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Antimatter atoms produced and trapped at CERN (cern.ch)
250 points by jcsalterego on Nov 17, 2010 | hide | past | web | favorite | 89 comments

Next, suspend it in a mercury-like globule between two battery-powered magnetic plates, and place it beneath the Vatican...

Although the cost to create antimatter is very high, our government is actually working on creating antimatter munitions. (I've worked on creating a portable antimatter trap, which was funded by the U.S. government.)

I call bullshit. The cost is not "very high", it's astronomically high.

My advisor also worked on creating antimatter traps at government labs, but none of the projects had any kind of defense related purposes.

There are only a handful of interesting research questions about antimatter that exist at reasonable scales. Most of those are either fundamental physics or medical in nature.

EDIT: Looks like there has been some Air Force funding for positron traps for defense purposes. Never underestimate the insanity of some generals. I think my physics comments still stand, though.

I call bullshit. The cost is not "very high", it's astronomically high.

(Comments like this make me want to stop reading Hacker News.) Just because the "gunpowder" is expensive doesn't stop the production of containment vessels or delivery mechanisms:



Additionally, "antimatter" can include positrons, which are much cheaper to produce than antiprotons.

My advisor also worked on creating antimatter traps at government labs, but none of the projects had any kind of defense related purposes.

Your advisor may not have been involved in all imaginable projects related to antimatter.

There are only a handful of interesting research questions about antimatter that exist at reasonable scales. Most of those are either fundamental physics or medical in nature.

Along with research into directly producing weapons, antimatter can also be used to initiate (micro)fusion, and has been researched for space travel: http://en.wikipedia.org/wiki/Antimatter_catalyzed_nuclear_pu...

While I kinda agree with the spirit of your comment (we'll get there someday), there's a few problems with the specifics.

A pure (or high percentage) positron weapon would be very hard to handle. The repulsive forces would be enormous. As in we have a hard time containing the equivalent mass of electrons. And that's without worrying about annihilation.

And really, I think RK's response was spurred on more by rubypay's tone/phrasing. The original phrasing easily sounds like we're on the verge of practical anti-matter weapons. Which we're not.

(Comments like this make me want to stop reading Hacker News.)

If that's not trolling, I don't know what is. I will remind the gentle readers that I even edited my post (with a tag) for correctness almost immediately.

Just because the "gunpowder" is expensive doesn't stop the production of containment vessels or delivery mechanisms:

Actually that's exactly why such a project doesn't make sense. Kind of like building a fancy castle to put your Holy Grail in before you've found it. Read any of the articles or commentaries based on actual science, they say that such a weapon is so far fetched from an engineering stand point, that it's not worth pursuing.

Ref.: http://public.web.cern.ch/public/en/Spotlight/SpotlightAandD...

Or the same wikipedia article you linked:


Your advisor may not have been involved in all imaginable projects related to antimatter.

Thank you for ignoring my edit.

I'm not saying that any of this is impossible, just that it's horribly impractical, needing probably an order(s?) of magnitude more than Manhattan Project level of effort.

No knock on you and your research which seems pretty cool, but it really saddens me that motivation for government spending into this research is to build a bigger, better, more lethal weapon.

I wish the energy supply rationale were the real motivating factor for funding here.

Antimatter munitions scare me personally because they're a fail-deadly weapon. If the positron trap fails it goes kaboom. If a thermonuclear bomb fails in any way except a precisely calculated implosion you at worst you get a fissle, at best a guy in Whateveristan in the year 2040 gets his roof collapsed by a slightly radioactive dud.

I hope, the only thing these are being designed for is some gamma-ray laser for a new ground based Star Wars system and not as an actual munition of any sort. The complications are astronomical, especially given that gamma-rays are the EMP-producing portion of a nuclear reaction. An positron trap light enough to be contained in a weapon going off without a tamper to produce an explosion from the gamma-ray heating could be devastating for a modern society.

I'd never call playing god with this shit, I call playing stupid.

I'm pretty sure I've read somewhere that if you did just dump a quantity of antimatter (e.g. by turning off the containment device) you wouldn't get a nice explosion - more a long drawn out messy fizzle.

I would guess that a antimatter bomb would have to a similar design to fission or multi-stage devices where things are held together long enough by implosion for a significant proportion of the fuel to react.

I've done the math, you get an explosion quite rapidly. In a matter of nanoseconds the reaction of air in contact with the surface of the anti-matter chunk will release enough energy to vaporize the anti-matter and transform it into a growing ball of hot gas/plasma thoroughly mixed with matter, annihilation of the anti-matter completes in a matter of micro-seconds after that. This is if the anti-matter is just sitting in the open air, if it comes into direct contact with solid matter the process would probably proceed faster.

With what purpose? How would such a thing act?

For its size, it would be many times more powerful than a hydrogen bomb, by several magnitudes.

Only because the mass to energy conversion is 100%. But, if you factored in the size of whatever object you use to contain the antimatter, then your mass to energy conversion is probably comparable to a hydrogen bomb. Further, factor in the the energy required to contain the antimatter and it seems like it's losing proposition, probably until you start to approach the size of a small house or larger.

So then the argument turns into critical mass vs. critical structure mass.

Anyways, the technique they used is much more interesting than the fact that it's antimatter. Of course, CERN still has to play the PR game too just like anybody else, and I don't fault them for that.

The "object you use to contain the antimatter" is not very large, it can be wheeled around in a lab. The "energy required to contain the antimatter" is not very significant, liquid helium cooled inside a liquid nitrogen shell, and some rather ordinary (in terms of power usage) electric and magnetic fields. 100 grams of antimatter has a yield similar to a 4 megaton hydrogen bomb.

A 4 megaton thermonuclear warhead can be crammed into shockingly little space and weight, the question is whether the antimatter containment device can be smaller and lighter.

However, the real benefit to using anti-matter in munitions would be as a catalyst, not necessarily as a primary source of energy.

Consider a conventional multi-stage thermonuclear weapon, conventional explosives compress a fission primary bomb which goes off and serves as an x-ray light-bulb inside a radiation channel to provide ablative compression of the fusion secondary which, with the aid of a fission bomb "spark plug" ignites a self-sustaining fusion reaction. If you had significant quantities of anti-matter available you could change this design significantly. In the simplest design you could replace the primary with perhaps a single gram or less of anti-matter. Saving significant amounts of weight and also possibly allowing for much smaller thermonuclear weapons. More so, it may be possible with anti-matter to completely remove the need for fissile components in thermonuclear warheads. This could be useful in civilian applications (in an Orion drive spacecraft, for example).

Actually, the real benefit to using anti-matter in munitions is that it's a hell of a cash cow. Nobody expects it to actually work or ever be used, but you get paid a fortune anyways. Everyone wins -- the air force general gets a staff of 40 to manage the project, and the defense contractor gets several hundred million dollars.

But the question is what kind of infrastructure is needed to to contain 100 grams of positrons? There's no way you've contained 1/1000th of that amount otherwise you wouldn't be telling us about it on the internet (assuming you have Q/Top Secret clearance)

Also, assuming it is positrons, I'd imagine you might also have to worry slightly about relativistic background electrons and gamma rays/pair production, unless you're under 10ft+ of concrete. The extremely rare case that a 10^19 eV cosmic ray hits you head on sounds like an awesome way to possibly produce a spontaneous "detonation", or when some jokester thinks it's awesome to point a LINAC right at you.

There's no way you've contained 1/1000th of that amount otherwise you wouldn't be telling us about it on the internet (assuming you have Q/Top Secret clearance)

If he has one now, he won't have it for much longer at this rate.

Because we need a bigger deterrent that complete loss of life on earth via hydrogen bomb?

Well, we can't allow a positron-trap gap, now can we?


Cheap literature says so ( http://en.wikipedia.org/wiki/Angels_%26_Demons )

I had hoped that less people on HN are familiar with Dan Brown's books.

Everybody makes bad choices in life, the important thing is to learn from them.

Off topic but I had a very interesting experience reading Dan Brown. I read 'The da Vinci Code' without knowing anything about it or Brown, and I really enjoyed reading it. Then I saw the movie and I immediately recognized the massive holes in the plot, holes that I never saw while reading it. It surprised me.

I saw the holes in the plot (and characterization, and writing, etc.) while reading it and recognized the book as the worst sort of hollywood-esque masturbatory dreck. Nevertheless, despite all its defects the book was written well-enough to get me to keep reading it avidly, and for that I'll give Dan Brown a modicum of credit. Realistically, a lot of much more well thought of writers are no better than Brown.

It may be a guilty pleasure like junk food. McDonald's may not be worse for you than lots of other food, but it sure does feel bad.

To play a little devil's advocate, a lot of progress starts out with weapons. If we ever become a space-faring society, having more powerful weapons could possibly be a good thing. Space is big and we have no idea what's out there ( I'm not talking about aliens, but they could be there too. ) Though I do agree that as a terrestrial race, we have no need for weapons like this.

The article doesn't spell it out, and I know practically nothing about the subject, but... what happens at the end of the 0.2s? Do the antimatter atoms drift out of the magnetic fields used to contain them? Do matter atoms drift in? Or is it some property of the atoms or magnetic fields? Basically, what needs to change to increase the 0.2s?

Just based on what the article says, I suspect that even at the vacuum pressures they can achieve, there's enough normal matter around that eventually one of them penetrates the field and annihilates it.

Isn't the annihilation supposed to cause an explosion? How much energy is generated?

Isn't the annihilation supposed to cause an explosion?

It releases lots of energy proportional to the mass, yes, but one proton + one anti-proton annihilating at a time, it's a very small explosion. And they only had 38 anti-protons.

I believe that one of the the articles quotes one of the Physicists saying that it "wouldn't even warm up a cup of coffee"

Edit here you go:

Prof Rob Thompson, head of physics and astronomy at the University of Calgary, one of the 42 Alpha investigators, said: 'This is a major discovery. ... We've been able to trap about 38 atoms, which is an incredibly small amount, nothing like what we would need to power Star Trek's Starship Enterprise or even to heat a cup of coffee.'

Just take the resting mass of an hydrogen atom and multiply it by c^2. Try feeding Wolfram Alpha with "(mass of hydrogen) * (speed of light ^ 2)" or something, if you are lazy.

It's not very much in everyday units.

1 amu of anti-matter annihilates with 1 amu of matter and releases 0.3 nanoJoules of energy in the form of gamma rays. Or about 1.86 gigaelectronvolts (GeV, another unit of energy). In comparison, the particle collisions at the Large Hadron Collider occur at energies of about 14 TeV, or roughly 7,000 times more energetic, and occur numerous times per second.

They are neutral hydrogen atoms - why does a magnetic field affect them anyway?

The BBC article that's further down the front page at the moment brings it down closer to my level:



"Atoms are neutral - they have no net charge - but they have a little magnetic character," explained Jeff Hangst of Aarhus University in Denmark, one of the collaborators on the Alpha antihydrogen trapping project.

"You can think of them as small compass needles, so they can be deflected using magnetic fields. We build a strong 'magnetic bottle' around where we produce the antihydrogen and, if they're not moving too quickly, they are trapped," he told BBC News.

Such sculpted magnetic fields that make up the magnetic bottle are not particularly strong, so the trick was to make antihydrogen atoms that didn't have much energy - that is, they were slow-moving.


So, basically, magic. I'm just curious what the specific limitation is (but realize it may not be trivial to explain without understanding the entire containment process better).

Atomic clocks have the same problem. They use caesium atoms, which are hard to trap, and they want them moving very slowly so that thermal, doppler, and relativistic effects don't screw up the frequency signal you get from them. Hence caesium fountains, which fire the atoms upwards so that they come to the top of their gravitational parabola at about the time they drop a hyperfine energy level and emit the magic microwave photon.

Hydrogen (and anti-Hydrogen) is diamagnetic.

The link under further reading (http://cerncourier.com/cws/article/cern/30577) provides some insight.

Neutral atoms still have a magnetic moment. These do interact with magnetic fields. I'm way over my head here, so won't attempt to explain more.

"Geneva, 17 November 2011"

A message from the future...

In accordance with Feynman's idea that the positron is an electron moving backwards in time... (http://en.wikipedia.org/wiki/Retrocausality#Antimatter)

Wheeler invoked this concept to explain the identical properties shared by all electrons, suggesting that "they are all the same electron" with a complex, self-intersecting worldline.

Quantum mechanics is so cool!

If I remember correctly, Feynman quickly suggested to Wheeler that this is probably wrong, as it would imply that there are as many positrons as electrons. At least in our little piece of the universe, this is definitely not the case.

Maybe we haven't seen the positrons yet because they're still traveling back in time from the future!

Showing that this makes no sense is left as an exercise to the reader.

If the universe has toroidal topology, then the Big Bang is connected to the Big Crunch, and the number of positrons doesn't have to equal the number of electrons.

Of course, dark energy makes that all impossible.

Something went wrong when they built the earth. It shouldn't be spinning.

We have the Higgs Boson to thank for this.

So far they have 38 atoms. I wonder what the price per kilo or pound of antimatter is... :)

Yet another substance cheaper than printer ink, whatever its price.

I actually once bought a new printer (and ink for it) because the combo was cheaper that replacement ink for the printer a family member had bought...


I wanna say that it's 17 billion per gram. I'm looking for a citation though. though I think thats for anti-protons.

... so slightly less than saffron.

EDIT: eh wikipedia say 25gigabucks per gram, 62 trillion for antihydrogen http://en.wikipedia.org/wiki/Antimatter#Cost

Actually, I think they have had 38 atoms, since

  it is possible to hold on to atoms of antihydrogen in this way for about a tenth of a second.

Let the bidding war... begin!Bidding is over! The ex-antimatter goes to...

I won the auction, and all I got was this stupid matter!

(ex-antimatter == !(!matter) == matter)

Actually, the annihilation mostly produces photons, which aren't either matter or antimatter (or both, whichever way you like.)

Though you might have been lucky and gotten an antineutrino instead. Now you just have to find it...

Antimatter and matter annihilate each other upon contact, releasing the energy from both atoms. So the ex-antimatter would be half the released energy from the collision. I think?

Your equation is wrong. Why are you negating matter twice?

If you have anti-matter it will annihilate with matter making gamma rays. Those gamma rays can then participate in pair production making an electron and an anti-electron (positron), but that only happens in a strong magnetic field.

That positron will then annihilate again if it meets an electron (maybe even the same one, but it doesn't have to be). Which would then make gamma ray, which can start the process again. You can theoretically do this over and over forever, but realistically the gamma ray will probably be absorbed in something. Also, I think the annihilation may make two gamma rays, dividing the energy.

Edit: Is your equation a joke on the english words, ex and anti?

It was a joke based on the english meaning of the words and was not meant to be scientifically accurate.

That depends on how much it cost per atom. I am going to say somewhere between 1 cent and 1 million dollors so:

  1 KG of Hydrogen has ~1000 * 6.02 * 10 ^ 23 atoms.
  @ 1 cent per atom that's 6.022 * 10 ^ 12 trillion dollors.
  @ 1 million $ per atom that's 6.022 * 10 ^ 20 trillion dollors.

The correct evil business model is to get permanent funding to maintain power to the containment system.

I hope they will finally definitely answer if anti-matter also has anti-gravity.

Not a single scientist thinks it does, but it's one of those things you just want confirmed.

Antimatter has opposite charge, not opposite mass. It has the exact same magnitude and sign of gravitational interaction as normal matter. It's never been directly observed, but I'm not aware of any models that predict otherwise. http://en.wikipedia.org/wiki/Gravitational_interaction_of_an...

Maybe you're thinking of exotic matter? http://en.wikipedia.org/wiki/Exotic_matter

Isn't that why we have experiments, to check the predictions of models?

I would have thought this had already been tested on antiprotons, but I'm not seeing any references for it. Just a note that results from testing anti-hydrogen for gravity should be had in the next few years. Maybe containing something so charged overwhelms gravity?

As has been alluded to, gravity is an extremely weak force, so any gravitational effect is easily masked by electroweak forces until you accumulate a very significant mass. There's no way they can measure this on a single atom.

But easy to test with 2 atoms! Smash them together at a high enough speed where e=mc^2 says they would create a black hole. If they are destroyed in a blip of Hawking radiation, they had gravity!

Doesn't sound like it would work.

I'm not sure it's easy to distinguish the Hawking radiation from the stuff that comes out otherwise. I guess the Hawking radiation should be thermal but for a borderline small black hole there will be few particles.

Most antiprotons move too fast to test. Plus the charge is strong enough to overwhelm any signal from gravity.

Gosh, it sure would be nice if the actual scientific results weren't locked behind a paywall...if I paid taxes in the EU I'd be pissed.

If you really want I can send you the pdf.

I think they got it backwards. Our world is made of antimatter, it's the matter that's disappeared

It doesn't matter anyways.

This must be true - since the electrical charge on our electrons is the wrong way around.

"The collaboration reports success in producing antihydrogen in a so-called Cusp trap, an essential precursor to making a beam."

The article doesn't really say, but why are beams needed? Is it because these (anti-)particles are always moving or have such a short lifespan, or is there some other reason beams are so important?

(The sci-fi nerd in me first thought of weaponizing it, but I hope that never happens)

It's probably so the beam can be fired at a beam of hydrogen, as in a particle accelerator.

Geneva, 17 November 2011 -- Seems like the date is wrong

It's right... they just didn't mention that other experiment they did.

So Primer was a documentary?

Just mentioning Primer is enough to send my brain into tilt.

I have to watch in again tonight.

Also at the same facility is the experiment to investigate using beams of antiprotons to treat cancer.


I, for one, am just glad that CERN didn't create a black hole or otherwise destroy spacetime before they managed to do the kind of thing we normally have to turn to science fiction to read about.


Their developments are so fascinating to read about I can't wait to hear more.

For now, they seem happy enough to annihilate the world one atom at a time.

"antimatter seems to have disappeared" This is not very mysterious. If there was lots of antimatter lying about nearby, we could not be alive to see it. So, any antimatter must be a long way away or otherwise separated from us.

The anthropic principle is not an explanation.

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