[tsally]

This isn't correct. Science fiction routinely has elements that violate the laws of physics and nature as we know them today. Having actual science is in most cases a disqualifier (there is some SF that sticks to science, but that's hardly the norm). If your imagination is required for the work to make sense, it's probably not science.

[nihilocrat]

If I had a dime for every science fiction story with super-realistic spaceflight yet also with completely unexplained "ansible" technology that allows instantaneous communication with anyone in the universe....

[ericd]

And good on Enders Game for trying to fill it in with ansible tech.