Next week it is likely that I'm going to mention science quite a bit in my reviews so I thought it would be best to talk about this now.
We're not living in the pulp days where someone could write a story about some aspect of physics or chemistry. Most science fiction these days has more to do with technology than science. As a result few science fiction authors include a lot of science in their books. That is not necessarily a bad thing.
So I don't spend a lot of time dwelling on the science in these books. I could nitpick them apart; while that's good for starting nerd fights I'm not really interested in that. What bothers me is that when it is so egregiously wrong that it breaks suspension of disbelief. I know that different people have different levels of "egregiously" but to me that means that someone with only a basic knowledge of the science involved can immediately tell that something is wrong.
One problem is when the author gives actual numbers since they assume that readers won't do the math. If the author hasn't done the math then this can quickly become a situation where the reader is going to pick up a problem. A planet with a twenty-five year long orbit and fifty-five hour long day with a five hour night in the temperate zone on the solstice is obviously not going to be habitable to humans no matter how much handwaving the author does (and in the case I'm thinking of the author did a whole lot of handwaving much later in the book that made things worse to in an attempt to justify that). You don't need to do the math to know this, just enough about the solar system to know that a twenty-five year long orbit is going to be pretty far our and enough experience with life on Earth in general to recognize that having days that much longer would be very hot.
Another is to anthropomorphize external forces. Evolution is a popular choice for this but I've seen it applied to other things. It's natural for human beings to do this but when it becomes a key plot element that DNA has desires and an understanding of what constitutes an "improvement" from a human point of view then that suspension of disbelief snaps.
That falls a bit under the "_______ is magic!" meme. As long as science fiction has existed writers have dropped fantastic elements into stories and explained it as the cutting edge science of the time. Never mind that anyone with the knowledge gained from reading a popular magazine article about that subject would know that it doesn't make sense, the writer puts it in because they equate it with magic. Radiation was a popular choice for magic for a while, computers had their turn, and these days it tends to be quantum physics, nanotechnology, and genetic engineering.
So as you might guess I'm about to get into some books with scientific errors. Errors so bad that it snapped my suspension of disbelief and there was nothing good in the book to even attempt to reattach it. It's not impossible to deal with scientific errors but if the author can't put anything in the book worth reading it makes those problems stand out more.