Published in June of 1981, The Entropy Effect has the distinction of being the first original novel in the Pocket Books line. The novelization of Star Trek: The Motion Picture by Gene Roddenberry had been released two years earlier, and Vonda N. McIntyre was chosen to write the followup.
It is important to remember while reading this novel that not much had yet been established about the Star Trek universe before this point. As far as “canon” Trek goes, we only had The Original Series, The Animated Series (the canonicity of which is still debated), and the film Star Trek: The Motion Picture. This left a lot of room for McIntyre to flesh out the Trek universe. Some authors might have preferred to play it safe and operate well within the bounds of what had already been established, but McIntyre chose to expand the universe and show us things the television show and film hadn’t.