Antimatter falls down, not up: CERN experiment confirms theory : science

[-] someguy3@lemmy.world 92 points 11 months ago* (last edited 11 months 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.

[-] LanternEverywhere@kbin.social 64 points 11 months ago* (last edited 11 months ago)

You may have heard of a "PET scan" used in medicine. This uses a type of antimatter called a positron.

https://bigthink.com/hard-science/positron-emission-tomography-antimatter-cancer/

[-] float@feddit.de 14 points 11 months ago

The complexity behind this is fascinating.

[-] joelthelion@lemmy.world 5 points 11 months ago* (last edited 11 months ago)

Just wait until you find out about MRI :)

[-] float@feddit.de 5 points 11 months ago

That's pretty awesome too, but they don't need molecules with atoms that were modified using particle colliders just minutes/hours before you need them.

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[-] JohnDClay@sh.itjust.works 61 points 11 months ago

That might be dark matter you're thinking about

[-] someguy3@lemmy.world 18 points 11 months ago

Maybe!

[-] BloodSlut@lemmy.world 30 points 11 months ago

Not only does it exist, but bananas give off a fair bit of antimatter due to their decaying potassium isotopes.

Allegedly, im not smart enough to verify it

[-] plistig@feddit.de 27 points 11 months ago

Would an anti-banana give off normal matter?

[-] Sargteapot@lemmy.nz 18 points 11 months ago

Does it matter?

[-] taigaman@kbin.social 21 points 11 months ago

I don't think it would antimatter

[-] elbarto777@lemmy.world 12 points 11 months ago

Argument anihilated!

[-] 768@sh.itjust.works 15 points 11 months ago

AFAIK, yes, you might wanna look into β+- and β־-decay

[-] marcos@lemmy.world 5 points 11 months ago

AFAIK, yes.

There are some very small differences between matter and anti-matter, but I don't think any of them affect radioactivity.

[-] sushibowl@feddit.nl 21 points 11 months ago

Bananas produce antimatter, but just barely. The main radioactive material in bananas is Potassium-40. A banana is about 0.358% potassium in all. About 0.012% of naturally occurring potassium is the radioactive Potassium-40. Only 0.001% of all radioactive decay events in postassium-40 produce an antiparticle (a positron).

An average banana produces a single positron about every 75 minutes.

[-] Evil_incarnate@lemm.ee 7 points 11 months ago

Brb. Making a fruit-based matter-antimatter annihilation power plant.

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[-] wols@lemm.ee 6 points 11 months ago

El psy kongroo

[-] ekZepp@lemmy.world 4 points 11 months ago

[-] postmateDumbass@lemmy.world 8 points 11 months ago

We need a Far Side where ape scientists are colliding two bannanas at high speed

[-] ChickenAndRice@sh.itjust.works 4 points 11 months ago

They say if you microwave bananas, you will get green gel bananas

^dont ^actually ^try ^that

[-] SkyeStarfall 27 points 11 months ago

Antimatter was first observed physically back in 1932. A positron, more specifically. Its existence has been confirmed, and accepted, for ages, and some of our technology already operates using antimatter to do its tasks.

[-] orrk@lemmy.world 17 points 11 months ago

anti-matter? ya, we have been observing it for quite a while (testing is difficult for reasons), it naturally accumulates in parts of the Van Allen belt.

Dark matter on the other hand is still completely up for question

[-] FlyingSquid@lemmy.world 17 points 11 months ago

The Large Hadron Collider wouldn't work if antimatter wasn't confirmed.

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[-] RagingHungryPanda@lemm.ee 20 points 11 months ago* (last edited 3 months ago)

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[-] dudinax@programming.dev 13 points 11 months ago

But from the antimatter's perspective, it falls up.

[-] cmbabul@lemmy.world 4 points 11 months ago

Then it really is lost!

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[-] Sibbo@sopuli.xyz 12 points 11 months ago* (last edited 11 months 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 40 points 11 months 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 9 points 11 months ago

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

[-] LanternEverywhere@kbin.social 33 points 11 months ago

No, charge is the right word. But i was wrong about charge being the only difference, apparently antimatter's "parity" and "time" are also opposite of normal matter. Whatever that means.

https://en.m.wikipedia.org/wiki/Antimatter

[-] magoosh@feddit.nl 15 points 11 months 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 5 points 11 months 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 6 points 11 months 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 5 points 11 months ago* (last edited 11 months 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

[-] SeabassDan@lemmy.world 4 points 11 months ago

Would that mean that they're not falling, but rather actually rising?

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[-] JohnDClay@sh.itjust.works 9 points 11 months 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 19 points 11 months ago* (last edited 11 months 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 7 points 11 months 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 14 points 11 months ago* (last edited 11 months 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 9 points 11 months 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.

[-] Sabin10@lemmy.world 15 points 11 months ago

You're describing the matter-antimatter asymmetry problem

https://home.cern/science/physics/matter-antimatter-asymmetry-problem

[-] BreadstickNinja@lemmy.world 8 points 11 months ago

I mean if you just thought of all those questions on your own, that's damned impressive. You just summarized one of the greatest mysteries in particle physics. Here's a story about that exact question - what was the process that gave preference to creation of matter over antimatter?

https://www.scientificamerican.com/article/why-is-there-more-matter-than-antimatter/

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[-] BT_7274@lemmy.world 8 points 11 months 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.

[-] drbluefall@toast.ooo 4 points 11 months ago

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

[-] TheOnlyMego@lemmy.world 4 points 11 months ago

For the simple case of electron-positron annihilation, they transform into high-energy photons, whose total energy is equal to the total mass-energy of the electron and positron. See: https://en.wikipedia.org/wiki/Electron%E2%80%93positron_annihilation

[-] Davel23@kbin.social 3 points 11 months ago* (last edited 11 months 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.

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[-] InternetTubes@lemmy.world 4 points 11 months ago* (last edited 11 months ago)

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