[HN Gopher] ALICE finds first ever evidence of the antimatter pa...
___________________________________________________________________
ALICE finds first ever evidence of the antimatter partner of
hyperhelium-4
Author : elashri
Score : 272 points
Date : 2024-12-09 19:01 UTC (1 days 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
| 3form wrote:
| https://en.m.wikipedia.org/wiki/Exotic_atom this is also a
| supplementary fun read. I find it interesting that you could
| come up with many such combinations, and then answer to "could
| it exist?" becomes "why, yes!" more often than I would expect.
| andreareina wrote:
| Everything not forbidden is compulsory.
|
| https://en.m.wikipedia.org/wiki/Totalitarian_principle
| amai wrote:
| Unfortunately the lifetime of these hypernuclei is of the order
| of picoseconds. They will not revolutionize material sciences.
| automatic6131 wrote:
| Material sciences are generally electromagnetic effects only.
| I'd be surprised when nuclear changes alters chemistry or
| engineering in any way that has significance outside of
| nuclear reactors.
|
| Well, I suppose, radioactive decay is of negative use in
| chemistry and engineering.
| indoordin0saur wrote:
| One interesting counterexample to this is deuterium and
| water made from it. It is 11% denser than normal water, ice
| made from it sinks in normal water, it has a higher heat
| capacity, is more viscous and has a higher boiling point.
| It's also completely stable!
| ndsipa_pomu wrote:
| You can also drink it, though not a good idea to have
| more than a few sips due to the extra weight and
| different reactivity. You might feel dizzy if you drank a
| few glasses worth and it replaced the ordinary water in
| your inner ear.
|
| Also, heavy water is typically slightly radioactive due
| to it usually containing tritiated water (T2O), though
| regular water can also contain that.
|
| Apparently, swapping 20% of your cells' water with heavy
| water is survivable, but if you try this, don't blame me
| if you go sterile (cell mitosis will likely be affected).
| amai wrote:
| Of course you can find videos of people on YouTube who
| drink deuterium:
| https://www.youtube.com/watch?v=xcO1yCAO-pI
| automatic6131 wrote:
| Wow that's pretty interesting. I'm least surprised that
| deuterated chemistry is what's first mentioned, and I'm
| sure that there are some other good stuff in the
| category. I bet heavy gasoline (lol) has a lower octane
| number, for example.
| 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
| westurner wrote:
| My mistake, my mistake.
|
| It seems I had my Antimatter confused with mah Dark matter.
|
| Antimatter: https://en.wikipedia.org/wiki/Antimatter
|
| Dark matter: https://en.wikipedia.org/wiki/Dark_matter
|
| Antimass:
|
| I and the Internet have never heard of antimass.
|
| Negative mass: https://en.wikipedia.org/wiki/Negative_mass
|
| Dark energy: https://en.wikipedia.org/wiki/Dark_energy
|
| Dark fluid: https://en.wikipedia.org/wiki/Dark_fluid :
|
| > _Dark fluid goes beyond dark matter and dark energy in
| that it predicts a continuous range of attractive and
| repulsive qualities under various matter density cases.
| Indeed, special cases of various other gravitational
| theories are reproduced by dark fluid, e.g. inflation,
| quintessence, k-essence, f(R), Generalized Einstein-Aether
| f(K), MOND, TeVeS, BSTV, etc. Dark fluid theory also
| suggests new models, such as a certain f(K+R) model that
| suggests interesting corrections to MOND that depend on
| redshift and density_
| nsxwolf wrote:
| Negative mass was what I was going for with "antimass".
| For some reason I thought that was a common term but I
| guess it is not.
| westurner wrote:
| Not sure why I confused the terms.
|
| FWIU this Superfluid Quantum Gravity rejects dark matter
| and/or negative mass in favor of supervaucuous
| supervacuum, but I don't think it attempts to predict
| other phases and interactions like Dark fluid theory?
|
| From "Show HN: Physically accurate black hole simulation
| using your iPhone camera"
| https://news.ycombinator.com/item?id=42191692 :
|
| > _Ctrl-F Fedi , Bernoulli, Gross-Pitaevskii:_
|
| >> _" Gravity as a fluid dynamic phenomenon in a
| superfluid quantum space. Fluid quantum gravity and
| relativity." (2015) https://hal.science/hal-01248015/ _
|
| There's a newer paper on it.
|
| Alternatives to general relativity > Testing of
| alternatives to general relativity: https://en.wikipedia.
| org/wiki/Alternatives_to_general_relati...
|
| The new Sagittarius* black hole image with phase might
| help with discarding models unsupported by evidence. Are
| those knots or braids or fields around a vortical
| superfluidic attractor system? There doesn't at all
| appear to be a hard boundary Schwarzschild radius.
|
| But that's about not dark matter not antimatter.
| 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)
| westurner wrote:
| Thank you all for corrections and clarifications.
|
| I had confused Antimatter in particle theory (where there
| is no gravity) and Dark matter, which has no explanation in
| particle theory and maybe probably shouldn't be necessary
| for a unified model that describes n-body gravity at
| astrophysical and particle scales.
| westurner wrote:
| > [dark matter] _has no explanation in particle theory_
|
| From
| https://news.ycombinator.com/item?id=42369294#42371561 :
|
| > _One theory of dark matter is that it 's strange quark
| antimatter._
| 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...
| GuB-42 wrote:
| Not really a problem, relativistic effects are negligible
| at the very low accelerations MOND is about. Should MOND
| work with galaxies, a theory that say "if the force is
| less than a threshold, use MOND, otherwise, use general
| relativity" is not pretty, but good enough to match the
| observations, and that's the important part.
|
| There are more elegant ways of doing it (ex: TeVeS), but
| before looking at the best way to reconcile general
| relativity and MOND, something we know is possible, it is
| important to make sure that MOND works at the scales it
| is supposed to work with. Currently, it doesn't, but dark
| matter doesn't either. More research is needed, as they
| say.
| kuschku wrote:
| Disclaimer: Personal Opinion:
|
| Personally, I don't think MOND will be the solution. But
| I don't think it's going to be dark matter either.
|
| 1. We don't have a a way to unify relativity and quantum
| mechanics yet 2. Dark matter and MOND effects show up at
| extremely low accelerations.
|
| I have a hunch it's going to need a theory of quantum
| gravity to properly solve this.
|
| A century ago, quantum mechanics was initially formalized
| to explain the uktraviolet catastrophe of blackbody
| emissions.
|
| The difference between the classical emissions curve and
| the quantum based emissions curbe is very similar to the
| correction factor applied by MOND. I don't think that's a
| coincidence.
| orwin wrote:
| I never said it was correct, but people smarter than me
| work on this and I do not have the scientific baggage to
| say they're wrong.
|
| To me they are as right as people working on lambdaCDM or
| dark fluid, as long as none of those theory is able to
| predict anything.
| wbl wrote:
| How is MOND nice? It has a totally unprincipled function
| appearing that gets adjusted to fit.
| orwin wrote:
| It plays a nice song to the 'einstein/newton was wrong'
| crowd, and it is philosophically interesting to think
| that our observations validating Newton second law were
| (at the time) only made on earth.
|
| And some MOND derivatives are interesting, TeVeS is
| mathematically nice. I'm pretty sure most people working
| on those do it for the math more than to be correct tbh,
| but people way more competent than me work on this
| subject and I would not dare claim knowing they're wrong
| or lying.
| gus_massa wrote:
| MOND isn't dark matter.
|
| The idea of dark matter is that the problem is caused by
| matter we can't see. We assume the standard equations and
| from the rotation of the galaxies we have some missing
| mass. But we have a few equations, like gravitational lens,
| where we also can meassure missing mass and we can compare
| the results of the different methods. There are a few
| examples in https://en.wikipedia.org/wiki/Modified_Newtonia
| n_dynamics#Ou...
|
| MOND is an alternative solution to the same problem.
|
| I expect that most people working in dark matter are
| astronomers an cosmologist. I don't expect many particle
| phycicist realy care about dark matter. I've seen a lot of
| claim of particle phycicist that their new pet theory may
| be the dark matter, but it's mostly overhype to try to get
| more grant money.
| orwin wrote:
| MOND is a theory that try to explain the 'dark matter
| problem' we have with our current theories. It is in that
| sense a dark matter theory, one that doesn't use matter
| as an explanation, like entropic gravity, negative mass
| or f(R) gravity.
|
| And dark matter is an area of research and experiment in
| particle physics (at least it was 10 years ago)
| pfdietz wrote:
| One theory of dark matter is that it's strange quark
| antimatter. An asymmetry in the behavior of quarks and
| antiquarks in the very early universe would have led to
| antiquarks being preferentially squirreled away in tiny
| ultradense nuggets of quark matter. While explaining dark
| matter, this would also explain the observed matter-
| antimatter asymmetry. Or, rather, it would explain it by
| saying matter and antimatter are present in equal amounts,
| but the antimatter is in a different form.
|
| If this theory were true, tiny nuggets of this antimatter
| would be passing through the solar system all the time.
| Perhaps a future society could detect them and somehow trap
| some for use as an energy source.
| lazide wrote:
| For that to be true at the scale required to 'balance the
| scales', we'd have constant annihilation events - which
| would be impossible to miss.
| pfdietz wrote:
| Not true: the surface area of the nuggets could be so
| small they'd fall below detection threshold.
| lazide wrote:
| Any interaction with normal matter (including solar wind
| or the interstellar medium) would result in extremely
| energetic annihilation events. these aren't subtle.
| pfdietz wrote:
| And if the nuggets have sufficiently small surface area
| then the rate of these events would be low enough to be
| obscured by the background from other processes. It would
| not be like the annihilation from antihydrogen atoms
| hitting hydrogen atoms. The density of nuclear matter is
| some 15 orders of magnitude higher than ordinary matter,
| so nuggets 1 angstrom in diameter could have 10^15 times
| the mass for a given upper bound on the interaction rate
| with ambient gas.
| lazide wrote:
| There is no way anyone would miss the radiation emitted
| though. It would be, at a minimum, a very perceptible
| 'glow' over the volumes of space we're talking about.
| pfdietz wrote:
| It's not ruled out by evidence, AFAIK, and could explain
| some observational puzzles.
|
| https://indico.fnal.gov/event/6199/contributions/94686/at
| tac...
|
| (that was 2013; perhaps observations since have made it
| less likely)
|
| 2021 paper: https://arxiv.org/abs/2105.08719
|
| 2020 paper: https://www.researchgate.net/publication/3425
| 73954_Antimatte... ("a large region of the parameter
| space remains unconstrained, most notably for nuclear-
| dense objects.")
| ben_w wrote:
| > The current best guess is that there is some matter that we
| can't see for some reason. Nobody is sure what it is.
|
| My pet conjecture (it's not detailed enough to be a
| hypothesis) is that this is related to the baryon asymmetry
| problem.
|
| The antimatter symmetry problem is more than just baryons,
| despite the name, as we also have more electrons than
| positrons, not just more protons/neutrons than anti-
| protons/anti-neutrons.
|
| There's a few possibilities:
|
| 1) the initial value just wasn't zero (an idea I heard from
| Sabine Hossenfelder)
|
| 2) the baryon number is violated in a process that requires
| conservation of charge
|
| This would suggest antiprotons or antineutrons do something
| which involves the positron at the same time, so perhaps the
| anti-neutron is weirdly stable or something -- neutron decay
| is a weak force process, and that can slightly violate the
| charge conjugation parity symmetry, so this isn't a
| completely arbitrary conjecture.
|
| If we've got lots of (for example) surprise-stable anti-
| neutrons all over the place... it's probably not a perfect
| solution to the missing mass, but it's the right kind of
| magnitude to be something interesting to look at more
| closely.
|
| 3) the baryon number (proton/neutron/etc.) and/or lepton
| number (electron/positron/muon/etc.) is violated in a process
| that _does not_ require conservation of charge.
|
| If you have some combination of processes which don't each
| conserve charge, you're likely to get some net charge to the
| universe (unless the antiproton process just happens to occur
| at the same rate as the positron process); in quantum
| mechanics I understand such a thing is genuinely meaningless,
| while in GR this would contribute to the stress energy tensor
| in a way that looks kinda like dark energy.
|
| But like I said, conjecture. I'm not skilled enough to turn
| this into a measurable hypothesis.
| westurner wrote:
| What about virtual particles, too?
|
| Virtual particles:
| https://en.wikipedia.org/wiki/Virtual_particle :
|
| > _As a consequence of quantum mechanical uncertainty,_ any
| object or process that exists for a limited time or in a
| limited volume cannot have a precisely defined energy or
| momentum. _For this reason, virtual particles - which exist
| only temporarily as they are exchanged between ordinary
| particles - do not typically obey the mass-shell relation;
| the longer a virtual particle exists, the more the energy
| and momentum approach the mass-shell relation._
| ben_w wrote:
| Virtual particles are the generalisation to all quantum
| fields of what near-field is in radio to just photons.
| It's where you don't really benefit much from even
| calling things "particles" in the first place, because
| the wave function itself is a much better description.
|
| Unfortunately the maths of QM doesn't play nice with the
| maths of GR, which is also why zero-point effects are
| either renormalised to exactly zero or otherwise predict
| an effect 10^122 times larger than observed.
| gus_massa wrote:
| Even if antineutrons were stable, mixed with normal matter
| they will colide with protons and release a poiton and a
| lot of energy. (And the positron annihilate with an
| electon.)
|
| Anyway, I think there is still a chance that dark matter is
| antineutrinos. I'm not sure if it has been ruled out.
| wbl wrote:
| I think cosmological limits plus the neutrino
| observatories put some tight bounds on that.
| ConceptJunkie wrote:
| > If you want some antimmater, you can go to your nearby
| physics suply store and buy some radioactive material that
| produce positrons
|
| Or buy some bananas. You'll get a positron every once in a
| while from the occasional Potassium-40 decay.
| gus_massa wrote:
| I had to look up. Most of the radioctive potassium 40 in
| bananas decay by electron emmision. A tiny part by positron
| emision 0.001%. So you will get a lot of noise in the
| radioacivity detector.
|
| A few sources like
| https://alpha.web.cern.ch/science/positron-source and
| https://ifj.edu.pl/private/jdryzek/page_r12.html recomend
| sodium 22.
| 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.
| pfdietz wrote:
| There has been an idea that quark matter with roughly
| equal numbers of up, down, and strange quarks could be
| absolutely stable, the ground state of nuclear matter.
| Ordinary charged nuclear matter would be inhibited from
| converting to it (or being absorbed into it) by a strong
| potential barrier at its surface. However, if this were
| true neutron stars would actually be quark stars. There
| is some evidence that this isn't so, so the theory is not
| held to be very likely these days.
| 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".
| brian-armstrong wrote:
| Perhaps searches for exotic matter should take place in
| tropical regions?
| jagged-chisel wrote:
| Now here is a science recruiting tool
| 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!
| ykonstant wrote:
| In the case of the CMB, a blast from the past.
| 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.
| dhosek wrote:
| Not necessarily--perhaps it's something like what we have
| right now is the residue of a slight variation from 50/50
| in our local part of the universe (so it might have been
| 50.01% matter, 49.99% antimatter, and after the bulk of the
| matter and antimatter interacted and destroyed each other,
| the observable universe is that .02% left over. Do we know
| enough to be able to search for evidence of this in the
| cosmic background radiation?
| kadoban wrote:
| My guesses are:
|
| A universe that did that would have too much energy (from
| the mutual annihilation) once the orders and orders of
| magnitude of "extra" matter/antimatter interacted to make
| that likely/possible.
|
| Wouldn't we also see clouds of antimatter just hanging
| around? What proportion of matter has ever interacted
| with anything else? My guess is "low".
| vl wrote:
| >There's no known reason for all the matter to be over here
|
| The problem is there is no known reason for universe to
| exist. As such it could have been created in any
| configuration possible - including one where we observe
| matter, but antimatter is beyond event horizon.
| Dalewyn wrote:
| >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).
|
| For curiosity's sake: Wouldn't something like quantum
| mechanics defy that argument?
| semi-extrinsic wrote:
| Nope, see for instance good explanations in [1] and [2].
|
| The TL;DR is that you can't actually get information out of
| a measurement of entangled quantum states placed at
| locations A and B without also transmitting classical
| information between A and B.
|
| But good question!
|
| [1] https://en.wikipedia.org/wiki/Quantum_teleportation
|
| [2] https://www.forbes.com/sites/startswithabang/2020/01/02
| /no-w...
| ben_w wrote:
| > I've always wondered whether the "missing" antimatter in the
| universe is simply too far away to see, past the light horizon.
|
| I wondered the same thing, but it doesn't work out. Rolling
| enough dice to get _enough_ of the antimatter far enough away
| -- by a combination of Heisenberg for most of it and local
| annihilation of what was left -- is just _too_ unlikely, given
| what we see. Boltzmann-brain levels of unlikely.
| dhosek wrote:
| TIL: https://en.wikipedia.org/wiki/Boltzmann_brain
| 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.
| naveen99 wrote:
| It doesn't really help with the origin. If the universe is
| infinite, any possibility will happen in some part of the
| universe but not necessarily in the part accessible / visible
| to us. So our part of the universe could have antimatter or a
| different part could...
| K0balt wrote:
| So, are you saying that it might be possible that there are
| antigalaxies somewhere out there beyond the visible horizon
| in spacetime ? I mean, of course "possible" like flying
| elephants possible, but maybe theoretically predictable?
|
| Like maybe the matter went this way, and the antimatter went
| that way in spacetime? Or maybe all the antimatter went
| before the Big Bang and the matter went after?
|
| I mean that's wild but it would fix the symmetry problem!
| Cthulhu_ wrote:
| I'm an amateur at best but I've only recently realised the
| implications of the _observable_ universe, that is, we only
| know of the existence / size of the universe in what we
| can see, and there may be (and correct me if I'm wrong) way
| more Stuff beyond this 'boundary' whose light hasn't / will
| never reach us.
| robotworgen1994 wrote:
| My understanding is for the geometry of our observable
| universe to make sense, our actual entire universe must
| be substantially larger to account for the mass needed to
| make it so.
| K0balt wrote:
| So, what I'm hearing is that between us 3 amateurs, we
| should write an ebook on antimatter asymmetry and sell it
| on a website with healing crystals and magnetic
| antimatter bracelets? I can publish the paper, when do we
| start?
| marcyb5st wrote:
| While this might be possible, we would see annihilation
| events at the boundaries of matter/anti-matter zones.
|
| Additionally, statistically speaking, such a degree of order
| is highly unlikely since it would have much lower entropy
| compared to an homogeneous mix.
|
| It is much more likely that there is some unknown physical
| process that broke the symmetry between matter and anti-
| matter and so our universe is matter rich and anti-matter
| poor.
| amai wrote:
| ,,Using a machine-learning technique that outperforms
| conventional hypernuclei search techniques, the ALICE researchers
| looked at the data for signals of hyperhydrogen-4, hyperhelium-4
| and their antimatter partners."
|
| Which ML technique are they using? Could it be XGBoost, because I
| heard CERN is using it?
| amai wrote:
| I found the link to the publication:
|
| https://arxiv.org/abs/2410.17769
|
| And in fact, they used XGBoost.
| znpy wrote:
| Reminded me of this weird but cool song: Large Hadron Rap -
| https://www.youtube.com/watch?v=j50ZssEojtM :)
|
| Oh god I just noticed it's from 16 years ago... I'm getting old
| gosub100 wrote:
| Surprised the rapper name lil Hadron isn't taken yet
| ChuckMcM wrote:
| It will be interesting to see if this work will help us
| understand why the universe isn't half anti-matter.
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