It should be remembered that gravity will always be different depending on the place. For example, there are some areas in the universe wherein gravity does not increase. There are some that may have a little bit of gravity but it will not be enough to keep people on the ground.
It is best that you check out the level of gravity on each section of the universe in order to learn more details about it. The center of gravity of the universe will highly depend on where the location is. For example, in one location, there is a center of gravity. It will be different from one location to another.