Personally, I'd move nanotech to the information age. We're already getting close to getting true nanotechnology, as we already have some of the basics down.
The "Space Age" was technically the time of the space race, as the greatest pioneering of space technologies occured there. And one small impracitality of railguns for infantry is the sheer kickback will rip off their own limbs. (the US military is now working on destroyers with railguns.)
And for the ages, I recommend:
The Information Age, The Nanotech Era, The Empires Period, The Quantum Age
Information age is based on the assumption that it starts at the 70s, and the Internet is like an early wonder. Then it advances to fission power, followed by miniaturization and early robotics, then early genetic engineering, fusion power, and kinetic weapons, and it ends with proto-Nanotechnology.
Nano-tech era begins with Nano factories, 293K Superconductors, and advanced hydroponics, moving onto advanced robotics, true AI, orbital colonies and orbital everything pretty much, and next early laser weapons, genetic enhancement, proto biogenesis, and it ends with sub-atomic manufacturing, simple weather control, and early thought controls (sort of like thinking of doing things, and they happen).
Empires Period starts off with true energy weapons, quantum computers, proto-physics manipulation, and large scale asteroid mining. Next it advances towards molecular armor and combat power armor. Then advanced combat mechs, early energy shielding, and teleportation. The period ends with orbital energy cannons (basically the ICBM equivalents. Nukes earlier will be more like cruise missiles).
The Quantum Era starts with artificial gravity modifiers, quantum manipulation, and FTL travel. Next comes quantum reactive armor, true invisibility, and singularity shields (equal to the SDI missile defense). And finally, it ends with picotechnology (sort of like comparing 20th century technology to 2nd century technology).