What makes science fiction "hard" is a respect for logic and adherence to the known laws of physics, versus "soft" science fiction which assumes we can innovate around any limitation (often including holes in a plot). Hardness is pretty subjective (just check out the debates on Reddit), but this list includes series that are generally seen to qualify.
Terrific premise--a Western-themed amusement park populated by robotic hosts where guests can live out their fantasies. The show is ambitious--tackling lots (too many?) Big Questions and delivers visually stunning special effects. Like Game of Thrones, the series relies on production value to compensate for sub-par writing as the seasons move on.
A police detective in the asteroid belt, the first officer of an interplanetary ice freighter and an earth-bound United Nations executive slowly discover a vast conspiracy that threatens the Earth's rebellious colony on the asteroid belt.
Two families, the Graystones and the Adamas, live together on a peaceful planet known as Caprica, where a startling breakthrough in artificial intelligence brings about unforeseen consequences. A spin-off of the Sci Fi Channel series "Battlestar Galactica" set 50 years prior to the events of that show.