> 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?
I 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.
Yeah... 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.
Some 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.
> 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.
Also 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.
> 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.
Some 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.
Just imagining a single particle hitting the perfect spot and just getting massively accelerated by thousands of thousands of galaxies in a very specific path.
I 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”.
> 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?
- 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.).
Any 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.
Hmm, 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.
That 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.
Yep 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.
So I'm confused. If some specific relatively small devices (relatively to the size of the Earth) managed to pick up several of these over the years, surely some of these are hitting people? Are people randomly feeling like they got impacted (if not punched, as per a sister comment) out of nowhere? Apologies if this is a ridiculous question; physics was always my weak suit.
If you got hit by one of these then you wouldn't feel anything. The energy is about 50 joules, or about 1/2 of the heat that a human body produces in a second.
Interesting. I see from your link that this particle had 1/6 of the energy of a lethal dose of x-rays.
I'm guessing I would probably survive, but certainly wouldn't volunteer to get hit with such a particle, and I'm guess that if it went through my brain stem or maybe my heart, there's a good chance it would kill me.
> The Oh-My-God particle had 10^20 (100 quintillion) times the photon energy of visible light, equivalent to a 142-gram (5 oz) baseball travelling at about 28 m/s (100 km/h; 63 mph)
For comparison a typical professional baseball pitch is around 90mph. At 63mph I guess it might not break your face, but it would certainly leave a bruise (if it was actually a baseball -- who knows what the actual particle would do to flesh and bone). I know people are pretty derisive about using swimming pools or whatever for measurement, but I think this one is pretty good for bringing incomprehensible numbers into the realm of lay-understanding.
Note that such a baseball with the same energy as this particle would still have much more momentum than the particle. So getting hit by the particle wouldn't "leave a bruise".
Is this equivalent to a 14 gram bullet (10x less than your example) travelling at 1000 km/h (10x more than your example)? Or a 1,4 gram bullet at 10.000 km/h hitting you?
I don't think so, no. Kinetic energy grows with the square of velocity, and linearly with mass. So a 14g bullet travelling at 316km/h or a 1.4g bullet travelling at 1000km/h. But for what it's worth, I think most people have more experience catching baseballs than bullets (and I don't know how much bullets typically weigh or how fast they travel).
No idea about a particle like this one but, I've read that cosmic rays pass through flesh leaving a microscopic track of destruction[1]. However atomic collisions result in a shower of particles. And very high energy you get multiple showers. A problem if you're trying to shield people in space for a long time. You need enough shielding to stop the secondary showers of particles.
[1] Extreme example from memory... meh google, In 1978 Soviet physics student Anatoli Bugorski got zapped by a proton beam which burned a track through his head. Recovered with damage, completed his PhD and is still alive.
> Reportedly, he saw a flash "brighter than a thousand suns" but did not feel any pain.
He was hit with a 76GeV beam; this was a single particle with 320 billion GeV. I do wonder how many particles at 76GeV he was hit with.
And yeah... damage.
> The left half of Bugorski's face swelled up beyond recognition and, over the next several days, the skin started to peel, revealing the path that the proton beam had burned through parts of his face, his bone, and the brain tissue underneath. As it was believed that he had received far in excess of a fatal dose of radiation, Bugorski was taken to a clinic in Moscow where the doctors could observe his expected demise. However, Bugorski survived, completed his PhD, and continued working as a particle physicist. There was virtually no damage to his intellectual capacity, but the fatigue of mental work increased markedly. Bugorski completely lost hearing in the left ear, replaced by a form of tinnitus. The left half of his face was paralysed due to the destruction of nerves. He was able to function well, except for occasional complex partial seizures and rare tonic-clonic seizures.
One thing to keep in mind is that the particle will likely only lose a 'tiny' fraction of its energy in a collision (the article mentions 2900 TeV for an atom of nitrogen) and it might not even cause a 'hard' collision. A collision will probably create a shower of particles which will carry away most of the energy.
The critical factor here is less the energy of the particle than the mechanism of transmission.
As others have noted, the total energy equivalent is that of a moderately-fast baseball throw, which, in the case of a baseball is perceptible but generally not harmful.
The transmission mechanism for the baseball is the electromagnetic force, where the individual molecules of the baseball are interacting with the individual molecules of your body, and the imposed and reactive forces are roughly equivalent.
In the case of the OMG particle, as a proton it would exert a positive charge, and might steal an electron (becoming a hydrogen atom in the process), or interact directly with a nucleus, though likely splitting that. The atoms of your body are principally carbon, hydrogen, oxygen, and nitrogen, atomic numbers 1, 12, 14, and 16, respectively. The result of such an interaction might be isotopes of: H, He, Li, Be, or B, numbers 1--5 inclusive. There would likely be a chain of such interactions depending on the effective cross-section of the incident particle, atoms in your body, and any collision particles, though this is pretty much where my physics knowledge abandons me.
Online sources suggest that this is pretty accurate: the particle would pass straight through you:
Presuming there is a collision within your body, at this point you have a particle stream, interacting with other material through electromagnetic and nuclear (strong and weak) forces. Again, you're dealing with exceedingly high energies, and it seems likely to me that those particles would tend to exit your body and have further interactions with the surrounding region (air and solid matter), which would result in some local ionisation and light heating. The question is the interaction cross-section of the incident particle, atoms within your body, and any collision and decay products.
Point being that you don't want to necessarily direct the maximum energy at a target, but the energy that will disrupt or interact with that target in the manner in which you intend.
Cosmic rays are striking your body all the time, though at lower energies. The effects tend to be local ionisation and, most critically, damage to genetic material. The latter is the most significant from a biological perspective.
My new best guess is that most of the energy would no be contained in your body but would be ejected out as a bunch of other high energy particles (just not that high energy).
>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
>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)?
Are 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?
How 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?
54 comments
[ 4.1 ms ] story [ 101 ms ] threadCan 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?
About one nanometer per week in case that is more relatable.
Though, to me it seems that the article's explanation is the ELI5 of your equation, not the other way around...
> The particle's energy was unexpected and called into question theories of that era about the origin and propagation of cosmic rays.
> 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.
Imagine traveling 10% of the size of the observable universe in 2 days.
note: not a physicist so my understanding may be off.
https://www.science.org/content/article/physicists-spot-pote...
> 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.
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”.
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?
- 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.).
https://www.pbs.org/video/the-oh-my-god-particle-54npwl/
https://www.youtube.com/watch?v=osvOr5wbkUw
It’s more like getting punched. Really hard.
https://en.m.wikipedia.org/wiki/Orders_of_magnitude_(energy)
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.
I'm guessing I would probably survive, but certainly wouldn't volunteer to get hit with such a particle, and I'm guess that if it went through my brain stem or maybe my heart, there's a good chance it would kill me.
For comparison a typical professional baseball pitch is around 90mph. At 63mph I guess it might not break your face, but it would certainly leave a bruise (if it was actually a baseball -- who knows what the actual particle would do to flesh and bone). I know people are pretty derisive about using swimming pools or whatever for measurement, but I think this one is pretty good for bringing incomprehensible numbers into the realm of lay-understanding.
[1] Extreme example from memory... meh google, In 1978 Soviet physics student Anatoli Bugorski got zapped by a proton beam which burned a track through his head. Recovered with damage, completed his PhD and is still alive.
> Reportedly, he saw a flash "brighter than a thousand suns" but did not feel any pain.
He was hit with a 76GeV beam; this was a single particle with 320 billion GeV. I do wonder how many particles at 76GeV he was hit with.
And yeah... damage.
> The left half of Bugorski's face swelled up beyond recognition and, over the next several days, the skin started to peel, revealing the path that the proton beam had burned through parts of his face, his bone, and the brain tissue underneath. As it was believed that he had received far in excess of a fatal dose of radiation, Bugorski was taken to a clinic in Moscow where the doctors could observe his expected demise. However, Bugorski survived, completed his PhD, and continued working as a particle physicist. There was virtually no damage to his intellectual capacity, but the fatigue of mental work increased markedly. Bugorski completely lost hearing in the left ear, replaced by a form of tinnitus. The left half of his face was paralysed due to the destruction of nerves. He was able to function well, except for occasional complex partial seizures and rare tonic-clonic seizures.
Yikes.
As others have noted, the total energy equivalent is that of a moderately-fast baseball throw, which, in the case of a baseball is perceptible but generally not harmful.
The transmission mechanism for the baseball is the electromagnetic force, where the individual molecules of the baseball are interacting with the individual molecules of your body, and the imposed and reactive forces are roughly equivalent.
In the case of the OMG particle, as a proton it would exert a positive charge, and might steal an electron (becoming a hydrogen atom in the process), or interact directly with a nucleus, though likely splitting that. The atoms of your body are principally carbon, hydrogen, oxygen, and nitrogen, atomic numbers 1, 12, 14, and 16, respectively. The result of such an interaction might be isotopes of: H, He, Li, Be, or B, numbers 1--5 inclusive. There would likely be a chain of such interactions depending on the effective cross-section of the incident particle, atoms in your body, and any collision particles, though this is pretty much where my physics knowledge abandons me.
Online sources suggest that this is pretty accurate: the particle would pass straight through you:
<https://www.technology.org/how-and-why/if-proton-nearly-at-l...>
Presuming there is a collision within your body, at this point you have a particle stream, interacting with other material through electromagnetic and nuclear (strong and weak) forces. Again, you're dealing with exceedingly high energies, and it seems likely to me that those particles would tend to exit your body and have further interactions with the surrounding region (air and solid matter), which would result in some local ionisation and light heating. The question is the interaction cross-section of the incident particle, atoms within your body, and any collision and decay products.
Point being that you don't want to necessarily direct the maximum energy at a target, but the energy that will disrupt or interact with that target in the manner in which you intend.
Cosmic rays are striking your body all the time, though at lower energies. The effects tend to be local ionisation and, most critically, damage to genetic material. The latter is the most significant from a biological perspective.
The kinetic impact alone would get your attention.
<https://news.ycombinator.com/item?id=37793828>
>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_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:
>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)?