A good way to explain the idea of the counter balanced universe between space and mass is with the words of
Steven Hawking.

Picture digging a hole at the begging of the universe, for every shovelful full of mass you dig out you leave space in the form of a hole.
Over time you have a huge hole and a big pile of mass. The hole space equals the mass pile.

A stable universe will always seek to keep this balance of the energy of space with the energy of stuff.

In our universe a ittle tiny bit of stuff is equal to and enormous amount of space.