8 ms·
Oh-My-God Particle
- michaelcampbell 3y ago> At this speed, if a photon were traveling alongside the particle, it would take over 215,000 years for the photon to gain a 1 cm lead, as seen from the Earth's reference frame. Can someone ELI5 what this means? This particle was going .(some # of 9's)C, so does this mean a photon traveling at 1.0C is SO CLOSE IN SPEED that in order for Ct >= 1cm + (0.999C)t (where t is time), t would have to be 215k years?
- marcellus23 3y agoI wish the article included a bit more info about the significance of the particle, instead of just describing how energetic it was. For example, it never expands on this, which is IMO the most interesting sentence on the page: > The particle's energy was unexpected and called into question theories of that era about the origin and propagation of cosmic rays.
- brucethemoose2 3y agoYeah... It makes more sense when this article is linked from other Wikipedia pages. See the linked article: > The Greisen–Zatsepin–Kuzmin limit (GZK limit or GZK cutoff) is a theoretical upper limit on the energy of cosmic ray protons traveling from other galaxies through the intergalactic medium to our galaxy. The limit is 5×1019 eV (50 EeV), or about 8 joules (the energy of a proton travelling at ≈ 99.99999999999999999998% the speed of light). The limit is set by the slowing effect of interactions of the protons with the microwave background radiation over long distances (≈ 160 million light-years). The very highest energy cosmic rays are theorized to come from Active Galactic Nuclei (very hot stuff around the giant black hole at the center of galaxies) or supernovae (large exploding stars), or even from the magnetic fields of galaxies themselves, all which are mostly outside the Milky Way. The implication is that some of these particles could be coming from smaller, closer sources, close enough to not be slowed by the MBR. This is unusual because it seems like closer phenomenon shouldn't be able to accelerate a proton that much.
- simonh 3y agoSome black holes spin at more than 90% the speed of light. Shock waves driven by magnetic fields in the plasma close to the event horizon would probably do it.
- twic 3y ago8 joules is the kinetic energy of a British one-penny coin travelling at 150 miles per hour. You'd feel that!
- huytersd 3y agoThat’s so insane to think about a single proton feeling like a bullet fired at you!
- deleted 3y ago[deleted]
- dvh 3y ago> If the proton originated from a distance of 1.5 billion light years, it would take approximately 1.71 days from the reference frame of the proton to travel that distance. Imagine traveling 10% of the size of the observable universe in 2 days.
- jkyrlach 3y agoIt's murder on one's brakes.
- jkyrlach 3y agoFixed spelling.
- willismichael 3y agoRegenerative braking FTW
- AnimalMuppet 3y agoNah, it used aerobraking.
- dmitrygr 3y agolithobraking !
- platz 3y agoBut due to Lorentz Contraction, what would be the length of that space in the direction of travel from the particle's frame?
- fancy_pantser 3y agoAbout two light days.
- miteyironpaw 3y agoAlso at this speed a space ship a 100 m wide viewed from earth would appear to be 0.3125 nm wide or roughly size of a single water molecule. It would certainly be a way to travel! note: not a physicist so my understanding may be off.
- gnatman 3y ago> More recent studies using the Telescope Array Project have suggested a source of the particles within a 20 degree radius "warm spot" in the direction of the constellation Ursa Major. https://www.science.org/content/article/physicists-spot-potential-source-oh-my-god-particles https://www.science.org/content/article/physicists-spot-pote...
- marcellus23 3y agoSome choice interesting quotes about the potential origin of such particles: > Instead, theorists generally expect that the most energetic cosmic rays rev up over millions of years in unidentified accelerators the size of galaxies. > Physicists think that the highest energy cosmic rays cannot come from more than 500 million light-years away, as interactions with lingering radiation from the big bang ought to snuff out cosmic rays from more distant sources. But no obvious candidate for a nearby cosmic accelerator lies directly in line with the hotspot, Sokolsky says. He notes, however, that in that region a filament of galaxies kinks toward Earth and speculates that magnetic fields in that string might help rev up particles.
- ambicapter 3y agoJust imagining a single particle hitting the perfect spot and just getting massively accelerated by thousands of thousands of galaxies in a very specific path.
- AnimalMuppet 3y agoAh, Dr. Sokolsky. I had him as an undergrad. He taught (IIRC) my quantum mechanics class.
- opportune 3y agoI wonder what the math is behind this. It’s kind of like saying “the universe is so big that there’s likely an arrangement of matter in just the right configuration to accelerate particles to this extent”. In the absence of better theories it’s reasonable but like… pragmatically it seems simpler for a simpler but unknown process to be the root cause. That, or an advanced civilization. I kind of buy “high energy particles are type 1 civilizations’ pollution” more than “there exists gravitational pockets arranged in a manner capable of accelerating single protons to contain as much energy as a baseball”.
- bArray 3y ago> The energy of this particle was some 40 million times that of the highest-energy protons that have been produced in any terrestrial particle accelerator. If it were me observing this, and I didn't observe it again, I would attribute it to something else. However rare, I would consider some phenomenon as part of the sensor (for example decay causing a release of energy), or two particles arriving at the same time, some localised event, etc. I'm sure they already addressed this, but I would be considering some other source of such a high energy particle. It's just too perfect, why would we see such a high energy particle and nothing inbetween?
- jackmott42 3y agoAs the article states, it was observed again eventually.
- dredmorbius 3y agoGenerally observations might be confirmed through: - Repeated observations. - Simultaneous independent observations: multiple devices/instruments. - Observation of primary and corresponding secondary events, e.g., an initial interaction with the atmosphere and further observations consistent with collision / decay particles arising from an initial interaction. Put another way: if you see a bright flash (visual sensation), and some seconds later hear a heavy rumble (audio sensation), and within a few minutes observe heavy rain, odds are quite strong that the initial observation was lightning. This is based on multiple independent channels of information. If you and multiple other people see the same flash at the same time, you have independent observations, and can validate the initial observation by that means. In a world of increasingly high-plausibility generative tools (images, audio, text, video), the ability to show multiple independent observations of a given event becomes far more critical than the emergence of any one high-detailed, realistic document (where document refers to a record in text, audio, image, video, etc.).
- ck2 3y agoone of my favorite series, PBS Space Time, covers this at a great level: https://www.pbs.org/video/the-oh-my-god-particle-54npwl/ https://www.pbs.org/video/the-oh-my-god-particle-54npwl/ https://www.youtube.com/watch?v=osvOr5wbkUw https://www.youtube.com/watch?v=osvOr5wbkUw
- elil17 3y agoAny thoughts on what it might feel like to get hit with this particle? I imagine the collision would turn into heat pretty quickly and the heat energy would conduct out from where you got hit and, if it was near any nerves, you might feel a warm spot on your body. Since energy scales with the square of velocity and momentum scales linearly with velocity, I can't imagine you would feel like you'd been hit by an object.
- TooKool4This 3y agoWikipedia has it in the comparison. It’s more like getting punched. Really hard. https://en.m.wikipedia.org/wiki/Orders_of_magnitude_(energy) https://en.m.wikipedia.org/wiki/Orders_of_magnitude_(energy)
- KyleBerezin 3y agoHmm, I think the effect would be more localized, and involve a lot of strange forms of matter. My guess is it would be similar to what happened to Anatoli Bugorski when he stuck his head into a proton beam.
- orangea 3y agoThat doesn't mean getting hit by this particle would feel like a punch, since what you feel when you get punched is a transfer of momentum rather than a transfer of energy.
- TooKool4This 3y agoYep but just an easy first approximation since the article didn’t have any numbers on the momentum of the particle. I’m sure if you wanted a really good answer you would need more than momentum and actually need to analyze the products of the collision like another poster suggested. Also wanted to share this table since energy expressed in eV sounds like big numbers but it’s nice to understand that the definition of the eV is small in our usual definition of energy.
- petercooper 3y ago
- matonias 3y agoCould you get hit by this during your sleep and wake up?
- KyleBerezin 3y agoI don't think it would like flying through our atmosphere.
- kstrauser 3y ago> equivalent to a 142-gram (5 oz) baseball travelling at about 28 m/s (100 km/h; 63 mph). The kinetic impact alone would get your attention.
- deleted 3y ago[deleted]
- dredmorbius 3y agoNot through any plausible causal interaction: <https://news.ycombinator.com/item?id=37793828 https://news.ycombinator.com/item?id=37793828>
- hifromwork 3y agoTFA: >The Oh-My-God particle was an ultra-high-energy cosmic ray detected on 15 October 1991 by the Fly's Eye camera in Dugway Proving Ground https://en.wikipedia.org/wiki/High_Resolution_Fly%27s_Eye_Cosmic_Ray_Detector https://en.wikipedia.org/wiki/High_Resolution_Fly%27s_Eye_Co...: >The High Resolution Fly's Eye or HiRes detector was an ultra-high-energy cosmic ray observatory that operated in the western Utah desert from May 1997 until April 2006 (...) >The HiRes discovered the Oh-My-God particle, an ultra-high-energy cosmic ray, on 15 October 1991 http://www.cosmic-ray.org/reading/flyseye.html http://www.cosmic-ray.org/reading/flyseye.html: >The new Utah experiment began observations in 1981 and was operated until 1993. A second detector site was completed in 1986. Interesting, some dates are clearly wrong here. I don't feel confident enough to edit the Wikipedia article, but I guess there were actually two observatories - the "old" one (1981-1993, detected the particle) and the "new" one (1997-2006)?
- 3seashells 3y agoAre these the sprites? As in the thunderstorm provides a field raising the likelihood of interaction and a oh my god particle slaps through the earth into the field?
- rapjr9 3y agoHow does matter moving at near light speed exhibit gravity? From the particles frame of reference time is moving much more slowly than for things like planets. So does this mean the gravity is also time dilated?