Joe Haldeman and The Forever War
For a bit of background, Haldeman got a BS in physics and astronomy before he was drafted into the military. He served as a combat engineer in Vietnam (1967-9), where he was severely wounded, earning a Purple Heart. Later on 1975, he got an MFA. The range of degrees was an early demonstration of the complexity of his interest in science and art, and hard SF with which he's generally identified. His experiences in Vietnam have marked many of the books he's written as well.
In The Forever War interstellar travel is effected by collapsar jumps, which basically means the futuristic marines fly their ships into wormholes for space travel. The troopers are sent off on many engagements to fight their alien foes, and after a while they get to return to earth. By doing these wormhole jumps the troops experience little to no aging, but once they get back to earth, many years have passed, and they find it hard to adjust to the many changes. They experience alienation from the civilization for which they are fighting. Different things within our culture have changed. One of the things about the story I found fascinating is those return trips, and how the world has changed. I certainly won't spoil it here.
Tonight while looking around on the web I ran across this page written by Haldeman on his brother who had died a few years back from cancer. I found it very poignant in how he eulogized his brother, and it also gives a bit of background how they both got into writing, how and where they both grew up when they were younger, and how they both developed an interest in the SF genre. It's certainly worth a read for those interested. Check it out here.