Do you think that the author accurately describes scientific principles in the novel? Why or why not?

Bradbury does not accurately describe scientific principles in this story or in most of his work. He is a poetic storyteller more than a wonkish, nuts-and-bolts sci-fi writer. He uses fantasy scenarios, such as going to Mars or Venus, the aftermath of a nuclear holocaust, or, in this case, time travel, to explore deeper questions about humankind's weaknesses and the meaning of life.
One of Bradbury's main thematic concerns, which is explored in this story, is human pride in our ability to control technology. Bradbury believes we are too quick to adopt new technologies and that we think too little about the consequences when we do so.
In this story, what matters is not getting the technicalities of time travel straight. After all, we don't know how time travel works. What matters to Bradbury is his fear that if we did have this technology, we would use it in frivolous ways (such as sending rich people on a dinosaur-hunting safari) and be too quick to trust that we humans could handle it without problems. The story reveals the terrible consequences of rushing to use a new technology, showing that just because we can do something doesn't mean it is a good idea to go ahead and do it.