A science fiction writer is—or should be—constrained by what is, or logically might be. That can mean simple fidelity to facts (which, in science, are always more important than theories—though Lord knows the two help shape each other, undermining the convenient, complacent separation of observer and observed). To me it also means heeding the authentic, the actual and concrete. Bad fiction uses the glossy generality; good writing needs the smattering of detail, the unrelenting busy mystery of the real.
Gregory Benford