[HN Gopher] New exotic matter particle, a tetraquark, discovered... ___________________________________________________________________ New exotic matter particle, a tetraquark, discovered at CERN Author : mherrmann Score : 385 points Date : 2021-07-30 15:04 UTC (7 hours ago) (HTM) web link (phys.org) (TXT) w3m dump (phys.org) | 4e530344963049 wrote: | https://trimread.org/articles/31 | spxtr wrote: | > The new particle contains two charm quarks and an up and a down | antiquark. Several tetraquarks have been discovered in recent | years (including one with two charm quarks and two charm | antiquarks), but this is the first one that contains two charm | quarks, without charm antiquarks to balance them. | | This is not the first time a tetraquark has been measured, but | instead it's the first time a tetraquark with two charm quarks | and no charm antiquarks. That's still nice work, but I was | initially confused by the headline ("didn't they discover those | already?"). | archsurface wrote: | Why do these things take so long to find? Do they not show up in | all collisions - why not, wrong matter, wrong speed? Do they | regularly appear, but the "camera" has limitations? Is the | "camera" all-seeing, but measurement interpretation inefficient? | All/some of the above? | ManBlanket wrote: | I think it's a matter of theory supporting observed data. They | point the, "camera" at a bunch of experiments, which generates | a ton of data, then it's up to theoretical physicists to | explain the results. Once the results of a theory have been | explained and then reproduced it stands on solid ground. I'm | just speculating, of course. But that is sort of how astronomy | works, at the polar opposite end of a similar field. | mirthless wrote: | Does it fit into the standard model? I thought higgs boson was | the last undiscovered particle according to the standard model. | xhrpost wrote: | You're referring to elementary particles. This is not | elementary as it is composed of Quarks, which are part of the | standard model and are elementary. | x3n0ph3n3 wrote: | tetra-quark: 4 quarks. It's composed of particles that are | already part of the standard model, just an a previously unseen | arrangement. | ur-whale wrote: | Particles are compositional. | [deleted] | jdeaton wrote: | I wonder if the sophons from Trisolaris would have blocked this | discovery. | tux3 wrote: | The article points to an ongoing conference as the source, | unfortunately (despite having no registration fee) the live- | stream is password protected for non-participants :( | | https://www.eps-hep2021.eu/live_stream/ | | Edit: It seems the talks may be released, in the end | | >We would like to record your presentation at the EPS-HEP2021 | conference and make it publicly available via the INDICO page and | the DESY media streaming server until one week after the end of | the conference. | jandrese wrote: | They probably don't want internet randos jumping in and | flooding the chat with porn. | tux3 wrote: | That makes sense for the zoom sessions. | | But, although I've never run a conference, I naively can't | see that broadcasting the plenary session's video a little | broader (to the three to five latecomers likely to stick | around!) would really cause problems. | | Not to be a stereotypical "Concerned Facebook Taxpayer", but | in general I'm really fond of CERN's transparency, and I | appreciate all the work they do to keep science open. They're | usually way ahead of the field and it's refreshing to see, I | love following what comes out of the LHC data. | | So all that to say, maybe I've set my expectations a little | high when it comes to physics and public access =) | kkylin wrote: | Many online conferences I've attended this past year have | both a Zoom meeting for registered participants and a | YouTube "simulcast" for people who don't care about asking | questions. I haven't run one and don't know if the | logistics are complicated; maybe the organizers just didn't | think of doing it. Anyway, these days most conferences seem | to be pretty quick at putting videos out, though of course | our attention will be elsewhere next week... | xondono wrote: | Congratulations for the discovery of the next epicycle! | amai wrote: | What is the charge of a tetraquark? Is it neutral? | jjk166 wrote: | This particular one is +1e but there are many other forms a | tetraquark may be able to take. | whatshisface wrote: | A tetraquark is four quarks. There exist three -1/3e quarks | (dsb), three +2/3e quarks (uct), and then their +1/3e and -2/3e | antimatter counterparts. 1e is the charge of one electron. The | stability of a tetraquark is mainly a color/strong force thing | and the electric charge comes along for the ride. Stable atomic | nuclei, which are held together by the strong force, go up to | +83e and they still don't fall apart due to electric repulsion. | | However, there is one constraint that might show up in charge. | Tetraquarks always have two antiquarks, which is necessary for | the color charge to come out to zero. Working out every | possible combination is left as an exercise for the reader. :) | im3w1l wrote: | The highest possible charge is 2/3 + 2/3 + 1/3 + 1/3 = 2. | Every swap of a quark to a lower charge one reduces the total | charge by 1. So the possibilities are 2, 1, 0, -1, -2. | pseudobry wrote: | I recently finished The Three-Body Problem and The Dark Forest, | which explore the concept of aliens using their super advanced | technology to mess with the results of Earth's particle | accelerators, thereby stopping humanity's ability to develop | technology based on new physics. | | Is this discovery exciting? Or are we living in The Three-Body | Problem? | tomudding wrote: | Unrelated to this topic, but Death's End is also a great book | if you haven't started reading it. I can also recommend Ball | Lightning which more or less takes place before the events in | the The Three-Body Problem. | majkinetor wrote: | You spoiled it for me, I am on 1/4 of the first book :S | whytaka wrote: | Oh blood, I just got this book. Is this a huge spoiler? | pseudosudoer wrote: | Don't worry, I'll just use a sophon to revert your memory. | rsynnott wrote: | Eh, it's hinted at, pretty early on. If you knew there were | aliens in the book, I don't think it's THAT huge a spoiler. | BrissyCoder wrote: | No not at all. Keep reading. | ASalazarMX wrote: | It's plot-establishing, but not a huge spoiler. | svennek wrote: | Well, it kinda spoils some/most of book 1. | | But IMHO the book 2 is the best and most intriguing anyways | and that is totally unaffected... | kryptn wrote: | Same. It's been on my list, but this is more detail than I | wanted to see. | efsavage wrote: | Rest easy, there is a _lot_ more to the books than that. | bequanna wrote: | Interesting. | | For what reason are the aliens trying trying to stop us from | discovering new physics? Stop us from blowing ourselves up? | Blowing them up? | godelski wrote: | The aliens are coming to Earth to take it over. They aren't | much more advanced than us and so don't want us to be more | advanced than the fleet that arrives (it takes them a few | hundred years to get to Earth). | sylens wrote: | Without ruining too much of the books (they are worth a | read), there is conflict between us and the aliens and | limiting technological progress is an important part of their | strategy | misiti3780 wrote: | which book was better? | ASalazarMX wrote: | In the books, the Sophons got in the way of the accelerated | particle beam but somehow avoided being destroyed themselves. | They wouldn't have allowed a new particle to be discovered. | godelski wrote: | They were destroyed but could bring themselves back together. | The thing is that the particles are intelligent so could | break apart in random ways that didn't match what particle | physicists expected (they would then recombine outside the | detector as to not be exposed). | FinanceAnon wrote: | If aliens don't like us, then why wouldn't they just destroy | us, rather than troll our physicists and mess with the results? | | Why would they specifically mess with the particle accelarators | at this point? Why not with earlier physics? | AdamN wrote: | In the book that's the state of human science when they learn | of our existence. Also, they want our planet and it will take | them a long time to get to earth - so long in fact that they | predict that if our physics is allowed to mature they won't | be able to beat us militarily by that time. They need to stop | progress asap. | gizmo686 wrote: | Spoilers below: | | _The Three Body Problem_ trilogy breaks down if you think | about it too hard. The in-universe explanation was that the | aliens did want to destroy us, and had an attack fleet | heading towards us. However, the attack fleet was relativly | slow, and they were concerned that by the time it reached us | we would have advanced to the point where we might win in a | fight. To prevent this, they sent smaller probes to us at | near light speed. In theory, these weren 't capable of | causing significant damage, but they could cause enough of an | effect that they could make the results of particle | accelerators useless. Without being able to use particle | accelerators, we wouldn't be able to advance our knowledge of | fundamental physics, so the aliens were confident that when | their attack fleet reached us we would be defenseless. | | By itself, what I have written is not particularly absurd, | but if you look at the other things those advanced probes | ended up being able to do, they could have easily just killed | everyone. | ASalazarMX wrote: | Killing everyone is too much to ask, remember they were | ultimately just protons, physically they're not more | powerful than cosmic rays. | | Their strength was information gathering and special | effects. | HotHotLava wrote: | Tbf, from the way they were described it should have been | fairly easy to defeat the Sophons even without any | science-fiction technology; just build e.g. 10-20 | particle accelerators distributed over the world and take | measurements close enough in time to each other that you | cannot be at multiple sites without exceeding the speed | of light. Then at most 3 of them could be corrupted for | any given run, and these can be thrown out as statistical | noise. | xster wrote: | I think the argument was that they could send Sophons | faster than we can build particle accelerators. | gizmo686 wrote: | Protons that could cause controlled visual hallucinations | in people. If they can cause that level of interference | with our nervous system, they can kill us. Even if they | were somehow limited to visual hallucinations, a well | timed hallucination is easily lethal. They probably ought | to be able to hack into computer systems with that as | well. | wdwvt1 wrote: | Totally agree with this, the effort to retard development | could have been better spent with a myriad of ecosystem | destroying actions or geopolitical manipulations. Also just | send the indestructible probe to kill every human... | | My bigger problem with this book was that the author seems | to wholely confuse secrecy for strategy. The entire conceit | behind the wallfacers seemed ridiculous to me. The best | strategic plan need not be secret (eg MAD). Make it clear | that humanity will destroy every planet in the solar system | and you've got at least MAD in the centuries the | trisolarians will take to arrive. | saiya-jin wrote: | They cared about our stable single sun more than planets. | We were not on the level to destroy our sun, or the | planets themselves | gizmo686 wrote: | More spoilers below: | | They actualy did a fair amount of geopolitical | manipulations. That formed most of the plot. | | In the end, it turned out to be MAD that saved us, but | setting up the MAD scenario involved secrecy from them | (or else they would have stopped us before we could | trigger it), and from the rest of humanity (because an | official plan to destroy Earth would never have been | approved). | shhsshs wrote: | > In the end, it turned out to be MAD that saved us | | Read the rest of the series and this answer gets more | interesting. I will not say any more about the outcome | (spoilers) | wdwvt1 wrote: | It seems like the manipulations were exceedingly silly. | It seems like having the sophont start a nuclear war | would be straightforward. It was hard for me to suspend | disbelief in the sense that it had planet-sized | computational power and the ability to manipulate some | information on the subatomic level, but couldn't find a | vulnerability in aging nuclear launch protocols? The | history of near misses with human controlled nuclear | weapons suggests a variety of vulnerabilities exist that | wouldn't require e.g. directly hacking into command and | control. Could it spoof images/data to a sub? Could it | cause hallucinations in a large sensor array that feeds | data to Norad or a Chinese/Russian equivalent? | | Re MAD: I think a plan to destroy Earth would have been | easily approved - much like it was in 1960-now, with ICBM | and SSBN retaliatory strike capability. Obviously | somewhat different in that those MAD-based nuclear wars | would be extinctive but not deny the planet to the | trisolarians, but the idea that human governments aren't | ready to commit to that seems wrong given our history. | bmh100 wrote: | The aliens specifically wanted Earth because of its life. | A nuclear war would damage the planet's ecosystem too | much. | rsynnott wrote: | The sophons don't seem to be able to do anything much | beyond bother particle accelerators. The later droplet | probes _are_ very nasty, but it's at least implied that | those weren't even available at the time they set out. | JetSetWilly wrote: | Because your interstellar equivalent of the CIA can obtain | the political capital to prevent a civilisational rival from | emerging via subtle manipulations, but it can't obtain the | political capital and consensus needed to commit wholesale | genocide. | | There's a big difference between the scenarios. | midrus wrote: | Maybe because we're their big brother tv show or just their | zoo | nolok wrote: | Haven't read those specific books, but "keep the species at | the level they were when discovered for preservation" is a | very common trope of such things, and usually mapped on how | humanity considers that "preserving a species" means keeping | it exactly as they were when first discovered. | yarky wrote: | If you insist on looking at it from our perspective, how | about curiosity? Let's see how far they (us) keep trying to | make sense out of this nonsense. Trolling in the name of | science I guess. | | People from North Sentinel Island might ask themselves the | same question about us. | artursapek wrote: | I troll people I don't like all the time | kingkawn wrote: | Because they're hundreds of years of space travel away so | they send sentient protons to sabotage our particle physics | so that we can't develop advanced enough technology to stop | them by the time they arrive. | sweetheart wrote: | While the entire series is absolutely incredible, I _loved_ | the premise of human beings knowing 400 years in advance | that aliens are coming. Such a fascinating start to the | trilogy. | joshspankit wrote: | Here's a possibility: They are in the next universe over, and | so far the only thing that passes between is gravity. Fine- | grained control over gravity could allow them to mess with | things but not destroy us (if they even wished to. I don't | even think Earth would vote to destroy an unknown | civilization if the roles were reversed) | maininformer wrote: | maybe we are their toys, or maybe our emotions is their | energy source | rsynnott wrote: | In the Three Body Problem, the naughty aliens break | reproducibility in particle accelerator experiments; they start | giving random results. So we're good for now. | f6v wrote: | It's a great book, but it suffers from the same old issue. A | civilization that is capable of packing a robot into particle | by manipulating higher dimensions doesn't need to take our | planet. They could terraform Mars or any other planet they | want. | s5300 wrote: | Perhaps we look to be an exceptional vacation spot, and there | are space Karen's who desire an "all natural" planet instead | of a terraformed one. | hllooo wrote: | iirc the solar system contained the closest planets, which is | why they chose it. I don't think it matters if they want mars | or earth, there's no way we would let them do that (send a | massive military fleet definitely just to mars). they wanted | to ensure their technology remained superior by the time they | arrived | alasdair_ wrote: | I had the same problem with the books. If the sophon is that | omniscient and that powerful, it could do far more than just | mess with experiments. | | I also never understood the wallfacers - why can't they | communicate via encryption, using a private key stored in | each individuals mind alone? | bo0tzz wrote: | How would you use that private key without it 'leaving' | your mind? | danielheath wrote: | The same way you use a private key in a computer without | transmitting it? | EthanHeilman wrote: | The sophons are not that powerful and have very limited | capabilities. Humans perceived as being very powerful | because we doesn't understand how they work and they are | being used to frighten us. It's like showing a gun to | someone who doesn't know what a gun is. The limitations | such line of sight, range, limited ammo are not immediately | obvious. It looks as though you have a god-like ability to | strike anyone dead by wishing it. | micromacrofoot wrote: | Couldn't trisolarans have broken the encryption? Many of | our old methods of encryption have been rendered obsolete | by our own technology. | shoto_io wrote: | Why not just for fun? Like riding horses even though you have | a car. | coldacid wrote: | Or trolling. | dice wrote: | "Teasers are usually rich kids with nothing to do. They | cruise around looking for planets that haven't made | interstellar contact yet and buzz them." | "Buzz them?" Arthur began to feel that Ford was enjoying | making life difficult for him. "Yeah," said | Ford, "they buzz them. They find some isolated spot with | very few people around, then land right by some poor | unsuspecting soul whom no one's ever going to believe and | then strut up and down in front of him wearing silly | antennas on their head and making beep beep noises." | | -- HHGTTG | cmurf wrote: | Human story tellers are very attached to humanity, so the | stories tend to anthropomorphize aliens. Most alien stories | rehash old religious and hero stories. What do we have to | offer aliens? In the category of vague as well as less is | more, _Arrival /Stories of Your Life and Others_ are about as | compelling as it gets - humanity hasn't yet achieved full | potential, going further out on a limb is folly (however | entertaining it might be, it becomes less compelling). | | The more truly alien, the less in common we have in all | respects, the more boring that story turns out to be because? | We're a selfish, self-interested, loathsome species who | consistently overestimates its importance. The more different | a fellow human is, the vast majority of people reject that | individual because of their (weird) non-social behaviors. | | So these alien stories strike me as deification, angels, | devils, i.e. the supernatural, and don't adequately explain | why or how any alien civilization would take interest in us, | except via our own attachments to ourselves. This is central | to good science fiction because they are stories ultimately | about exploring something about humanity, it's not really | about aliens at all. They're entirely incidental even if they | seem important, aliens are just a literary device. But | getting to science-non-fiction, a factual case of aliens, | that's quite hard for most humans to imagine at all. | | Consider how poorly most people coped with covid, and then | consider how much more traumatic an alien visit would be, | even assuming they were nice. | | In Arthur C. Clarke's _Childhood 's End_ (1953) those aliens | were "nice" but with a really big caveat. (And neatly | explained devils.) But again, humans are the central part of | that story, not aliens. It wouldn't and couldn't have been | interesting to focus on the interests of the aliens without | us being part of the story - we're just too self-interested | by nature. The aliens' interests would have been boring to | us, we just don't have the necessary common frame of | reference with such beings. How could we? | micromacrofoot wrote: | Spoiler: It took them so long to get to earth that they were | concerned about humans becoming a formidable opponent in the | meantime. Had human advancement not been halted humans would | have much faster access to Mars than they would. | WORMS_EAT_WORMS wrote: | The whole book is fun and creative fiction. Just enjoy it | like you would enjoy any non-real TV or movie. | | If you haven't read the series, saw the spoilers here, and | are no longer thinking about it... don't get discouraged. Pay | off in Book 3 via the space concepts are worth it still. Mind | blowing fun stuff | Panoramix wrote: | Spoilers ahead | | It was such a letdown, the book starts great, and then the | explanation turns out to be magical Alien proton computers? | Yikes. It was so promising. | | I eventually read the whole trilogy, I have very mixed | feelings about it. It had some pretty cool ideas but it's | hard to get past all the giant plot holes and outlandish | fantasy. I guess you have to be in the mood to constantly | brush off the bad parts (and boy there are many) and plunge | forward. | jjoske wrote: | There where some good ideas in it but it never really | worked for me, I have often wondered if it was translation | issues. | megablast wrote: | Thanks for the spoilers. | cynicalkane wrote: | Spoilers. | | There are a few parts of the book, according to the | translator, that are done in the manner of a Chinese | folktale, which he tried to translate to a different style | in English. I'm no expert, but I got the impression the | sophont chapter was in this category. It has this | otherworldly silliness with the multiple attempts to create | a sophont going wrong in different dimensions, calculated | to fit the repetitive pattern of a fairy tale. | | I think the thrust, which might be hard to read in | translation, is this: we can't imagine the technology a | superior alien species would come up with, so it's related | as a fairy tale beyond technological realism. | | Anyway, I doubt it was meant to be hard sci-fi. | shmageggy wrote: | > _Anyway, I doubt it was meant to be hard sci-fi._ | | Which was extremely disappointing, given that it was | billed as such by many, and until the aforementioned | mumbo-jumbo was doing a seemingly nice job on that front. | visualradio wrote: | A more materialist approach would be to say that it is the | artists and authors of such books which are influenced by | cosmos and the three body problem is an error detection | code for repairing memory errors in collective | consciousness to prevent civilizations from repeating | unpromising patterns of development which have already been | simulated. | whymad wrote: | True for what it is, but this is handled in the books. They | literally don't want our planet, they want our _star_. | | And the dark forest: without a history of correlated | interaction we have no reason to believe they will allow us | to live, so we can't allow them to live, so they can't allow | us to live. | | Eliding a more major spoiler, they absolutely intended to | annihilate us on arrival and they would have gotten away with | it if it weren't for, ah, "those meddling kids". Everything | else was cloak and dagger. | | They definitely would have terraformed every planet in the | system once they were sure we were gone. Or more likely | deconstructed them, at that point in their development. | wisty wrote: | It's a good book, but while some elements are good sf it's | not all hard sf. They're looking for a new planet and | didn't even send a probe 50 years ago? | EthanHeilman wrote: | Because the trisolarans didn't know who was out there | until they received a message from Earth. They were | worried that if they sent a probe to another star then a | more advanced civilization perhaps hiding around that | star would see the probe arrive, trace the source and | annihilate them. | ansible wrote: | > _True for what it is, but this is handled in the books. | They literally don't want our planet, they want our star._ | | That's... an odd reason. There are plenty of stars out | there, unless the aliens started out right next door (like | in Alpha Centauri) there's not much reason to go after | _our_ star. | | I haven't read the books... | seanc wrote: | Well, the thesis is that with exponential growth and a | modest amount of time there _aren't_ plenty of stars out | there. | Dylan16807 wrote: | If you're growing that fast, then a system or two is a | rounding error. You won't have plenty no matter what you | do, so how about _not_ wiping out other species for that | extra smidge? | godelski wrote: | > unless the aliens started out right next door (like in | Alpha Centauri) | | This is where the aliens are (a trinary system). It still | takes them 400 years to get to Earth and so they are | trying to stifle Earth's technological advancements | because 1) we know they are coming 2) our technological | growth is faster than them (this is partially explained | due to different biological and environmental factors. | The aliens can't lie to one another and have | environmental factors that frequently wipe out or pause | their technological advancements). The aliens in question | are supposed to be only a few hundred years (max) ahead | of us technologically (or smaller than the difference in | time that it takes them to get here) | bkanber wrote: | > unless the aliens started out right next door (like in | Alpha Centauri) | | :D | | Strongly recommended reading. | mannerheim wrote: | > unless the aliens started out right next door (like in | Alpha Centauri) | | They did. | ASalazarMX wrote: | Super spoiler below: | | Their tri-solar system was too unstable to terraform, they | needed a stable solar system to migrate to. Of course ours | was the nearest with an habitable planet (otherwise there | wouldn't be much of a story), so they can immediately | colonize Earth, and probably begin the centuries-long process | of terraforming the neighboring planets. | rnjesus wrote: | an aside: i really wish hn had a redaction-style, click-to- | reveal spoiler system. not that i don't appreciate the | spoiler warning here -- it's quite kind that people mark | their comments as-such -- but even when i've seen "spoiler | warnings" for other content that i'd rather not be spoiled | on, it's very hard to not skim the next few proceeding | lines out of habit (especially on mobile). i can't imagine | i'm the only one who does this. | cogman10 wrote: | Still doesn't make sense. Why limit our tech when they | ultimately want to just eliminate us all together? | | Drop a super virus on us or irradiate the whole planet. Any | species capable of disrupting our particle accelerators is | more than capable of wiping us from existence. | AmericanChopper wrote: | They did also send weapons towards earth ahead of their | fleet. They arrived much faster than their fleet, but | much slower than the sophons. | dylan604 wrote: | It's kind of like nuclear warfare here on Earth. If you | want to eliminate every living thing, then sure do some | sort of scorched Earth type of thing. However, that | leaves the planet in an un-inhabitable condition. | | If you need to wipe out the inhabitants but leave | everything else so you can now use it, you need to not | destroy everything in the first place. Otherwise, you now | have to terraform a planet that you chose because you | didn't need to terraform it. | EthanHeilman wrote: | The book makes the claim that the sophons they send over | are very limited. It seems reasonable to surmise that | they could not create a super virus. Yet they can disrupt | sub-atomic experiments. We are talking about an advanced | basically magic tech the author made up for the purposes | of the plot. So the author can set the rules that the | magic tech can do X but not Y. | temporalparts wrote: | More spoilers: | | In the book, they were scared of humanity's technological | growth rate. They were observing our technological | advances and noticed that it was significantly faster | than theirs. While they were, at the time, | technologically superior, they were afraid that after the | 250+ years it would take for them to get to Earth, | humanity would have become technologically superior; too | strong for them to overtake. | numlocked wrote: | That was probably the plan; but the "tech-blocking | particle" gets here at the speed of light, ensuring that | we are still sufficiently behind, technologically, by the | time their e.g. virus or radiation gizmos arrive. It | "freezes" development to ensure that they still have | technological superiority when the much-slower, barely- | relativistic, big guns arrive. | SkyMarshal wrote: | They could send the subatomic particles from Trisolaris | to Earth at light speed, and then use the entangled pair | of particles (one on earth, its mate on Trisolaris) to | monitor events on earth in real-time. | | As already said, that preserves the planet, prevents a | potential enemy from further developing technologically, | and enables real-time monitoring of and interference with | that enemy's activities. | Vecr wrote: | I can't reply to roywiggins for some reason, but it's | possible that the solar systems are closer in other | dimensions or something like that. Probably not though, | because the higher dimensions are so small. I assume the | author didn't think about it until it was too late, or | they couldn't fix it. | roywiggins wrote: | >and then use the entangled pair of particles (one on | earth, its mate on Trisolaris) to monitor events on earth | in real-time. | | This, of course, breaks the known laws of physics, since | lightspeed is a hard limit on the speed of causality. You | can't use entanglement that way in the real world (if QM | is anywhere close to correct) | AmericanChopper wrote: | The sophons themselves were a piece of magic science | fiction. Which I think is fine because the author really | doesn't ask you to suspend your disbelief all that much | throughout the books. The star plucking is another | example, as far as we know you can't use a star to do | that. | | But accelerating them towards earth "at the speed of | light" isn't exactly a problem. The LHC accelerates | protons to about 3 m/s less than the speed of light, and | as far as the plot is concerned the sophons travelling | here at the speed of light, or some tiny fraction of a | percent less than the speed of light doesn't make any | difference. | shoto_io wrote: | Oh great! I just started reading the book... | | /s | AlexCoventry wrote: | There's also the weird aspect that [rot13'd for spoilers] gur | fbcubagf frrz gb or noyr gb vasyhrapr naq dhrel znggre, ohg | pna'g frrz gb ernq crbcyr'f zvaqf be xvyy gurz. | bo0tzz wrote: | Gung'f abg dhvgr evtug, gurl qba'g npghnyyl unir gur znff | gb rkreg zhpu vasyhrapr ba nalguvat | bkanber wrote: | Gurl jrer cebgbaf, evtug? Fb gurl ernyyl pna bayl nssrpg | guvatf nebhaq gung znff naq raretl enatr. Gurl pna zrff | jvgu cnegvpyr nppryrengbe rkcrevzragf ohg pna'g nssrpg gur | znpeb jbeyq. | BrissyCoder wrote: | TIL google translate doesn't do ROT13. | amelius wrote: | Or perhaps the laws of physics that we observe are becoming | more complicated over time, as a consequence of some deeper law | of physics. | alasdair_ wrote: | The simulation we all live in is getting a new patch with | higher resolution models. | blackboxlogic wrote: | I wonder if we're in PROD, STAGE, QA or DEV? _waves | humanly_ | whatshisface wrote: | Two more technical treatments: | | https://cerncourier.com/a/new-tetraquark-a-whisker-away-from... | https://lhcb-public.web.cern.ch/Welcome.html#Tcc | thereddaikon wrote: | Is this the one that makes all the Sci-Fi gadgets do the | impossible? I need to know if I should be excited or not. | | /s | dmitriid wrote: | You just need to apply more quantum. | [deleted] | oldspleen wrote: | someone please ELI5 and how this discovery is important for | furthering our understanding of quantum numbers | whatshisface wrote: | The laws governing the strong force are somewhat well-known at | this point, but calculations involving them are difficult and | in many cases beyond our reach. Furthermore the fundamental | constants are not known to a very high precision. Both of these | problems can be addressed by collecting experimental data about | how these particles behave in real life, both to pin down the | constants, and to accept or reject calculation techniques. | lcfcjs wrote: | No 5 year old could follow that. | xwdv wrote: | Can someone explain the practical use for this? Better batteries | or something? | piyh wrote: | Another tick forward in fundamental physics that will pay off | as some theoretical framework getting slightly more grounded | and paying off in a tangential way 70 years from now. | skinwill wrote: | Normal human here, can someone speculate on potential industrial | uses? | Zenst wrote: | Too early for that, though does open up other science that may | well. Might finally pave the way for gravity shields, food | replictor...or nothing. | | The aspect that this tetraquark breaks down into something with | more mass will certainly be interesting for study. | nabla9 wrote: | Nobody expects noting. No reason to expect anything whatsoever. | | The particle is incredibly short-lived, requires a massive | particle accelerator to create, and is hard to detect. | | This is just another high-energy physics experiment. The hope | is that someday something comes out that does not fit into | existing models and is a sign of new physics. | WaitWaitWha wrote: | I am unclear if they produced a tetraquark particle, or they | simulated the particle. | | > ... used Google's quantum computer to demonstrate a genuine ... | Algol wrote: | I don't see a mention of quantum computers in the article. I | think LHCb detected the particle. | akomtu wrote: | The article (light on details, as usual) mentions that a slightly | different configuration of a tetraquark would be very stable | (again, not sure if that means nanoseconds or hours). If such | stable multiquarks exist, without an electric charge they would | be effectively untraceable, right? The only way to see such a | particle would be to hit it precisely with an even smaller | particle and get it to bounce back. | sethhovestol wrote: | The more likely (I'm not a physicist) is to watch the decay of | the particle and trace it back from there. | whatshisface wrote: | > _The only way to see such a particle would be to hit it | precisely with an even smaller particle and get it to bounce | back._ | | Bounce back from what force? Whatever forces would make it | interact with a single particle would make it interact with a | detector, which is itself made out of particles. | | They say the extra-stable tetraquark would only be susceptible | to decay via the weak force, which means you'd have to wait | around until it decayed, and then you'd often be able to see | some charged remnants. | akomtu wrote: | Can such tetraquarks form semi stable macroscopic structures | like atoms? For example, if they aren't completely neutral, a | group of them would be able to maybe attract an electron and | become a quasiatom of some sort. | whatshisface wrote: | The stable-to-strong-decay species they're talking about, | bb anti-u anti-d, would have a charge of (-1 -1 -2 -1)/3 = | -5/3 times the electron charge. I guess its antiparticle | would be positive, so maybe an electron could hang around | for a while. I don't know how long that tetraquark is | expected to live, though. | FreeFull wrote: | The charge would actually be (-2 + 1 - 1 - 1)/3 = -1 of a | proton's charge. There isn't any physically viable | combination of quarks that would produce a non-integer | charge. The article mentions the bb tetraquark can only | decay through the weak force, but I'm not sure how long | it'd live either. | enkid wrote: | I don't think that's a unique property to tetraquarks. Neutrons | or neutrinos also are not electrically charged. I'm not sure | what you mean by untraceable, but neutrinos rarely interact | with other particles and many, many of them pass through you | every second without you even noticing. | danslo wrote: | >Such proximity in mass makes the decay "difficult," resulting in | a longer lifetime of the particle, and indeed Tcc+, is the | longest-lived exotic hadron found to date. | | So... how long does it live? | kmm wrote: | Fun fact, the reason strange quarks are named strange is | because when we discovered the first hadrons containing those | quarks, they were strangely long-lived. | | Long-lived here meaning 10^-10 seconds, instead of 10^-20 | seconds. A whole tenth of a nanosecond! | ansible wrote: | That is actually quite a long time at the quantum scale. | whatshisface wrote: | The resonance width is inversely proportional to the lifetime, | and if the resonance width is about 400keV, the particle would | live for about 10^-21 seconds. For comparison, neutrons decay | via the weak force in about 800 seconds, and delta baryons, a | randomly chosen strong force decay, live for 10^-24 seconds. | That makes this tetraquark long-lived for a strong decay, but | that's way, way faster than a weak decay. | | https://en.wikipedia.org/wiki/Resonance_(particle_physics) | Gravityloss wrote: | So not usable as spaceship fuel | whatshisface wrote: | If you're allowed to use something produced in an | accelerator as your fuel you can't beat antimatter, which | is as stable as normal matter until Kirk orders warp one. | adrianN wrote: | I like black holes because once you have one you don't | need an accelerator for refueling. | https://arxiv.org/abs/0908.1803 | hnuser123456 wrote: | Huh, "black holes move when you push them" is | interesting. I suppose you could feed it with a beam, but | focusing a beam down to attometer-size beamwidth seems | like the hardest part, ignoring making a subatomic black | hole in the first place. But sure, I suppose capturing | the radiation and redirecting most of it back into the | black hole to push it and maintain its size, and just | enough spare to push the ship itself at the same speed is | feasible. Feels like a "free energy" invention but I | don't see where it fails, especially if you could capture | the majority of the radiation and feed it back into the | black hole directionally, minus whatever used to | accelerate the rest of the ship. | | I see, after more thinking, redirecting the radiation | into the black hole would push the ship backwards with | equal energy, so half the energy needs to be reflected | back into the black hole at the correct direction, and | the other half needs to shoot out the back as exhaust, | and you'd need additional mass to prevent the black hole | from shrinking and getting hotter. | | They seem to conceptualize a ~100-year black hole which | balances semi-feasible mass, power output, and lifespan, | which is radius 2.7 attometers, 1.8 million tons, and 17 | petawatts (!) of power. Looks like the saturn V was about | 50 GW of power, so having ~500,000x the power, with only | less than 1000x the mass (2900 tons vs 1.8m), means this | thing would propel at hundreds of G's of acceleration, | unless the ship itself was another 500 million tons? It | looks like the WTC towers were "only" about 500,000 tons, | so if you wanted to drop the acceleration to something | survivable by humans, you would either need a much | larger, colder black hole, or a ship of proportions of | 1,000 WTCs. | | The 10-attometer black hole, with "only" 1 petawatt of | power and mass 6.7 million tons and lifetime 5,000 years, | seems more reasonable, you'd want a ship with mass 58 | million tons to have Saturn V levels of acceleration, | only 100 WTCs and the black hole is still only about 10% | the mass of the ship. Still, this is only about 6x the | width of a proton where we're trying to beam on the order | of a petawatt. We would probably need a lot of lasers | packed densely together near the back of the ship to | focus together on this point to avoid the beam itself | being near capable of creating black holes, all coming | from the same direction where we need to exhaust equally | (or more) as much power to get the ship to keep up with | the black hole. | | Next step would be to figure out how big of a net we'd | need to collect enough mass to maintain the black hole | but I've spent enough time on this already. | | Alcubierre drives almost seem more reasonable than this, | almost. | | Oh, and the temperature of this thing would be around a | trillion degrees, pretty sure most of that radiation | would be gamma rays. Need to figure out how to reflect | gamma rays with efficiency. This is apparently around the | temperature of a SMBH's accretion disk, the temperature | of a new neutron star, and the temperature where matter | doubles in mass due to relativistic effects. | | All this being said, if we can balance the mass of the | black hole with that of the ship, with a black hole with | lifetime 5000 years, and we achieve 1g constant | acceleration, we can cross the galaxy in 24 years and | park it for up to a few thousand years before needing to | feed it to prevent it from getting too small/hot. https:/ | /en.wikipedia.org/wiki/Space_travel_using_constant_ac... | | Imagine if you could see the other side of the galaxy and | make it back to Earth before you turn 50 (though Earth | will have experienced 200,000 years), or, since once | you're already at such relativistic speed, see Andromeda | and come back before you're 60. Apparently we could round | trip to the edge of the (Earth's?) visible universe in | right around 100 years. Of course, by time you made it | back, Earth would be 26 billion years older, the sun will | have exploded, etc. Of course, if these are drone ships, | we don't need to worry about human-survivable | acceleration, and we could retrieve data much faster, but | then no biological lifeform would have been there. | zinglersen wrote: | This was such a cool read, thank you! | | What is hardest for me to comprehend is probably the last | part about time being relative. All this stuff makes me | think about how everything is made of the same matter and | then, what am "I"? | | Btw this part from the wiki link cracked me up "Constant | acceleration is notable for several reasons: It is a fast | form of travel." | Gravityloss wrote: | Power scales to the square of exhaust velocity while | thrust linearly, so if you have a very good power to | weight power source like a black hole, you can use a very | high exhaust velocity and thus can get by with very | little reaction mass. Which is good. | | Also, you can make a spaceship out of an asteroid (or | from asteroid materials) so multi WTC mass is not a | problem. | Gravityloss wrote: | There's always many considerations. Energy density, | stability, what kind of energy can you convert it to, can | it be directed easily, how hard is it to store etc... | whatshisface wrote: | Antimatter's reputation for being incredibly difficult to | store comes from the fact that it's produced as | individual particles. A superconducting antimatter hockey | puck would be much easier to store than a cloud of | antiprotons of the same mass. | | And yeah, you'll need a way to build gamma ray mirrors | before antimatter reactions will push you in any | direction (the energy comes flying out isotropically and | we can't presently do anything to stop or direct it), but | we can cross that parsec when we come to it. :-) | 8note wrote: | Superconductors pretty notoriously need to be kept cold, | which adds another difficulty of cooling the antimatter | without touching it | kadoban wrote: | For now. By the time anyone could even possibly create | enough antimatter to matter (heh), critical temperatures | should be much higher. The record is broken fairly | commonly. | whatshisface wrote: | If it was surrounded by a cold mass that it could radiate | photons to across a vacuum, its equilibrium temperature | would be that of its container. | human wrote: | I would be so nervous to be in the middle of space with | an hockey puck of antimatter. | yccs27 wrote: | I guess I'd be just as nervous in space with thousands of | tonnes of explosive propellant. Spaceflight always | operates on the very edge of what's possible, not of | what's safe. | jjk166 wrote: | Presumably antimatter would be your energy source, but | not your propellant. The gamma rays from a small number | of annihilations would heat up a much larger amount of | normal matter. | | At least for the first generation, you likely also | wouldn't be using antimatter as the main source of | energy, but rather as a method of initiating some other | reaction. For example where in a conventional fission | reaction you get a relatively clean split of a nucleus | into two halves plus a few extra neutrons to drive a | chain reaction, an antiproton will blast apart such a | nucleus like a billiard break, allowing fission reactions | with much less than a conventional critical mass. A quick | burst of positrons hitting the surface of some lithium | deuteride would be able to replace a fission primary and | make a pure-fusion explosion. Either of these options | could be used as either incredibly low-mass nukes for an | orion drive or as a light weight reactor for a more | conventional nuclear propulsion method. While about 600 | times less energy dense than pure antimatter, you're | still talking 10 million times better energy density than | our best current rocket fuels, while using several orders | of magnitude less antimatter. | ashtonkem wrote: | Gamma ray mirrors sound like they'd be extremely useful | for nuclear power too. | coldacid wrote: | I think that's what the dilithium crystals are for. ;D | im3w1l wrote: | Despite free neutrons decaying in 800s, there are many stable | elements containing neutrons. Would it be possible to imagine | a tetraquark as an ingredient of a stable particle? | phkahler wrote: | Are these decays equivalent to drops to a lower energy state | where that energy is mass? | whatshisface wrote: | The term "lower energy state" is a funny one, because isn't | energy conserved? What's happening is a drop to a more | spread out state, where you have several particles making | great time flying away from each other instead of one high- | energy-density locus in the center. | | Edit: Just to clarify, the time-variant system exception | does not apply in this case. It really is an entropy thing, | moreso than an energy thing (which is constant in every | particle decay that happens on Earth.) | MengerSponge wrote: | Fun fact: in the most general case, energy is not a | conserved quantity. | | https://www.preposterousuniverse.com/blog/2010/02/22/ener | gy-... | tux3 wrote: | This is lovely. Wikipedia sent me from energy not being | conserved, to time translation symmetry breaking, to time | crystals as a source of perpetual motion. | | Just need to find a tie-in to 5G and I can write my own | time-cube parody website. | | (The article is also very interesting, of course!) | debrice wrote: | Isn't information a better unit? | thechao wrote: | MengerSponge's article is raising an extremely subtle | point about how we translate modern physical theories | into English: we do it _poorly_. | | Conservation laws (Noether's theorem) are dependent on | the way the physics is voiced, mathematically. Saying | "energy is conserved" is the moral equivalent of looking | at Newton's laws and just _ignoring_ GR. GR tells us new, | precise, and amazing things about conservation laws. It | 's just that, unfortunately, they're a little hard to | translate into English. | whatshisface wrote: | > _Saying "energy is conserved" is the moral equivalent | of looking at Newton's laws and just ignoring GR._ | | If you're not expecting the spacetime background to be | changing rapidly during your experiment, it's pretty | moral to say energy is conserved. | teknopaul wrote: | my friend that thinks if he plays the breaks properly on | his EV he generates energy, will be happy very hear this. | renewiltord wrote: | All he has to do is push his Tesla to the top of the | hill! | whatshisface wrote: | The idea that spacetime itself has energy, which balances | out the apparent lack of energy conservation in matter | fields, is a far stronger interpretation than the article | suggests. Spacetime energy bends spacetime, which is why | gravitational waves exist. It's even called the stress- | energy tensor. ___________________________________________________________________ (page generated 2021-07-30 23:00 UTC)