Everybody seems to love this book. And I WANTED to love it, but it just didn't do it for me. It's a good premise, but the writing is very much in need of a editor (or a new editor) both for grammatical errors and story flow.
For me, the story started off strong, an interesting mystery, interesting characters, and time travel. What's not to like? But then after about 25% it just all fell apart - got confusing, the plot line didn't seem like it was making any progress, had occasions where two years would pass in one sentence and others where every little action was drawn out (like showing the one character how to fish where the process for making a hook is described). For most of the book I had no idea where the story was going, and not even any idea what steps the characters were trying to accomplish on their way to the end goal.
With any time travel story, it's typically best to not try to explain the process, as it results in too much made-up "science", which is almost never pertinent to the storyline. The author largely avoids this, which is good. The characters basically just concentrate and it happens. But then the author does go on to try to describe the concept of bonding with the rock, and puts a lot of effort into describing the "quantum realm", which just isn't necessary and bogs the story down.
Then there were the grammatical errors, which tend to really take me out of a story. Numerous examples of missing articles and prepositions ("It felt like someone had turned the volume eleven"). Numerous examples of changing tense, including in the middle of paragraphs and sentences ("Clement brought up the last feed of the control room. They have watched it dozens of times and didn't learn anything new").
As I mentioned, lots of potential here, but in need of a helpful editor.