The life as we know it is a billion year old phenomenon. It started with the simplest to the complicated/conscious life forms that we see today (including humans).
However, the life came a lot late when the universe came into existence as we know it today with a bang. Happenstance of Big bang is a scientifically established point. While we definitely can't say what was before that, there are hypothesis about how the expansion which started with big bang is going to end.
The thing with hypothesis is that this gives the scientific freedom to critically build a theory and bring the proof if possible, mathematically or otherwise. The book describes the five major hypothesis/scenarios how the universe is going to end. None of them are very pleasant to hear but the universe doesn't care much about pleasantries. It is such a human trait to expect everything to behave in a way which is inline with what we understand as humans even the emotions that are very specific to us.
When the universe will end (less likely the Earth will survive that long) in a really long time, it is expected to go back to what it was before big bang, an unimaginably high density (not the material density as we know it) but with a hope that it will expand again (human psyche of pulsation or cycle which may or may not imply in case we don't remember that the universe don't behave in human terms and on hopes).
Definitely a good read to philosophize about how everything came into existence and how it is going to end. But end of universe is not the end of it, it is just the end of how we know it now. It will exist in a form that a human mind can't imagine right now or may not be able to for a very long time in the future.
Peace