Thread:Ghelæ/@comment-29927902-20161001081010/@comment-47205-20161001110249

A "navigational deflector" is simply a weak shield use to protect a shield from the hazards of space travel, e.g. cosmic rays and dust when travelling at relativistic speeds. As for the other shields, they come into two categories: what they're made of and "phase".

What they're made of: plasma shields are made of a bubble of plasma, while metric shields involve engineering the metric of spacetime. The former are standard sci-fi shields and work partly due to the viscosity of plasma dissipating the energy of incoming projectiles, partly due to free electrons and ions interacting with coherent laser light, but mostly via handwaving. The the latter are essentially walling something off in its own pocket universe (although "nightshades", which might not be geometrically possible, are more like one-way mirrors such that objects can leave but not enter). "Energy" shields are synonymous with plasma shields: energy isn't a substance, so talking about something "made of energy" is nonsensical; people usually mean "glowy stuff" when they say "energy", so plasma vaguely fits.

"Phase": technobabble taken from Star Trek. Regular shields, which we thus call "phasic", have a time-varying phase which means that you can bypass them by modulating your weapons (either beams or the shields of missiles) to match. Multiphasic shields are probably then a superposition of phases such that no single modulation will work against them. Non-phasic shields do away with the silly concept entirely and practically function as a solid sphere of plasma.