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Physicists drive antihydrogen breakthrough at CERN
- chasil 11mo agoI think the same subject was addressed in both of these... https://news.ycombinator.com/item?id=45979220 https://news.ycombinator.com/item?id=45979220 https://news.ycombinator.com/item?id=46011889 https://news.ycombinator.com/item?id=46011889
- gus_massa 11mo agoThe first one "220" has a nice discussion, in particular a comment by pfdietz: > It increases the rate of production of neutral antihydrogen from antiprotons and positrons by a factor of 8. It doesn't increase the efficiency of production of antiprotons, which is the extremely inefficient, energy intensive part.
- modeless 11mo agoThis piece argues that antimatter could be feasible for space propulsion and we could start developing it now: https://news.ycombinator.com/item?id=46073414 https://news.ycombinator.com/item?id=46073414
- p2detar 11mo agoThere was also a great episode on antimatter engines recently by PBS Space Time. https://www.youtube.com/watch?v=eA4X9P98ess https://www.youtube.com/watch?v=eA4X9P98ess
- IsTom 11mo agoIf you can electromagnetically trap enough antimatter to use it as fuel you could as well trap a miniature charged black hole that can be fed regular matter to produce power, which skips the whole inefficient part of making antimatter.
- DennisP 11mo agoDepends. Do we know how to obtain a miniature black hole?
- octaane 11mo agoThere have been several proposals. This paper proposes a feasable mechanism[1]: -"a SBH could be artificially created by firing a huge number of gamma rays from a spherically converging laser. The idea is to pack so much energy into such a small space that a BH will form." 1. https://arxiv.org/abs/0908.1803 https://arxiv.org/abs/0908.1803
- piannucci 11mo agoThere’s a recent paper on the formation of such a “kugelblitz”; it’s argued to be unfeasible. https://arxiv.org/abs/2405.02389 https://arxiv.org/abs/2405.02389
- randallsquared 11mo agoThe biggest problem is that if you're creating it with lasers, you're only going to get the energy out that you put in. You really want to be able to feed it matter, which would effectively make it an anything-to-gamma-radiation converter, which means you have to feed it quite a lot of matter, against the radiation pressure of all that energy coming out. The paper mentioned assumes a worst case of not being able to feed the black hole at all, but doesn't (in my skim) address the fact that this means you have to put in all the energy you'll be using for the lifetime of the black hole at the creation of it, which seems significantly more outrageously infeasible than the bare necessity of creating a black hole at all.
- jojobas 11mo agoDoes anyone address the fact that a black hole will be falling towards the center of the earth at 1g? How do you handle a black hole?
- teamonkey 11mo agoFor those who are time-rich and knowledge-poor: https://youtube.com/watch?v=i6jMnz6nlkw https://youtube.com/watch?v=i6jMnz6nlkw (Angela is genuinely a great science communicator and that video is time well spent if you are interested in this topic.)
- doug713705 11mo agoYou can skip the first 42 minutes that are about how bad is an article titled "how antimatter space craft will work". This part is absolutely boring as hell !
- einpoklum 11mo agoWhat's the key point regarding how we would get a bajillion times more anti-matter than we can now generate, and without expending all the energy we now expend on getting it?
- modeless 11mo agoHis point seems to be that we haven't yet seriously tried optimizing for energy efficiency of producing antimatter. It's a call to action. If we actually tried it's plausible that we could get to a level that, while still fantastically inefficient in an absolute sense, would still be worthwhile for spaceflight propulsion, where energy density is vitally important. As far as I know, antimatter is the most energy dense fuel possible in known physics by many orders of magnitude. Also he proposes a few ways that antimatter could be practically used for propulsion, including as a catalyst for fission which seems interesting.
- pfdietz 11mo agoBefore we get too excited, this current "breakthrough" is making less than 1 antihydrogen atom per second. This corresponds to a delivered annihilation power of less than 1 nanowatt.
- fooker 11mo agoNeutrons were first definitively observed in 1932. First nuclear reactor was 1942, and bomb was 1945. Once the science is established, we have smart engineers to make a short work out of it. Fusion energy is really the only counterexample in history, which makes me think we are still missing some crucial physics about how it works, for example in stars. Specifically the particle physics view of how it's reliably triggered with minimal energy.
- fsh 11mo agoThe antiproton decelerator at CERN has been operational for 25 years, and they have plenty of smart engineers there. Unlike in the 1940s, the underlying physics has been well understood for many decades. I would argue that nuclear fission is the counter example that happens to be surprisingly easy to do.
- fooker 11mo agoCERN is trying to do fundamental physics, not trying to weaponize antimatter. If/when it comes to that, the pace will pick up. Also, 25 years to the breakthrough discussed in the article seems like a reasonably good pace.
- fsh 11mo agoAll experiments at the AD are strongly limited by the low rates. If there was a straightforward way to improve this by many orders of magnitude, they would have done it a long time ago.
- antonvs 11mo ago> Fusion energy is really the only counterexample in history, which makes me think we are still missing some crucial physics about how it works This is magical thinking. We know how fusion works in great detail. And “reliably triggered with minimal energy” is essentially not a thing, unless by minimal energy you mean something like 10 million times the energy of an air particle at room temperature, for every particle in a reactor. What we’re trying to do is recreate the conditions at the core of a star - which is powered by gravity due to hundreds of thousands of Earth masses. And since we don’t have the benefit of gravity anything like that, we actually have to make our plasmas significantly hotter than the core of a star. And then contain that somehow, in a way that can be maintained over time despite how neutron radiation will compromise any material used to house it. The reality is, we still don’t know if usable fusion power is even possible - there’s no guarantee that it is - let alone how to achieve it. The state of the art is orders of magnitude away from even being able to break even and achieve the same power out as was put into the whole system.
- teleforce 11mo agoAs a side note, it's mind boggling that overwhelming majority (more than 98%) of the visible universe's mass are only from two most lightweight of chemical elements namely Hydrogen and Helium.
- irjustin 11mo ago> it's mind boggling that overwhelming majority is it though? I mean literally everything has to start there and the only way get to heavier elements is via stars and many-many iterations. it's not like heavier things popped into existence.... or did they...
- gizmo686 11mo agoThere is a theory that primordial black holes formed in the very early universe. I'm not sure when this process would happen relative to the formation of atoms. But, if it actually happened, it would have been long before stars started forming.
- idiotsecant 11mo agoYes, it's a little mind boggling because the typical human context is this rocky ball of what is ultimately a very uncommon distribution of heavy elements. It's a strange feeling to know that almost everything is utterly unlike the everyday human experience. If you turn down the uhm acksshuwlly a few notches I think parent post's point is quite obvious.
- simonh 11mo agohttps://xkcd.com/2640/ https://xkcd.com/2640/ The alt text is on point.
- soVeryTired 11mo agoThe average density of matter in the universe is one proton per five cubic meters or so. We're very much the outlier!
- simpaticoder 11mo ago
- seeknotfind 11mo agoHow many times does the rate need to be increased 10x before it's a problem?
- chasil 11mo agoIf I remember correctly, 6.023x10^23 protons (with electrons) is one gram of hydrogen.
- iNic 11mo agoCan't we argue for the low amount of anti-matter as a type of anthropic principle? The early universe was super dense meaning that areas with imbalance would quickly annihilate and leave only one type of matter. Then, due to rapid expansion, our observable universe is dominated by only one type of matter. If we imagine a universe with a more even mix it would be less welcoming to life, so we are less likely to observe it. Has someone modeled something like this?
- kaashif 11mo agoThe anthropic principle doesn't imply that our entire observable universe has to contain only matter. Why shouldn't we observe clouds of anti matter and matter annihilating millions or billions of light years away? Why does the annihilation have to have happened so early on that we can't see any evidence anywhere? I think there does need to be an explanation and it can't be an anthropic principle cop out.
- adrian_b 11mo agoNot only there is no evidence for the existence of antimatter in quantities comparable with matter, but there also is no logical necessity for this. People who entertain the idea of an initial state with equal amounts of matter and antimatter do this because thus the properties of the matter that are conserved, except the energy, would sum to zero in the initial state. However, such people forget that not only the particle-antiparticle pairs that can be generated or annihilated through electromagnetic interactions have this property that the conserved quantities except the energy sum to zero. The particle-antiparticle symmetry is important only for the electromagnetic interactions, while other interactions have more complex symmetries. All the so-called weak interactions are equivalent with the generation or annihilation of groups of 4 particles, for which all the conserved properties except energy sum to zero. Such a group of 4 particles typically consists of a quark, an antiquark, a charged lepton or anti-lepton and a neutrino or antineutrino. For instance the beta decay of a neutron into a proton is equivalent with the generation of 4 particles, an u quark, an anti-d quark, an electron and an antineutrino. The electron and the antineutrino fly away, while the anti-d quark annihilates a d quark, so the net effect for the nucleus is a change of a d quark into an u quark, which transforms a neutron into a proton. The generation and annihilation of groups of 4 particles in the weak interactions are mediated by the W bosons, but this is a detail of the mechanism of the interactions, which is necessary for computations of numeric values, but not for the explanation of the global effect of the weak interactions, for which the transient existence of the W intermediate bosons can be ignored. So besides the symmetry between a particle and an anti-particle, we have a symmetry that binds certain groups of 4 quarks and leptons. There is a third symmetry, which binds groups of 8 particles. For instance, there are 3 kinds of u quarks, 3 kinds of d quarks, electrons and neutrinos, a total of 8 particles that belong to the so-called first generation of matter particles (i.e. the lightest such particles). All the conserved quantities except energy sum to zero for this group of 8 particles. The neutrino is necessary in this group so that the spin will also sum to zero, not only the electric charge and the hadronic charge. These 8 kinds of particles are exactly those that are supposed to compose in equal quantities the matter of the Universe at the Big Bang. So all the conserved quantities except energy sum to zero for the Universe at the Big Bang, when it is composed entirely of ordinary matter, without any antimatter. Therefore there is no need for antimatter in the initial state. There is no known reason for this symmetry between the 8 particles of a generation of quarks and leptons, except that this allows for the initial state at the Big Bang to have a zero sum for the conserved properties. It can be speculated that this symmetry might be associated with a supplementary hyper-weak interaction, in the same way as the symmetry between certain groups of 4 quarks and leptons is associated with the weak interaction. Such an interaction would allow the generation and annihilation of ordinary matter, without antimatter, but with an extraordinarily low probability.
- dev1ycan 11mo agoCan't wait for the day we can trap more antimatter so that governments that right now pretend this is for science weaponize it into a bomb way larger and harder to detect than nukes
- b3lvedere 11mo agohttps://www.youtube.com/watch?v=-hYNl1hnwUc&t=115s https://www.youtube.com/watch?v=-hYNl1hnwUc&t=115s
- OBELISK_ASI 10mo ago[dead]
- quinndexter 10mo ago[flagged]
- tomhow 10mo agoPlease, no. We detached this comment from https://news.ycombinator.com/item?id=46075749 https://news.ycombinator.com/item?id=46075749 and marked it off topic.
- quinndexter 10mo agoOkey doke. Still not wrong.
- tomhow 10mo agoIt’s not clever or profound to note this. Yes indeed, countless things are both true and deeply vile. HN if for people who have much higher standards than this.