Earth.
B
The universe grew quickly at first, but as it has become larger, its expansion has slowed.
C
Heavier elements were only able to be formed once the universe had expanded.
D
The universe is unevenly distributed with cosmic background radiation.
Explanation
As the balloon inflates, the distance between every pair of dots increases. This models the expansion of space, which makes distant galaxies move farther apart and appear to recede from Earth. The balloon does not show how the expansion rate changes, how elements formed, or patterns in cosmic background radiation.
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