The Forever War/Headscratchers

• The novel was written in 1974. The first chapter takes place in 1997. In that slim, 23-year stretch, humans have developed spacecraft that can accelerate to 99.9% of light speed and now routinely make journeys to collapsars a light-year or more away from Earth, to the point where they've encountered an alien species and have gone to war with it. In Real Life, we don't even have feasible designs on the drawing board today for spaceships that can go more than a few percent of the speed of light before running out of fuel, and no spacecraft that's actually been built has a delta-v budget anywhere near that high. Surely, Haldeman should have been able to tell that his timetable was a bit ... overly optimistic?

• The Tachyon Drive allows a starship to accelerate continuously, at several g, without ever running out of fuel. Since acceleration implies kinetic energy, and lots of it, this further implies access to an almost unlimited source of energy. Such an energy source should easily be able to power human civilization many times over, resulting in an unprecedented age of prosperity. Yet by 2007 Earth has become a Crapsack World where nearly everyone is a hair's breadth away from abject poverty. Even with the best and brightest turned into cannon fodder by the Elite Conscription Act, shouldn't the existence of unlimited energy more than make up for it?