Uh oh, I feel an essay coming one. (Can you tell I’m procrastinating from writing my own sf story? Well, I am.)
Hard science fiction is not a thing, but one end of a continuum, and one that has varied greatly over the years.
The 40s and 50s were the era of classic science fiction, the big names, when Asimov and Heinlein and the crew at Astounding Science Fiction set their stories in what SF critic Steve Carper calls “The Consensus Future.”
This is the world image that culminated in The Jetsons, the future of soaring cities, flying cars, easy rocket space travel, four-hour workdays, robot helpers, and electronic marvels. This world was a strict and straight extrapolation off of current white, middle-class American culture. There were few aliens in these stories, because John W. Campbell, editor of Astounding, didn’t like aliens (even earthly ones from other cultures) except as minor figures for his heroic Americans to lose to.
The Consensus Future is still the image of science fiction in many people’s eyes, because it is simple, optimistic, and oh-so-American.
But the world was always far more complex than these stories could portray and by the 60s and 70s a new generation of writers added sociology, anthropology, political science, media, and mythology to the list of sciences and resources that they would extrapolate from, and added minorities and women to the cast of characters. Many of the greatest works in the history of the genre came out of this period: Ursula K. LeGuin’s The Left Hand of Darkness; Roger Zelazny’s Lord of Light; Samuel R. Delany’s Babel-17; Frank Herbert’s Dune; Joanna Russ’ The Female Man, John Brunner’s Stand on Zanzibar; and the genius period of Robert Silverberg, when he put eight different novels on the Best Novel shortlist in six years.
The 80s saw the coming of cyberpunk, a worldview that extrapolated off the coming interconnectedness and fragmentation that writers saw that a wired world would bring. Although Babel-17 is the Ur-cyberpunk novel and Vernor Vinge really invented the genre with the novella “True Names” in 1981, William Gibson kick-started the genre with Neuromancer in 1984. He and especially Bruce Sterling took the effect that science had on societies to new levels.
Today’s hard science fiction has a variety of flavors. But the cutting edge belongs to writers who toss around cultures, futures, and universes in ways that Doc Smith could only envy. Stephen Baxter, Wil McCarthy, Robert Metzger, Iain Banks, and Charles Stross are only some of the new names working in this vein. Stross especially is so high-extrapolated-tech that his work can be as difficult to read as James Joyce. Mind-blowing, but no place for a newbie to start a journey into the field.
And that’s part of the difference between today’s hard sf and that of the Consensus Future. Virtually anyone who had read the morning’s paper and had heard about the wonders of science that were being promulgated everywhere could read Asimov and Heinlein and understand what they were saying. Reading a serious hard sf writer today is a feat even for the experienced. I still haven’t figured out how Wil McCarthy is working his science magic in Collapsium, which is a building material made of black holes that allows ringworlds and teleportation towers to be built.
But as I said at the beginning, these books are merely the far end of a continuum and there are many flavors of hard sf, most of which are not nearly as daunting. Biologically-oriented sf has been prominent for many years, from writers like Nancy Kress, Nicola Griffith, Octavia Butler, and Catherine Asaro, and while these may involve aliens, they are also more people-oriented.
In fact, when I look at the winners of SFWA’s Nebula Award, I see many of these names. Except for last year’s winner, American Gods by Neil Gaiman, every winner of the past dozen years has been hard sf of some flavor or definition.
There can be no way to say whether the OP will like hard sf or any particular book of hard sf, but that’s true of just about anything. Try some of the names and titles I’ve given and see if you want to read more.