Null Infinity: A Novel: Book 2
Development of the superluminal boundary drive was fraught with dangers, but after years of effort Harry and Lauren Stimson succeeded.
The boundary drive led to the discovery of the bulk and another world-universe in the bulk that physicists called the strong gravity brane. Exploration of the other brane was the obvious next step.
But what wasn't obvious was how that exploration would affect our world-universe, until disaster struck in the form of a changing gravitational constant.
Now that her parents were retired, it was up to the Stimson's daughter, Elle, to come up with a solution before the change in gravity went too far.
Null Infinity: Book 2 is the second story and the second novel in the Forgotten Earth Universe.