Genre Definition and Recommendation is a feature where I will define a genre and a sub-genre definition and the make some recommendations.
Science Fiction - Definition found on Wikipedia
Science Fiction- is a genre of fiction dealing with imaginary but more or less plausible (or at least non-supernatural) content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities.
Parallel Universe Definition found on Wikipedia
A parallel universe or alternative reality is a hypothetical or (fictional) self-contained separate reality coexisting with one's own. A specific group of parallel universes is called a "multiverse", although this term can also be used to describe the possible parallel universes that constitute reality. While the terms "parallel universe" and "alternative reality" are generally synonymous and can be used interchangeably in most cases, there is sometimes an additional connotation implied with the term "alternative reality" that implies that the reality is a variant of our own. The term "parallel universe" is more general, without any connotations implying a relationship, or lack of relationship, with our own universe. A universe where the very laws of nature are different – for example, one in which there are no Laws of Motion – would in general count as a parallel universe but not an alternative reality. The correct quantum mechanical definition of parallel universes is "universes that are separated from each other by a single quantum event."
Every Day meets Cloud Atlas in this heart-racing, space- and time-bending, epic new trilogy from New York Times bestselling author Claudia Gray.Marguerite Caine’s physicist parents are known for their radical scientific achievements. Their most astonishing invention: the Firebird, which allows users to jump into parallel universes, some vastly altered from our own. But when Marguerite’s father is murdered, the killer—her parent’s handsome and enigmatic assistant Paul—escapes into another dimension before the law can touch him.Marguerite can’t let the man who destroyed her family go free, and she races after Paul through different universes, where their lives entangle in increasingly familiar ways. With each encounter she begins to question Paul’s guilt—and her own heart. Soon she discovers the truth behind her father’s death is more sinister than she ever could have imagined.A Thousand Pieces of You explores a reality where we witness the countless other lives we might lead in an amazingly intricate multiverse, and ask whether, amid infinite possibilities, one love can endure.
Trail by Fire by Josephine Angelini
This world is trying to kill Lily Proctor. Her life-threatening allergies keep her from enjoying experiences that others in her hometown of Salem take for granted, which is why she is determined to enjoy her first high school party with her best friend and longtime crush, Tristan. But after a humiliating incident in front of half her graduating class, Lily wishes she could just disappear.Suddenly, Lily is in a different Salem—one overrun with horrifying creatures and ruled by powerful women called Crucibles. Strongest and cruelest of them all is Lillian . . . Lily's other self in this alternate universe.What makes Lily weak at home is what makes her extraordinary in New Salem. In this confusing world, Lily is torn between responsibilities she can't hope to shoulder alone and a love she never expected.