# Restricting antimatter - practical rather than legal measures

Antimatter is relatively easy, but heinously expensive, to make using modern technology. I have two universes with the same problem; energy is free and for all practical purposes infinite, this should make antimatter dead cheap. I want to keep antimatter weapons out of my settings despite this situation because I want to keep the mechanisms of mass destruction to a bare minimum, but how can I restrict its production technologically rather than legally?

The settings are going to be surprisingly technologically stagnant, so not having advances within particular key fields is practical. I suppose what I'm asking is: what field or fields of science need to be held back, or even regressed from where we are now, to prevent easy access to and/or weaponization of antimatter?

To be very clear I want to restrict antimatter at source because of technological considerations because legal measures can be subverted but if the technological base isn't there to do the manufacturing then wanting, and being willing, to circumvent the law does you no good you still can't have what you shouldn't. I understand that I'm talking about a very artificial measure, I want to know where to put the pressure to keep the measures as subtle as possible.

Let me be clear this question is not about what else you could do with unlimited power or the nature or applications of antimatter it is about the technologies that are used to generate, store, and transport antimatter as we know it. Answers should focus on which of these technologies can be restricted with least effort to keep antimatter expensive and dangerous.

• Comments are not for extended discussion; this conversation has been moved to chat. – L.Dutch - Reinstate Monica Jul 24 '18 at 16:00
• "relatively easy" I see what you did there. – Jake Jul 24 '18 at 17:09
• "Infinite energy" and "infinite power" are different. Energy is an absolute measure of work, power is work over time. I can get practically infinite energy from star light, but it's very low power and will take a very long time to gather enough to charge my cell phone's battery. While energy in my cell phone's battery is finite, it can deliver a lot of power. Anti-matter is just a very good battery which you don't need if infinite power is available. It would help if you clarified how much power people can get, store, and transport. – Schwern Jul 24 '18 at 19:32
• @Schwern This only matters if you want to argue the validity of the question it doesn't help answer the question which is about technology concerned with antimatter weapons not the relative usefulness of an antimatter weapon under the circumstances. – Ash Jul 24 '18 at 19:46
• How will you judge the best answer? – JBH Jul 24 '18 at 21:42

Since your question allowed for the presence of antimatter technology but just not the usage of antimatter weapons, I am going to go into various things that will let you keep your antimatter reactors but avoid the bombs, or at least make them less deadly.

## Antimatter energy release is in the form of gamma rays

A lot of what follows hinges on this fact.

Well, not exactly, but some of the other stuff decays right away into gamma rays too. For practical purposes, we can just say that the energy is all in the form of gamma rays, and that approximation will be sufficient.

Gamma rays are electromagnetic radiation of a certain frequency. The antimatter EM radiation will all be at a particular frequency.

## Metamaterials bend light, and different materials work better for different frequencies

Metamaterials are used to bend light around objects. Usually, people think about them for their potential as a cloaking technology. Right now, we don't care about staying invisible... we just want to stay alive in the era of antimatter bombs.

Your people could have a metamaterial which works amazingly well for the particular EM frequency that makes up an antimatter bomb's blast. Although an antimatter bomb packs a huge punch, that punch won't be so bad if it goes around you. Put these on all your space ships, space ports and buildings, maybe even your ground vehicles.

## Antimatter, whether bombs or batteries, might be easily detectable

Others have stated why antimatter bombs are not feasible because of things such as their massive containment requirements. You could use that in a different way.

Contained antimatter in your world could be easy to spot because of its huge containment facilities. It could also be detected by sensors looking for its gamma ray signature - heck, there could be dedicated satellites that allow the government to always know where all antimatter is at all times.

So you say your bad guy has put something around his antimatter containment to block the radiation so it's not detected, so he can move his bomb and sneak it into somewhere? Everyone sees the ridiculous attempt because you can't hide a huge, moving antimatter containment vehicle, so there really is no way to get away with it.

## Antimatter bombs are not as dangerous as people make them out to be

Don't get me wrong; there is a colossal, unfathomably huge amount of power to be released from even 1kg of antimatter, and I would not want to stand next to it. However, because of the way that the energy is released practically all as EM radiation, a lot of it will be spread around more or even lost out to space.

An antimatter bomb might release a lot more energy than a nuclear bomb of the same fuel mass, but a lot more energy will be wasted too. So antimatter bombs are not necessarily the best weapons.

## You might as well not worry unless you're going to worry also about similar problems

As mentioned above, nuclear bombs do a better job of transferring their energy to their immediate surroundings in a manner which destroys things.

Even discounting nuclear, there were huge bombs even before, but they just happened to be massive amounts of chemical bombs.

So whatever your response is for those, you can just do the same for antimatter. If you're just not going to mention nukes or other things, then just don't mention antimatter weapons either. If you are going to go into a big deal about why antimatter weapons aren't available, then you kind of need to do the same for those other things too.

Unless antimatter batteries/reactors are a big part of your story, then that makes more sense.

## It has been discovered that you cannot make a reasonable antimatter WMD

This one is slightly more made up, but it sounds so reasonable that it would require little to no suspension of disbelief...

When you contain your antimatter as a gas in a magnetic trap, some atoms escape if they get too energetic or if a normal matter atom makes it in to annihilate with them. The more antimatter you have in one dense spot, the more this happens. There comes a point at a high enough mass where long term storage is not reasonable, and this point happens to be less than the mass required for a weapon of mass destruction.

So there are no antimatter weapons because you cannot keep an antimatter weapon viable long enough to use it.

Fortunately, even small amounts of antimatter are useful as batteries. Also, even though a large mass of antimatter cannot be kept together reasonably, that doesn't stop you from having multiple smaller amounts near each other... not suitable for a bomb, but suitable for energizing a system and replacing with fresh antimatter periodically.

• I like, especially the thought that imperfections in magnetic bottles might be insurmountable, that's exactly the kind of limiter that I was wondering about. – Ash Jul 25 '18 at 10:34

# Redundancy

Go the other way. Rather than restricting access to, or use of, antimatter, let it be a thing that's known but not particularly useful in a weapons situation.

With effectively free unlimited energy there's no reason why something as difficult and dangerous to handle as antimatter would be a weapon of choice. All you need is something as effectively dangerous which is much safer to handle and possibly even easier to make. Perhaps along the lines of direct energy discharge rather than delivered explosive.

If you're in a starship situation then also consider make the standard navigational shields or other equivalent system specifically resistant to stray anti-matter particles and hence also resistant to antimatter weapons without really thinking about it.

### Reasoning

Antimatter isn't an energy source, it's a storage system. The difference between using a PV panel or a battery. With that level of energy available there's no reason to put it into storage, you just use it directly.

• Brilliant answer! If you have effectively limited energy & it can be directed in a beam with the equivalent energy density of antimatter, then why manufacture antimatter? Plus one. – a4android Jul 24 '18 at 5:54
• You and Maxander have made choosing an accepted answer very difficult, these are both really good. – Ash Jul 24 '18 at 15:03
• @Ash. there's no requirement to pick an answer, leave it for now and choose one when you work out where the story goes. – Separatrix Jul 24 '18 at 15:24
• @Separatrix I know I don't have to pick a single answer but I do like to reward good work. – Ash Jul 24 '18 at 15:25
• schlockmercenary.com/2008-05-11 A good reference for how it could be handled.(The entire arc deals with it) – godskook Jul 27 '18 at 13:19

Making antimatter requires a big accelerator and lots of time- with present-day technology, the global production rate of antimatter is measured in nanograms. To make a WMD-level bomb, you'd require somewhere in the ballpark of a gram of antimatter, which would require geological timescales at the present production rate. Even a vast industrialization of antimatter production likely wouldn't suffice to make antimatter bombs common- and if antimatter is being industrialized, presumably a bunch of that is being used for economic ends. Essentially, antimatter shouldn't be an issue unless you posit huge advances in particle physics engineering.

• To add on to this: even if your energy is free, the cost of your antimatter factories and the land they are on is not. It's essentially infeasible with modern technology, even if we did have unlimited energy. – Skyler Jul 23 '18 at 19:29
• According to the antimatter calculator - edwardmuller.com/index.php?Page=calculator - one gram will yield you about 43 kilotons of TNT equivalent. That's enough to level a city (about 3x Hiroshima). 20% of that would be enough for terrorist purposes. Plug that into the Nukemap - nuclearsecrecy.com/nukemap/… - and you get almost 100,000 fatalities if exploded in NYC. – Tom Jul 24 '18 at 6:51
• @Skyler If energy is free and unlimited land could be "created". Everything can eventually be overcome with enough time, and if you want it sooner you simply throw more free energy at the problem. – Pod Jul 24 '18 at 14:46
• You and Separatrix have made choosing an accepted answer very difficult, these are both really good. – Ash Jul 24 '18 at 15:03

The energy density of antimatter is unbeatable, but the energy density of contained antimatter is not certain to be at all scales for all conditions.

To build a containment system costs mass and volume which could be spent on the heart of a less volatile energy system. Consider the conditions for using gasoline vs batteries; Gasoline is orders of magnitude higher energy density than any battery, but it would be silly to build a generator to power a cellphone. As technology progresses where the cross over point is changes, but the smaller and less independent you get the more sense it makes to use simpler energy storage. If you are killing people only a few dozen at a time kg's (assuming incredible advances once there is interest) of shielding for ng's of payload isn't any better than kg's of payload and g's of shielding to achieve similar effects with conventional explosives.

Storage is inherently tricky.

It requires large magnetic fields and the currently required cooling systems mean there is a hot side somewhere. Making them readily detectable, potentially vulnerable to interference and continually cost lots of energy. These are not the hallmarks of a good weaponsystem. Similar to other WMD's most of the engineering would be about mitigating how much threat they posed to the user. By limiting the spread of the knowledge about safety features you strongly limit the practicality of using it as a weapon.

• a very clever and correct answer – Fattie Jul 23 '18 at 18:17
• Or, to put it short: Everyone might be able to produce them, but no-one wants to have to handle them. It's just to easy to blow yourself up. Failure of a magnet, boom. Failure of power supply, boom. An antimatter bomb falling off the shelf, boom. A near hit by a conventional weapon, well, you've never seen a grenade being so effective... – cmaster Jul 24 '18 at 22:35

As of today's technology I would hold back superconductivity. Why?

Well anti-matter has to be held in some kind of storage as it immediately decays in combination with normal matter. In order to store it you'd need extremely strong magnetic fields, which currently can only be made by cooling magnetic coils with liquid helium in order to achieve superconductivity. So if you can't store it, you can't really produce it. As soon as you create anti-matter it decays.

energy is free and for all practical purposes infinite, this should make antimatter dead cheap

First, anti-matter is just the most energy dense battery we can conceive of (except maybe a captive black hole). But it's also the most dangerous and unstable. A good battery has to be both energy dense and stable. This is why petrol is such a good fuel and we're still using it despite having discovered more energy dense substances.

Your 1 g of anti-matter is no longer so energy dense if you need 10,000 kg to contain it. As others have pointed out, the problem with anti-matter isn't just the energy needed to produce it. Then you need to somehow keep it from touching matter, that stuff which is everywhere. This means a complex apparatus to maintain as close to a pure vacuum as possible, and a powerful magnetic field to keep the trapped anti-matter away from the apparatus containing it. Not only does this add cost and complexity, it also significantly reduces the energy density advantage.

To put some numbers on this, anti-matter has an energy density about 100 times greater than that of fusion. If your fusion reactor is 100 kg for 1 kg of fuel, and your anti-matter reactor is 10,000 kg for 1 kg of fuel, there's no benefit to using anti-matter.

If any part of that fails, boom. Instantly. Immediately. At the atomic level.

Shows like Star Trek make an enormous leap in assuming not only can they store anti-matter, but they can make it so safe they can carry huge quantities of the stuff into battle, near space anomalies, and land it on planets.

In the real world we have all sorts of explosives and rocket fuels and chemicals that store huge, enormous amounts of energy; far better than conventional fuels. We don't use them because they're highly unstable or highly caustic or both. They're just too difficult and dangerous to work with that they're not worth it. Or we use them in very small quantities in specialized situations. Books such as Ignition! An Informal History of Liquid Rocket Propellants, or Derek Lowe's In The Pipeline blog, or Scott Manley's The Most Dangerous Rocket Fuels Ever Tested video cover numerous examples.

In your universe, make the opposite assumption from Star Trek: they can't. Anti-matter is just too unstable, the engineering complexities are too difficult and expensive. Any organization crazy and desperate enough to mess with it is too small to contain it. Any organization large enough to contain it has more cost-effective weapons and only uses it in very specialized (and expensive) situations.

One paragraph to dismiss the notion is all you need for your story.

We have all the energy we want, but how do you store it? How do you transport it? Anti-matter? Too bulky, too expensive. All that extra containment, vacuum pumps, magnetic bottle... might as well use a compact fusion reactor after you bolt all that junk on, and we do. Anti-matter? Make one mistake for a millisecond and it blows up taking half the planet with you. Might as well run around in a glass starship filled with grenades. No, we couldn't make anti-matter efficient. Compact fusion reactors are the way to go.

• If you build the containment out of antimatter it is 100% efficient as a weapon, but 10^7 g would destroy the Earth in the Alderan sense. – user25818 Jul 25 '18 at 19:59
• @notstoreboughtdirt 10^7 g of anti-matter is about 10^21 J. The Earth gets hit by an asteroid about that energetic every million years or so. The dinosaur killer was 10^23 J. Bad, but it didn't blow the planet apart "in the Alderaan sense". That means overcoming the Earth's gravitational binding energy, about 10^32 J. You'd need about 10^18 g of anti-matter to blow the Earth apart, roughly equivalent to 1% of all the water on the Earth. – Schwern Jul 25 '18 at 20:17

The way to create anti matter is using beam particles (or wait for radioactive decay if positrons are what you are looking for).

To steer and focus beam particles one need magnets and knowledge of electromagnetism.

Hold back any development there, and they would be far away from anti matter. It would turn much like a steampunk world, for what it matters.

With infinite energy available, Antimatter is pointless as a weapon. Antimatter is a compact store of energy (ignoring containment); if you can produce as much as you want, there is no need to store energy.

Simply generate 4 * 10^20 J of energy (100 GT) and dump it into a sink (say, the ground under your feet); unless it is neutrinos or other weakly interacting particles, that amount of energy becomes a massive WMD-style explosion.

Want more boom? Try 2 * 10^32 J; that'll destroy much of the Earth (as in, turn it into plasma/debris). Not enough? 2 * 10^41 J, blow up the Sun. Heck, produce 6* 10^52 J -- the entire Milky Way evaporates from that. Most of the energy misses, goes off into empty space? Generate 10^20 more of it.

What form that energy takes really doesn't matter, especially if you can just generate more. Even if you are generating it as Neutrinos -- another 10^100 will make weakly interacting particles interact plenty. (actually it will form a massive black hole; which is just another application of "infinite energy" -- enough energy will form a black hole powerful enough to swallow the universe)

Infinity is big. Your question is like someone from the stone age asking "if someone can build an industrial civilization, how do we stop them from developing a longer spear?"

If they have an industrial civilization, longer spears are not weapons of concern. If they have infinite energy availiable, antimatter is not a concern.

Have a field which suppresses annihilation.

There was a book where you could project a field that suppressed everything starting from fire and including annihilation, leading to combats between starships full of boardings with cold weapons.

• That would be adding new technology, really strange "does not conform to the rules of reality" technology at that, not avoiding known technologies to remove an issue. – Ash Jul 23 '18 at 12:53
• Also, that field would be make containment of anti-matter much more practical. So, if anything, existence of this field would foster antimatter weapon proliferation... – cmaster Jul 24 '18 at 22:48
• @cmaster Wow it would too, I hadn't thought of that implication. – Ash Jul 25 '18 at 10:35
• The answers to this Q that do not meet its terms are being flagged as low quality. I don't know who flagged your answer, but it, indeed, doesn't meet the terms. However, this is a good oportunity to review Meta discussions about frame challenges (and here) to see how to better frame your answer. – JBH Jul 25 '18 at 19:37

By forbidding the containment of anti-atoms, you can make antimatter at will, but you can not pack it into a bomb.

Today containment of anti-matter is done with magnetic field. But this only works well with charge particles, if you make anti-atoms (for example anti-hydrogen) the result is neutral and really hard to confine at all.

If storing anti-atoms is impossible, you have to store positrons or anti-protons in a reasonably small space. However, as I show below, the electrostatic energy contained in a plasma of reasonably close anti-protons far exceed the energy that annihilation would produce, making antimatter bombs irrelevant.

To avoid the possibility of magnetically trapping atoms, you need to remove their spin. This will break physics big time and forbid the existence of permanent magnet, but I am sure you will be able to deal with it.

Optional math part

For the following, let only consider anti-protons as they are more massive.

The electrostatic energy due to repulsion of $N$ anti-protons is given by: $$U_\mathrm{E} = \frac{1}{2} \sum_{i=1}^N q_i \sum_{j=1}^{N(j\ne i)} k_e \frac{q_j}{r_{ij}} = \frac{k_e e^2}{2} \sum_{i=1}^N \sum_{j=1}^{N(j\ne i)}\frac{1}{r_{ij}}$$

where we used the fact that the charge of an anti-proton is $q_i = -e$, $k_e$ is Coulomb constant and $r_{ij}$ is the distance between charges $i$ and $j$. Here computing this exactly is tricky, so let just consider a lower bound. Define $R = \max(r_{ij})$, so we have

$$U_{\mathrm{E}} > \frac{k_e e^2}{2} \sum_{i=1}^N \sum_{j=1}^{N(j\ne i)}\frac{1}{R} = \frac{k_e e^2}{2} \frac{N (N-1)}{R}$$

Now let's assume we pack $1kg$ of anti-proton in a sphere of diameter $1 m$, thus having $R = 1 m$. The energy of annihilation would be

$$E_{\mathrm{A}} = 2 m c^2 \approx 9.0 \times 10^{16} J$$

But you need about $N = 6.0 \times 10^{26}$ anti-protons to make $1 kg$. Which gives

$$U_{\mathrm{E}} > 4.1 \times 10^{19} J$$

Therefore you would release at least $500$ times more energy due to the electrostatic repulsion than due to the mass annihilation. In other words using anti-proton is irrelevant, you would have the same punch by packing $1 kg$ of normal protons.

• Sorry how is this bit, "To avoid the possibility of magnetically trapping atoms, you need to remove their spin." a thing? Atoms of most elements are both neutral and nonmagnetic so they can't be kept in a standard magnetic bottle anyway can they? – Ash Jul 26 '18 at 11:17

"I want to keep antimatter weapons out of my settings despite this situation because I want to keep WMDs to a bare minimum, but how can I restrict its production technologically rather than legally?"

The same way we now restrict WMDs: the desire not to kill ourselves, which leads to treaties severely restricting WMDs

• Treaties are a legal measure. – Ash Jul 25 '18 at 10:23
• @Ash yes, they are. But unless you're going to posit some Applied Phlebotinum, antimatter is the result of the Standard Model of physics. It will be discovered. I upvoted Maxander's answer because of his points on the impracticality of antimatter weapons. – RonJohn Jul 25 '18 at 12:31
• It's not about not having any antimatter it's about keeping it technical difficult, expensive, and dangerous. – Ash Jul 25 '18 at 12:42
• @Ash it's already technically difficult, expensive, and dangerous, even with unlimited available energy. – RonJohn Jul 25 '18 at 13:52
• And I want it to stay that way in the face of scientific progress that makes space travel routine, so the question is what fields of science need to stay where they are to do that? – Ash Jul 25 '18 at 14:12