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The big deal about these events is that, if you reasonably assume that it's a proton, then it violates a bound called the Greisen–Zatsepin–Kuzmin limit. Anythin
by idlewords 3y ago
The big deal about these events is that, if you reasonably assume that it's a proton, then it violates a bound called the Greisen–Zatsepin–Kuzmin limit. Anything going that fast should be energetic enough to interact with the cosmic microwave background, which is hugely blueshifted in its frame of reference. The GZK is a kind of cosmic speed limit over long distances.
So anything this energetic would need have a nearby source (in astrophysical terms) so it doesn't have time to slow down. But when we trace these things back, we see bupkus in the direction it came from.
This means there is either (almost certainly) interesting new astrophysics, or (with tiny probability) new particle physics involved. Whatever is giving individual protons the energy of a thrown baseball is probably something worth studying.
- willis936 3y agoI'm relatively lay in astrophysics. Could the origin not be galactic magnetic field lines between Earth and the galactic nucleus? Like the magnetic mirror between Earth and the Sun but much larger.
- smueller1234 3y agoTo our best understanding, particles of such high energy do not originate in our own galaxy. We don't have a good understanding of what exact process might be putting this much energy into a single particle, but the commonly accepted acceleration mechanisms of, eg., supernovae don't reach anywhere near these energies. GP also said "nearby source (in astrophysical terms)" which in this case is code for "could be over 100 million light years".
- unsupp0rted 3y agoOr a nearby emanation source we can’t readily detect?
- bee_rider 3y agoI think that might fall under > This means there is either (almost certainly) interesting new astrophysics, possibly. An emanation source they can just barely pick up is a mystery they can puzzle out, right?
- newZWhoDis 3y agoProbably a leaky warp reactor on a passing starship :)
- araes 3y agoHonestly, still mildly crazy. If: - Whatever Star Trek says about warp reactors (matter / antimatter reaction) is valid. Reacts "some" amount of matter/antimatter every second. - Klingon Bird of Prey can maintain an effectively infinite cloaking time from a human observation perspective, so it can be nearby. - Warp reactor "occasionally" leaks (1% of 1% of 1% of reactions? I dunno...) so we might actually detect something. "Slightly" imperfect shielding. - Problem: 5E1 J for OMG Particle (people say its a proton). 1.8E14 J for 1 gram of matter / antimatter annihilation. Except: 1 Proton = 1.6726231E-24 g. Proton rest mass energy is 1.503E−10 J. So the particle is more energetic than a Proton / Antiproton annihilation event (by a lot). It's been upshifted More than 100,000,000,000 from the rest mass energy. - It "might" work if the one proton escaping represented a single proton gaining enough energy to overcome reactor core shielding confinement, which, in my opinion, seems somewhat plausible physics by Star Trek standards. - PS: Personal guess is a Q-Clearance [3] experiment at a DOE lab we deny exists. [1] https://en.wikipedia.org/wiki/Orders_of_magnitude_(energy) https://en.wikipedia.org/wiki/Orders_of_magnitude_(energy) [2] https://en.wikipedia.org/wiki/Proton https://en.wikipedia.org/wiki/Proton [3] https://en.wikipedia.org/wiki/Q_clearance https://en.wikipedia.org/wiki/Q_clearance
- ricksunny 3y agoTo the casual HN reader - my recommendation to you is to neithet laugh at nor dismiss out of hand analyses such as this (even as logic intrinsic to them merits as much picking apart as any other analysis one sees everyday on HN). Robin Hanson's description of long-lived stars (usually strongest in infrared - i.e. the 3 stars our eyes lack the spectral response to see for every 1 star that we do see when looking into the night sky) significantly updated my priors on the likelihood of intelligent, non-human life roaming about the cosmos. https://youtu.be/cQq2pKNDgIs?t=1210 https://youtu.be/cQq2pKNDgIs?t=1210 (timestamped) tl;dr: Red-dwarf stars have been around -- with all that goes with that.. -- for much, much longer than our sun.
- captainmuon 3y agoI wonder if it could be a background source that we don't understand. Maybe some freak coincidence where particles come in in exactly the right angles to fake a hyperenergetic photon. Or somebody messing with laser pointers. Or birds or whatever. I used to work in particle physics, and never shared the confidence of my colleagues in rare events. If you just have 3-4 signal events, considering the expected number of events, you might statistically have a discovery. But you can't be sure how your detector is going to behave for those extreme events, because you have no benchmark. You have to assume a proton is a proton, an electron is an electron, and no weird things happen at high/low energies and angles (or that you understand how things change). It is even worse if you are trying to disprove some specific model. You see no events of a certain kind. Does that mean you disproved the model, or that your setup (detector, triggers, event selection ...) is just blind in this very narrow part of the parameter space?
- idlewords 3y agoIf you go out in space and look at what extrasolar stuff zaps you, you'll find a very standard power law distribution of charged particle energies, with no known upper limit. This is a better position to be in (from a detector confidence standpoint) than seeing a completely bananas event every few years. Here it's bananas (and progressively less bananas) all the way down.
- jp57 3y agoI assume that limit accounts for the time dilation, too. At the speed the particle was traveling it wouldn't have had much time in its reference frame to interact with the background radiation, even blue-shifted as it would be, right?
- idlewords 3y agoYeah, the model does account for it, and the time dilations are nuts. For the Oh-my-god particle (a similar early detection), I remember that it would have crossed a billion light years in what it perceived as a day.
- liamwire 3y agoImagining that reference frame is a beautiful thought. Galaxies and stars coming into and out of existence in real time, supernovae exploding like fireworks constantly as the entire universe zips by.
- jacquesm 3y agoUntil that trip ends by being snagged by some puny detector on an even punier planet that just so happened to intersect your trajectory. "I came across a billion lightyears, and all I got was this scientific paper". Not even a t-shirt...
- whoopdedo 3y ago> either interesting new astrophysics or new particle physics Or measurement error which historically has been the most frequent explanation of these rule-breaking observations. Someone else will look at the data and notice an anomaly which once accounted for will make everything fit within expected models.
- lamontcg 3y agoIn this case though they've been observed over the past 30 years at at least 4 different detectors, which provides independent confirmation across multiple different research groups. It is very unlikely to be a "oops we didn't plug the cable in firmly" kind of situation. It would need to be something fundamental about the design of these detectors, which has been replicated four independent times, which has completely escaped the notice of physicists for >3 decades (which includes 3 decades worth of grad students incentivized to take a look at the problem with fresh eyes and make a name for themselves by explaining it all away).
- emmelaich 3y agoHow different are those detectors? Is it possible they share a common or similar design?
- lamontcg 3y ago> It would need to be something fundamental about the design of these detectors, which has been replicated four independent times, which has completely escaped the notice of physicists for >3 decades
- lovemenot 3y agoYour parent wasn't suggesting you hadn't considered it, they were asking for more information about the designs. To what extent is / isn't common design mistake the probable cause?
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- a_wild_dandan 3y agoWhat initial speed must the proton have for consistency with our observed final “dragged down” speed (assuming some ballpark galactic distance)? Alternatively, could a “clump” of particles have smashed into our detector? Whatever the new physics winds up explaining this bonkers momentum, it’ll be fascinating.
- cozzyd 3y agoIt would certainly be convenient for me if it is a proton, given the experiments I work on (protons at the highest energies -> more ultrahigh energy neutrinos -> maybe my experiments will see something!), but, unfortunately for me, I don't think we know that. Nuclear species composition can typically only be done statistically, and it looks like this wasn't even measured in the fluorescence detector, which would give the best measurement of the penetration depth of the particle in the atmosphere (the best handle on particle id). In,the journal article, which admittedly I've just skimmed, they give direction reconstructions giving different species assumptions (and Milky Way models, which are important for heavier nuclei) and say that while they can exclude a photon (which... would be weird!), without data from the fluorescence detector, they can't tell the difference between a proton and a heavier nucleus. Though given how TA mass-composition measurements turn light at the highest energies, they may perhaps privately argue it's likely a proton. But, alas, Pierre Auger Observatory would argue otherwise. I'll ask Toshihiro what he thinks next time I see him... It is intriguing that the smaller TA has seen more high-energy events than the bigger PAO. Maybe there really are big differences between the northern and southern hemisphere at play here...
- idlewords 3y agoIf Santa handed you a hundred billion dollars or so to study this stuff, what would be your dream detector?
- cozzyd 3y agoProbably a integrated in-ice Cerenkov + radio neutrino detector with a giant cosmic ray detector (scintillators + water cerenkov tanks + fluorescence detectors + radio) on top, perhaps with some fluorescent/radio detectors deployed on tethered aerostats to look for upgoing air showers from taus. Sort of like IceCube Gen2 Radio on steroids, mishmashed with Auger and ANITA/PUEO/EUSO-SPB. Both in Antarctica and in Greenland to get both hemispheres. But there are arguments for other types of detectors too, and perhaps I'm not thinking big enough since 100 Billion is several orders of magnitude above what is probably reasonable :)
- 3y ago
- rthomas6 3y agoCould it be a small black hole orbiting the sun?
- simne 3y agoYou missing important part - the larger rest mass of particle, the less it will interfere with cosmic vacuum. So, high energy electrons must be from near source (mostly, inside our galaxy), because otherwise they will slow down by magnetic field of our galaxy. For high energy protons, this eased, but I could not remember approximations for possible distance. And for heavy nucleus, may be possible to travel from very distant source, even from borders of Universe.
- simne 3y agoBTW, I remembered interest fact, that on some particle accelerators run experiments on accelerate macro-objects, like dust. Latest accelerators are not very suited for such activity, but earlier linear accelerators works well on this, and give very interesting data.
- darkerside 3y agoAlien spacecraft?
- mock-possum 3y agosomething akin to a standing wave, where an exceptional signal develops out of otherwise unremarkabley noisy surroundings?
- opportune 3y agoI think the simplest explanation is that we're just not accurate enough at determining the trajectory of the particle in question. They tried matching against sources "just outside its arrival direction" but without access to the paper (the DOI link just doesn't work for me, loads an empty page) or knowledge about the instruments being used it's hard to say how much that rules out. At least looking into the Telescope Array's workings, it seems plausible that it'd struggle to produce accurate trajectory data. It works by analyzing the light produced by cascading collisions of particles with the incoming one: https://en.wikipedia.org/wiki/Air_shower_(physics) https://en.wikipedia.org/wiki/Air_shower_(physics). At first glance this seems like it would be very noisy for determining trajectory.
- smueller1234 3y agoMy recollection from the Pierre Auger telescopes was 1-2 degrees uncertainty. TA is likely a similar order of magnitude. So matching a single event against candidate sources might not be the most reliable analysis. (Caveat: I didn't dig up papers to check my memory from 15 years ago.)