[csense]

From a layman's point of view antimatter seems like an ideal spacecraft fuel. It's as energy dense as E = mc^2 allows, and if you have infrastructure to make it, the only input you need to produce it is electricity.

Being able to transport it seems like an important piece of that puzzle.

Production and storage would need to be scaled by many orders of magnitude, but that's merely an engineering problem...right?

[pfdietz]

The confinement scheme used here is likely a Penning Trap. Such devices are limited in the amount of antimatter they can store by the Brillouin limit. The energy stored will be no more than the magnetic energy of the field of the trap, and so much less than the explosive yield of a mass of TNT (say) equal to the mass of the trap.

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

[bovermyer]

From a layman's point of view, I'm more interested in antimatter's potential as a weapon.

Not necessarily because I want to use it, but because I have a vague idea of what it's capable of, and what that would mean in the hands of certain groups capable of producing it.

[pfdietz]

The big advantage of nuclear weapons is they are very cheap per unit of energy yield. Bang for the buck, if you will.

Antimatter production is so inefficient that they will be much more expensive per unit energy yield.

[garciasn]

There are a lot of completely random statements about how much a gram costs floating around out there. Anywhere from $60T to $3,000T.

According to, Michael Doser, a prominent particle physicist at CERN, "one 100th of a nanogram [of antimatter] costs as much as one kilogram of gold."

S: https://www.abc.net.au/news/science/2023-02-19/antimatter-fa...

[thaumasiotes]

> According to, Michael Doser, a prominent particle physicist at CERN, "one 100th of a nanogram [of antimatter] costs as much as one kilogram of gold."

Those aren't comparable costs. The cost given for antimatter is the cost of producing it from nothing. The cost given for gold is the market price of buying gold that already exists.

Consider the cost of producing one kilogram of gold from nothing.

(Consider also the cost of ownership. Gold has a higher-than-average cost of ownership; you have to provide security or it will be stolen. Antimatter's cost of ownership is far, far beyond that.)

[adrianN]

The relevant cost for the buyer is how much they need to pay to obtain the object. So far we haven't discovered any primordial antimatter deposits that we could mine, so creating it from scratch is the only way.

[garciasn]

Please do take it up w/Doser from CERN and/or the author of the source article; I just was parroting what he was quoted as saying.

[ReptileMan]

Not that great. Chances are you will destroy your country before you destroy some other.

[mastersummoner]

That's just an engineering problem as well.

[everforward]

It’s a fundamentally different and riskier paradigm. Nuclear weapons at rest are inert, and can even be disarmed. If the lock falls off the gate at the compound, the nukes won’t spontaneously explode.

Antimatter is always “armed” and is only rendered safe by containment. If containment fails, it explodes. It’s more like keeping a massive stockpile of fluorine, but somehow worse and harder to contain.

[fragmede]

Not to be dramatic, but wouldn't that level of destruction threaten all life on Earth? After the immediate destruction of the first county, extreme climate change would cause the same kind of problems as nuclear winter would, no?

[TheOtherHobbes]

Antimatter bombs are not a realistic technology. Aside from the unsolved technical issues - many, and fatal - no country has the GDP needed to make 1g of antimatter, which would make an explosion around 40kT.

We can't afford to blow up ourselves that way.

There are plenty of other ways we can afford, so antimatter isn't top of anyone's worries.

[drfloyd51]

But they were wrong and we were right!

[d_silin]

Very tough engineering problem. Amount transported is 92 atoms. A mole (1 gram) of anti-hydrogen is 6.23x10^23 atoms.

[wiredfool]

When I visited CERN, they mentioned that there were some large number of protons in the ring at a time, and the runs would last a significant amount of wall clock time. (Don’t remember the exact numbers, but I think it was like 10^19 atoms of H, and days of wall clock)

The upshot was, it was likely that less than a mol of hydrogen had been run through the ring.

[d_silin]

If humanity doesn't perish in the next hundred year and masters interplanetary spaceflight, antimatter drive is the logical next step in propulsion after fusion.

Interstellar spaceflight will become (barely) feasible once spaceships can reach velocity between 0.02 to 0.1c are possible. Even assuming non-100% conversion efficiency, antimatter has enough energy density to provide this capability.

[TheOtherHobbes]

Interstellar flight is a new physics problem, not a smash-the-tiny-rocks-together-to-make-bigger-bang problem.

We're not going anywhere without a revolution in our understanding of the universe.

[BobaFloutist]

My memory is that 1g of constant acceleration grants sufficient relativity to make it to the edge of the known universe in a current human lifespan.

Now, it's true, there's some slight issues such as radiation, food storage/production, psychological effects, and any random space rocks obliterating your craft, all of which could reasonably turn out to be enough to make it not work. We also don't have a fuel source that can provide 1g of constant acceleration for 80 years for a reasonably sized space ship, though again my memory is that nothing prohibits it from a physics perspective (this is where my knowledge/understanding get prohibitively poor. I'm not sure how the math works if you stick a thousand ion drives to a spaceship that's already in space or if you just need a huge snifter of compressed hydrogen or if you can just use nuclear propulsion but I'm pretty sure that antimatter would do it, if you could bring yourself to waste the money. But maybe we don't have a plausible way to contain it so what do I know).

Maybe I'm remembering wrong, or maybe I glossed over what's currently considered a physics, rather than engineering/economic/materials science problem, but that's what it looked like last I checked.

[dbetteridge]

Alpha Centauri yes, the edge of the universe no :D

Edge of observable universe is something like 46 billion light-years away, even at 0.9c thats 50 billion years of travel (22 billion years experienced by the traveller)

But yes, you can travel places by constant acceleration but unfortunately it still dwarfs in comparison to those places out of our reach.

Unfortunately also, the universe is expanding at a rate faster than the speed of light so you actually cant ever reach the edge

[d_silin]

You don't need new physics for interstellar spaceflight - 16 km/s of dV is enough. you don't even need to go that much faster to slowly spread among the stars. There are a lot of smaller bodies all the way from Sun to Alpha Centauri. As long as you hop between them within reasonable time in a few thousand years you can become a true interstellar civilization, while going at much-slower-than-light velocity (similar to Polynesian colonization of Pacific).

[inetknght]

Not with that attitude, we're not!

[JumpCrisscross]

> antimatter drive is the logical next step in propulsion after fusion

Maybe. Beamed propulsion makes a hell of a lot more sense in the solar system.

[amelius]

> ideal spacecraft fuel

If you're ok with the looming threat of total annihilation.

I suppose at least it will kill you faster than your neurons can communicate so you wouldn't even notice.

[teiferer]

> If you're ok with the looming threat of total annihilation.

Don't you have that problem with any energy-dense fuel? It's just that it doesn get more dense than that, so you can be very space and weight efficient.

It's like everybody saying that a hydrogen car is a rolling bomb because of the energy stored in the hydrogen. Well, sure, but gasonline has just as much energy stored. Which is the whole point of fuel. To store energy. It's not like you are bringing 100x as much energy with you just because it's hydrogen. So that doesn't make an ICE car any less of a bomb...

[antonvs]

Antimatter is a completely different story.

The difference is that antimatter annihilates with any normal matter that it comes into contact with. This means you can't just put it in a tank, the way you can with hydrogen. You can't e.g. combine it with some metal to make a metal hydride to make it safer to store, the way you can with hydrogen.

At an absolute minimum, you need extremely strong magnetic confinement and an extremely hard vacuum. And even then, you're going to get collisions with stray atoms and annihilation events which release gamma rays and other radiation products - although shielding is probably the least of your worries in this scenario.

A typical research lab at a university or large corporation can't make a vacuum strong enough to store even tiny quantities of antimatter for more than a few minutes, and they can't produce the magnetic confinement strength required to store macro quantities of it, either.

So the question with an antimatter-powered car is not if it's going to destroy the surrounding region and bathe it in hard radiation, but how many milliseconds (or less) it will take before that inevitably happens.

But probably luckily for us, this is all moot, because we have no way of producing enough antimatter for this to be an issue. If all the antimatter that's ever been created by humans annihilated simultaneously, only scientists monitoring their instruments closely enough would notice, because it's such a microscopic amount.

Edit: for perspective, you'd need about 7 billion times the 92 antiprotons transported in the truck in the story to produce the energy produced by a single grain of gunpowder.

[micw]

You can easily put it into an antimatter tank ;-)

[teiferer]

I love the suggestion. It's like a taco bowl or soup bun.

[antonvs]

Only if you wear antimatter gloves while doing it.

Also, now your tank is just fuel as well.

[micw]

You can throw matter on it. But this needs to be confined carefully...

[nomel]

How is it possible to make as hard of vacuum as they did? I assume it's not perfect, so what's the trick? Does the magnet setup create a volume that's simultaneously high probability for antimatter and low for everything else?

[antonvs]

For this antimatter transport experiment, they only transported 92 antiprotons. To store and transport that, the requirements for the magnetic field and vacuum are many orders of magnitude lower than what would be needed for macro-scale quantities.

Also, if there was an accident and all those protons annihilated, the consequences would be unnoticeable except to sensitive instruments. The energy involved is about one seven billionth of the energy in a single grain of gunpowder.

[Tadpole9181]

Surely you understand there's a difference?

Liquid gasoline does not spontaneously explode like an action movie. You can put a match in the fuel tank and (presuming infinite oxygen availability) it'd just start a small fire. Heck, may even just give a little puff and then put out the match.

Antimatter in any sufficient fuel quantity, the moment it breaks confinement, will completely annihilate and release ALL it's energy in a single moment, setting off a chain reaction to the remaining antimatter. It's like sitting on an armed nuclear bomb, where you rely on electrified, highly sophisticated containment equipment never failing a single time for months to years... In a radiation-heavy environment known for causing sophisticated electronics to have errors.

And, yes, hydrogen cars were looked at critically because of the perception they can Hindenburg (I'm unsure if it's true or not). Which is a good example because you don't particularly see any hydrogen blimps anymore - we made them illegal because they're dangerous.

[SoftTalker]

Any compressed gas fuel is inherently dangerous. There's a video of a CNG-fueled bus falling off a lift and sending a fireball through the maintenance facility.

Batteries have some of these same risks: they store a lot of energy and it can be released very quickly under the wrong circumstances.

[Tadpole9181]

Which is why we generally don't use highly volatile fuels in vehicles, like I just said?

And, no, batteries can have outbursts but they're nowhere near as catastrophic as compressed, explosive gases or an antimatter bomb.

[im3w1l]

Volatility and energy content are not necessarily related.

[thaumasiotes]

They are; something with no energy content can have no volatility either.

[crooked-v]

If you're on a spacecraft you're sitting on a tank of rocket fuel anyway. It's the same problem, just slightly less total.

[sigmoid10]

Average human threat perceptions simply aren't useful here. People will also make wild assumptions about what kind of catastrophic thing could happen in aviation and then happily enter their car to drive somewhere without a thought in the world. In fact noone thought about designing gasoline fuel tanks in a safe way before we had cars. Not even really until people started burning. If we're already thinking about transporting antimatter safely today, this kind of technology will probably have an even better track record than planes.

[queuebert]

Antimatter reactions are about a million times more powerful than conventional combustion. They surpass even nuclear explosions in energy release. That means even a small mishap becomes a large mishap.

[adrian_b]

Nuclear energy is limited to a little less than 1% of the energy release possible with antimatter, per mass.

The practical limit for nuclear energy is about 5 to 10 times less than that, because the theoretical limit corresponds to the transmutation of hydrogen into iron, coupled with the capture of the entire energy, which will not be achievable any time soon.

But there is an essential difference between nuclear energy and antimatter energy. Nuclear energy is stored in our environment and you just have to exploit it. Antimatter energy is a form of energy storage, so you need some other form of energy to make antimatter. The energy efficiency of making antimatter is many orders of magnitude worse than the factor of less than 100 that exists between nuclear energy and antimatter energy and the mass of the confinement device needed for storing antimatter is also orders of magnitude greater than the mass of the stored antimatter.

For now, there is absolutely no hope of ever using antimatter in practice for storing energy. Such a thing could be enabled only if some technologies that we cannot imagine would be invented.

Despite the great technological progress of the last couple of centuries, it is hard to say that there have been many inventions that have never been imagined before. After all, already 3 millennia ago the god Hephaestus did his metal smith work with the help of intelligent artificial robots.

[AngryData]

Yeah but when you are talking about energy levels in the nuclear bomb range, the threat to the passenger stops going up. If im in a craft with 1 Hiroshima bomb of energy and another guy is in one with a million tsar bombs worth of energy, we would both be obliterated before we knew anything was wrong no matter how small of a mishap.

[ComputerGuru]

You can carry exactly (or roughly) as much energy in the form of antimatter as you would energy in the form of fuel.

[amelius]

The problem is that a tiny leak will eat away your spacecraft, thereby making the situation worse.

[ComputerGuru]

A very different problem then the one I proposed an answer to, no?

[amelius]

Except rocket fuel lines are often leaking, and the most common cause of launch delays.

With antimatter the tiniest leak will annihilate your ship.

[yibg]

Not familiar with the subject so genuine question. HOW would antimatter be used as fuel? There is energy released in matter antimatter annihilation, but where would the force to move a spacecraft come from?

[jjmarr]

> Various antiproton-powered rocket systems have been proposed. All of which rely on the particles released to supply direct thrust or to heat a working fluid by interparticle collisions or by heating a solid core first [14]. There is also the possibility to use the heated working fluid to generate electricity for electric propulsion systems [14].

> Following Fig. 9, beam core and plasma core configurations can produce direct thrust by directing the charged particles produced into an exhaust beam using a magnetic nozzle. Gas core systems use the energy released from the reaction to heat a gas that is exhausted for thrust. Finally, solid core configuration heats a metal core like Tungsten that acts as a heat exchanger to a propellant that is then exhausted from a regular nozzle.

Not the same paper, but goes into more detail.

https://www.sciencedirect.com/science/article/pii/S266620272...

[daveguy]

The always excellent PBS Space Time recently did an episode on antimatter drives:

https://m.youtube.com/watch?v=eA4X9P98ess

[goda90]

Use the antimatter as an electricity source to power ion thrusters, maybe?

[BiraIgnacio]

my absolutely-non-expert guess is that it would work much like any other fuel? Combine with matter, get a lot of head out of it and use that in the best way we know.

[estimator7292]

I don't like antimatter because it's the most volatile fuel possible. If power is ever interrupted for any reason for any amount of time, the entire mass explodes.

A slightly less insane fuel source is a micro black hole. Drag a tiny black hole behind your ship and drip-feed it any kind of mass you come across. You still get >90% mass-energy efficiency which is far beyond anything else we know of.

Besides, one of the big problems with antimatter is that it's a battery, not a fuel source. We must first collect the unimaginable amount of energy and then process it into antimatter one particle at a time. If you build a ton of factories around a star you can get meaningful production. But a black hole drive can suck up interstellar gas or any asteroids you come across. Matter is easy to get. Don't ask where the micro black hole comes from.

[andrewflnr]

Black holes have similar problems to antimatter. A micro black hole is pretty close to an ongoing antimatter explosion in terms of effects on its surroundings. If any part of your shielding fails, it irradiates you or melts you. Their radiation increases as they get smaller, and if not fed they're always getting smaller, until they "explode" (yes, but even more so) and disappear. So you still have the problem that if you don't maintain it just right, it will annihilate your ship. So, "less insane" is dubious IMO. (Still my favorite starship idea, though.)

[ant6n]

How heavy is the micro black hole? How do you “drag” it?

[adrianN]

Black holes are good star ship engines because they turn everything into Hawking radiation.

[throwaway894345]

Can you elaborate? Why is HR useful for starship engines?

[nkrisc]

I suppose they mean if you could harness Hawking radiation to do useful work, then you could use any matter as fuel.

[adrianN]

https://en.wikipedia.org/wiki/Black_hole_starship

[scotty79]

To propel things in space you don't need as much energy as you need momentum. With antimatter you just have momentum of the photons that were produced in the annihilation. I don't know if that's the best way of getting momentum. Might be.