# Does antimatter material function the same as matter material? **URL:** \ **Category:** Factual Questions\ **Created:** [April 6, 2017, 6:22am UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872 "2017-04-06T06:22:49Z")\ **Posts on this page:** 17\ **Page:** 2
**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\ **Post date:** [April 7, 2017, 12:11pm UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/22 "2017-04-07T12:11:13Z")
Somewhere in the universe, are _we_ someone else’s antimatter? ---
**Author:** ![Pasta](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pasta](https://boards.straightdope.com/u/Pasta)\ **Post date:** [April 7, 2017, 8:05pm UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/23 "2017-04-07T20:05:52Z")
> [@eschereal](#): > > Really? How would they know? Antimatter [looks just like](http://gizmodo.com/antimatter-looks-surprisingly-like-regular-matter-1790279870) matter, so far as we can tell. There _could_, theoretically, be vast regions swimming with antimatter and we might never know it. In addition to the 511 keV gamma rays we’d see from the boundaries between regions, we would also see antinuclei streaming about the place, accelerated ourward from highly energetic astrophysical events. Searches for both of these tell-tale signatures have turned up empty. > [@MikeS](#): > > The problem comes in with neutrinos. As noted by **Chronos** , neutrinos aren’t really special here. It is the nature of the weak interaction that leads to parity and charge-parity violation. Neutrinos are produced and detected via the weak interaction, so they are subject to the vagaries of the interaction, but so too can be all the other fermions. CP violation, for instance, has only ever been observed in quark systems and has not yet been observed with neutrinos. > [@Chronos](#): > > Last I saw, everyone agreed that the evidence was 100% clear in favor of one of those theories. That is to say, the proponents of the Majorana theory argued that the evidence was 100% in favor of Majorana, and the proponents of the Dirac theory argued that the evidence was 100% in favor of Dirac. I wouldn’t characterize the zeitgeist as anywhere near that dogmatic. If there were a net bias today, it would be toward Majorana due to its subjective elegance and the fact that it yields fewer net unsolved problems than the Dirac model. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 8, 2017, 12:52am UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/24 "2017-04-08T00:52:29Z")
Personally, I favor Dirac, mostly just because it seems like lepton number is awfully well-conserved for something that doesn’t even exist. And of course it’s an exaggeration to say that everyone’s 100% convinced, especially since I myself don’t consider it settled. But there are certainly a fair share of dogmats out there (at a conference where I was presenting that neutrino work, for instance, there was one questioner in the audience who seemed offended that I had even considered both possibilities). ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [April 8, 2017, 1:38am UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/25 "2017-04-08T01:38:12Z")
> [@Chronos](#): > > Personally, I favor Dirac, mostly just because it seems like lepton number is awfully well-conserved for something that doesn’t even exist. > > And of course it’s an exaggeration to say that everyone’s 100% convinced, especially since I myself don’t consider it settled. But there are certainly a fair share of dogmats out there (at a conference where I was presenting that neutrino work, for instance, there was one questioner in the audience who seemed offended that I had even considered both possibilities). So you know how in linear algebra, there’s a whole family of solutions that are exactly the same? Wouldn’t this be the same for theoretical physics? There’s technically an infinite number of solutions that fully explain all observations up to the present. So until proven otherwise, using the _simplest_ one would be the way to go… I mean, its highly unlikely that anyone is going to discover within the next 1000 years the One True Laws of physics. Whatever math formula you write down will never be quite the way the Universe is deciding on what will happen… ---
**Author:** ![Pasta](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pasta](https://boards.straightdope.com/u/Pasta)\ **Post date:** [April 8, 2017, 2:15am UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/26 "2017-04-08T02:15:42Z")
> [@Chronos](#): > > Personally, I favor Dirac, mostly just because it seems like lepton number is awfully well-conserved for something that doesn’t even exist. Ah, but that isn’t a very good distinguisher because even without lepton number as a thing you can’t help but get an effective version of it due to the chiral nature of the weak interaction (and the lightness of neutrinos to make spin flips difficult). And what’s more, the very lightness of neutrinos – a problem for the Dirac case – is neatly explained in the Majorana scenario. Win-win. > [@](#): > > at a conference where I was presenting that neutrino work, for instance, there was one questioner in the audience who seemed offended that I had even considered both possibilities. Curious. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 8, 2017, 12:22pm UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/27 "2017-04-08T12:22:34Z")
Well, you also need spin-counting and conservation of baryon number to get emergent pseudo-lepton-number, but those are both on pretty sound footing. And yes, I do recognize how psuedo-lepton-number could emerge from those other laws. It just offends my sense of symmetry for all fermions to be either leptons or bosons, and for bosons to be conserved very strongly, and yet for leptons to not have a number at all. ---
**Author:** ![leahcim](https://avatars.discourse-cdn.com/v4/letter/l/b4bc9f/32.png) [@leahcim](https://boards.straightdope.com/u/leahcim)\ **Post date:** [April 8, 2017, 12:29pm UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/28 "2017-04-08T12:29:41Z")
Recent Ars Technica [article](https://arstechnica.com/science/2017/04/latest-test-for-a-standard-model-replacement-comes-up-empty/) on an experiment that would, if it got positive results, prove that neutrinos are Majorana particles. No positive result as yet, though. ---
**Author:** ![leahcim](https://avatars.discourse-cdn.com/v4/letter/l/b4bc9f/32.png) [@leahcim](https://boards.straightdope.com/u/leahcim)\ **Post date:** [April 8, 2017, 3:15pm UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/29 "2017-04-08T15:15:34Z")
> [@Chronos](#): > > It just offends my sense of symmetry for all fermions to be either leptons or bosons, and for bosons to be conserved very strongly, and yet for leptons to not have a number at all. /s/boson/baryon/g ? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 8, 2017, 3:27pm UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/30 "2017-04-08T15:27:09Z")
Hey, I got the first letter right, that’s good enough! ---
**Author:** ![HoneyBadgerDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/honeybadgerdc/32/1033_2.png) [@HoneyBadgerDC](https://boards.straightdope.com/u/HoneyBadgerDC)\ **Post date:** [April 8, 2017, 3:27pm UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/31 "2017-04-08T15:27:34Z")
Is it likely that more than 99% of the existing matter was annilated early on through collisions of the two matters and what is left is simply a natural distribution variance of two equal things randomly distributed? ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [April 8, 2017, 3:36pm UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/32 "2017-04-08T15:36:48Z")
If that was true you’d expect matter to predominate \*here \*and anti-matter to predominate _there_. Because the total across the entire Universe would still be 50/50. So there’d have to be some places where the regions of different type matter abutted. And hence would be interacting “now”. As noted upthread there’d be observable consequences of that now. People have looked carefully and have not (yet) seen. So the conclusion so far is that your idea is not what really happened back in the immediate post Big Bang era. All physics data and theories are always tentative under a big enough magnifying glass; this one is pretty well locked down as these things go. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 8, 2017, 3:45pm UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/33 "2017-04-08T15:45:35Z")
To be fair, it’s still possible that the Universe as a whole is split evenly, but that our local zone of matter-dominance happens to be larger than the observable universe. This would be surprising if true, but it’s possible. And given that nobody has yet managed to come up with an actually _good_ explanation, we’d be hasty to rule it out. ---
**Author:** ![HoneyBadgerDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/honeybadgerdc/32/1033_2.png) [@HoneyBadgerDC](https://boards.straightdope.com/u/HoneyBadgerDC)\ **Post date:** [April 8, 2017, 3:49pm UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/34 "2017-04-08T15:49:23Z")
What are some of the implications of having equal parts of both matters? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 8, 2017, 4:11pm UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/35 "2017-04-08T16:11:55Z")
Having equal parts of both is not, in theory, problematic at all, and in fact is what we would expect. The problems all come from observations that it is not in fact true, at least within the observable universe. If it’s true that it’s balanced overall, and only imbalanced in our local region, then explaining that is what becomes problematic. ---
**Author:** ![Pasta](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pasta](https://boards.straightdope.com/u/Pasta)\ **Post date:** [April 8, 2017, 6:58pm UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/36 "2017-04-08T18:58:06Z")
> [@Chronos](#): > > It just offends my sense of symmetry for all fermions to be either leptons or bosons, and for bosons to be conserved very strongly, and yet for leptons to not have a number at all. Baryon number is also not imposed but can instead be viewed as a consequence of the interactions. In fact, neither baryon number nor lepton number are strictly conserved in the Standard Model (though they are in the perturbative regime). > [@leahcim](#): > > Recent Ars Technica [article](https://arstechnica.com/science/2017/04/latest-test-for-a-standard-model-replacement-comes-up-empty/) on an experiment that would, if it got positive results, prove that neutrinos are Majorana particles. No positive result as yet, though. To add to this: it would have been a surprise to see a signal so far. Given current limits on neutrino masses, even a Majorana neutrino would lead to a rate of this particular lepton-number-violating nuclear decay below existing experimental sensitivity. There are many experimental efforts pushing the sensitivity further, though. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 8, 2017, 8:17pm UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/37 "2017-04-08T20:17:48Z")
Wait, what in the Standard Model would allow for violation of conservation of baryon number? I know that most GUTs allow for violations, but that’s beyond the Standard Model. ---
**Author:** ![Pasta](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pasta](https://boards.straightdope.com/u/Pasta)\ **Post date:** [April 10, 2017, 4:17am UTC](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872/38 "2017-04-10T04:17:08Z")
> [@Chronos](#): > > Wait, what in the Standard Model would allow for violation of conservation of baryon number? I know that most GUTs allow for violations, but that’s beyond the Standard Model. [Sphalerons.](https://en.wikipedia.org/wiki/Sphaleron) To the general line of discussion in the thread: The raw lack of antimatter isn’t the only piece of evidence related to the baryon asymmetry. An important indirect observable is the ratio of the baryon excess abundance to the photon abundance – that is, a measure of how much extra matter there was over antimatter scaled to how many photons are kicking around. This is strongly connected to the rate at which light isotopes (H-2, He-3, etc.) were produced in the early universe, and we can measure those abundances directly today. If you assume symmetric behavior and calculate the baryon/photon ratio that would remain today after the annihilations have frozen out(\*), you miss the mark by nine orders of magnitude. However, if you posit that matter and antimatter behave a little bit differently (something we know they do already in certain corners of the Standard Model and that they are able to do in other, uncharted corners), then you can nail this ratio, and you don’t need to introduce anything that breaks anything we already think we know. In contrast, forcing symmetric behavior and then trying to tuck the antimatter elsewhere requires inventing new mechanisms that touch on physical bedrocks like entropy, without any gain in predictive power. (\*) freeze out = when the reaction is halted due to the reaction’s rate dropping below the expansion rate of the universe [Previous page](https://boards.straightdope.com/t/does-antimatter-material-function-the-same-as-matter-material/783872.md?page=1)