So I have this superweapon. He's a powerful lifeform made to devour other races so this one race can colonize their worlds. He's given a near unrelenting hunger as persuasion to do so. The problem is that he'd need to be able to fuel himself using various types of lifeforms of all sorts of elements, but

He can't just eat random stuff like the planets themselves... (Can eat silicon based lifeforms but not regular rocks) He can't convert matter into energy, only store loads of energy from food and use stored energy to fuel his powers (super strength and speed, electrical shocks, energy blasts) and create more mass when needed or regenerate (it is my understanding that it takes tons of energy to create a small amount of matter).

Would he really have to eat tons of food? Is there any loophole to energy-matter conversion/conservation of mass? Anything theoretical even? Extradimensional? How could I make this work?

Honestly I don't know if anyone can figure out what I'm trying to communicate here I barely can.

  • 2
    $\begingroup$ Your question seems a bit unclear. Eating food > energy storage > fueling (super)powers IS matter~energy conversion. It's just that we don't destroy the matter we eat. We convert matter/energy into energy + matter. What is the actual problem you're trying to solve? Can he not just eat & crap like everyone else? $\endgroup$
    – elemtilas
    Commented Apr 18, 2020 at 20:53
  • $\begingroup$ I'm not sure I get the mechanics of this question. How hard an answer are you looking for? I'd go feeding off psychic energy, maybe generated by the suffering of sentient life forms. I can't tell if this is an answer or not. $\endgroup$
    – DWKraus
    Commented Apr 18, 2020 at 21:25
  • 1
    $\begingroup$ If he was big enough, he could store a black hole bomb in his chest or something, like Galactus + overpowered battery. Just an idea. $\endgroup$
    – user75058
    Commented Apr 18, 2020 at 22:43

2 Answers 2


Other races are very nourishing.

Your super weapon is "made to devour other races". I take devour to mean eating them. There is a lot of food energy in other races, whom themselves have reproduced to their status of race by eating food and accumulating it in their own biomass.

Your super weapon devours them. That is its purpose. They may or may not be tasty, but there is probably food value in the biological races and when it devours these entire other races it has access to a lot of caloric energy. These races may themselves have laid away stores of food for themselves; for variety your super weapon can eat the foods of other races also unless its masters want it to save that for them. Races may have also accumulated knowledge about seasonings and spices as well as preparation techniques; your super weapon might capture some individuals and learn their secrets, then apply that knowledge while carrying out its main purpose.

It occurs to me that if this goes well, your super weapon might not devour individuals of other races who prove skilled in techniques of preparation and seasoning, but instead bring these individuals with to the next world whose races it will devour. Your superweapon might accumulate a coterie of chefs, some of whom are the sole survivors of their races.


How Much Power Can You Harvest?

The human body contains an average of 137,000 kcal of energy which be converted to 57,320,800 joules. Multiplied by the ~7.6 billion people on Earth, that is ~1.041e15 kcal which if all released at once would result in a one gigaton explosion. (20 times bigger the the biggest nuke ever tested.)

What About Non-human energy?

Humans are only about 0.001% of the world's biomass (give or take an order of magnitude since estimated figures on this vary wildly). This means if your weapon were to consume all biomass on an Earth like planet it would have a potential energy of about 10 Teratons.

What if it can also consume fossil fuels?

Fossil fuels are also an organic(ish) source of energy; so, maybe your weapon can consume this as well. Current estimates of the world's remaining fossil fuels are as follows:

  • 1.730e12 barrels of crude oil @ 6.118e9 joules per barrel totaling about 1.058e22 joules.
  • 1.1e12 tonnes of coal @ 2.931e10 joules per tonne totaling about 3.224e22 joules.
  • 6.923e15 cu.ft. of Natural gas @ 1.055e6 joules per cu.ft. totaling about 7.304e21 joules.

This totals out to about 5.012e22 joules or about 12 additional Teratons of potential energy yielding a total energy of 22 Teratons or about 1/4 of the energy releasesed by the Chicxulub impactor.

Storing that much power

The most efficient way to store power in any sort of science based way is antimatter. One gram of antimatter reacting with one gram of ordinary matter results in 43 kilotons-equivalent of energy; so, storing the entire bio-chemical energy of an Earth like planet would require just over 1/2 a million kilograms of antimatter.

While that is a lot of mass, since your monster has superhuman strength you can work around this by compressing your antimatter into a super dense ball. Matter and antimatter are both mostly just empty space. If you were to collapse this fuel down to the density of a neutron star, it could be contained in a space just over one cubic millimeter.

Consuming that much power

A single person only contains about as much power as a 1/2 gallon of gasoline. Weighing in as much as a WWII destroyer, your monster would have to spend more calories walking from one victim to the next than it would get from each meal. To offset this, I would couple your monster with some sort of grey goo feeding system where it sends out a swarm of self replicating servitors that scower the planet of all life bringing the spoils back to the super dense monster that stores all the antimatter to power and control things.


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