This is a setting in a lot of thematic movie novels about prolonging life, or continuing the existence of the plot for a longer period of time.
For example, hibernation.
This is in many movies, hibernation silos are set up in a variety of settings, in fact, the main purpose is to "suspend life". It is known that the human lifespan is only a hundred years, which is too short for the long timeline of the sci-fi genre, and is not conducive to plot advancement. So, substitute the setting of hibernation to suspend lifespan and conserve limited life.
The other category is the most delightful of sci-fi tropes, the outright extension of lifespan.
Longer lifespans, stronger bodies, smarter brains. It can be extended by internal factors, such as modifying genes. It can also be prolonged by external factors, such as a certain scientific accident, a fortuitous providence.
Any clue in between can lead to a series of science fiction works.
The second category, transportation.
Humans want to cross planet-to-planet distances, and they certainly can't do it with the modes of transportation now known. The central idea is that it's too slow.
First of all, there's the problem of fuel.
To go faster and farther, you need to factor in fuel. And with fuel factored in, there's volume to consider. It's a series of extensions that require a lot of setup to round out the pit.
With the advancement of real technology and the updating of scientific theories comes more and more inspiration for sci-fi in terms of "fuel".
From the old understanding of rocket fuel, to fusion, fission, and even small artificial black holes as energy supplies.
So the problem of fuel was gradually solved.
Then came the problem of speed.
The fastest speed we know of is the speed of light, but that's still not nearly fast enough for planet-to-planet, galaxy-to-galaxy.
At a casual calculation, that's how many light-years, how many thousands of light-years, which is too long for human lifespans to consume, and too long for civilization to consume.
So all sorts of terms entered science fiction, concepts like transmigration, warp speed, and even artificial wormholes.
The purpose is one, to shorten the time of such long-distance voyage during human interstellar voyage. Otherwise, a voyage of fifty or sixty years, wait until the destination, are close to embracing the grandchildren.
So, in science fiction, transportation is also an old and enduring theme. Like Doctor Who, for example, which runs from one part of the universe to the other in the space of a pee. Traveling back and forth across the timeline is also a family affair.
The third category, practical.
Science fiction is really just a genre that can be mixed and matched with any genre, and finding the right balance, even with magical genres, can be blended together and not feel out of place.
So, when setting up sci-fi gear, practicality becomes key. For example, in Alita, mechanical prosthetics. The wide variety of weapons set up for competition, the nanotech used for ancient mechanical fighting, etc.
Another example is Star Wars, from the smallest black and white PK with lightsabers, to the variety of air, land and sea weaponry, to the largest planetary weapons directly destroying multiple planets. Since it can easily destroy a bunch of planets, there is absolutely no need to take high-tech cold weapons and physically fight there. Because, the plot needs it, and all of this is set up to serve the plot.
Then there's the ever-so-vilified Star Trek that traveled from a black hole back into the solar system. From Wanderlust, point Jupiter to propel Earth.
While all have a great deal of implausibility based on known scientific theories, they have the utility of being necessary for the plot of a sci-fi work to move forward.
So, both weapons and ancillary sci-fi gear exist in the plot because of their utility to the plot. There's no way to scientifically theorize the possibility of a descending blow, for example.
The fourth category, the core category.
Science fiction works, if only exists in some big brain tech products, the story is actually very boring. There aren't many people who can sit through an hour and a half of sci-fi product explanations in a movie theater, I suspect.
All the tech setups serve the plot, whether it's scientific enough or not. The plot is coherent and engaging enough to "sell" the sci-fi setting in the work.
No matter how hardcore a sci-fi setting is, there's no way sci-fi can unfold without an enjoyable storyline, with plausible interpersonal, social, racial, and intergalactic tensions.
So, in sci-fi, there will be a class of black-tech settings that make it rare and precious. Lacking a certain amount of **** enjoyment, it becomes the centerpiece that contributes to the conflict, thus driving the plot and laying out various situations.
This core can be the Infinity Progenitor with unlimited energy in the Marvel series, which has a certain level of danger and cannot be taken seriously.
It can be a fragment of the Hyperspace Core from Homeworld 2, an ancient lost black technology that saves lives.
It could be from Punch Out Serenity, the truth.
Or it could be The Man from The Fifth Element.
In general, the advantage of sci-fi is that you can conjure up technology out of thin air that serves the plot, and as long as it's plausible and vaguely plausible, it can fit into the plot.
The disadvantage is also here, that by sticking too close to modern tech, a lot of it will be hard to round out. Because there will be a large number of people who are interested in whether the setting is contrary to known scientific theories, and they don't care if it's necessary for the plot, they're going to take a sci-fi work and discuss scientific research, and try to refute a sci-fi work with scientific theories.