I'm trying to find this book I remember partially reading about 15-20 years ago. I believe it alternated sci-fi stories with short essays/postscripts that went into whether the story's details were possible in the real world/universe. I don't know if the stories were by one author, or a variety of authors. The parts I remember were about space travel/colonization, but I don't know if all the stories focused on that.
The two plot details I remember:
One story was about someone travelling on a spaceship where people were being preserved in "pods." He/she woke up for some reason, then died when a backup pod failed.
The other story was about people traveling to a space colony - they were traveling for a long time and had to wait until a certain age before reproducing, but a married couple in the story was hoping they could have kids right away if they got to the colony soon.
More book details: I think I read it in the late 1990s or early 2000s, but the book itself was likely older. I'm pretty sure it was a hardcover. I got it from my hometown library (I have emailed them too to see if they might be able to find it). Definitely meant for an adult audience (not a kids' book). I've looked at some Asimov books recently and I don't think this one was by him (his writing "voice" didn't ring a bell for me).