I've been thinking about possible super weapons for a little while now, but I'm not really sure of any ideas that could fit into a semi-realistic setting. One idea I had was firing out a slug of helium or some other material, and then using lasers to heat it up into a giant hunk of plasma which would presumably do quite a bit of damage upon impact. This seems very iffy though, and especially variable in how it would work.

The main parameters for such a weapon would be preferably be able to be mounted inside a larger sized spaceship, while being able to deliver a large amount of power to a target. Preferably, I'd want a more AOE type of weapon where it could fight a fleet of ships, but a single impact would work fine as well

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    $\begingroup$ VTC Needs details. I'm happy to retract the vote once the details are added. I can't actually tell if you're even asking a question. Are you asking us to invent a weapon of mass destruction for you? That's off-topic as too broad (see help center, don't ask questions were all answers are equally valid). Are you asking specifically about the helium idea? It sounds very much like you're fishing for ideas, which doesn't work well here. SE's model is one-specific-question/one-best-answer. What specific question are you asking? $\endgroup$
    – JBH
    Commented Jan 3, 2021 at 21:39

3 Answers 3


Plasma is bad for delivering energy to a target.

1: It is really hot, but it is also really nondense. Imagine an oven full of air at 450 degrees F because you are roasting a chicken. You peek in and 450 degree air rolls past you. It is fine and harmless for you and it smells great but you realize you forgot the shallots. If you throw a shallot into the roasting pan and some chicken fat heated to 450 degrees spatters on you, it will be unpleasant. Liquid is more dense than gas and so carries more thermal energy.

Plasma has even less mass than gas and so even less capacity to carry energy and transfer it to a target. The hot plasma will roll past the target ship but will not even smell like roast chicken being in space notwithstanding.

  1. Plasma is really nondense. Did I mention that? But this is point #2 so a different reason. Getting whacked with a big mass off plasma is like getting whacked by a big bag of feathers but without the bag. Plasma just does not pack much whack. So for delivering kinetic energy the least effective phase of matter. Plus ( this is reason #3) plasma is wiggly and tends to spread out just from bumping into its own molecules. Hard to make plasma go anywhere in a bundle.

Maybe you could have a wad of hydrogen in a bottle and make it stick to the enemy ship, then use your lasers to trigger a fusion reaction in the helium? That would definitely make a hole in the ship and ship bits would fly in there and do more damage. It would take some trick shooting. You could send a lot of the hydrogen wads in because hydrogen is cheap and so are plastic bottles.


In space , your biggest weapon is kinetic energy.

Plain old chunks of matter moving at high velocity.

If you get the velocity high enough, you can make the mass very small and still deliver a punch.
"But no, I want WMD I said, not just a shotgun in space"

Kinetic energy is mass multiplied by velocity. Multiplied by velocity again. And if you get near lightspeed, it manages to pack even more punch into the same package.
You do not need to hit the enemy with something big. Whether it is a person or a Battleship or a Fortified Planet, it does not matter. All you have to do is hit your target, and do so with a tiny speck of matter moving as fast as you can.

If you hit a planet with a BB gun pellet (0.35 grams), but you manage to shoot that BB pellet at 99.999999% of lightspeed ( 8 nines)... then not only will they not see it coming at all, but it will impact with the energy of the Tsar Bomba hydrogen bomb.

Or take that same BB-pellet amount of matter, but divide it into 50 000 specks the size of talcum powder. Disperse this in a cloud at your target. It is moving too fast to see, AND it is intrinsically invisible. It is basically a puff of dust. And even if the DO detect it, how do you evade a widely-spread puff of dust?
Each of those microscopic little flecks will impact with an energy of 1000 tons of TNT. Quite sufficient to blow a hole in anything, and remember you have 50 000 of them wafting towards the enemy.

  • disclaimer: Yes it will take great huge stonking amounts of energy to shoot stuff this fast. The scenario assumes you have the energy to throw around, it's just how you plan to use it. Whether you pump this energy into a plasma weapon, or just speed up a tiny ballbearing, is merely a matter of application. The difference is really that you can take your time accelerating the ballbearing, that actually makes it easier.
  • $\begingroup$ OK, now someone else pop in an answer about antimatter, or portable black holes. Both of those work great for blowing stuff up, too. They just need a bit more tech behind them. $\endgroup$
    – PcMan
    Commented Jan 3, 2021 at 21:12


WMD's often look and feel powerful in movies. Powerful things, often big but sometimes small to offset for it's incredibly destructive capabilities launched at each other.

But the true danger can be much faster and invisible. Whether it's computer viruses or biological, both are incredibly dangerous on spaceships.

The computer virus can take control of one or multiple systems, either crippling them, removing control or giving control to someone else. Doors, lights, oxygen, navigation. The options are numerous. You might tear the ship apart by activating all boosters in opposite directions, or pressurise one cabin and depressurise another, and opening a door in between. Poison the air or lock them out. Short circuit or underpower systems. Depending on your goal it's versatile both for story purposes as well as for the crews goals.

The second one is biological. Much more difficult in space battles, but not unimaginable. If you can somehow spike the enemy ship, you can already win. The space version of VX nerve gas, a bacteria that'll eat them from the inside and avoid electronics, a virus that'll simply kill them or a cordiceps fungi that controls them to open up all the airlocks.

AI is incredibly dangerous, allowing you to have a mathematical edge if it's better than another. This can help with navigation, targeting and automation. Potentially you just put van Neumann bots at work, attacking a ship and using the materials and energy to make more of itself until the target(s) are destroyed.

There is one very good WMD in space. EMP. Spaceships might be shielded, but only up to a certain amount. Setting off a significant EMP next to a spaceship can render them inoperable, leaving the crew floating in the dark in an increasingly deteriorating ship. Turning off systems as they do in movies isn't very effective against this.

You can also go for the "normal" explosive and kinetic route to WMD's. That is just putting enough of a certain amount of energy on your target. Physical, heat, electrical or whatever. If you put too much of it on your target you're generally golden. The only way is to deliver it. Potentially you can just use a lot of lasers pointed at the exact right spot, instantly heating it to a degree that it'll weaken too much. Then your WMD power is mostly calculation.

  • $\begingroup$ If people would say why they give a -1, I can do something with the feedback. $\endgroup$
    – Trioxidane
    Commented Jan 4, 2021 at 14:23

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