A star destroyer can level a planet by itself, Blue shadow virus is deadliest weapon actually (kills any organic life form) There are other super weapons. Death star OBLITERATES planets (other than an object 66% the density of the planet crashing into it, a star, or a black hole, NOTHING ELSE aside from the force, can do that in star wars universe!) Destroy a planet big deal huh? THE 18 HALO RINGS only obliterate nervous systems of every un shielded organic human life form in 1 galaxy with sub atomic radiation that in quantum physics DOESNT ACTUALLY WORK. So even that DOES NOT break down or cause a reaction as severe as the death star super laser when it hits a planet. (100,000x one TRILLION human beings worth of nervous systems DOESNT even equal the mass of MARS (1/3 the size of earth 1/3 to 1/5 the mass of earth) DO SOME MATH.

Actually the halo rings obliterates all sentient life down to the atomic level. It doesn't attack the nervous system only. It simply reduces humans and every other form of sentient life into gas and dust. So yea......I think that if, you take every single sentient being in the galaxy, they would weight a lot more than Mars and probably more than any terrestrial planet. And those shields are specifically made around certain outposts to keep the effects of the halo out I border to re-seed the Galaxy. So just any old shield won't do. It has to be made with the technology of halo on mind.