An energy being or astral being is a theoretical life form that is composed of energy rather than matter.

We can kill a person by damaging his/her body physically. How about killing an energy being? You can't use a knife to stab an energy being. (Other physical attacks also don't work.)

I want to have a battle scene in my story. I watched some Japanese animations that involve energy beings, such as Fate/zero. I saw some energy beings using weapon to battle, and those energy beings act like matter being. They die when their bodies are heavily damaged. Also, those energy beings can hold physical objects. I don't know what the rationale is behind this.

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    I'm pretty sure there is no rationale behind this :-) – PatJ Jul 11 '16 at 13:20
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    Only "energy" we are aware of that is not tied to matter are photons. And photons can be disrupted in all kinds of ways. – Euphoric Jul 11 '16 at 13:21
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    What's an "energy-being" made of? Photos? Electricity? plasma? warped spacetime? electromagnetic fields? just saying "energy" is like saying that it's made of "tightness, like the tightness in a tightly coiled spring" the kind of energy makes a big difference to what would make sense to work. – Murphy Jul 11 '16 at 15:15
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    matter is energy – Keltari Jul 11 '16 at 15:22
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    Make it have children. That will sap the energy right out of it. – Excellll Jul 11 '16 at 21:25

19 Answers 19

up vote 20 down vote accepted

Use a knife to stab the energy being.

Physical weaponry works against material beings by disrupting the body. A priori, there is no reason why energy beings should be immune.

Do walls pose an obstacle to your energy beings? Does the ground support them? If you answered yes, then your energy beings ought to be vulnerable to physical weaponry as well, since they work on the same principles.

Commonly, the "immunity" to physical weaponry that exotic beings enjoy is simply due to a lack of optimization. The weapons you use to kill a human are designed to cause the sort of damage that impairs humans.

E.g. a stab by kitchen knife can puncture organs and cut blood vessels, leading to organ failure or bleeding out. However, stabbing a water elemental doesn't sever anything important and does little. Slashing with a larger knife, though, could separate a limb from the main body, and thus rendering it inert as it no longer has the currents that carry the magic animating the elemental. The cutting board the knives were lying on might make for an even better slashing weapon.

OTOH the reverse can be true as well, where the physical being is the one with 'immunity'. Whacking a human with an antenna probably wouldn't do much more than cause pain and make them angry. But it could cause critical damage to that lightning elemental by forcing its way into the circuitry of its body and siphoning off some of the electric current.

Since it's your universe, you get to design the biology of your beings so that they are vulnerable to the things you need them to be vulnerable to, and resistant to the things you need them to be resistant to.

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    Although it seems to start off naïvely, it doesn't end that way. +1 for "use a knife". – wizzwizz4 Jul 12 '16 at 16:10
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    "Do walls pose an obstacle to your energy beings? Does the ground support them?" << It seems ... more problem arise if I have energy beings in my story. I think I better don't use the idea of energy beings. LOL – fairytale Jul 12 '16 at 21:38
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    Did you just bring an elemental to a knife fight? – Wayne Werner Jul 13 '16 at 12:41

You can:

  • Absorb its energy;
  • Cut it off from its source, thus causing it to starve;
  • Use energy weapons to destroy its energy body.

Energy cannot be destroyed, it can only be transformed... Just like matter can't be destroyed, it can only be transformed as well. When you hack a physical being's body, you are just rearranging its matter in a way that does not sustain life. The same should be valid for the energy of energy beings.

  • No need to exclude nuclear reactions; even in those cases matter is simply transformed to other matter and energy, never destroyed. – Annonymus Jul 11 '16 at 14:54
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    @Annonymus I think Renan is tugging at the fact that, in a nuclear explosion, some of the matter is converted directly into energy, which makes it a violation of the simplified phrasing, "... matter cant be destroyed, it can only be transformed." – Cort Ammon Jul 11 '16 at 14:59
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    @Annonymus I think that is why modern physicists have stopped using energy/matter in "conservation sentences" and instead use mass, since mass covers energy and matter. – Jake Jul 11 '16 at 15:06
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    You could also convert that energy into matter. Converting an energy being into a coffee table would probably be pretty effective, and nets you a nice little trophy to boot. – Ellesedil Jul 12 '16 at 0:03
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    Instead of killing it you could trap it forever (or until it escapes in the sequel) in some sort of magnetic field, depending on what kind of energy it is. – Jason C Jul 12 '16 at 6:40

From a physics point of view, life is about lowering your own entropy by transferring it outside your body.

Now, I don't know how your energy being exactly works, but you can either try to starve it or overfeed it.

  • Starve it: Find a way to perfectly isolate it. A strong electromagnetic field or a black hole should do the trick. The being's entropy will rise and it won't be able to expel it.
  • Overfeed it: Put a lot of energy around it. I suggest a hydrogen bomb or heavy metal music. The being won't be able to control its entropy and burn.
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    I laughed at metal music being used to destroy an energy being XD but anyway you have my +1. – Renan Jul 11 '16 at 13:36
  • Thanks! After all, no mention is made about the energy levels in place :-) – PatJ Jul 11 '16 at 20:36
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    Good... but you made a small mistake. Techincally, from a physics point of view, life is 42. – wizzwizz4 Jul 12 '16 at 16:02

Continuing with the general concept introduced by Renan, you need weapons that operate on the same kind of “energy” as the being. It is made from patterns and has a state determined by dynamic interactions, since energy isn't stuff you can build with.

So you use the same kind of energy, disrupt or jam the patterns, or something that interacts with that energy so it can dampen it or prevent the patterns from perpetuating themselves.

One such thing made of the same energy working in the same manner would of course be another such being. So a trained attack dog (analog) or a nest of angry beetles (analog) or a disease would be good. You didn’t think there was only one energy being, right? It’s part of an ecosystem.

The advantage of using another energy animal is that you don't have to understand the energy and invent something. Just find what exists already.

There's a question here of whether you're trying to kill a single being or commit genocide. I'm going to assume the former.

As has already been mentioned, energy is conserved, however energy can be converted into another form. In this case, sound.

First you need a way of containing your being, forcefields of some sort are fine as they'll be self generating for the duration.

Once you have captured and contained your being, an exercise left to the reader, simply shove a terminal through him, plug in your sound system and the power controller for your force fields and you're good to party all night long.

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    I KNEW heavy metal could help! – PatJ Jul 11 '16 at 13:57

What you need is an empty battery. Lots and lots of empty batteries.

Attach some 'clamps' to said energy being and charge up your batteries. Leaving your energy-being depleted and defeated.

Such clamps can be in the form of conducting rods (swords), cables/ nets (whips or nets), oh and resistors (Shields).

Don't forget to surround your defensive position with a 'circle of salt' water. Energy-beings hate salt water. This should prevent surprise attacks from behind. Never ever break the circle! (Edit, sorry this should be pure water -Less conductive than salt water.let's make it holy water)

Don't try and plug your energy-being into the national grid in an effort to drain his power. He will simply 'reverse the current' and become the biggest 'big-bad' you have ever seen.

Once energy-being is in batteries. Ensure no one uses them. This would release small portions of his soul back into the world. Keep all batteries as far away from one another as possible. Bury them in salt water! Like I said, energy-beings hate salt water. (edit, this should be a fresh water lake or maybe a glacial lake).

Oh and forget about chainmail and guantlets. What you want is thick rubber gloves, rubber soled shoes and protective goggles. Maybe a rubber poncho. To ensure that your 'sword' is not hampered by you holding it with a rubber glove, have the 'hilt' covered in black insulation tape instead of leather strips and/or jewels.

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    Why batteries? Just hook it up to a resistor (-> anything that consumes power, perhaps even the railgun that your army is using against the opponent) and it will be destroyed, rather than stored. This also solves the problem of "releasing the energy in the batteries releases the being", if that is assumed possible. – Annonymus Jul 11 '16 at 14:59
  • Good point but if it is a particularly intelligent energy-being, surely it would be able to figure out how to transfer from one form of energy to another? Anything that consumes energy has to release some sort of energy. I have the strangest feeling that energy cannot be created nor destroyed...but it can be stored! :) – EveryBitHelps Jul 11 '16 at 15:16
  • You are thinking energy = electricity? But we know electricity doesn't make beings. – JDługosz Jul 11 '16 at 22:49
  • Um. 'energy-beings and astral bodies' the OP even quotes that they only theoretical life forms. I think the field is wide open on what you can imagine an Energy-being to be made of. – EveryBitHelps Jul 12 '16 at 6:58

Since energy by itself isn't sufficient to create a being, you need to look at what is happening to the energy to make to function. Is it a manipulation of space-time in order to hold photons in place via gravity? Is it some sort of standing wave or wave pattern? Is it actually something else which is being described as an energy being (i.e. a dense plasma being at the core of a star?)

Once you identify the "how" the energy being is being held together and operating, then you will know and understand what sorts of countermeasures will be needed. A creature which manifests as a warping of space-time is not going to be affected by something which can disrupt a pattern of standing waves, for example.

On the other hand, outside of the technical aspects, which depend on the nature of the being, the overall rule is to somehow increase the entropy in the region of the energy being, in order to change the energy from an ordered and organized pattern to a random and disorganized pattern. For most sorts of energy or sort of energy beings (like the plasma creature inside a star), a sudden massive introduction of energy via a bomb or laser may do the trick. This is especially useful if the energy being requires some sort of medium for a standing wave pattern to propagate, but with sufficient energy (i.e. a matter-antimatter device) then it could be possible to disrupt space-time in the region that the being is instantiated for a very brief period.


Depends on how ‘hard science’ you want to be. There cannot be an ‘energy creature’ in real physics. ‘Energy’, treated as an object is simply a bastardization of mass/energy conservation by the general public and New Age woo. You can not simply have Energy; to make energy into an object is to store in the form of some mass, say petroleum.

So when you say convert mass into energy, it isn’t turning into another ‘object’, it is being turned into massless particles (photons). That massless photon exists only as long as it takes to interact with a particle with mass, a detector, your eye, or Russell’s teapot, at which point it might turned into another photon, or matter (binding other molecules and atom, like a plant making sugar).

If an energy create were to exist, it would have to be able to localise itself well enough to be a threat. Which in turn would have to mean it would have to redirect its energy sometimes. Which would require a physical medium or at least mass. Which then would mean it is not an energy creature anymore or could not exist outside say the horizon of a blackhole.

If you want to bend the laws of physics for a good story...

Heat Death

If the create can exist for some reason, one way to defeat it would to be expose it the vacuum of space where its photons could not be stopped. They would whiz away at the speed of light into the infinite beyond. It would become so cold/diffuse that it would not be a threat.

Blackbody Device

For a more technobable solution, perhaps it could be defeated by a (another scientifically inaccurate) Blackbody Device. Here they can Ghostbuster the creature into a prison where its energy cannot escape. How to get it in the prison would need some hand-waving too.


Another would be the good old, black hole as others have described, though a little cliche.

Photons operate within space-time field that is affected by gravity. Any gravity weapon would affect the creature as well as creatures with mass. Perhaps a gravity weapon would create a micro-black hole that consumes the creature's photons which would immediately evaporate and the creature suffers damage.

Remember it is your monster, it may come into existence by some strange physics and can be defeated by as such.

Sentience is really just a dynamic thinking configuration of stuff. The configuration is intricate enough to observe, problem solve, and perceive the self. Any being, matter or energy, may be killed if this configuration is disrupted.

Since your question is pretty open-ended regarding exactly what "type" of energy composing your being, I'm going to let my imagination run wild.

You may

  • Use gravity. Suck it down a black hole or just disrupt it with a gravitational field massive/dense enough to disrupt it. Heck get creative and throw a black hole at it, or maybe a graviton beam?
  • Magnets or electric fields may play hell with it, especially if it's plasma.
  • Concussive force may work as well. Shockwaves will cause major disruptions in whatever medium it resides. May kill it depending on how you wish to handle the exposition.
  • Trap it in a particle accelerator
  • If it exists as a living electric field then could your characters kill it with a compressing faraday cage? As the container compresses the creature may start to feel 'pressure', heat up, and die. I don't know how scientifically accurate that would be, but I've never seen in happen in fiction. On that note...
  • Extreme heat? Entropy may cause the necessary disruptions to kill it
  • Are you in space? Lure it into an ion-storm, or throw an ion storm at it.
  • Is it a star? The sentient star from Dr. Who seemed pretty mad when part of it was siphoned off by that mining ship. That certainly caused it a lot of pain.
  • Maybe it's fantasy dark energy? In which case, pull the 'ol power of friendship, hope, or smack it with a legendary weapon. Always works in anime and Paper Mario.
  • If it's scientific dark energy, then perhaps you could put a large object into warp near the being.
  • If your being is capable of siphoning off energy to feed itself, then you could try either starving it or overloading it. As Dr. Who put it, "You're 80% water but you can still drown".
  • Beings of pure psychic energy may die when cut off from their source, be it a portal to hell, the warp, the nearest terrified mutant child...

At the end of the day the universe always tends towards entropy. All forms of sentience may exist only within a very limited subset of configurations, and these configurations will always become disrupted and move into a "non-sentient" configuration. No matter what your being's form, its life is as delicate as a human's. I would wager given the universe's numerous gravity wells, super-novae, solar flares, and space expansion/contraction quantum mechanical bullcrap that any being of "pure energy" would have a much tougher time staying alive than us mere mortals.

Same way you kill anything else. Dump it past the event horizon of the nearest black hole.

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    But be careful, the energy being will (during its infinitely-long descent into oblivion) have plenty of time to figure out how to absorb the black hole into itself, thus making itself that much stronger... – fluffy Jul 12 '16 at 0:09
  • @fluffy Maybe it becomes a black hole being in doing so, thanks to its high density of energy. So it can pretend to be the black hole until the sequel. – wizzwizz4 Jul 12 '16 at 16:06
  • If you have FTL (and you probably do to to pull this off), there is no reason to think of an event horizon as the ultimate barrier anymore. – Joshua Jul 12 '16 at 17:33

If a bomb went off beside me, it would be a problem if that bomb could transfer energy (thermal/kinetic) to my matter. That's essentially how i'd die - the energy would shake my matter apart, and i'd become simpler matter.

Conversely, an energy being would probably be rather upset if you turned its energy to matter. How you'd do this depends on what kind of energy it is - for example a thermal being wouldn't be too happy if you used its heat to create new chemical bonds. But i'd stay away from true physics here for the purposes of storytelling and go with a sword/gun that when it connects with your energy beings converts some of their energy into gas/liquid/solid. Perhaps the more powerful the weapon/being, the more dense the matter it becomes on death. Small beings when struck might get a chunk of their body turned into hydrogen, which then explodes in air leaving behind water. Larger beings might become heavier atoms each with their unique properties, like liquid nitrogen, or solid carbon (diamond) for a big boss.

You would first decide if you want to stick with a science-based explanation or completely leave science and invent new kinds of energy.

If your story was somewhat based on our understanding of physics, you would have to first figure out the mechanics of this being. Start with which of the 4 forces (Gravity, Weak Atomic, Strong Atomic, Electromagnetic) gives it life. Reading about these 4 fundamental forces, I learn that,

Each one is understood as the dynamics of a field. The gravitational force is modelled as a continuous classical field. The other three are each modeled as discrete quantum fields, and exhibit a measurable unit or elementary particle.

Then, consider that any being must be an organized swirl of information. When you kill one of us biological beings, the way you know we are dead is if the information we contain is destroyed. So, whichever kind of energy it uses, how does it store the information? Answer this and you can begin to imagine how to kill it.


Being an energy being requires precise manipulation of that energy field so that it could move, act, think and interact with its environment. Thus if you cause it to malfunction by a weapon that would interfere with this ability, it can cause damage. This could be a physical object, sword or bullet, or an energy weapon. Obviously there are many interferences out there that would cause issues to said being. Thus these creatures should have a skin like shield that you would need to penetrate.

This answer assumes your energy being partially is, or at least uses electromagnetic fields in its "biology". If not, then use the same principle but substitute with whatever conducting material for whatever other form of energy your being is or uses (you are totally in the realm of fiction here, so you can make it be any way you want). The answer also assumes the energy being has some large scale internal structure, though it might work weaking it also if it is an amorphous blob with no structure.

Simply create a ball of metallic mesh, which can expand, and which is constructed to form a Faraday cage. The material might need to be something which can withstand high temperatures, such as as some Tungsten alloy. It could also be carbon nanotubes, provided there is no oxygen to burn it away.

The important detail is, that the mesh/net has hole size small enough to block creature's vital EM frequencies, but large enough that it will just pass through the energy being otherwise.

Then shoot the balls at the being with a mass driver. Have them start expanding by suitable trigger (such as timer, losing radio contact with the gun, starting to heat up). If the being can repel the balls, shoot them faster, or increase their mass, so it will need to expend more energy to repel them. If the energy being can make holes in itself, then just shoot them fast enough so that it can't match the speed.

The expanding spheres will form growing Faraday cages inside the being, essentially making holes in it, and disrupting its "biological" functions, either directly by blocking off parts of its internal structure, or just making it weaker by blocking off parts of it, if it has no structure.

Servants in Fate do have physical bodies, which they create with mana. That is how they hold stuff and are visible and so on. This post includes Fate spoilers (all series).

You can see this in action in F/Z when Rider bursts through rolling shutters while carrying some things, Waver berates him and tells him to use spirit form, and Rider remarks that he wouldn't have been able to take the items in that form.

But they are never seen taking pure physical damage. They do go at each other with seemingly physical means of attack, but it doesn't count as purely physical when it's a Magic Item (which includes all the weapons they ever use) and anyway anything a Heroic Spirit does doesn't count as purely physical damage.

In some other cases we see a human doing damage to a Heroic Spirit in several ways, for example Souichirou Kuzuki (magically enhanced by Caster), Shirou Emiya (magically projected weapons), Bazett Fraga McRemitz (rune imbued gloves), Rin Tohsaka (uses magic and a magic-enhanced body), Illya (with a kaleidostick) and there's probably a lot I'm forgetting, but no purely physical damage ever defeated a Heroic Spirit.

So basically, the Fate way to kill an energy being is magic.

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    @fairytale maybe read the Fate/Stay Night VN too, it has a lot of background information about the mechanics that you could borrow from. – harold Jul 12 '16 at 21:36

I'm currently reading Shutter, by Courtney Alameda. Ghosts in this book are beings of energy that are not usually visible. In order to capture/kill them, they take a silver plate charged with negative energy to attract the ghost's positively charged energy. Upon contact with a ghost, the ghost will be "sucked" into and trapped in the plate. After this, they either seal the plate in a non-conductive material, usually glass (starving it), or they melt down the plate (killing it).

Use a sufficiently strong EMP (electro-magnetic pulse) to disrupt the energy field.

This can be caused by lightning strikes, nuclear detonation or other strong sources of electro magnetic energy.

You could also attempt to contain them inside a Faraday cage.

Excuse my C- High School Physics class understanding of energy, but:

Shoot some protons or other Hydrogen ions at it; maybe something like heavy water. Energy (in the form of ions?) bonds to the hydrogen ions, forming plain hydrogen gas or something.

The benefit of this approach is that you can then spark it and blow up the remains of said energy creature.

Unfortunately, a being truly made of pure energy cannot be destroyed in the way you think. A living being needs interactions between molecules or some kind of inter-working network. Otherwise, it is a homogenous blob. By this reasoning, your energy being is of the same animalistic branch as an iron block, liquid nitrogen, and light. In fact, your being doesn't even need to be killed. It is literally an unchanging eternal block of energy. With every particle identical, there is no interelational reactions. Energy does not react to energy, anyway. Energy is nothing more than particles that have no rotational force, and therefore have all of their (unchanging) velocity pointed in one direction.

So, your energy being is either:

An eternal "missile" of pure energy that never loses trajectory until something hits it.


A blob of bouncing balls.

To kill the first:

Still a really big wall in front of it and watch the fireworks.

To kill the second:

Wait roughly 5 minutes for all the shells of bouncing balls to finally disperse in a big release of light.

I suppose if you want to use pseudo-science, give the second a forcefield that exists around it. However, even the tiniest hole will cause explosive decompression of pure light.

If you are meaning extradimensional or eldritch beings, then no luck to you. Extradimensional implies that the being is not even in the universe. It's like asking koopas in super mario to actually kill the guy holding the controller. You cannot. All you can kill is an avatar which could be of any form of your choosing. It does not even have to follow the laws of physics itself. Heck, it could just be a being that gives people the perception it exists, and then makes appropriate physical manipulations via magic.

Good luck on your story!

protected by Community Jul 12 '16 at 19:04

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