Talk:Antimatter/Archive 2

Archive 1

Archive 2

Antimatter in fiction

This section is truly awful. I really think that we should apply the Wikipedia notability criteria to the entries there. As the template says, lists should not be just a collection of miscellaneous items. I propose that we require entries to have a reference to a WP:RS which cites their notability in connection with antimatter.

For instance, the first mention of antimatter in SF, the first use on TV or movies or a work that has played a part in bringing antimatter to the attention of the general public would all be notable. On the other hand, The Man from U.N.C.L.E. might be notable as a TV series (it had a cult following) but its use of antimatter as a plot device is devastatingly non-notable.

As far as I can see, all the current entries do not meet this criteria, at any rate there are no references other than self-refs. The only one that could conceivably be relevant was Asimov's positronics which he came up with shortly after the discovery of the positron, but this has already been deleted as irrelevant.

Any comments before I wipe it? SpinningSpark 17:06, 22 September 2008 (UTC)

I don't have any objections to wiping the whole "Antimatter in fiction" section. I did some repairs on it, but I agree it is pretty much a random collection and doesn't add much value to the article. However, I don't think it will stay wiped - there will always be editors who want the page to mention that their favourite sci-fi TV series has an anti-matter plot device. Maybe this needs a separate spin-off article, like List of fiction containing teleportation or List of references to cold fusion in popular culture. You could perhaps consult the folks at Wikipedia:WikiProject Science Fiction on how best to handle this - I see they have put their tag above. Gandalf61 (talk) 08:31, 23 September 2008 (UTC)

One thing I have seen done on other pages is to put in some hidden text reminding editors of the requirement for inclusion in the list. Of course, as you say, this will still not stop it, but removal then becomes a mere mechanical operation on the grounds of "against consensus", no emotional investment required. Not noticed the Science Fiction template before, bit of a stretch for them to include it in their scope IMO but I will take up your suggestion and drop them a note. SpinningSpark 18:24, 23 September 2008 (UTC)

I liked the section "Antimatter in fiction", epecially the part about Stanislav Lem, and I want to recover it. Most of people know about antimatter, lasers and black holes from fiction. They may look for explanations, we should send them to the correct place. How about to move the contert to Antimatter in fiction? dima (talk) 04:01, 4 October 2008 (UTC)

You look like an experienced editor, I'm sure you know how to extract the material from the history. If you are going to use the material as-is (rather than a coherent article), I would suggest a title like List of fiction with references to antimatter since it is largely a list of otherwise unconnected items. SpinningSpark 10:00, 4 October 2008 (UTC)

I think we need to have some mention of Star Trek, given that it's perhaps the most notable science fiction TV show ever, and the fact that antimatter is central to the functionality of nearly all of its fictional science. 71.203.209.0 (talk) 22:09, 3 December 2008 (UTC)

I know it played a major roll in a book called Angels & Demons. I don't know if you wish to add that or not. I was going to until I saw that it told me to take it to the talk page so I'll let you guys & gals decide if I should add it or not. Money2themax (talk) 08:23, 24 January 2009 (UTC)

Yes, Star Trek is notable, yes, Angels & Demons is notable, and yes, they both feature antimatter in the plot. It is certainly appropriate to mention antimatter in those articles. What is not appropriate is to list every occurence of antimatter in fiction in the antimatter article. That would be as silly as listing every occurence of "car" in the car article. Only works of fiction that are of special significance to antimatter should be mentioned, and only when there is a source saying it is of special significance to antimatter in fiction. Otherwise you just end up with unmanageable listcruft. As a point of information, Dan Brown's book has been deleted from that section multiple times already, and not always by me. SpinningSpark 12:50, 24 January 2009 (UTC)

I don't think Angels & Demons is particlarly notable in this context; not only is it far from the first story to feature antimatter, it isn't even the first to feature an antimatter weapon (as far as I know that distinction is owned by Winter Snow, a short story published in 1980). — 92.40.6.56 (talk) 13:58, 15 July 2009 (UTC)

Ok well I figured I would mention it and at least see what you would say. Money2themax (talk) 10:18, 1 February 2009 (UTC) Money2themax (talk) 10:20, 1 February 2009 (UTC)

Jack Williamson's first Seetee story in 1942, "Collision Orbit," was not the first science fiction story to feature antimatter. The earliest story I have found is "Minus Planet" by John D. Clark. [1] and [2] are two sources. Nevertheless, because Williamson published a long series of antimatter stories in the most prominent SF magazine, his work brought attention to antimatter in a way that previous stories had not, and may still be worthy of mention in this article. See further disussion here: [3]Beamjockey (talk) 00:24, 24 March 2009 (UTC)

I agree, those are good references. Your first ref seems to also be saying that there was an even earlier story by Frank Long and that Arthur C was the first to propose antimatter as a propulsion system. SpinningSpark 10:26, 25 March 2009 (UTC)

I see talk but no action. This section is still very out of place and does not really enhance the article in anyway. Someone can write a better one in later if they wish but I am wiping it as I have been encouraged to be more bold in my edits. If you don't like it you can undo the wipe and I won't argue. Skeletor 0 (talk) 15:51, 9 April 2009 (UTC)

Mass?

I recently heard that antiparticles have a negative mass, so that when a particle-antiparticle pair forms on the event horizon of a black hole, and the antiparticle falls in, it adds a negative mass to the black hole. Also, E=MC^2 supposedly should be changed to E=+_MC^2 (positive/negative mass) in order to derive antiparticles. Additionally, if antiparticles are normal particles travelling back in time, then the have a negative speed to an outside referencer (which in the equation may be converted to negative mass). However, everything else says that the antiparticle has the same (not opposite) mass of its particle partner. Also, how does the black hole "know" which particle is falling into it, and therefore "decide" to grow or shrink appropriately? Last, I have also heard that the particle that escapes, gets a "kick" from the blackhole, stealing some energy. Are these just different paradigms? Also, the partners are antiparticles to eachother but not to themselves, so does that mean in their own frame-of-reference, they have a positive mass and the other has a negative; just as someone cannot travel back in time in their own frame of reference? Thanks 98.27.163.42 (talk) 01:04, 10 October 2008 (UTC)

Mass is positive for both particles and antiparticles, never negative. Before anything along those lines could be put in the article, you would need to cite a reliable source; "I recently heard . . " cannot be checked up by other editors. For your other questions, I highly recommend the science section of the Reference Desk where the volunteers there will be delighted to answer all knowledge questions. This page should only be used for discussing improvements to the article. SpinningSpark 08:38, 10 October 2008 (UTC)

What you heard is wrong, and the page is here: Hawking radiation. —Preceding unsigned comment added by 76.126.215.43 (talk) 17:53, 9 July 2009 (UTC)

this is a few questions based on the above. first of can you possibly explain to me the forces that would decide the charge contained by any particle in particular, more explicitly what would the difference be between say, a proton and anati electron if there is one? is it possible that these type of opposites are just the same animal called by a different name? My personal theory, which by the way, i realize has little to no standing in this setting, is that these particles can become interchangeable, and when a change takes place the simplest form aka "electron/ anti proton" would take the place farthest from its central anchor of gravity. Second Is there any reason why you could not move backwards in time in your own frame of reference? if possible would this not explain the antimatter issue in its own way? anyhow, i know that i am rambling and that i am grasping at straws in my concepts but i would love to hear a response —Preceding unsigned comment added by 76.208.29.138 (talk) 03:38, 3 February 2010 (UTC)

Electrons and antiprotons are completely different particles. Electrons are leptons; protons are baryons - composed of quarks. That also applies to antiprotons; antiprotons are just protons with the color and other charges reversed. They differ from electrons in mass, composition, etc. -RadicalOne•^{Contact Me}•_{Chase My Tail} 03:50, 3 February 2010 (UTC)

I would like to add a couple of experimental differences between positrons and protons. First of all, a proton has about 1800 times as much mass as a positron. This can be observed by watching the tracks they make in a photograph of their respective ion trails: the positron will curve a lot more in the same magnetic field because it is so much lighter. Also, when you put an electron and a proton together, it makes a stable hydrogen atom. When you put an electron and a positron together, they annihilate each other and release a pair of gamma ray photons. Before Anderson discovered the positron in 1932, Dirac tried to explain the possible existence of a positive electron as being a proton, but even he admitted there were serious problems with this idea. That idea was abandoned as soon as experimentalists were able to study real positrons and see that they were nowhere near the same in their behavior as protons. CosineKitty (talk) 16:38, 3 February 2010 (UTC)

calculation given for the amount of antimatter created by CERN per year

The calculations given for the amount of money it would take to create 1 gram of antimatter given CERN's annual production of "several picograms" is off.

If I assume "several picograms" is seven trillionths of a gram, and this costs $20 million, then the calculation (20 * 10^6) / (7) * (10 ^ 12) = 2.86 * 10^18, which is much more than the figure of 100 quadrillion dollars given.

I have no idea what the correct numbers are, however, I can't reconcile the two numbers given in the article.

Please fix. —Preceding unsigned comment added by 98.14.225.194 (talk) 03:25, 26 October 2008 (UTC)

These are pie in the sky calculations and should not be taken too seriously. Also, it is a quote (but unfortunately not referenced) of what someone has said. It may be wrong, but if that's what they said, then that's what they said. The numbers: you are not entitled to re-interpret several picograms as meaning seven. It is vague and could mean anything from "one and a bit" to a thousand. Looking on the CERN Q&A (ref 10) they say one nanogram in ten years. That's 100 picograms in one year. A gram will thus require 10¹⁰ years. The 10 year cost is stated as "a few hundred million swiss francs". That's few x 10⁸ SF. Multiplying by the number of ten year periods required gets a few x 10¹⁷ SF. One hundred quadrillion is 10¹⁷ (short scale) if I am not mistaken, which puts it in the right ballpark. I don't think the change from swiss francs to dollars is going to be significant on such a vague calculation, but the current rate is 1SF = 86 cents US. You would need to evaluate 0.86few to actually make the conversion. SpinningSpark 14:21, 26 October 2008 (UTC)

At Fermilab (where I work) the rate has steadily improved; as of June 2008, according to this article [4] the rate in 2007 was about 20x10¹⁰ antiprotons per hour and in 2008 is 25x10¹⁰ per hour. This is about 0.4 picograms per hour or 10 picograms per day. Fermilab does not run every day of the year, but in 2008 we have probably exceeded 2 nanograms and possibly exceeded 3. I find $10¹⁷ per gram to be a reasonable guess for the cost of antiprotons, approximately consistent with the CERN estimate.

Beamjockey (talk) 22:39, 31 October 2008 (UTC)

I am just wondering about the discrepancy in the article about the cost of Antimatter. In the Artificial Production section Sub Section Cost it is referenced that it would cost $62.5 trillion per gram. Whereas in the Uses section Sub Section Fuel it is mentioned it would cost 100 quadrillion dollars to produce a gram. Obviously these figures are completely different and would confuse anyone trying to research the area.

I believe these two figures should be clarified further to lessen the confusion people may have reading this article. As I understand the CERN figure comes from actual production of Antimatter; where does NASA obtain their estimates from?

Also maybe place the CERN figure inside the Cost section as they are related.202.81.18.30 (talk) 02:34, 2 June 2009 (UTC)

New Breakthrough in Production

In an acticle on Nov 17, it states thats they have discovered a new method of creating antimatter in a laser experiment on the order of billions of particles of positrons, Billions of particles of anti-matter created in laboratory, this is the most antimatter produced with the least amount of energy input.--Crab182 (talk) 15:45, 18 November 2008 (UTC)

That's interesting stuff, they used gold but perhaps other high-Z elements like tungsten would work? Is there any discussion on the theoretical basis for this experiment? Aksel89 (talk) 11:43, 21 November 2008 (UTC)

I wouldn't suggest changing the main page based on that - similar to WP:MEDRS, news reports generally don't describe science well (though a physics-dedicated news source might), and until this has been replicated and confirmed (and reported in a peer-reviewed journal) I would consider it undue weight to put a lot of emphasis on it. WLU (t) (c) ^{(rules - simple rules)} 11:53, 21 November 2008 (UTC)

Discovery?

Who "discovered" antimatter and how? Is this real or one of those theories that scientists tell us is just as good as fact? After looking into modern scientific theory I've lost faith in the Scientific Community. This article needs specific info on how antimatter was discovered, and how it was proven to be actual. This is just a list of "facts" and features of antimatter with no real context to show how these conclusions were reached or observed. 69.3.84.236 (talk) 19:04, 5 January 2009 (UTC)

The positron article has a fairly good discussion about antimatter discovery. may be a link would suffice? To the point of your question: The existence of antimatter was first proposed by Dirac in 1928. It is believed that its first observation happened in 1930, but that was not realized at the time. The official discovery date was 1932. I hope that helped. PS don't lose faith in science. Dauto (talk) 22:54, 5 January 2009 (UTC)

Antimatter is very real. Positrons (anti-electrons) were first observed in cosmic rays 1932, antiprotons were first created artifically by colliding beams of protons in 1955, and antihydrogen atoms were first created artifically in 1995. It even has a few practical applications, such as positron emission tomography. But other possible applications such as antimatter rockets and antimatter weapons are likely to remain theoretical for the forseeable future, because they require much larger amounts of antimatter than can conceivably be produced or collected. There is an interesting quote towards the end of the article that says that all of the energy in all of the antimatter ever produced at CERN is only enough to light a light bulb for a few minutes. Gandalf61 (talk) 09:59, 6 January 2009 (UTC)

Antimatter as fuel

This bit here seems a little suspect: "In fact, the energy in a few grams of antimatter is enough to transport an unmanned spacecraft to Mars in a few minutes." Doesn't *light* take a few minutes to get to Mars? I had heard of ideas for a manned antimatter-powered ship that would take about 3 days to get to Mars; although I don't have a source for that. Kyle90 (talk) 19:25, 22 January 2009 (UTC)

Yes, very suspect. That whole paragraph was unsourced, so I have re-written and shortened it. Gandalf61 (talk) 09:35, 23 January 2009 (UTC)

Note: 1 megaton is equal to about 4.184 petajoules. 180 petajoules is therefore equal to 180 / 4.184 = 43.02 megatons. Corrected the megaton yield figure. Ilithi_Dragon 11:23, 21 September 2009

This whole section is essentially uncited and really needs to be cleaned up. I count 4 citations for 9 paragraphs... Alphachimera (talk) 22:56, 18 March 2011 (UTC)

Antimatter Production Versus Antimatter Collection/Refining

Most people would not state that Gold, or other valuable commodities are Produced. Rather, they are refined or concentrated or collected from pre-existing starting materials. The article by Bickford "EXTRACTION OF ANTIPARTICLES CONCENTRATED IN PLANETARY MAGNETIC FIELDS", which looks promising (though is far from containing ideas which I would say have been verified) indicates a scheme of antimatter concentration.

ConcernedScientist (talk) 00:55, 18 February 2009 (UTC)

Can you explain then, why "gold production" gets 537,000 ghits but "gold extraction" only gets 39,900? Of your other terms only "gold collection" gets significantly more hits but most are for a different meaning of the term, as in jewellery collection. SpinningSpark 13:40, 12 March 2009 (UTC)

"Ante matter"

Ante matter was just created as a redirect to this page. Is this really a "common misspelling or misnomer" for antimatter? Otherwise CSD R3 applies. decltype (talk) 12:38, 12 March 2009 (UTC)

I very much doubt it is a common mispelling. But in fact the article was turned into a redirect to get rid of this: Matter from other realities. Also called Exotic Particles, Z Matter, which is nonsense and the redirect is an improvement, but it does indicate that the author thinks that it is something different from antimatter. The origianl should have been AfD'd, but the conversion to a redirect is a good excuse to speedy it. In either case I agree it should be deleted. SpinningSpark 13:26, 12 March 2009 (UTC)

Yep, I was about to speedy it as nonsense, but then I noticed that exotic particles actually "exist", and in the meantime, another editor made a redir. decltype (talk) 13:55, 12 March 2009 (UTC)

Yes, exotic particles do exist, and so does the Z boson and who knows what exists in alternate realities, but none of them are (or need to be) anti-matter. SpinningSpark 14:02, 12 March 2009 (UTC)

On second thoughts, having now done a google search and got a surprising number of hits, perhaps the redirect should stay, even though a lot of those hits are from game playing sites which seem to have a concept of "ante matter" rather similar to the original article. SpinningSpark 13:57, 12 March 2009 (UTC)

Just wondering

I may be mistaken but it is my understanding that matter antimatter reactions are the only reactions that are exempt from entropy (in other words they are 100% efficient). I was wondering if this should be put in the article as it is a very interesting characteristic that has an effect on many of the applications of antimatter. Skeletor 0 (talk) 15:41, 9 April 2009 (UTC)

The statement "matter antimatter reactions are the only reactions that are exempt from entropy" doesn't strike me as being very meaninfull. If you mean that those reactions somehow avoid the second law of thermodynamics, that is incorrect. Dauto (talk) 06:03, 10 April 2009 (UTC)

But they do (I think...) They produce pure energy with no waste products whatsoever. No matter or antimatter is left (assuming there was equal amount of both to start with. Thus you get 100% of equivalent energy of those masses as described by E=Mc2. Right? Skeletor 0 (talk) 18:00, 14 May 2009 (UTC)

Seeing that half the energy released in annihilation is in the form of neutrinos, it is hard to conceive of a way of putting it to work...--Cancun771 (talk) 12:25, 4 September 2009 (UTC)

Let's go through the different formulations of the 2nd Law:

1) The change in entropy of any process is greater than or equal to zero. In the case of matter-antimatter anihilation, two slow-moving particles collide, resulting in a cascade of faster-moving (hotter) particles. No latent heat or anything like that, so entropy has increased. 2) No process exists the sole result of which is conduct heat against a temperature gradient. Even if this were happening, lots of other stuff is going on, so the heat flowing from cold to hot is not the sole result. 3) There is no process that completely converts heat into work. No work is really being produced anywhere to speak of. Nor is any heat being used. 4) There is no heat engine more efficient than the Carnot engine. The system is not even a heat engine. 5) In every neighbourhood of any state S of an adiabatically isolated system there are states inaccessible from S. Not even going to bother with this one.

Mistakes... and difficulties correcting them :(

According to this article, Tsar Bomba required the use of hundreds of kilograms of fissile material. This is nonsense - Tsar Bomba was a fusion weapon and as such, did not contain hundreds of kilograms of fissile material. The energy was from fusion, not from fission.

Later in the article, this brilliant conclusion: "But cold antihydrogen is far more difficult to produce than antiprotons, and so far not a single antihydrogen atom has been trapped in a magnetic field." Another nonsense, since you obviously can't trap a neutral atom in a magnetic field.

But worst of all, it's very difficult to actually remove such crap from wikipedia articles. If I try to delete it, it gets automatically restored. If i write a comment in the article, it gets deleted (the comment, not the nonsense). If I write a comment in the discussion, nothing happens. It took me several days to remove an obvious fraud from the radiation poisoning article (a story about natural radium mine...), now I don't even want to try again...unsigned contribution by user:80.250.238.104

fusion weapon contains a fission bomb as a primary stage or "trigger", and may also contains fissile material within the secondary stage. The "hundreds of kilograms" may be an exaggeration, though. Gandalf61 (talk) 14:35, 24 June 2009 (UTC)

Technically, less than one hundred kilograms of plutonium should have been enough for the trigger. More importantly, the article says "Tsar Bomba... reacted an estimated yield of 50 megatons, which required the use of hundreds of kilograms of fissile material (Uranium/Plutonium)." For someone who is not already competent in the subject (and that's the target audience of the encyclopedia, yes?), this phrase means that "hundrers of kilograms of fissile material" generated the yield of 50 megatons. Which is wrong.unsigned contribution by user:80.250.238.104

Pictures?

Does anyone have a picture of the small amount of anti-matter we have? I was watching a documentary about space, time and the universe, and they talked about anti-matter and showed the real anti-matter containment unit with enough anti-matter inside that could be seen with the naked eye. It looks incredible! I was looking to see if I could find an image on Google Image Search, but I got zilch. If someone has an image of the real anti-matter container with what they have in it, please please PLEASE add it to the article! Necro-File (talk) 00:50, 3 July 2009 (UTC)

I am quite sure that there has never been enough antimatter to see with the naked eye; the documentary must have been mistaken. Rapidly moving antiprotons are stored in the Accumulator[5] at Fermilab and the Antiproton_Decelerator at CERN; LEAR (Low_Energy_Antiproton_Ring), now converted to another purpose, was also at CERN. (I will try to request Fermilab to release images for use on Wikipedia.) For images of devices that store slow-moving or "cold" antiprotons, follow links from ATHENA, ALPHA_Collaboration, and ATRAP. The first trap for cold antiprotons was created by G. Gabrielse's collaboration in 1986.[6] One could also find tracks left by antiprotons or other antiparticles in film, bubble chambers, etc., but antiparticles themselves are much too small to see directly.Beamjockey (talk) 00:29, 8 July 2009 (UTC)

I strongly suspect you're right, but I can't rule out the possibility that a very tenuous plasma was trapped that gave enough of a glow to show up on a long-exposure photograph. Moot point, of course, as unless there's a reference, it doesn't go into the article. --Christopher Thomas (talk) 04:22, 8 July 2009 (UTC)

Well, they did say they only had a few nano grams of it, but in the documentary it did show the containment unit and something inside that was an odd luminescent blackish-blue color. I don't suspect it was a recreation of it, because I have never seen anything quite like that before or since, even in science fiction. But I do have a new question about it; if we had enough to actually be visible without a microscope, are antimatter particles even visible to the human eye? 75.6.176.201 (talk) 01:49, 18 July 2009 (UTC)

Amounts produced so far are much less than nano-grams. Inside a plasma containment chamber you'd see a faint pinkish or purplish glow, similar to what's shown in the right hand part of this picture (a photo of the Joint European Torus fusion reactor).

If antimatter was cooled to room temperature, and you had macroscopic amounts of it, it'd look exactly like ordinary matter. The charges on the particles within it are reversed, but it'd still have the same structure of molecular and atomic energy levels and would interact with light in exactly the same way. --Christopher Thomas (talk) 06:33, 18 July 2009 (UTC)

Matter - Antimatter balance

I see innumerable statements that matter and antimatter are unbalanced, I've seen plenty of arguments that they must balance, I've never seen any discussion of how they could become unbalanced, I've never seen any strong evidence that they are unbalanced (except locally), and all the discussions on related topics imply that any imbalance would be mostly undetectable. So why do we have the statement here, and if we must, could we please provide a cite of evidence (and not just a cite of a talking head)?

Balance: Equal amounts created at Big Bang CERN: AMS.

Can't be unbalanced: two ways to get rid of antimatter: annihilation and black holes. Annihilation gets rid of matter as well, we'd have noticed. Preferential deposition into black holes is possible, but why? What's the reasoning?

Detection: Since the spectral band of antimatter (see Antihydrogen) is identical to that of matter, and since photons are antiphotons, the only way to distinguish remote antimatter galaxies, quasars, etc, is bridging and "cosmic rays". In cosmic rays only the larger (alpha) particles count because anti-protons are a common result of a matter cosmic ray striking other matter like the atmosphere or the interstellar medium.

If you collide a galaxy against an anti-galaxy you get an annihilation surface which generates immense photonic pressure which will tend to push the galaxies apart. Agreed we don't know that we have ever detected these. But the result would be either all energy or one would remain much reduced, or a galaxy / anti-galaxy pair moving apart. In a galaxy cluster the anti-galaxy will eventually be destroyed or ejected. One could say that there is a natural tendency for matter and antimatter to be separate. However there are many vast (maybe) empty spaces between clusters of galaxies and therefore bridging is unreliable.

Finally the "
p
A →
p

p

p
A" process for generating antiprotons (see Antiproton) in the interstellar medium is indistinguishable from the "
p
A →
p

p

p
A" mechanism even in our own galaxy (as far as newly created
p

p
pairs are concerned). Assuming we are located in a matter cluster we would expect the second equation to be invoked less than the first, but correlation with observation is achievable since the cosmic proton flux is a derived value anyways.

Pretty much the only conclusion compatible with the Big Bang and observation is that matter and antimatter are present in equal amounts and partitioned into disjoint regions of the cosmos and this seems to be the actual view of modern science. 76.126.215.43 (talk) 18:39, 9 July 2009 (UTC)

You state yourself why we'd notice if half the mass in the unverse was antimatter: we'd see annihilation gamma rays everywhere from the boundaries between regions. Despite having many gamma ray telescopes in orbit over the years, we haven't seen this, and they're very, very noticeable (a sharp spike at 511 keV from electron/positron annihilation).

As for why more matter was produced than antimatter, you can read more about this at baryon asymmetry. Long story short, while the laws of physics seem to be CTP-invariant (acting the same when you swap matter and antimatter and run time backwards), they aren't CP-invariant (acting the same when you just swap matter and antimatter). We know of processes that work differently depending on whether matter or antimatter is involved, and most astronomers and physicists believe that asymmetric processes of this type (though not the low-energy ones we've studied so far) are responsible for the imbalance.

The web page you link does not claim to represent the "view of modern science". It's one person giving an unusual take on a particle detection satellite (the Alpha Magnetic Spectrometer). The purpose of this satellite is to study the compositions of cosmic rays, looking for anything unusual. Quite a lot of cosmic ray components will be antimatter, but not because the universe is made of the stuff: it's because the processes that produce high-energy cosmic rays are energetic enough to produce both matter and antimatter from thin air. Cosmic rays also produce antimatter (and matter) when scattering off of anything they hit. The resulting particles are called "secondary cosmic rays".

I hope this clarifies the situation for you. --Christopher Thomas (talk) 04:35, 10 July 2009 (UTC)

Update: the baryon asymmetry article is a stub, and barely mentions the CP-violation arguments. The baryogenesis article has a much more detailed discussion. --Christopher Thomas (talk) 02:09, 11 July 2009 (UTC)

Just as an inquiry, there is talk on the article of the universe containing more (at least visible) matter than antimatter, and that this poses a physics problem. Is it not possible though that since antimatter for all intents and purposes appears the same as matter, that there are large portions of the galaxy that are composed of antimatter and are simply divided from the matter portions by vacuum? In which case there would be no reactions between the two to observe? I mean we've only been watching the galaxy for less than a nanosecond of time in relation to it's total age, so is it not conceivable that any areas of matter and antimatter that weren't divided by vacuum have long ago annihilated each other? Livingston 15:59, 22 July 2009 (UTC)

We aren't seeing any sharp dividing lines between regions of the universe. Instead, galaxies and dust clouds seem to be distributed in a mesh of interconnected filaments. We'd really notice if even small regions of matter and antimatter were in contact, for reasons described above. --Christopher Thomas (talk) 19:52, 22 July 2009 (UTC)

Nevertheless the main article must contain at least one sentence on this matter, maybe with reference to baryon asymmetry article for detailed discussion. As a Wikipedia consumer I was interested if in the last years any effect has been discovered allowing the distant antimatter galaxies distinguishing and respectively proving the antimatter lack in the visible universe. Intuitively I open the Antimatter article and found answers, but in the talk page. In my opinion adding some of the above phrases to the main article will improve its quality. Dobrichev (talk) 00:10, 25 November 2009 (UTC)

Costs

Can someone clear this up? One part says it costs $60 trillion (???) per gram, near the bottom it says they can now do it for $25 million per gram.

Very confusing —Preceding unsigned comment added by 70.67.26.95 (talk) 21:48, 3 August 2009 (UTC)

Science Fiction?

Why is Antimatter in the Wikiproject Science Fiction. I did notice anything in the article to indicate that its Science Fiction. Neosiber (talk) 13:05, 11 September 2009 (UTC)

There used to be a science fiction section but it was unilaterally deleted. SpinningSpark 01:27, 12 September 2009 (UTC)

Arguably it would be better to put this sort of thing at an antimatter in fiction or antimatter in popular culture article, and just link it from this one. Properly sourcing an "...in fiction" or "...in popular culture" article in a way that establishes notability of the examples used is a royal pain, though it should be possible for a concept like this one. --Christopher Thomas (talk) 05:54, 12 September 2009 (UTC)

I don't have much interest in writing such an article, but the deleted content [7] was well sourced. However, this was only created by me when I deleted the random collection of unsourced content [8] in order to have a good benchmark for deleting future unwanted additions. If you are thinking of writing this article, there is more sourced content mentioned in the discussion at the top of this page. SpinningSpark 10:35, 12 September 2009 (UTC)

I don't have the time to write such an article myself, unfortunately (that's also why I handed off interstellar travel in fiction). The issue with sources is that they should demonstrate notability, not just demonstrate that antimatter was a plot point in the fictional work. In a nutshell, in order to keep an "...in fiction" or "...in popular culture" article, you'd have to show that 1) the concept in question strongly influenced fiction and/or popular culture as a whole, and 2) the examples you were using in the article were the most influential/relevant/important ones. It's possible I'm misunderstanding the guidelines, but this is what I'd be looking for if I was the one evaluating the inevitable AfD of such an article. I touched on this more at talk:interstellar travel in fiction. I should probably post an essay about it, so that I can just refer to that instead. --Christopher Thomas (talk) 16:06, 12 September 2009 (UTC)

Did you actually read any of the material I wrote before you decided to go down the teaching grandma to suck eggs route? Yes it was notable in the way you define as well as being sourced. Why are you telling me this, I already said I don't want to write an article; it was you who suggested an article, I was merely giving you what I thought was helpful information. SpinningSpark 18:28, 12 September 2009 (UTC)

First, please assume that I'm trying to be helpful, rather than lashing out at me. Second, your edit described milestones in the treatment of antimatter in fiction (point 2), but didn't reference why they were significant to science fiction as a whole (point 1). This is a great start, but it's still hard to make an ironclad case for keeping it in. To clarify, I'd keep your section in if editing myself, but since neither of us seems to feel strongly enough about it to revert the deletion or spin off a secondary article on fictional use and defend it against AfDs, it looks like it's in limbo. Do as you see fit; I'm probably going back on sabbatical. --Christopher Thomas (talk) 18:56, 12 September 2009 (UTC)

Coining of term

Some seem to claim that Arthur Schuster coined the term antimatter, but my reading seems to indicate that he called his postulated material "potential matter", and that it was Dirac who used the anti- prefix. Does anyone know? Dbfirs 02:16, 3 October 2009 (UTC)

Citations of the Schuster letters and to Dirac's letters on the subject would help. There's at least one library in the city where I should be able to find them, and maybe a couple of others. --Christopher Thomas (talk) 06:42, 3 October 2009 (UTC)

Thanks, that would indeed settle the matter. The topic arose recently because of an enquiry at the Science Reference Desk where there is disagreement. Dbfirs 07:34, 3 October 2009 (UTC)

Don't thank me yet; someone still has to dig up the full citations for these articles so that I can try looking them up. I don't plan to make the field trip until I know what I'm looking for :). --Christopher Thomas (talk) 07:52, 3 October 2009 (UTC)

This is (editor)Edison's research: "Google Scholar has a source stating that the term "antimatter" was coined by Sir Arthur Schuster in 1898, and as support offers a website. This in turn cites "Quantum Generations: A History of Physics in the Twentieth Century" by Helge Kragh, Princeton University Press, 1999, and links to the publisher's website, which is the source for the Schuster 1898 credit. I could not find at Google Book search an 1898 publication by Schuster. Schuster was the predecessor of Rutherford as Langworthy Professor, supported Einstein's Special Relativity in lectures in 1908. He was vice president of the Royal Society 1919-1920). He lived until 1934 and published a fair amount, so his coining of the term, even in a period before Dirac's theories, might have been known to the next generation of physicists."

The OED records the first usages of "anti-matter" in 1953 (in the NY Times on October 23rd, and slightly earlier in "Sci. News Let." on March 14th). This was a logical development from Dirac's 1931 usage of "anti-electron". In his letters (Nature, 58, 367 (18 August 1898) Schuster uses the term "Potential matter" and in another letter in the same year he seems to have credited the term "negative matter" to Karl Pearson. I don't know if this helps. Dbfirs 08:30, 3 October 2009 (UTC)

I am not sure I understand the problem here. The article claim is sourced to Edward Robert Harrison, Cosmology: the science of the universe who quotes Schuster on p.266, and again on p.433, as saying "Astronomy, the oldest and most juvenile of the sciences, may still have some surprises in store. May antimatter be commended to its care!" and sources this to;

• Schuster, A. "Potential matter: a holiday dream", Nature 58, 367 (August 18, 1898).

Is the objection that Harrison has misquoted Schuster or that Schuster's use of antimatter does not count as coining? Or maybe every one else did not read the ref? SpinningSpark 10:37, 3 October 2009 (UTC)

The question was whether Schuster ever used the word. Obviously he discussed the concept. Have you found an actual usage of the word in Schuster's letters? Dbfirs 16:26, 3 October 2009 (UTC)

Now you have really confused me. Harrison quotes Schuster. The quote contains the word antimatter. QED Schuster used the word. ...unless Harrison is lying, and there is no reason to think that he is. Easily resolved if someone has access to the Nature article by Schuster linked above which is where the quote comes form. SpinningSpark 18:53, 3 October 2009 (UTC)

Also quoted here [9] and a full version of the letter reproduced in this [10] document (German). SpinningSpark 19:13, 3 October 2009 (UTC)

Apologies, and thanks. From previous links, I was able to see only "Potential matter" used by Schuster, and rejection of the coinage by others caused me to doubt (wrongly) the Harrison quote (I thought he might have substituted the modern term). Thanks for clearing this up. I wonder why the OED, and others, have discounted this first usage. Dbfirs 05:29, 4 October 2009 (UTC)

If I have time, I'll check the 1898 hardcopy next weekend, just for due diligence. Toronto Reference and Gerstein each might have it. I'm pretty sure that the concept Schuster was applying the term to isn't quite what Dirac's paper (and later physics) described, so this distinction should probably be made clearer in the Wikipedia article. --Christopher Thomas (talk) 06:42, 4 October 2009 (UTC)

I think it is also probably wrong to say that "potential matter" is Schuster's term for antimatter. He seems, rather, to use potential matter in the sense of the possibility of creating matter/antimatter out of nothing. Could you check up on this point also if you visit the library (I was mistaken that Markert has the full letter, a more careful reading shows it to be only excerpts) SpinningSpark 07:21, 4 October 2009 (UTC)

Schuster articles, other articles, and negative mass

I've gotten photocopies of both of Schuster's letters from the Toronto Reference Library. They seem to be out of copyright (definitely in the UK, where they were published, and almost certainly in the US due to their pre-1923 publication date), so I've uploaded medium-resolution scans of the photocopies:

• First letter, mentioning antimatter by name
• Second letter, referencing other works, page 1
• Second letter, referencing other works, page 2

I suggest looking at them soon, because even with clearly expired copyright, the US Wikipedia tends to err on the side of caution and remove scans of published works. If anyone has an account at one of the European Wikipedia instances, I encourage transferring the pictures there (copyright still ends 70 years after the authour's death over there if I understand correctly, and Schuster died in 1934).

Regarding content of the articles, the main one (the first one) is explicitly flagged as a speculative piece (written while on a holiday). In it, Schuster references an existing idea that gravity is due to an incompressible fluid (aether) flowing out of all atoms (referencing a paper by Maxwell, which in turn quotes Kelvin as making the suggestion). He then proposes the idea of a different type of atom that acts as a sink rather than a source of this fluid, but that is otherwise identical to normal atoms. This corresponds to the modern idea of particles with negative mass, but he applies the term "anti-atoms" to these atoms at several points in the article, and "anti-matter" to objects composed of such atoms at another point. Most of the rest of the article is devoted to conjectures that the existance of such negative mass atoms may solve astrophysical problems of the time (the origin of comet tails, the lifting of solar prominences against gravity, and the net angular momentum present in star systems given a presumed-zero total angular momentum of the matter from which they formed).

The most interesting parts of the article are discussions about mixtures of normal atoms and "anti-atoms". As gravity is weak compared to electromagnetism, he noted that they could form chemical bonds normally, and that the resulting mixed matter would have peculiar properties. He suggested that comets were mixed matter of this type, with the negative-mass component pushed away by the sun's gravity as the comet approached the sun, forming the tail. He also noted that a 1:1 mixture of bound matter/"anti-matter" would have zero net gravitational mass. How this would affect inertial mass was unclear, but he noted that if this also meant it had zero inertial mass, you'd be left with matter with "none of the attributes which characterise matter" (sic). He called this unobservable, massless, inertialess substance "potential matter", having "potential mass" akin to the more conventional "potential energy". If the mixture was disturbed in a way that broke the chemical bonds, you'd end up with the matter components clumping and being drawn towards other regions dominated by normal matter, and with the "anti-matter" components clumping and repelled to distant regions dominated by negative-mass matter (this idea has been revisited in more recent speculations about negative-mass exotic matter).

The only reasons I'd consider this "anti-matter" concept to be analogous to the present use of the term "antimatter", rather than exclusively referring to what we'd now call "exotic matter", are that 1) he touched on the idea of quantum numbers summing to zero, though this predates any formal concept of quantum numbers, 2) in paragraph 4, he makes mention of an idea similar to parity transformationtime reversal ("If matter is essentially dynamical, and we imagine the motion within an atom to be reversed, ...").

In practice, I think this letter would be relevant to reference both here and at exotic matter; just with a much shorter note here (pretty much saying that he was applying the term to what we'd now call exotic matter with negative mass).

Regarding the content of the second article, it's a response to other letters that pointed out that others had come up with the idea of matter with negative mass before him (one with explicit reference to aether, one by extending Newtonian gravity to behave more like electromagnetism). Tracking down some of these other references might also be a good idea, as they'd be worth citing at the exotic matter article. I haven't heard of the term "anti-matter" being used in any of these previous articles, but I hadn't heard about Schuster's use of the term either. I don't plan to do the literature search for this, but if anyone sends a list of citations my way, I can probably track down the articles in question. --Christopher Thomas (talk) 23:16, 7 November 2009 (UTC)

Thinking about it, time reversal, not parity transformation, is probably what Schuster meant by "the motion within an atom [being] reversed". There wasn't much of a concept of atoms having internal structure at that point, and he'd already referred to an outflow of moving fluid from atoms. A reversal, producing inflow, would best be described as a time reversal in modern terms. Still vaguely analogous to matter/antimatter symmetry (under CPT symmetry, antimatter can be thought of as matter with either charge and parity reversed, or time reversed). --Christopher Thomas (talk) 23:56, 7 November 2009 (UTC)

I would have thought that could go to Wikisource, although it is not a project I have ever had much to do with. SpinningSpark 00:18, 8 November 2009 (UTC)

I haven't touched it at all, so you're more familiar with it than I am. If you feel that's a good place to put it, by all means do so (or bring it to the attention of one of the regulars there so that it can be moved). My main concern is that it should be put in a repository where it's very clear that the laws of that repository's country have it in public domain. --Christopher Thomas (talk) 04:56, 8 November 2009 (UTC)

Antimatter...

I'm NOT Hawking, Kaku...or Sagan.

But I read, re-read, re-re-read and look-up things I do not, cannot comprehend.

Fascinating stuff though!

Adds to Dan Brown's "Due-Dilligence", when he wrote "Angels & Demons"!

He is a SUPERIOR write! —Preceding unsigned comment added by Mccormickbom (talk • contribs) 19:03, 12 January 2010 (UTC)

Hypothesis

I put forward a hypothesis - the centre of kernels of "hot" planets and stars always is the antisubstance (antimatter). The radiation arising in the course of operated annihilation - copes strong gravitation and pressure (i.e. the antisubstance is in a hover in the kernel centre) is extinguished by nuclear/thermal reaction by the top layers of a kernel. The second hypothesis - between antisubstance and substance occurs strong gravitational interaction - pulling. The third hypothesis - between antisubstance carried on distance - strong interaction of pushing away.

Dmitry I. Goldobin d_i_g@list.ru —Preceding unsigned comment added by 217.116.52.162 (talk) 14:03, 14 January 2010 (UTC)

Did Dirac really predict the positron?

This article, and several others, states as fact that Dirac's 1928 paper predicted the possible existence of an anti-electron. In the case of this article, the statement is worded, "The modern theory of antimatter begins with a paper by Paul Dirac in 1928 who realised that his relativistic version of the Schrödinger wave equation for electrons was predicting the possibility of anti-electrons." In the article Positron, I have recently re-worded this based on my own reading of the paper. I realize this is problematic under WP:PRIMARY. I'm looking for help on this topic, because to the best of my ability, it seems to be a myth that Dirac actually predicted the existence of anti-matter. He was definitely aware there was something odd going on in his math, but he described it as "difficulties" that were "unresolved". If we can show with reliable sources prior to Anderson's actual discovery that he or other physicists thought that paper was predicting anything like a positron, I would be convinced. I am tempted to reword here and elsewhere, but I would like to discuss here before doing anything controversial. See also the discussion on the positron page. CosineKitty (talk) 18:39, 24 January 2010 (UTC)

CosineKitty's questions may be resolved by consulting Laurie M. Brown's excellent paper "Prehistory of the Antiproton Discovery"[11] as a guide to the primary literature. (There may be even better sources, but this is one I happen to have read, and Brown is a prominent historian of physics.) It is true that Dirac did not "predict the anti-electron" in his 1928 paper; he wrestled with the implications of his "holes" for some years, thinking that they might be protons, then abandoning the idea. Brown quotes a 1931 article in which Dirac finally suggests the name "anti-electron" for "a new kind of particle... having the same mass and opposite charge to the electron." Carl Anderson had not read Dirac's work, but when he reported a positively charged particle, others recognized it as Dirac's anti-electron. Brown's article might help you to craft a more accurate phrasing to describe this discovery process. Beamjockey (talk) 20:39, 26 January 2010 (UTC)

Thanks, Beamjockey! That's exactly the sort of thing I am looking for. CosineKitty (talk) 21:48, 26 January 2010 (UTC)

annihilation

Is the process by which this occurs understood? Was it anticipated before it was observed experimentally?

In order for the conversion to energy to occur, must a particle meet its antiparticle or would, say, a positron react with an antiproton?--Jrm2007 (talk) 19:28, 18 May 2010 (UTC)

"Conversion to energy" is a misleading (albeit common) description. What happens is that the particle/antiparticle pair is converted to a different collection of particles, usually lighter, and usually also containing photons. Conversion of elementary particles into different elementary particles is very common, with radioactive beta decay being the most easily observed example. All that's required is that the total energy (rest mass plus kinetic energy) and certain quantum numbers describing the nature of the collection of particles involved stay the same. Some conversions, like the conversion of a "down" quark to an "up" quark (plus electron plus antineutrino) in beta decay, happen slowly. Antimatter annihilation reactions happen much more quickly (because those conversions don't require the involvement of the weak nuclear force).

Conversion of an electron/positron pair to photons can happen, because the endproducts have the same total energy, the same charge, the same total momentum, and so forth. A positron and an antiproton wouldn't interact (any more than an electron and a proton would). An electron and an antiproton also wouldn't interact (at low energy), because together they have a net electric charge of -2, nonzero baryon number, and nonzero lepton number. There isn't anything lower-energy for them to be converted into that also has these values (photons have zero charge, zero baryon number, and zero lepton number).

As for being understood (beyond "yes, particles can do that"), the usual way of describing it is to consider interactions of the particles involved with a sea of virtual particles, but other descriptions exist. The exact nature of the description depends on the mathematical tools are used to construct it. --Christopher Thomas (talk) 19:55, 18 May 2010 (UTC)

Thanks for your answers -- but did Dirac, for example, foresee the interactions of matter and antimatter? BTW, I actually saw Dirac in person once.--Jrm2007 (talk) 21:12, 19 May 2010 (UTC)

How much he thought about it/wrote about it depends on whether he considered "holes" in the electron sea real, or at least interesting enough to publish about. Check his papers from shortly after the creation of the Dirac equation to find out. My guess is that he did consider the possibility of recombination of electron/"hole" pairs, but I'm not sure what he would have predicted the consequences of such recombination being (beyond the electron and positron vanishing). A literature search should turn up the answer to that.

After antimatter was actually observed, of course, the mechanisms for annihilation were very quickly understood. --Christopher Thomas (talk) 07:16, 20 May 2010 (UTC)

He was certainly aware of the possibility of pair creation and annihilation in his Nobel lecture of 1933. However, by this time, experimental evidence was starting to come in, so it might have been a bit of both theory and experiment. SpinningSpark 09:26, 20 May 2010 (UTC)

Edit request from Jasielo, 22 May 2010

{{editsemiprotected}} Hey I have noticed a typographical/grammatical error in this antimatter article. The error lies under the HISTORY OF THE CONCEPT, third paragraph, first sentence. I think what you meant to say was REALIZED instead of REALISED. For the most part, this was an amazing article.

Jasielo (talk) 02:02, 22 May 2010 (UTC)

Actually, realised is the accepted British spelling of the word. There doesn't seem to be a preferred style on the article, so I've just left it as-is since Dirac was British. ~ Amory (u • t • c) 04:06, 22 May 2010 (UTC)

Arthur Schuster

I followed the link to the Arthur Schuster bio wherein it is said that in 1898 Schuster postulated that if antimatter and matter met, energy would result. Is this true? Years before the equivalence of matter and energy was published?

What would have made someone imagine this at that time?--Jrm2007 (talk) 06:54, 25 May 2010 (UTC)

This is discussed above, at Talk:Antimatter#Coining of term. I obtained photocopies of Schuster's articles about "potential matter" at a local reference library. Scans of these are linked from the thread I indicated (they're out of copyright in most jurisdictions, including the US if I understand correctly). --Christopher Thomas (talk) 07:21, 25 May 2010 (UTC)

Cleanup needed

I added a {{cleanup}} and several other tags to the Antihydrogen section. Reasons and selected extracts are:

{{cleanup|reason=above paragraphs read well but remaining have problems: lack of citations; unhelpful "stated above" - where exactly? "no known way to store" - vague and uncited, better would be "as of 2010 scientists can keep antihydrogen within the instrument for only x ms";}}

Another limiting factor to antimatter production is storage.{{Clarify|date=June 2010|reason=reword to precisely explain meaning of storage: half-life of antihdrogen remaining in chamber?}}

Hydrogen atoms are the simplest objects that can be considered as "matter" rather than as just particles.{{Citation needed|date=June 2010|reason=cite needed; who considers this? What definition of matter is meant? Matter has "no single correct scientific meaning". Positron-electron exotic atoms? What is simplest? Lowest mass baryonic matter?}}

-84user (talk) 15:26, 11 June 2010 (UTC)

Interpretation of Antimatter

Although annihalation is mentioned, this article does not discuss the interpretation of antimatter as matter traveling backwards in time. But from my reading, that is clearly the most common interpretation of what antimatter actually is. I would like to hear others' thoughts on this. Although I am not the most qualified to write on this subject, I will attempt to add this section if no one else does. My references include several articles online and the book "Deep Down Things" by Bruce A. Schumm. —Preceding unsigned comment added by 70.187.148.145 (talk) 19:07, 24 July 2010 (UTC)

Actually I found it mentioned under The Feynman-Stueckelberg interpretation in the Antiparticle article. Can't these two articles be consolidated? The The Feynman-Stueckelberg interpretation should be mentioned in this article as well, in more detail. —Preceding unsigned comment added by 70.187.148.145 (talk) 19:12, 24 July 2010 (UTC)

Straw poll: positron vs anti-electron

The lede has been switching back and forth between "positron (also called antielectron)" and "antielectron (also called positron)" for quite some time now. In an attempt to settle the issue, I'm starting a straw poll. Straw polls are a non-binding tool for measuring consensus. If no consensus exists, then it'll be time to start a (binding) content-RFC with wider community involvement, but hopefully a consensus will emerge with just the straw poll.

Please indicate which of the following versions of the lede's phrase you consider most appropriate (or abstain, or suggest an alternate version, or what-have-you):

a) For example, an antielectron (also called a "positron") ... (most recently used by User:Headbomb)

b) For example, a positron (also called "antielectron") ... (most recently used by User:ShadeofTime09 and User:Teacherbrock)

Endorsements

• Endorse positron (version b). I hear the term "positron" used frequently, I see it frequently in textbooks, and I see it frequently in academic papers. I see "antielectron" far, far less frequently. --Christopher Thomas (talk) 21:29, 13 August 2010 (UTC)
• Endorse positron - much better known. Casliber (talk · contribs) 21:40, 13 August 2010 (UTC)
• Endorse positron - this is the most widely-used term. If we want to emphasise the point that it is antiX+antiY=antiZ (per the edit summary of User:Headbomb's version), how about something along the lines of "For example, the anti-particle of the electron, called the positron or antielectron, and an antiproton can form an antihydrogen atom..." Icalanise (talk) 21:47, 13 August 2010 (UTC)
• Endorse "positron". When it's helpful for clarity, "positron (antielectron)" is also good...here antielectron is used more as a description instead of as a terminology. In Icalanise's example, I would prefer "For example, the antiproton and the positron (antielectron) can form an antihydrogen...". --Steve (talk) 22:50, 13 August 2010 (UTC)

Endorse b). Xxanthippe (talk) 22:51, 13 August 2010 (UTC).

• Positron is the name, antielectron is the description. So use Positron when you would use the particle name. --Falcorian ^(talk) 23:32, 13 August 2010 (UTC)
• Positron is the name by which it is almost always called. (Joking: Or how about we call the electron an anti-positron; or call the positron an anti-negatron while the electron is called negatron (this name was really used sometimes)). JRSpriggs (talk) 23:45, 13 August 2010 (UTC)
• Endorse "positron". We've got to keep one primary name for that particle, and antielectron can't be used for solid state physics and most beam-related articles (e.g. "positron annihilation" is a fixed expression there). As Falcorian mentioned, antielectron (if used) is mostly used as a descriptor, a rare synonym, not the name. Materialscientist (talk) 23:50, 13 August 2010 (UTC)
• If we're going back to inferior nomenclature, at least let's go with Icalanise's version as so to not confused people. Headbomb {talk / contribs / physics / books} 00:04, 14 August 2010 (UTC)
• Couldn't care less leaning towards positron. SpinningSpark 01:00, 14 August 2010 (UTC)

• Endorse antielectron. While positron is by far the most common term, the sentence needs to emphasize the "antiX+antiY=antiZ", and we need to clarify that it is positron the common name for what is an antielectron, not viceversa. Icalanise wording is a nice attempt to compromise but it is awkward: "anti-particle of the electron" = "antielectron". --Cyclopia^talk 13:54, 15 August 2010 (UTC)
• What about "a positron (the antiparticle of the electron)"? A. di M. (talk) 15:26, 18 August 2010 (UTC)
• Endorse A. di M.'s proposal. This agrees well with Falcorian's comment that positron is the name and anti-electron is its description. The extra four words are in this case worth it in my opinion. TStein (talk) 21:40, 18 August 2010 (UTC)
• Endorse positron. All the text bopoks that I have seen when I am teaching use the word positron. Nobody seems to have come up with any current reliable sources using the word anti-electron, nor has anyone given any indication that there is any move in either the industry or accademia towards using the name anti-electron in place or positron. As Falcorian mentioned, antielectron (if used) is mostly used as a descriptor, a rare synonym, not the name. Martinvl (talk) 15:04, 24 August 2010 (UTC)

Comments

• I would prefer avoiding the use of parentheses, they interrupt the flow of a sentence. But I would not regard them as a showstopper. Icalanise (talk) 19:15, 20 August 2010 (UTC)

  But the other option would be commas, which makes the sentence slightly harder to parse. What about dashes? "A positron – the antiparticle of the electron – and a ...", or "The antiparticle of the electron – called a positron – and a ..." A. di M. (talk) 08:29, 21 August 2010 (UTC)

• I don't understand why do we have to say "the antiparticle of the electron" when just "antielectron" would suffice. --Cyclopia^talk 20:15, 20 August 2010 (UTC)

• Well at that point in the article we haven't really introduced the idea that the antiparticle is given the name of the normal particle prefixed by "anti"... we basically throw in terms like "antiproton" or "antielectron" with no explanation. Icalanise (talk) 21:37, 20 August 2010 (UTC)

These aren't terms that need any explanation for even aunt Jenny to understand that the antiproton is formed of "anti" and "proton" and so must be the antiparticle of the proton. The etymology is quite obvious especially giving the context. It's not as if a reader will be confused "oh, I thought antiprotons and antielectrons were a type of ants". Headbomb {talk / contribs / physics / books} 08:51, 21 August 2010 (UTC)

Well of course it is obvious if you've been dealing with particle physics for ages and ages. Your point that a reader might think these terms are ants is a classic example of a strawman argument. Icalanise (talk) 10:25, 21 August 2010 (UTC)

• Because its name isn't antielectron (which has zeronine occurrences in the Corpus of Contemporary American English for either the singular or the plural, compared to 182 of positron and 100 of positrons). (Some people have called it that way, but it's a very minoritarian usage.) A. di M. (talk) 08:24, 21 August 2010 (UTC)

Things can have more than one name. Antielectron is one of them. Positron is another. We are free to chose whichever is the clearest (in this case, antielectron).Headbomb {talk / contribs / physics / books} 08:33, 21 August 2010 (UTC)

And there are several hits in that Corpus for "antielectron", from Science News, Physics Today and Natural History. Headbomb {talk / contribs / physics / books} 08:42, 21 August 2010 (UTC)

Weird, if I search for antielectron or antielectrons singularly it finds them but if I search for [antielectron] it finds neither... In any event, using very unusual names (in this case, more than 30 times as rare as the more common one) is not a good idea. I'm quite sure than if I referred to an electron as a negatron I'd be instantly reverted. A. di M. (talk) 09:16, 21 August 2010 (UTC)

In Our Time

The BBC programme In Our Time presented by Melvyn Bragg has an episode which may be about this subject (if not moving this note to the appropriate talk page earns cookies). You can add it to "External links" by pasting * {{In Our Time|Antimatter|b00808w8}}. Rich Farmbrough, 02:59, 16 September 2010 (UTC).

Edit request from Rafael.ferragut, 24 September 2010

{{edit semi-protected}} I am interested to add two Websites about antimatter:

• Website of the AEgIS: Antimatter Experiment: Gravity, Interferometry, Spectroscopy, CERN
• Website about antimatter (positrons, positronium and antihydrogen). Positron Laboratory, Como, Italy

Thank you. Regards Rafael Ferragut Rafael.ferragut (talk) 11:02, 24 September 2010 (UTC)

Not done: While perhaps good as sources, the add nothing more to the external links list. Check WP:EL. SpigotMap 13:10, 24 September 2010 (UTC)

Exactly what is anti-matter made of?

In the article as it is today it is never precisely said what anti-matter is; it is simply said that antimatter is the negative of matter; which is anything that has volume and occupies mass? But to a non-technician that really doesn’t make sense (if something has no mass, then where is it)? It might be a good idea to write in background info on physics in general, and clarify the nature of antimatter. theBOBbobato (talk) 22:01, 5 June 2011 (UTC)

The first sentence of the article is "In particle physics, antimatter is the extension of the concept of the antiparticle to matter, where antimatter is composed of antiparticles in the same way that normal matter is composed of particles." That is perfectly clear and it does not say that antimatter is the negative of matter (other than in the history section where older, discredited, ideas are discussed) nor does it say that antimatter has no mass - which is simply wrong. The second sentence of the article goes on to describe an example of an antiparticle, the positron, which is like an electron but with opposite charge. However the mass is the same. SpinningSpark 22:20, 5 June 2011 (UTC)

There is no intrinsic difference between matter and anti-matter. They just happen to be made of particles that happen to have some of their properties opposite to each other. For instance, matter contains electrons which have negative charge while anti-matter contains anti-electrons AKA positrons which happen to have positive charge. The important point is that positrons are indeed required to exist by an underlying symmetry of nature that requires that for every particle there must exist another particle with some of its properties (such as electric charge) reversed. Dauto (talk) 16:42, 7 June 2011 (UTC)

Abundant source discovered!

See [12]. This information should be added to Natural production section and perhaps also to the Fuel section because of its implications. --93.139.143.215 (talk) 15:38, 7 August 2011 (UTC)

The article doesn't say it's an abundant source in an absolute sense, only that it is the most abundant source. Which basically means, larger than zero. Looie496 (talk) 16:22, 7 August 2011 (UTC)

Taking a quick read of the paper itself, it's talking about antimatter produced by cosmic ray showers being trapped in the magnetosphere. This is indeed worth mentioning in the "natural production" section. The paper itself doesn't talk about using that as a fuel source (that's just the press article).

Regarding the absolute amount present, back of the envelope calculations give about 0.1 ng or less, in the entire belt. Its source is cosmic ray events, with a flux of stored antiprotons about 1000 times greater than the flux of generated antiprotons, so once you drain it, it'll take quite a while to recharge. By comparison, a 1 MW antiproton production plant would take about a day two minutes to produce 0.1 ng of antiprotons (at the best proposed efficiency of 1e-4; normal efficiency is more like 1e-6, taking about 3 months 3 hours).

So, long story short, I wouldn't get excited about this as a fuel source. --Christopher Thomas (talk) 20:53, 7 August 2011 (UTC)

Are you sure about your antiproton plant production numbers? According to the numbers in this article, CERN would need 10 years to produce 0.1 ng of antiprotons... --Roentgenium111 (talk) 21:55, 7 August 2011 (UTC)

CERN isn't a dedicated antiproton production plant. The usual efficiency quoted for factory proposals is about 1e-6, with best-possible efficiency for a plant that exploits resonance and what-have-you as much as possible quoted as about 1e-4, if I'm remembering correctly. That said, I did mess up the calculation. 1e6 W times 1e5 seconds times 1e-4 efficiency, divided by 1e17 J/kg, gives 1e-10... kg. For 1e-10 g (not kg), it'd take about 2 minutes at 1e-4 efficiency, or about 3 hours at 1e-6 efficiency. I've corrected the values in my previous post.

That said, all of this is handwaving until someone actually builds a dedicated antiproton synthesis plant and measures its efficiency. --Christopher Thomas (talk) 23:26, 7 August 2011 (UTC)

Elsewhere on the page, I gave Fermilab's rate as 10 picograms per day, so Fermilab's (non-handwaving) antiproton facility would generate 0.1 nanograms in about ten days. It will be turned off about 54 days from now; when the Tevatron is shut down, as I understand it, there will be no reason to manufacture, cool, and store further antiprotons. Beamjockey (talk) 03:46, 8 August 2011 (UTC)

This 2007 Centauri Dreams post quotes (in a comment down the line by the admin) a report (p. 12) that there is a total of 160 ng of antiprotons in the Earth's belt. (Presumably based on theoretical data alone.) And it claims that this antimatter could be harvested "5 orders of magnitude less expensive" than the usual artificial production, at a rate of 25 ng per day. --Roentgenium111 (talk) 14:59, 10 August 2011 (UTC)

Request semi protected edit

"This was longer than neutral antimatter had ever been trapped before.[28] [29]" shows an extra space between the references. Sorry, but it bothers me. Add Hominy (talk) 18:41, 13 August 2011 (UTC)

 Done Brambleclawx 18:42, 13 August 2011 (UTC)

Edit request from Ronbennett2001, 1 September 2011

Antimatter in Fiction

Antimatter has been used as a plot device extensively in fiction.

In the movie (and novel) Angels and Demons, by Dan Brown, a vial of antimatter

created a CERN is used as a bomb to threaten the Vatican.

The Orion's Arm Universe Project is a collaborative fiction webiste with antimatter

widely used in weapons, as rocket fuel, and for energy generation. Orion'a Arm is a

hard sci-fi website and the production and uses of antimatter are based on known

science.

Antimatter Hazard Warning Label used in the Orion's Arm Universe Project

Ronbennett2001 (talk) 17:22, 1 September 2011 (UTC)

Ronbennett2001 (talk) 17:22, 1 September 2011 (UTC)

This is original research and too limited and specific for a section of this nature. If you can find reliable sources talking about antimatter in fiction (third-party), you can use that. — Bility (talk) 18:57, 1 September 2011 (UTC)

Please merge antimatter and antiparticle. they are related.

Please merge antimatter and antiparticle. they are related. — Preceding unsigned comment added by 116.71.30.224 (talk) 17:05, 6 September 2011 (UTC)

Gamma bursts ?

"If antimatter-dominated regions of space existed, the gamma rays produced in annihilation reactions along the boundary between matter and antimatter regions would be detectable"

Would it be possible to explain why gamma-ray bursts cannot be considered as candidates ? 82.226.27.88 (talk) 02:38, 7 September 2011 (UTC)

Annihilation from boundaries would have a strong spike at 511 keV (electron/positron annihilation) and probably also at an energy corresponding to neutral pion decays (produced by proton/antiproton annihilation). The glow would be constant and from a distributed area, as interaction would mostly be between clouds of gas (which hold most of the normal matter in the universe; most haven't yet formed stars). Gamma ray bursts, by contrast, have broader spectra and come from pointlike locations.

I agree that spelling this out in the text would be useful, but it'd take a bit of searching to find a source that explicitly discusses it. I'm afraid I'm not in a position to do that at the moment; another editor may be able to. --Christopher Thomas (talk) 03:09, 7 September 2011 (UTC)

Superparticles and antimatter

It is said in the supersymmetry article that "if the superparticles are found, it is analogous to discovering antimatter." Does this make any sense or is it mistaken for antiparticles?Mastertek (talk) 09:45, 20 October 2011 (UTC)

I don't see where the article says that, either before or after you just edited it. SpinningSpark 17:18, 20 October 2011 (UTC)

the simple way to explain(first paragraph)

Lets make 1, matter, now lets make -1, antimatter. Now lets explain it in simple math. 1+(-1)=0 when they are added together it creates nothing.

(please correct me if this is wrong it was a quick though anyways) — Preceding unsigned comment added by M4dh4t73r (talk • contribs) 20:29, 16 December 2011 (UTC)

I'm afraid this turns out not to be correct. Charge and parity sum to zero, but mass and energy don't. An annihilation doesn't produce "nothing"; it produces particles. For the simplest cases (like electron/positron annihilation) you get photons, but for more complicated cases (heavy particle/antiparticle annihilations, or high-energy collisions between particles and antiparticles) you have enough extra energy for pair production to make entirely new particle/antiparticle pairs.

For further questions like this, you can ask at the science reference desk. --Christopher Thomas (talk) 21:46, 16 December 2011 (UTC)

Potential reference for citation needed in preservation.

http://www.bbc.co.uk/news/science-environment-17284822 "The trick was to make use of the "magnetic moment" of the anti-atoms - the property that means they can behave somewhat like tiny bar magnets."144.124.121.100 (talk) 11:53, 8 March 2012 (UTC)

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