Using these:
Mass Hydrogen Atom (1): 1.674×10^−27kg
Density of Cold Neutral Medium: 35 atom/cm³ = 35,000,000 atom/m³
Front Spacecraft Profile: 100m²
Volume Transited/Second: 299,792,458,000*100 = 29,979,245,800,000m³
You receive 1.04927x10^21 hydrogen atoms per second. Or, 0.0000017565kg/s. 0.15176kg/day. 55.3925kg/year. Not exactly substantial. I could work out how much power that'd produce you with the CNO Cycle, but I'd rather not and just say it'd be very little.
[...]
The only places where hydrogen is much denser than in Cold Neutral Medium is in Molecular Clouds or H II regions--in other words, in nebulas, which do not comprise the majority of space. The majority of space is also not CNM. So the figure I just quoted you is probably optimistic.
[...]
Or I can use real physics to prove why they're bad. It's called inertia. The particles are effectively at rest relative to space. The kinetic energy of the particles along the way assumes they are moving at the velocity of the ship--if we use the ship as our frame of reference, then the particles are moving at that velocity relative to it (in the negative direction). If they enter some field of effect and are dragged along by it then their velocity vectors must be changed, and they must be accelerated in the positive direction such that their velocity relative to the ship becomes zero. Transiting from 1000c to zero velocity in any reasonable time for an uncontrolled object like a particle is impossible. They will enter such a field and tear a ship to pieces long before coming to rest relative to it.
Again you're dealing with more energy every 22 seconds than the human race produces annually. I don't care what magic voodoo Stigma physics relies upon--the initial energy allotment is achievable by humans, and therefore cannot conceivably stop something that is totally beyond their grasp. The dialogue basically goes:
Hydrogen: I'm the Juggernaut, . .. .. .. .. .!
Humans: ... damn.
Stigma mechanics as described effectively don't make sense.