# Anti-Matter

Just reading through the boards here and came across the one about the anti-matter bombs Rather than hijack that very interesting thread, i would like to pose my question here.

On one of the “Universe” specials on The Discovery Channel, IIRC when anti-matter meets matter, they annihilate one another.

If this is the case, wouldn’t a piece of anti-matter the size of a deck of cards only be able to annihilate a chunk of matter the size of a deck of cards?

Fight my ignorance!

Yes, this is true.

But turning 2 decks of cards into Gamma rays would result in quite a bang.

The problem with anti-matter isn’t that in can annihilate things, it’s that when it does so, it produces a huge amount of energy. E=mc^2 and all that. So even if the deck-of-cards piece of anti-matter can only annihilate a deck-of-cards piece of matter, that annihilation will produce an absolutely ridiculous amount of energy.

For comparison’s sake, the energy released by a deck of cards annihilating an anti-deck of cards would exceed that of four million tons of TNT exploding.

TWNPsycho, you’ve glossed over the fact that you cannot create or destroy energy!

In your example, you have the deck of cards running into a deck of anti-cards, and you incorrectly assumed that because the two have equal mass, they will essentially delete themselves from the universe. Quite a neat solution, but not the correct one

Like the others have said, the two will annihilate each other completely, in what might be the most complete method of annihilation. The very bonds that hold each molecule together, the energy that keeps the electrons, protons, and neutrons (and quarks, gluons, and leptons, etc) in place!

All thrown out the window in one spectacular BANG!

So, what should I do with this packet of “Instant Antimatter, Just Add Water” then?..

How much antimatter has ever been created by scientists? Can it be stored? How? (The only way I can think of at the moment is to keep it circling around a particle accelerator in a vacuum.)

Sidetrack, but this reminds me of a long-delayed ‘refrigerator logic’ moment from Star trek, the next generation. It’s one of the episodes where Wesley is taking a test to apply for Starfleet Academy, and one of the questions is this complicated scenario about engine requirements and whatnot, ending with “what is the correct matter-antimatter intermix ratio for the warp engines?” Everybody puzzles over it for a long time, until they realize WHOOPS - trick question. “The only logical matter-antimatter mix ratio is 1:1”

Which makes some sense on the face of it, until you realize that they talk about the warp engines generating high-energy plasma - that is, matter with a high level of energy contained within it as heat or electromagnetic current.

And that blows the problem wide open. Of course, the antimatter will only annihilate its own mass in matter, but what if we want to have some matter left over to form the plasma? You get a sort of spectrum effect, with a mix of 1:1 delivering pure radiant energy, not contained by matter of any kind, (assuming that you can actually match each particle of antimatter up with its corresponding matter particle,) to a mix like 1.01:1, which would deliver a very small amount of EXTREMELY high-energy plasma. From there, the more matter you have, the cooler the plasma is, (and the more of it you get.)

Okay, my ramble mode is now off. Did that little revelation make any sense though?

We’ve produced somewhere on the order of a microgram. Storing antimatter in small quantities is easier than you would think, at least, as long as the antimatter is charged; the matter can be contained by a magnetic field, as in a Penning trap. This takes surprisingly little energy–a trap could be powered by a 9v battery–although you’d also have to keep the chamber evacuated and cryogenic.

Producing antimatter in any quantities is an extremely difficult and inefficient process, basically consisting of accelerating heavy particles to very high (relativistic) speeds in a cyclotron or some other particle accelerator and colliding them into a target, and then waiting for the products to decay and trying to isolate the antimatter before it recombines with something else. However, it is relatively easy to produce isotopes that will undergo beta decay, producing a positron (positive electron). This is the basis for positron emission tomography (PET) where the isotopes are combined with a bioactive molecule (usually some kind of sugar) and then allowed to spread to areas of the body that are of interest and detect the resulting radiation. But the amount of antimatter released by beta decay is still very tiny and not useful for power generating applications.

Stranger

Thank you. It is surprising that it’s relatively easy to store antimater.

There’s also the matter that, if you use 1:1, then there’s an excellent chance that some of your antimatter fuel, rather than annihilating with your matter fuel, will instead annihilate with bits of the engine, since your ship is, after all, made of matter.

Silly. That’s what the dilithium crystals are for - they emit negatively-charged plottium particles, which reverse the polarity of the gravimetric field inside the engines, thereby containing all the antimatter.

My first skim of this post misread one phrase as “…gravimetric field mice…” :o

What would four million tons of TNT look like? Say, boxed in 100 lb packages. Also, what would it do? Make a big hole sure, but would it split the earth in half or something? Would it be possible to manufacture that much? (Information needed for my plan to destroy the planet!)

Like about 8.8 billion of them? Perhaps more usefully, a kiloton of TNT, according to wiki, is a cube roughly 10 m on a side, so you’re looking at 4,000 of those.

Well, the largest bomb ever detonated was the Russian Tsar Bomba, with an explosive yield of about 50 megatons of TNT. As you can see, the world remains in one piece.

Possible – yes, but it’d take you about two billion years to produce one gram of antihydrogen, using the facilities at the CERN at top output.

If you want to get serious about that, you should check out this site. It’s harder than you might think!

I hope Cronos can stop by and explain further, but in one post he mentioned that a matter-antimatter reaction released a lot of it’s energy in neutrinos. Kind of an anti-climax (I think that is a pun but am not sure ) when all that energy goes off in a form that won’t react with ordinary matter. But I am sure there is enough energy left over for a satisfying explosion.

In comparison, though I can’t find a reference now, I have read that the Sun will over it’s entire lifetime convert only 3% of it’s mass to energy. And that will power the Sun for billions of years.

[note, according to Wikepedia the Sun is kind of wimpy as far a relative temperature goes-it produces less energy per unit volume than for instance a candle flame. Good thing the Sun is so large]

Well, that depends on the particular kind of particle (and antiparticle) you’re reacting. Electrons and positrons are easy: Those will just go straight to gamma rays. A proton and an anti-proton, though, will most likely go to three pions, either all three neutral, or a neutral, a positive, and a negative. The neutral pions will, like electrons and positrons, go straight to gamma rays, but the most likely decay path for a charged pion (positive, without loss of generality) is to an antimuon and a mu neutrino, and the antimuon would in turn decay to an electron neutrino, a mu antineutrino, and a positron (which would then, in turn, eventually find an electron somewhere and annihilate it). The +0- case would be twice as likely as the 000 case, so for every three protons and three antiprotons that annihilate, you’ll get, on average, 14 photons and 12 assorted neutrinos, so if you assume that the energy is distributed equally among the final particles (it’s not, but I don’t feel like calculating exactly how it would be distributed), you’d end up with close to half of your energy in neutrinos. A neutron-antineutron reaction would be essentially the same, but a proton-antineutron reaction or vice-versa would be somewhat less efficient, and be weighted more in favor of the neutrino-producing reactions.

A fair bit less than that. Fusion of hydrogen to helium is about .5% efficient at releasing energy, and a star will, over its lifespan, fuse only about 10% of its initial supply of fuel. So you’re looking at about a twentieth of a percent of the Sun’s total mass.

Use AntiWater.

Why can’t this enormous release of energy from a matter / anti-matter reaction be harnessed for productive uses (that is, besides making bombs)? I mean, it did power the Enterprise’s warp engines after all.

Is it because the energy necessary to create the anti-matter is equally huge?

I believe you nailed it in one, sir.