The mixed reviews of this book fascinate me! I am wondering of this is due to how hard it is to understand the hard science. I am not a theoretical physicist, so my own understanding probably didn't even scratch the surface. But I became fascinated with the idea of sending messages to the past and considering that instead of having paradoxes, the universe would split and start a new timeline.
This story had a slow start and and found it hard to get into and understand the storyline, but once I did I was hooked!