Answer:
Closed universe theory.
Step-by-step explanation:
Scientists have calculated the "critical density" of the universe. Critical density is proportional to the square of the Hubble constant, which is used to measure the rate of expansion of the universe. Comparing critical density to current density can help scientists understand the cosmos.
If the actual density of the universe is greater than the critical density, then it contains sufficient mass to finally stop its expansion. In this case, the universe is closed, finite, though it has no end, and has a spherical shape. Once the universe stops expanding, it will start to contract. The galaxies will stop moving away and begin to approach. Finally, the universe will suffer the opposite of the Big Bang, often referred to as the Big Crunch. This is known as a closed universe.