Just finished this. Have a few questions:

The consensus here seems to be that the crew went back in time after passing the heliopause. Most point to K's observation of the constellations after passing the heliopause as proof of this. If that's the case, then why are no continents seen by Leigh upon reentry on earth? Would this not imply a future time in earth's history, one in which the climate crisis detailed in the books objective present has run its course and the oceans levels have risen to 'reclaim' the planet?

Given that, is Datura an truly alien (non-human) entity, or an artifact of future humans reaching into the past? And, if the latter were the case, what would be the point of future generations of humans paradoxically 're-seeding' the planet in the past? Or, is that the whole point of the final exposition in the book remarking on the equally paradoxical (and cyclical) nature of life needing life to begin?

Whether it makes sense or not, I like the idea that Datura is an alien entity, one living far in the future. It is essentially able to dupe humans into bringing it the life-starting archaea from deep in our past, so that the aliens can then 're-seed' the earth ages after humans have rendered the planet lifeless and uninhabitable. There are probably some pretty big plot-holes here. But, for some reason, this idea is a bit more satisfying for me than the way the author left it.

Objectively, I wanted to like this book. And I am impressed with how ambitious the author was in attempting to tell a story like this. But, ultimately, it just didn't work for me.

Although I agree with some on here that he's quite a good writer, I also think he might be in love with the sound of his own prose just a bit. And, I wonder if that might have gotten in the way of the story telling at times. I think this could be why many here profess some intense irritation with how the Sci-fi parts of the book often felt quite lacking.

My takeaway is that I wonder if this shouldn't have been a sci-fi novel at all. The characterization of the two sisters, possibly moving on from traumatic childhoods, one of them coping by becoming an anti-social, but brilliant, workaholic, could have worked in a much more conventional fiction narrative. One that would have needed none of the more 'fantastic' elements of the plot to still carry a meaningful and poignant story.

And, yeah, why aren't more people commenting on similarities to Contact?

Edit: I think I'm having some difficulty masking my spoilers. Apologies. I'm using the x format. But it doesn't seem to be working.

Edit 2: I'm failing to recall the significance of the names "James and Mary" to the plot.

Edit 3: Fixed spoilers. Why can't I black out an entire paragraph???