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.
(If you're curious about how I came to write this novel, check out this article Long Road To the Myth of the Maker.)
Amazon
http://amzn.to/2n7H4Uw
Audible (audiobook)
https://www.audible.com/pd/Sci-Fi-Fantasy/Myth-of-the-Maker-Audiobook/B079K92F1Z
Barnes & Noble
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Powell's Books
http://www.powells.com/
Deluxe hardcover at MCG
https://www.montecookgames.com/myth-of-the-maker/