• BarqsHasBite@lemmy.world
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    1 year ago

    Huh I didn’t know antimatter was a completely confirmed thing.

    After making a thin gas of thousands of antihydrogen atoms, researchers pushed it up a 3-metre-tall vertical shaft surrounded by superconducting electromagnetic coils. These can create a kind of magnetic ‘tin can’ to keep the antimatter from coming into contact with matter and annihilating. Next, the researchers let some of the hotter antiatoms escape, so that the gas in the can got colder, down to just 0.5 °C above absolute zero — and the remaining antiatoms were moving slowly.

    The researchers then gradually weakened the magnetic fields at the top and bottom of their trap — akin to removing the lid and base of the can — and detected the antiatoms using two sensors as they escaped and annihilated. When opening any gas container, the contents tend to expand in all directions, but in this case the antiatoms’ low velocities meant that gravity had an observable effect: most of them came out of the bottom opening, and only one-quarter out of the top.

  • JohnDClay@sh.itjust.works
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    1 year ago

    Hmm interesting. I wondered if it would be attracted or repelled by matter. It does annihilate when it comes in contact with mater, right?

    • Davel23@kbin.social
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      1 year ago

      The reason antimatter is “anti” is that an antiparticle has the opposite charge of its non-anti counterpart. Electrons have a negative charge, while their antiparticles, positrons have a positive charge. And since opposite charges attract, well, I think you can figure it out from there.

      And yes, matter/antimatter interactions result in annihilation.

      • Plibbert@lemmy.ml
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        1 year ago

        What exactly does “annihilation” mean in this context. Do both “atoms” give off energy and convert to sub atomic particles? Does one atom kind of “win” over the other and undergo fission instead of complete annihilation?

        • Contramuffin@lemmy.world
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          1 year ago

          At this tiny scale, energy and mass are essentially equivalent. So when we say that matter annihilates, we mean that they transform into pure energy (in this case, as photons of light). They don’t break into subatomic particles, because that still counts as mass. They just simply cease to exist.

          As a side note, the “conversion rate” of mass into energy (and vice versa) is governed by Einstein’s E=mc^2. All this equation means is that it takes a ridiculous amount of energy to create a small amount of mass, and vice versa, it only takes a small amount of mass to create a ridiculous amount of energy. Because antimatter annihilates completely (ie, 100% of its mass, as well as 100% of the regular matter’s mass, gets converted into energy), antimatter is currently the most explosive thing known to mankind

          • Plibbert@lemmy.ml
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            1 year ago

            Ok that makes sense.

            Man that’s pretty wild to think about. If antimatter was created at the same time as matter in the same quantity and distribution, then why are we here. Why didn’t the entire universe essentially cancel itself out? Was there some factor that benefited regular matter or hindered antimatter? Is there some level of chaos on the atomic or subatomic scale that played in regular matter being the dominant? Has some crazy philosophical implications.

            • scarabic@lemmy.world
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              1 year ago

              The universe very nearly did cancel itself out entirely. That’s why it is as empty as it is. The matter you see is the slight surplus there wasn’t enough antimatter to annihilate. Why this surplus? It’s one of the great remaining problems.

              I think there’s an extreme form of the anthropogenic principle we can apply here. Universes may pop into existence constantly and destabilize into nothing because their physical laws aren’t fine tuned for stability, or because they don’t have an uneven amount of anti/matter. Perhaps universes are part of some extra-cosmic superstructure that’s just frothing like mad. Some bubbles last a little longer than others before they pop. We could be one of those. Perhaps the multiverse is a little bit of suds in some leviathan child’s bathtub.

              • Plibbert@lemmy.ml
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                1 year ago

                Oh snap, you know this is a good point. What if the reason lies in other universes? Didn’t we detect a possible fingerprint of a collision with another universe In the cosmic heat map looking thing? What if we had a collision at just the right time that caused the destruction of just enough anti-matter to throw off the balance.

        • BT_7274@lemmy.world
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          1 year ago

          If I understand it correctly, annihilation is a 100% efficient process that converts all the matter into energy. After the process is complete there is no matter left over and only energy in the form of light, heat, and other energy forms that go way over my head remains.

        • Dr. Bluefall@toast.ooo
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          1 year ago

          Annihilation means exactly that - both particles destroy each other on contact, releasing the energy that composed them.

        • Davel23@kbin.social
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          1 year ago

          While atoms can be comprised of antimatter the interactions are generally on a subatomic level, i.e. electron/positron, and proton/antiproton. Since particles/antiparticles are identical to their counterparts aside from charge any such interactions are total with nothing left over other than the resulting energy release usually in the form of photons. The results of an atom reacting with an anti-atom could have a variety of results depending on the differences in weight between the two. Exactly what those results might be is a bit beyond my lay-understanding of the process.

  • Sibbo@sopuli.xyz
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    1 year ago

    So then it is not really antimatter in the sense that it is completely opposite?

    So antimatter still has positive mass?

    • LanternEverywhere@kbin.social
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      1 year ago

      In my limited understanding, antimatter just means the particles have the opposite charge of normal matter. All other attributes are not part of the definition of antimatter.

      • Bipta@kbin.social
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        1 year ago

        Charge isn’t the right word, although I’m not sure what the right word is. Otherwise you’ve got it right.

          • magoosh@feddit.nl
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            1 year ago

            The word is charge-parity. All physical systems (at least I’m quantum physics, I cant speak for other fields) are symmetric (nothing changes) if you change C(harge), P(arity) and T(ime reversal) at the same time. This is called CPT symmetry, see https://en.m.wikipedia.org/wiki/CPT_symmetry

            As antimatter can be described as normal matter going back in time (see the other comment), it means antimatter can also be described as normal matter transformed under the C and P operators. If T(particle) = antiparticle and CPT(particle) = particle then CP(particle) = antiparticle also.

            And the reason you can reverse time is because most of the equations are quadratic: they have a positive and negative solution, one describes particles moving forward in time, the other solution describes antiparticles going backward in time.

            NB: in quantum field theory it gets slightly more complicated, lets leave that as homework ;)

          • redcalcium@lemmy.institute
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            1 year ago

            The Feynman–Stueckelberg interpretation states that antimatter and antiparticles are regular particles traveling backward in time.[18]

            So just like in Tenet?

            • scarabic@lemmy.world
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              1 year ago

              Antimatter can interact with matter and create an explosion of energy that annihilates both.

              If you take some antimatter out of its containment cabinet and do that with it 5 minutes from now, you’ve done that in its “past” which means it can’t be there for you to procure in the first place.

              Or did you, in reverse time, cause a bunch of energy to converge and become matter and anti-matter, and then walk over and put the antimatter away in the cabinet?

              It’s reverse entropic as fuck but I guess that’s anti-time for you. Maybe this is how the Big Bang was caused. Anti-entropic flow of anti-matter into a highly ordered state in one point. Fuck.

            • LanternEverywhere@kbin.social
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              1 year ago

              What… How…

              EDIT

              i asked chatgpt if antimatter travels backwards in time, and this was the reply:

              Some physicists have proposed that antimatter is actually matter moving backwards in time, based on a mathematical equivalence that emerges from quantum field theory. This idea was first suggested by Richard Feynman, who wondered if all electrons could be the same electron bouncing back and forth in time. However, this is not a widely accepted interpretation, and there is no experimental evidence to support it. In fact, most physicists do not believe that antimatter is really moving backwards in time, because it is not clear what that would mean physically.

              One way to test this idea is to see how antimatter responds to gravity. If antimatter falls upwards instead of downwards, that would imply that it has a negative mass and a negative energy, which could be interpreted as moving backwards in time. However, a recent experiment at CERN has confirmed for the first time that atoms of antimatter fall downwards, just like normal matter2. This means that antimatter and matter have the same gravitational mass and the same sign of energy. However, this does not rule out the possibility that antimatter and matter might fall at different rates, which would still indicate a difference in their behavior under gravity.

              So, to answer your question, antimatter does not travel backwards in time, at least not in any obvious or observable way. It behaves very similarly to normal matter, except for having opposite charges and other quantum numbers. The mystery of why antimatter and matter did not cancel each other out completely in the early universe remains unsolved, and requires further investigation and experimentation

    • stebo02@sopuli.xyz
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      1 year ago

      Duh. Negative mass doesn’t exist. Antiparticles just have an opposite charge.

    • edryd@lemmy.world
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      1 year ago

      Because there is no theory of quantum gravity we have no idea how gravity could interact with anti matter. By showing that antimatter behaves just like matter when interacting with gravity we can learn a lot about it and cut the number of possible theories of quantum gravity in half.

    • Match!!@pawb.social
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      1 year ago

      Because things exist

      (the antigravity hypothesis was an attempt to explain why matter and antimatter haven’t annihilated each other)

    • foyrkopp@lemmy.world
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      1 year ago

      Because one common assumption was that the universe might contain as much antimatter as matter.

      Which begs the question: Where did it go? We would notice a huge amount of annihilation reactions in the solar system.

      “Antimatter falls up” (is gravitationally repelled instead of attracted by normal matter) was an easy hypothesis to explain that.