Relativistic time dilation and your pay rate

[Junghalli]

Question: does the society in question have bio-immortality?

Because that's going to matter a lot, not so much for the OP question itself but for the attendant issues that have been brought up. People will be more likely to willingly go on decades or centuries long journeys if they know the people they know will still be there when they come back (albeit they may have changed so much as to be effectively strangers), not to mention bio-immortality would probably slow down the pace of cultural change and make the transition to future-world much less disorienting.

Realistically people who could build ships like that (if they're military ships it'd almost certainly have to be a Bussard scramjet) should almost certainly have it, but you know how schizophrenic a lot of sci fi is about these sorts of things.

Another thing to consider is a civilization this advanced may well have basically invented everything there is to be invented, which will reduce the "your skills are useless when you return" problem. Of course, such a civilization would probably be effectively postscarcity, and wouldn't need a crew for its warships except maybe some humans there to tell the ship's AI what they want it to do (and that would be essentially unnecessary too).

[Gil Hamilton]

Finding enough volunteers is unlikely. This is the perfect service to employ old-style press-ganging for; they sure as hell can't leave in transit and when you get back to port and everything has changed, what are the crewmen to do? If they desert, you've basically left them with no useful skills in a futuristic world. They'd be forced to stay for another tour, and another, and another...

You've actually just made a good summary of the book "The Forever War" that's been mentioned in this thread. Every tour of duty Mandela ends up in makes it further unlikely for him to ever leave the military, because over the course of 1100 real years that he's in, Earth becomes completely alien to him. The only reason he gets out in the end was that the war had officially ended some time before the last battle that his unit fought in, something that they didn't know until they returned to Earth.

[Patrick Degan]

Also, the Earth depicted in Haldeman's book had quite neatly made it impossible for any military veteran to secure gainful employment by setting the bar high on experience, which anybody who's been in service won't have. So their options consequently become rather limited. No press-ganging is required.

[Simon_Jester]

Still a dangerous game to play; embittered veterans in relativistic starships have many ways to get troublesome.

[Straha]

The answer is simple:

Pay them a reduced wage based on Earth time.

For instance: if the going wage rate for orbital freighters is $100,000 per annum, pay the Einstein crew $33,000 per annum. This way when the Einstein crew get back they've got over six years pay for three years work AND they'll have accrued not-inconsiderable compound interest on the amount while gone. Makes sure the crew is well compensated and that the accounting is easy, best of both worlds.