The Forever War by Joe Haldeman

Cool little sci-fi novel. Bit of a classic, I suppose. Haldeman, who clearly served in Vietnam, writes the first half of his soldier’s story with a real ear for grunt dialog. Things get a bit steamy as he fantasizes about a free-love co-ed army. Then, once we delve into the meat of the tale, which addresses the social implications of faster-than-light travel, things start to get really interesting.

Our protagonist goes on several missions, one of which strands him in a galactic backwater. When he returns from each of these missions, some really significant periods of time have passed for Earth. The social and inter-personal revelations which unfold are fascinating and occasionally touching. Dan Simmons had clearly read Haldeman’s novel when writing a few of the tales in Hyperion.