There's been a lot of debate lately over whether science fiction needs accurate science — or whether it's even worth discussing the accuracy of science in science fiction. What kind of person expects a science textbook instead of just a fun romp? But as a new essay points out, this is really a matter of suspension of disbelief.
Neil deGrasse Tyson, in particular, has come in for a lot of flak as a spoilsport, who nitpicks the science in movies like Gravity and Interstellar to an unhealthy degree. Why does Tyson have to take everything so seriously?
In fact, the accuracy of the science is just one of many rubrics by which you can judge science fiction. You can judge a story by the believability of the plot, whether the story makes any sense, or the emotional and psychological depth of the characters. Or you can judge a story based on plausibility — and scientific accuracy is just one form of plausibility, which is a larger issue in fiction. If someone wrote a story set in the "real world," in which a person who has never learned to read or write goes to Harvard and becomes a famous professor, you might have a hard time buying the basic idea — and many of the scientific inaccuracies in today's science fiction are on that same level, for people with some scientific literacy. (The Moon's an egg, and you can fly from the International Space Station to the Chinese space station in no time, etc. etc.)
Edited to add: And as I said above, this is just one criterion among many. Some people worry more about plausibility, some people worry more about character development. Also, it depends how much your story is foregrounding the science, and what kind of tone it's going for — comedy versus serious realism. But it's absolutely valid for people to care about the scientific accuracy in a story, just like it's valid for them to care about any other aspect.
As an essay in the Berkeley Science Review points out, it's just a matter of suspension of disbelief — scientific ideas that run too wild make it harder to suspend your disbelief, just like that illiterate Harvard professor would. David Litt goes on to explain how some classic SF authors addressed this issue:
Robert Heinlein, author of classic SF books such as Stranger in a Strange Land and Starship Troopers, writes in his essay, On the Writing of Speculative Fiction, that while it is good and well to create a story that takes place in a fantastical and fictive universe, "as a result of this new situation, new human problems are created–and our story is about how human beings cope with those new problems". He is a stickler to the science, though, and demands that any SF author needs "(a) to bone up on the field of science you intend to introduce into your story; (b) unless you yourself are well-versed in that field, you should also persuade some expert in that field to read your story and criticize it".
Taking it one step further, Poul Anderson writes about one author who tried to make a planet circling a class B (one of the hottest) star with an atmosphere composed of hydrogen and fluorine gas. Under these conditions, the molecules would "react promptly and explosively", rendering a world incapable of supporting life (it would be an hydrofluoric acid bath…). Mr. Anderson cites this as typical of writing from authors whose only worlds are "a world exactly like our own except for having neither geography nor history, or else it is an unbelievable mishmash which merely shows us that still another writer couldn't be bothered to do his [or her] homework".
Fortunately, Mr. Anderson is equally encouraging and nurturing to new writers as he is curmudgeonly to the old, poor ones, and in his essay, The Creation of Imaginary Worlds, he provides lots of charts and graphs to help writers trying to create new environments. He spells out how to choose the size of a star, and what the expected luminosity (or energy output) would be, and the distance a planet would have to be from that star to support life without it being burnt to a crisp. But this is really only the start. After the planet mass and distance is decided upon, one needs to calculate the year of this planet, as it can affect seasons, and therefore the "rhythm of life" on the planet. But wait, there's more! If the luminosity of the star is more than our sun, a human space traveler might notice that the shadows on this new planet would be sharper than he or she is used to seeing. He goes on for pages, detailing the intricacies of planet creation, many of which may never appear in the final story, but should influence the author's formation of life, behavior, and habitation on their planet.
There's tons more at the link, but the basic point stands — don't send people to a planet whose atmosphere is full of chemicals that would instantly explode in contact with each other, or people will have a hard time taking the story seriously. [Berkeley Science Review]