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Comment by queuebert | Hacker News Reader

If you can ship antimatter, you can drop it on people. Luckily, we are still orders of magnitude away from a bomb-sized amount.

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Making antimatter bombs really doesn't make sense. We can only make miniscule amounts of the stuff at very high cost.

If you want evil bombs, we already have nukes.

Also, the amount of antimatter storable in a Penning Trap is limited such that its mass energy is comparable to the stored magnetic energy of the trap, which is small compared to the energy released by the same mass (as of the trap) of high explosives.

https://en.wikipedia.org/wiki/Non-neutral_plasma

(see discussion of the "Brillouin Limit")

Make an antimatter liquid with strong intra-molecular bonds (e.g. anti-H2O) that is only slightly ionized. That would be easier to contain magnetically.

How do you propose to do that? Getting any antielement beyond antihydrogen would require doing nuclear fusion on antiprotons.

Which is hard but theoretically possible.

Fusion of protons is theoretically possible in the sense of you can theoretically build a star from antihydrogen. Laboratory fusion of protons is very unlikely ever to be practical. The "S factor" (representing the fusion cross section aside from geometric and tunneling rate factors) for pp fusion is something like 24 orders of magnitude smaller than for DD fusion.

I'll add that maybe one could achieve fusion in a different way, by a means that's highly wasteful of energy. After all, the goal here is to get the fused nucleus, not achieve net energy production in doing so (as is the goal in fusion of ordinary nuclei).

Here, one might exploit the reaction p(p,pi+)d (or, rather, it's antimatter equivalent, which makes a negative pion), at a center of mass energy above threshold for creating the charged pion (which has a mass of 139.579 MeV. This is wildly energy negative, but if one has already invested many GeV in making each antiproton that's presumably acceptable. The cross section for this reaction is only ~200 microbarns, but that will be many orders of magnitude higher than the ordinary fusion cross section.

The solid antimatter one would probably target as an end goal would be anti-(lithium hydride).

There was a time that was said about nukes. They didn't really make sense. We were only able to make minuscule amounts of U-235 / Plutonium at very high cost... and had we wanted evil bombs, we had a thousand ways already to make them.

Didn't stop people then. And it won't stop sufficiently criminal governments today.

I'm not saying we already have nukes in the sense that will stop people from wanting a better bomb. I'm saying we already have a much better bomb than antimatter so why would people invest in making a much shittier bomb?

And we don't even have to reach for nukes. Dynamite is also a better choice for blowing things up than antimatter.

Look up comparative damage stats for Tokyo and Hiroshima/Nagasaki in WWII. The nukes were nothing compared to firebombing.

Now do the same for Gaza and anywhere other than WWII Warsaw. Carpet bombing isn’t necessary if you can aim with precision at the support infrastructure of occupied structures.

You're making my point: We had comparatively worse and cheaper ways to butcher each others. And yet, we build nuclear bombs.

Carpet bombing is not meant for eliminating military targets - it's an act of state-sponsored terrorism to get a population to rise against its leaders. Only, it has been proven over and over again: That doesn't work and often results in the exact opposite, making them rally behind the flag against the barbarous enemy who would attack civilians. Which is why we stopped doing that. Mostly.

What's the biggest barrier to creating a lot of antimatter?

Energy. Creating a single anti-hydrogen atom requires an absurd amount of energy to first create a collision in a particle accelerator and then capture that anti-hydrogen before it eliminates against another atom.

Only about 0.01% of the energy used to operate the particle collider creates antimatter, the vast majority of which is impossible to capture. All in all, the efficiency of the entire process - if you were to measure it in the e^2=(pc)^2+(mc^2)^2 sense - is probably on the order of 1e-9 or worse.

Has there been research on more efficient ways to generate antiprotons? (By the way anti-hydrogen isn't how you would store it as anti-hydrogen can't be trapped.)

Anti-hydrogen is routinely trapped in magnetic traps at CERN.

If anyone is curious how, I think this is vaguely the idea: https://alpha.web.cern.ch/science/2-trapping-antihydrogen

tl;dr: strong magnetic fields in a certain configuration since in a strong enough field anti-hydrogen acts like little bar magnets.

Nothing we do creates it at any kind of scale, and it's a pain in the ass to store.

Not to mention the only way to create it is with energy (it doesn't exist on Earth), and we can only do so at terrible efficiencies. So even theoretically it's pretty bad.

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