I moonlight as a fiction writer. I've been writing stories since kindergarten. As a middle schooler, I wrote a lot of science fiction. That whole imaginary worlds thing tapered off as I grew up and figured out how to deal with other people by writing about theoretical human drama. I'm glad I finally got back into science fiction; it's a lot more fun to imagine new concepts than it is to plot out the interactions between angsty teenagers.
Over the past several months, I've been working on a novel set almost a century into the future (at the very least). I call it my keitai novel because I've been writing it mostly on my phone during subway rides to and from the office. It's a little tricky to extrapolate current trends and research into what will actually happen a hundred years from now. But I remind myself that even Jules Verne and Gene Roddenberry didn't get everything right about the future, and they made up for it by illustrating the possibilities so enticingly that people decades and centuries later have taken it upon themselves to work toward substantiating the futures they described.
Some of the ideas I'm incorporating are a little more straightforward and technical, like bioencryption and the laws governing autonomous artificial intelligence. (Of course, the AIs don't call themselves that because they don't consider themselves "artificial".) But I've added other details that were extrapolated and analogized from current events, such as China descending into civil war, which means huge numbers of refugees with manufacturing and engineering expertise are fleeing China and turning stateless-- communities ripe for an alliance with rebel AIs that need people to repair them, and to help them enter the international political scene with some clout. Other details are largely visual and philosophical: this is a world where virtual/augmented reality glasses (VARGs) are widespread, and young people wear them all the time, adding a layer of psychedelic gamified nonsense on top of everything they experience.
It's fun thinking up what might be in store for humankind, but that's not really what this novel is about. To be an effective writer, I have to drop all of this history during the course of the story and not let it get in the way of the plot; I can't explain everything outright like I did above, because that would interrupt the novel's flow and believability. I think the best science fiction writers manage to convey a completely different world mostly in passing-- for example, William Gibson might drop a stray detail during a conversation that implies an entire war happened decades before the characters met. I want to create a future that can draw readers all the way in like that, but also compel them to dream about what's possible in the world we actually live in, and how to get from point A to point B.