Most current theories about the eventual fate of the universe draw their conclusions based on the universe’s
a. density
b. energy
c. mass
d. volume

The answer is (b.) Energy

Among the choices, energy is the closest to the answer. There are many theories about the universe and most of them draw their conclusions based on the energy in the universe. An Example is the theory of Big Freeze. It states that the universe has a fixed amount of energy and then when it runs out, the universe will slow down.