In the Mass Effect universe, there used to be limited need for ammo, since it was explained that each weapon used a large block of metal from which it would actively 'shave' off tiny pieces to use as bullets. Then, in the second Mass Effect video game, apparently guns got more powerful and therefore generated more heat. So they added the ability to replace heat sinks to keep firing the gun. Each heat sink had a limited number of shots before it expired.

The 'shaved' bullet is fired by using eezo (electrical current, positive or negative, can change the mass of an object) to reduce its mass so it can be easily accelerated to a high speed.

Since a weapon has to actively make its own bullets, charge the eezo chemical to reduce bullet mass, and propel the bullet, it is generating so much heat that the newer weapons need heat sink replacements regularly during combat (heat sinks were limited to maybe 20 or 30 shots per sink).

What is generating all of this power? Modern day weapons use explosives. But in the Mass Effect world that wouldn't be able to account for all that the weapons are supposed to do. How are these handheld weapons powered?

  • 5
    in fictional universes fictional powersources exist. Think "micropiles", miniature nuclear fusion (or sometimes fission) reactors not much larger than present day AA batteries which exist in Asimov's Foundation universe. In your case, the author probably never even considered the powersource, or he'd have mentioned it. As to replacing heatsinks: this is not fictional. Old watercooled machine guns needed to have their coolant replaced regularly or they'd overheat (and even newer ones regularly need replacement barrels and cooling shrouds because the heat makes the metal brittle) :)
    – jwenting
    Commented Oct 24, 2011 at 6:42
  • They're powered by magic smoke! secure.wikimedia.org/wikipedia/en/wiki/Magic_smoke
    – eidylon
    Commented Oct 24, 2011 at 19:36
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    According to the Mass Effect wikia (I can't get to it at work to get the link) the heat sink cartridges were a Geth invention, copied by most Council space weapons manufacturers, designed to allow a trained military person to more quickly overcome weapon heat. In the first Mass Effect if your weapon overheated then you'd have to wait 1-3 seconds for it to cool off before you could fire again. In Mass Effect 2 with the thermal clips you can "reload" in under a second and continue firing.
    – Xantec
    Commented Oct 24, 2011 at 19:45

7 Answers 7


Weaponry (and almost everything else) in Mass Effect is only possible through the use of Mass Effect fields. The simple explanation is that Element Zero + electricity = mass change, but this isn't quite the whole story. Element Zero, when subjected to an electrical field, produces Dark Energy, which can be used to (among other things) create Mass Effect fields.

In the Mass Effect 2 DLC "Arrival", the mysterious object Rho contained massive amounts of Dark Energy, and the scientists working on it guessed that all of its energy came directly from it. This implies that dark energy is capable of energy generation, but also implies that nobody knew how to do it directly. Given the energy generation capabilities of a mass effect field alone, however, I would be surprised if nobody had figured out a way of generating power using either dark energy or some product of it, though as the scientists in Arrival were flummoxed by Rho it would presumably need some external stimulus still.

I don't believe there are any canonical sources on tiny power generators in the otherwise expansive lore, but as most of the large departures from actual science tended to be explained away using some combination of "Eezo" and "Mass Effect field" I would be quite surprised if small scale power generation was not also solved via this method, especially given that they are clearly capable of it otherwise.

  • It is clearly stated that electrical current is required to be applied to eezo to have it be effective (with the exception of it passively adding biotic powers to organics sometimes). So it clearly needs a traditional power source. And if top minds are confused by dark energy, then it wouldn't make sense for that to be used in common devices like weapons for years even before the discovery of the dark energy.
    – Mufasa
    Commented Mar 7, 2013 at 13:43
  • @Mufasa: As things like lightspeed or FTL travel are possible using mass effect fields, it holds to reason it would not be absurd to build a system that used eezo to generate more energy than it took in.
    – Phoshi
    Commented Mar 7, 2013 at 17:11
  • Eezo doesn't generate energy itself. It requires electrical energy being applied to it to make the eezo have an effect on gravity. Effecting gravity is not the same as generating electrical energy. Eezo isn't a fuel or engine. Think a fluorescent light; supply electrical energy and they run forever--or until the contacts and filaments burn out; but the fluorescent gas in not burned up. Similar to how eezo is not burned up as fuel.
    – Mufasa
    Commented Mar 7, 2013 at 22:57
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    Yes, but fluorescent gas does not enable you to change the mass of objects. Eezo itself does not generate electricity, but I see little reason why you couldn't use ME fields to create a vastly more efficient generator. If it was completely unable to "create" energy in any sense, then it would be impossible to propel a craft to lightspeed, something which requires infinite energy for massive objects.
    – Phoshi
    Commented Mar 7, 2013 at 23:43

I'd have to agree with @jwenting and add a little more. The weapons probably use some form of on-board power like a miniature fission.

I'm tempted to say that the metal block that provides the ammo could also be used as a form of power. Perhaps the metal itself contains some element which could provide the power itself, or be used in some on-board power generation. It could also be that the metal block is actually composed of nano-structures which can provide both energy and ammunition.

As an aside, you might be interested in the guns from Old Mans War, where the weapons use a block of nanites which can assemble themselves into different form of ammunition (grenade, different bullets, etc.). Again, I'm not positive about the energy source, but I believe that the nanites provided it as well.


I thought the projectile weapons had something of a mini mass-effect field that propelled the bullets and the heat-sink catridges were there to keep the weapons cool.


They would need to be powered by some form of super-capacitor. The problem is that so much energy would be stored within the capacitor that it could double as a bomb and would explode if shot through by another gun.


I've always assumed that everything was powered by fusion reactors, its the only energy source directly mentioned in cannon. They use Helium-3, Deuterium reactors for space travel. In the back of my head I was assuming they were using different fusion cycles for other functions.

Given the fact that Eezo seems to give larger results than the energy provided (A biotic lifting a Krogan off the ground with the bio-electric energy generated from their nervous system). I figure they make fusion batteries, fuse helium-4 into Beryllium-8 with a maintained micro singularity, Beryllium-8 almost instantly decays into two alpha particles (Helium-4) allowing the cycle to begin again.

It would take an initial source to begin the reaction but after that, the battery should be able to power its own singularity.

You could even say that it doesn't work scaled up because a bigger singularity would allow a full Triple-alpha fusion reaction. turning your Beryllium-8 and Helium-4 into Carbon-12 (not a gas) gumming up the reactor core.

I hope some of that makes sense, even if it breaks physics as much as Eezo does.


Straight from the Mass Effect Codex:

Modern infantry weapons are micro-scaled mass accelerators, using mass-reducing fields and magnetic force to propel miniature slugs to lethal speeds.

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    We understand the use mass effect fields to accelerate the slugs. The question is how are those micro-scaled mass accelerators powered? The "mass effect" does not generate its own power--it needs power to achieve the mass effect.
    – Mufasa
    Commented Mar 11, 2013 at 0:12

The only solution I came up with is that weapons in Mass Effect are charged by the combat suits. The weapons don't need to have their own power generator, it takes the form of a powerful nanotech battery.

Then the question becomes: "What is powering the suit?"

  • Interesting. Do you have a source reference?
    – Mufasa
    Commented Jun 2, 2013 at 13:18

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