The end annihilation was actually the electron switching to backwards through time. At the beginning of the experiment the positron switches back to forward and continues on its way.
That's matter cruelty. We need more ethical ways to study those poor things. Does anyone know what happened after the experiment ? Did they finally let it go?
whats up with all the comments making analogies with AI torture repository?
One might measure the "amount of computation going on" as a proxy for consciousness, but "number of dissipative logic gates" can't be right since one can construct larger reversible circuits containing the same computation (and hence dissipation is a poor measure), although one could then use the total number of bits (including trash bits) as the measure.
but I don't understand why particle physics?
having all other comments (at the time of writing) be about consciousness of individual particles, seems to indicate these commenters specifically believe particle physics or antimatter to directly describe consciousness?
Or is this some kind of "disinfo inoculation campaign" to render us immune to "sentient rights propaganda"?
Don’t worry! If the single electron theory is correct, then this torture only represents an infinitesimal portion of its total lifetime, which is actually experienced in reverse and so it may feel increasing relief over time rather than increasing anxiety over being trapped.
As the sibling comments say, it's a single positron so the energy released is tiny. I tried to find positrons sources in common life, the best I could find was https://en.wikipedia.org/wiki/Positron_emission_tomography The relevant paragraph are
> For a typical dose (245 MBq) of FDG, one of the most common radiotracers used for PET neuroimaging and cancer patient management,[48] the effective radiation dose is 4.7 mSv.[49]
and
> This limitation restricts clinical PET primarily to the use of tracers labelled with fluorine-18, which has a half-life of 110 minutes and can be transported a reasonable distance before use.
Where "245 MBq" means 2*10^8 positrons per second for. And "110 minutes" means a half disappears every 2 hours, so the total sum is equivalent to 4 hours but I'm missing some small constant and they ae probably averaging the dose. I guess "3 hours" is a good compromise but multiply it by 2 or 4 if you prefer a smaller or bigger number. Anyway, 3 hours are 10^4 seconds, so the total numbers of positrons in a PET is approximately 2*10^8 * 10^4 = 2*10^12.
And whether it’s a positron or an electron (beta+ or beta- decay) doesn’t seem to matter that much as far as equivalent dose is concerned, the energy deposited is only fractionally higher in the case of a positron.
In addition to knowing how much stuff is released by one particle, we have a decent handle on how much is needed in order to be dangerous, due to us being constantly bombarded by various cosmic rays. That's how we can say that it's not dangerous.
The article is behind a paywall, but it seems likely that the bigger safety concern is whatever produced the large quantity of particles needed to have a chance of trapping just one. And those kinds of experiments are conducted in regulated facilities for good reason.
Exciting results. The electron's magnetic moment is probably the most precise standard model prediction, and Gabrielse's group has measured it with 13 digits of accuracy. The positron is predicted to have exactly the same magnetic moment, but this has not been measured since 1987. With the new trap, they should be able to finally match the electron's precision.
And yet the lifetime of free "thermal" neutrons is unknown (there are two measurements that give results off by ~1%) between 888 and 878 seconds.
Notably, neutrons are quite unstable outside of a nucleus and decay generating a proton, electron, and a neutrino. There are many theories on the discrepancy.
The parents of the anti-matter particle then freeze time just as the containment is about to explode, allowing Picard and Geordi to wander
around the facility looking for clues - until one scientists head slowly turns - they are also awake !!
I don't get how they know they have one in there. I mean they're measuring the magnetic field but how on earth do you make sufficiently precise measurements to detect a single particle!?!
They let it go and listen for the pop? Let it fall from the magnetic containment and you should see a predictable emission as it collides with some normal matter. Detecting single photons is what detectors are all about.
I think this is a fascinating technology. I wonder if it is currently energy positive (so that we can engineer it into a functional source) or at least if it can be extended to be captured in bulk (antimatter rockets!).
Energy positive? That made me laugh. Making antimatter is more energy negative than building a 747 out of gold. They burn through enough power to light a town in order to capture a literal handful of antimater particles.
In a rocket it would not be useful. It has the energy but would emit it as all sorts of highly penetrating radiation rather than hot gas for a rocket nozzle to turn into thrust.
In this case they are using 22Na that produces positrons. A quick search says that they cost like $50-$300. (I guess I'm in yet another list now.) I used one in the physic lab a few years ago. They are good enough to get a few blips in a Geiger counter or something similar.
I agree that if someone wants to make enough antiprotons and positrons to make enough antimater to power a rocket, the cost is prohibitive and there is absolutely no hope to make it cost efficient.
I know you’re being facetious but a 747 made out of gold is going to be ~24 billion dollars if you are doing a weight conversion. A 747 by itself is ~$400 million.
No way this experiment had that kind of funding. I would bet the experiment itself had a few million dollars in funding at most + another few for the salaries. Max 10M all in. Expensive but not prohibitive like a 747.
But electrons/positrons cannot become fuel. Positrons repel each other. So to make any real amount of antimater, beyond counting individual particles, you need anti-protons to keep the positrons happy and containable at scale. Creating the sort of anti-hydrogen one might want to collect as fuel, THAT requires golden 747s of energy.
I could be wrong but my understanding is that’s purely a function of our technological limitations in how we create antimatter, not in the fundamental energy required. Our tech of a particle acceleration is ~1e9 times less efficient than the actual energy required because most of the energy is lost, not converted. A gram would be $~6.2M/gram if we could get to 1% energy conversion efficiency. No one bothers of course to even try because it’s not worth it - expensive, difficult, and huge energy losses. Fusion reactors for space ships will probably come before antimatter gets cracked as a battery source.
Positrons aren’t useful because they annihilate to produce gamma rays, which can’t be contained. However, anti-proton annihilation produces a bunch of particles, including pions, which could be contained in a magnetic bottle and directed for thrust.
> In order to determine ωz and the number of trapped
positrons, the axial oscillation of a positron is driven with
oscillating potentials applied to the trap electrodes. The
frequency of the drive ωd is swept through resonance with
ωz.
> For the center-of-mass axial motion of
more than one positron, the damping (and hence the observed signal width) increases in proportion to the number of particles. A confirmation that only one positron
is trapped comes from spin flip observations that are discussed presently
The simple explanation: The positrons are trapped and fly around the trap center. In the z-direction, this is a simple "up and down" osscillation. There are electrodes in the top and bottom of the trap called the "end caps". The end-caps are connected to each other with a large resistor (technically, a coil forming an LC resonator with the parasitic capacitance, but on resonance it looks like a large resistor).
When the positrons are close to the top endcap, they attract negative charges into the top endcap. This is called an "image charge". When the positrons are close to the bottom endcap, the image charge into ottom endcap. This forms a a current, the "image current". The more positrons you have, the larger the image current.
Since the image current (on the order of femto Amperes) has to flow through the large resitor, it is turned into a voltage that can be amplified and measured by cryogenic amplifiers. But it has a second effect: The voltage "back-acts" on the positrons, damping their motion. If you have more positrons in the trap, this damping gets stronger, because each positron experiences the back-action of all other positrons.
In the paper, you can see pictures of the driven axial motion, where you take an RF excitation and sweep the frequency over the resonance, recording the positron's amplitude as a response. The more positrons you have, the "wider" this resonance, because of the damping effect.
As you reduce the number of positrons by doing a "dip" (making the trap really shallow, hoping that some, but not all, positrons escape), you can see the width getting smaller and smaller in discrete steps. That's how you know you are dealing with individual particles.
I haven't worked on Gabrielse's setup, but I have worked on other, very similar (better, ha!) experiments 10 years ago. I don't see what's so special about this trap, but putting antimatter into it always makes for a nice headline.
Annihilation. At low energies the antiproton and proton go through an interaction which ultimately results in photons (light energy). Matter is converted into energy as e = mc^2. Though the interaction passes through a number of exotic intermediate stages first.
It gets complicated, because protons and anti-protons are composite particles.
To simplify somewhat, one quark from each will annihilate, leaving four quarks and a lot of energy, which re-arrange into mesons (two quarks each), which then decay into photons, electrons, positrons and neutrinos.
Very cool! There's some wild ideas about antimatter capture in space via giant arrays of superconducting magnets trapping naturally occurring antimatter.
Apparently, nanograms / micrograms is enough to create a "antimatter catalyzed" fission/fusion propulsion system with enormous specific impulse / efficacy.
Similar work is done at the CERN LHC facility, where they can deliver antimatter to your door. Got a couple of hours? Check out Marco Reps' tour: https://www.youtube.com/watch?v=Yibef6nLCv8
I shudder to think of the paperwork the EU would require for authorization to transport antimatter off-campus. But they have hauled it around for up to 20 minutes (https://www.antimatter.hhu.de/en/about-us/base-step) so in principle it could go a bit farther!
There is like a 60% chance that they annihilate on the spot and a 40% chance that they form "positronium" that is similar to an Hydrogen atom but with an electron+positron instead of electron+proton. The positronium has a half life of less than a millisecond, so if you blink they go away and you can ignore the intermediate "positronium" step. More details https://en.wikipedia.org/wiki/Positronium#Formation_and_deca...
But it's more weird. In the research article they explain that they make positronium, then use microwaves to excite the positronium so it's bigger and the electron and positron are not very close and they don't colide (I think this increase the half-life), then they put the positronium inside the cyclotron and when they turn it on the electron escapes but the positron get's trapped.
Hope Aristotle with his 'telos' is wrong, and the antimatter particle does not have a purpose to annihilate itself with a +-matter particle. The universe will complain if it doesn't.
It's funny because I just read about One Electron Theory which is a fun thought experiment. But if it's true then you'd assume there's also One Positron. And we've got it. So if anyone has had a successful PET scan in the past month, maybe the theory is disproven.
110 comments
[ 0.24 ms ] story [ 45.4 ms ] threadhttps://en.wikipedia.org/wiki/One-electron_universe
"Wild? I was absolutely livid!"
One might measure the "amount of computation going on" as a proxy for consciousness, but "number of dissipative logic gates" can't be right since one can construct larger reversible circuits containing the same computation (and hence dissipation is a poor measure), although one could then use the total number of bits (including trash bits) as the measure.
but I don't understand why particle physics?
having all other comments (at the time of writing) be about consciousness of individual particles, seems to indicate these commenters specifically believe particle physics or antimatter to directly describe consciousness?
Or is this some kind of "disinfo inoculation campaign" to render us immune to "sentient rights propaganda"?
> For a typical dose (245 MBq) of FDG, one of the most common radiotracers used for PET neuroimaging and cancer patient management,[48] the effective radiation dose is 4.7 mSv.[49]
and
> This limitation restricts clinical PET primarily to the use of tracers labelled with fluorine-18, which has a half-life of 110 minutes and can be transported a reasonable distance before use.
Where "245 MBq" means 2*10^8 positrons per second for. And "110 minutes" means a half disappears every 2 hours, so the total sum is equivalent to 4 hours but I'm missing some small constant and they ae probably averaging the dose. I guess "3 hours" is a good compromise but multiply it by 2 or 4 if you prefer a smaller or bigger number. Anyway, 3 hours are 10^4 seconds, so the total numbers of positrons in a PET is approximately 2*10^8 * 10^4 = 2*10^12.
Good outlook. Positive vibes only.
The article is behind a paywall, but it seems likely that the bigger safety concern is whatever produced the large quantity of particles needed to have a chance of trapping just one. And those kinds of experiments are conducted in regulated facilities for good reason.
Notably, neutrons are quite unstable outside of a nucleus and decay generating a proton, electron, and a neutrino. There are many theories on the discrepancy.
https://journals.aps.org/prd/abstract/10.1103/PhysRevD.110.0...
I think this is a fascinating technology. I wonder if it is currently energy positive (so that we can engineer it into a functional source) or at least if it can be extended to be captured in bulk (antimatter rockets!).
In a rocket it would not be useful. It has the energy but would emit it as all sorts of highly penetrating radiation rather than hot gas for a rocket nozzle to turn into thrust.
I agree that if someone wants to make enough antiprotons and positrons to make enough antimater to power a rocket, the cost is prohibitive and there is absolutely no hope to make it cost efficient.
What would need to be true for the capability of creating and using antimatter to become feasible?
No way this experiment had that kind of funding. I would bet the experiment itself had a few million dollars in funding at most + another few for the salaries. Max 10M all in. Expensive but not prohibitive like a 747.
https://m.youtube.com/watch?v=jjp3WC8Unj8
> In order to determine ωz and the number of trapped positrons, the axial oscillation of a positron is driven with oscillating potentials applied to the trap electrodes. The frequency of the drive ωd is swept through resonance with ωz.
> For the center-of-mass axial motion of more than one positron, the damping (and hence the observed signal width) increases in proportion to the number of particles. A confirmation that only one positron is trapped comes from spin flip observations that are discussed presently
When the positrons are close to the top endcap, they attract negative charges into the top endcap. This is called an "image charge". When the positrons are close to the bottom endcap, the image charge into ottom endcap. This forms a a current, the "image current". The more positrons you have, the larger the image current.
Since the image current (on the order of femto Amperes) has to flow through the large resitor, it is turned into a voltage that can be amplified and measured by cryogenic amplifiers. But it has a second effect: The voltage "back-acts" on the positrons, damping their motion. If you have more positrons in the trap, this damping gets stronger, because each positron experiences the back-action of all other positrons.
In the paper, you can see pictures of the driven axial motion, where you take an RF excitation and sweep the frequency over the resonance, recording the positron's amplitude as a response. The more positrons you have, the "wider" this resonance, because of the damping effect.
As you reduce the number of positrons by doing a "dip" (making the trap really shallow, hoping that some, but not all, positrons escape), you can see the width getting smaller and smaller in discrete steps. That's how you know you are dealing with individual particles.
I haven't worked on Gabrielse's setup, but I have worked on other, very similar (better, ha!) experiments 10 years ago. I don't see what's so special about this trap, but putting antimatter into it always makes for a nice headline.
The link is cherry picked from a very good explanation by Gemini https://www.google.com/search?q=antiproton+hidrogen+colissio...
To simplify somewhat, one quark from each will annihilate, leaving four quarks and a lot of energy, which re-arrange into mesons (two quarks each), which then decay into photons, electrons, positrons and neutrinos.
Apparently, nanograms / micrograms is enough to create a "antimatter catalyzed" fission/fusion propulsion system with enormous specific impulse / efficacy.
PDF: https://www.niac.usra.edu/files/studies/final_report/1071Bic...
https://en.wikipedia.org/wiki/Alpha_Magnetic_Spectrometer
Or cut to the chase at the 'antimatter factory', at https://www.youtube.com/watch?v=Yibef6nLCv8&t=3186s
You mean if you live on the 4km loop 'serviced' by BASE-STEP?
https://www.youtube.com/watch?v=ja7ap6AEuYU
But it's more weird. In the research article they explain that they make positronium, then use microwaves to excite the positronium so it's bigger and the electron and positron are not very close and they don't colide (I think this increase the half-life), then they put the positronium inside the cyclotron and when they turn it on the electron escapes but the positron get's trapped.
Anti Matter did nothing wrong!
Tend to... Is there even any scenario at all in which they wouldn't?