One of the nice things about writing a sci-fi novel is that you're freed from writing strictly within the bounds of reality. You can take liberties by imagining different methods for traveling across space, protecting people during battle, and even speculate on what undiscovered natural things might exist in the universe.
Many of the everyday conveniences we enjoy today, like cell phones, can be seen depicted first in sci-fi shows. Sometimes, those fanciful guesses about what else might exist out there in the universe are more true than the creators of the show or book would have ever imagined at the time ... like Star Trek predicting white and black holes.
One of my goals for the Drifters series is to present things that may potentially actually exist along with adding in a healthy mix of fantasy to add a little more spice to things. Along with this I want to convey things like Quantum Theory and the structure of DNA in a way that normal non-scientifically minded people can grasp.
To wrap up this post, here's a list about some sci-fi things that were made real.