[HN Gopher] Alice finds first ever evidence of the antimatter pa...
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Alice finds first ever evidence of the antimatter partner of
hyperhelium-4
Author : elashri
Score : 121 points
Date : 2024-12-09 19:01 UTC (3 hours ago)
(HTM) web link (home.cern)
(TXT) w3m dump (home.cern)
| isoprophlex wrote:
| Wow, fascinating. I had no idea these hypernuclei even existed!
|
| Interesting background read:
| https://en.m.wikipedia.org/wiki/Hypernucleus
| westurner wrote:
| Does this actually prove that antimatter necessarily exists?
|
| Does this prove that antimatter is necessary for theories of
| gravity to concur with other observations?
|
| Do the observed properties of antimatter particles correspond
| with antimatter as the or a necessary nonuniform correction
| factor to theories of gravity?
| pvg wrote:
| Antimatter detection is not the new thing here, being nearly a
| century old:
|
| https://timeline.web.cern.ch/carl-anderson-discovers-positro...
| OscarCunningham wrote:
| You're confusing antimatter with dark matter.
| nsxwolf wrote:
| With a splash of antimass in that confusion too
| ranger207 wrote:
| Antimatter has been used in medical PET (positron emission
| tomography) scans since the 60s
| dragonwriter wrote:
| > Does this actually prove that antimatter necessarily exists?
|
| Antimatter definitely exists, it is detectable, and used; e.g,
| PET scans use positrons (anti-electrons), and there have been
| experiments (only in animal models last I knew) with anti-
| proton radiotherapy for cancers.
|
| This is the first evidence of a _particular configuration of
| antimatter_ , not the first evidence of _antimatter_.
| benbayard wrote:
| To be more specific this is the first time we have detected
| hyper-antimatter of Helium where one of the quarks in the
| nucleus is an anti-strange quark (an anti-lambda from the
| article)
| gus_massa wrote:
| My guess is that you are confusing " _antimatter_ " and " _dark
| matter_ ".
|
| If you want some antimmater, you can go to your nearby physics
| suply store and buy some radioactive material that produce
| positrons. It's quite easy. (Radioactive material may be
| dangerous. Don't fool with that!) If you want antiprotons or
| antihydrogen, you need a huge particle acelerator. They make
| plenty of antiprotons in the CERN, to make colisions. They are
| very difficult to store, so they survive a very short time on
| Earth.
|
| Dark matter is very different. We have some experimental resuls
| that don't match the current physics theories. The current best
| guess is that there is some matter that we can't see for some
| reason. Nobody is sure what it is. Perhaps it's made of very
| dark big objects or perhaps it's made of tiny particles that
| don't interact with light. (I'm not sure the current favorite
| version in the area.) Anyway, some people don't like " _dark
| matter_ " and prefer to change the theories, but the proposed
| new theories also don't match the experimental results.
| orwin wrote:
| > Anyway, some people don't like "dark matter" and prefer to
| change the theories
|
| It seems a bit more complicated than that, mostly because the
| vulgarization often available too is quite bad to explain the
| issue.
|
| My understanding:
|
| - Our current theories fail to predict/match an array of
| observations, as if more matter than what we can detect
| exist. Some scientists called that the "dark matter problem",
| that's what most physicists working on the subject refer to
| when they talk about "dark matter".
|
| - Every theory you talked about: dark matter big objects,
| dark matter particles AND the "change the theories" (i guess
| you talk about the Modified Newtonian dynamics, where you
| alter Newton's second law at low speed to match some
| observations) are dark matter theories: theories that tries
| to explain why the universe act as it is, not matching our
| current theories, either by adding new things, or by
| modifying our discovered laws to match our observations. Each
| of those theories have multiple branch investigated.
|
| - the "dark matter particle theory" is sometime vulgarized as
| "dark matter" on podcasts or in books/articles. This is
| because more scientists work on particle physics than on
| gravity or astrophysics (my country present like 3
| astrophysics thesis each year, and dozens of particle physics
| thesis). I think this caused a huge misunderstanding.
|
| - Some people with a common understanding (like mine, i meant
| non-physicists, it's absolutely not derogatory) like MOND
| because philosophically it is quite nice, and also tend to
| draw in people with minority/anti-etablishment habitus[0]
| (cf: most physicists working on those subjects are particle
| physicists). I'm not saying this theory is worse than the
| others at all, i'm just saying that the kind of layperson
| drawn to it can be _really_ sure they're right and profess
| their beliefs everywhere, and sometime claim that "MOND isn't
| dark matter", when they really confuse dark matter as a
| problem to be solved with "dark matter particle theory".
| Misunderstanding happen to everyone btw, it's really not a
| big issue.
|
| In case you did not talk about MOND but about theories that
| claim that the issue are with our tools to observe at a
| distance, some theories include that to explain some of the
| inconsistencies, never all of them, and those theories seems
| to really be a minority atm, so hopefull it wasn't about
| that.
|
| [0] Also, those habitus seems to draw in grifters who know
| they can make quick bucks by selling books/conferences if
| they look convincing enough, which is why MOND has a weird
| reputation now, but absolutely serious physicists and
| mathematicians work on the subject very, very seriously.
| kuschku wrote:
| > like MOND because philosophically it is quite nice, and
| also tend to draw in people with minority/anti-etablishment
| habitus
|
| MOND is a non-relativistic theory. It's not even able to
| explain the orbit of mercury, gravitational lensing or
| black holes.
|
| It's the equivalent of hot gluing jet engines to a roman
| quadriga, it won't fly.
| ars wrote:
| > MOND is a non-relativistic theory.
|
| Well obviously, it's literally in the name.
|
| A relativistic version of the theory is: https://en.wikip
| edia.org/wiki/Tensor%E2%80%93vector%E2%80%93...
| nsxwolf wrote:
| What is "hyperhelium"? Google only turns up things related to
| this article.
| Jabbles wrote:
| 2nd paragraph of TFA
| godelski wrote:
| For those that can't RTFA, here's the first sentence of the
| second paragraph > Hypernuclei are exotic
| nuclei formed by a mix of protons, neutrons and hyperons, the
| latter being unstable particles containing one or more quarks
| of the strange type.
| elashri wrote:
| It is an exotic nucleus composed of two protons, one neutron,
| and one lambda particle (which is a type of hyperon -fermions
| with three quarks- containing a strange quark). This
| configuration distinguishes it from regular helium-4, which
| consists solely of protons and neutrons. The inclusion of a
| lambda particle introduces "strangeness" into the nucleus,
| making it a hypernucleus [1].
|
| PS: By exotic here it I use the term as used by particle
| physicists which just mean not your ordinary stuff discussed in
| the "popular" working groups. Not the linguistic meaning of the
| word exotic.
|
| [1] https://en.wikipedia.org/wiki/Hypernucleus
| bilsbie wrote:
| What are the properties of this? Any cool applications?
| mrguyorama wrote:
| It decays in under a nanosecond. A reality of all exotic
| matter research is that it is exotic almost always because
| it cannot exist in a stable manner for longer than a
| second.
|
| The vast majority of applications, if any, will be
| extremely niche sensing applications. They are useful to
| further probe the edges of our knowledge of physics and
| look at the corner cases where our models give confused
| shrugs and odd answers.
|
| It's not going to power a warp drive.
| cogman10 wrote:
| LHC likely created these particles which means we have
| single atoms that have been created and not full compounds.
|
| Someone can correct me if I'm wrong, but the significance
| of this is mostly just further confirmation of the
| predictions of the standard model. The standard model says
| such particles should exist and now that we've created
| them, we've confirmed that they do indeed exist.
|
| I don't think there's much practical application beyond
| further refinement of theoretical physics and ruling out
| other candidate theories.
| ninalanyon wrote:
| Exotic is defined in the Cambridge Dictionary as:
|
| "unusual and exciting because of coming (or seeming to come)
| from far away, especially a tropical country"
|
| That doesn't seem too far from the use of it in physics. The
| "tropical country" part is clearly optional but could be
| replaced by "especially a special group of scientists".
| dhosek wrote:
| I've always wondered whether the "missing" antimatter in the
| universe is simply too far away to see, past the light horizon.
|
| And then there's the exotic theory that at the big bang, regular
| matter went one direction in time and antimatter the opposite
| direction.
| spullara wrote:
| they certainly can't hang out together for very long :)
| BuyMyBitcoins wrote:
| But when they do get together, it's a blast!
| short_sells_poo wrote:
| The issue with the "past the observable universe horizon" is
| that it is an entirely untestable theory. It may be true, but
| it may as well be irrelevant because according to our
| understanding of the universe, we are never going to be
| affected by this fact (since it's in a part of the universe
| from which information may never reach us).
| kadoban wrote:
| It also answers not much, just changes the question. There's
| no known reason for all the matter to be over here, where we
| are, and all of the antimatter to be way over _there_ outside
| of the observable universe. If anything that seems much less
| likely than there just being other imbalances in which gets
| created (or which survives over time, etc.). The universe
| would have to have preferred absolute directions in which to
| throw different types of matter/antimatter? That'd be very
| strange indeed, based on what we know.
| floxy wrote:
| OT, but does anyone have updates on potential for antihelium
| detection on the AMS aboard the ISS? Seems like they have a
| handful of detections, but aren't quite statistically good enough
| to be conclusive?
|
| https://en.wikipedia.org/wiki/Alpha_Magnetic_Spectrometer
| cryptozeus wrote:
| Wow TIL two cool facts for antimatter use.
|
| Exploring the Universe's Origins: The Big Bang should have
| created equal amounts of matter and antimatter, yet our universe
| is predominantly matter. Studying antimatter helps scientists
| investigate this imbalance, shedding light on the fundamental
| laws of physics.
|
| Medical Applications: Antimatter plays a role in medical imaging
| techniques like Positron Emission Tomography (PET) scans, which
| are used to detect conditions such as cancer.
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