Myth of the Maker has an answer. It's related to what scientists call dark energy, a medium that my protagonists learn to call the Strange.
In Myth of the Maker, computer programmer Carter Morrison sacrifices himself and his friends, killing them and locking them in a virtual world—all to save the rest of the planet from certain destruction. Morrison’s friends have no idea what he’s done—but as the “planetvores” approach, they must come to terms with the fictional worlds they now inhabit, which serve to insulate the real world from the horrors without. Not all of them are satisfied with their forced martyrdom, either, and a man named Jason Cole—known as The Betrayer—seeks a way out of the fiction and back to reality, no matter the cost.
Angry Robot (the publisher)
Barnes & Noble
Deluxe hardcover at MCG