The Most Powerful Cosmic Ray Since the Oh-My-God Particle Puzzles Scientists (nature.com) 63
Scientists have detected the most powerful cosmic ray seen in more than three decades. But the exact origin of this turbocharged particle from outer space remains a mystery, with some suggesting that it could have been generated by unknown physics. From a report: The puzzling cosmic ray had an estimated energy of 240 exa-electron volts (EeV; 10^18 volts), making it comparable to the most powerful cosmic ray ever detected, aptly named the Oh-My-God particle, which measured at around 320 EeV when it was discovered in 1991. The findings were published today in Science.
"It's amazing because you have to think of what could produce such high energy," says Clancy James, an astronomer at Curtin University in Perth, Australia. A cosmic ray, despite its name, is actually a high-energy subatomic particle -- often a proton -- that zips through space at close to the speed of light. In their ultra-high energy form, cosmic rays have energy levels that exceed one EeV, which is around one million times greater than those reached by the most powerful human-made particle accelerators. Cosmic rays with energies of more than 100 EeV are rarely spotted -- fewer than one of these particles arrive on each square kilometre of Earth each century.
"It's amazing because you have to think of what could produce such high energy," says Clancy James, an astronomer at Curtin University in Perth, Australia. A cosmic ray, despite its name, is actually a high-energy subatomic particle -- often a proton -- that zips through space at close to the speed of light. In their ultra-high energy form, cosmic rays have energy levels that exceed one EeV, which is around one million times greater than those reached by the most powerful human-made particle accelerators. Cosmic rays with energies of more than 100 EeV are rarely spotted -- fewer than one of these particles arrive on each square kilometre of Earth each century.
Energy (Score:1)
That is approximately the kinetic energy of an apple being thrown, which is quite a lot for a subatomic particle.
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"foot pounds"? What is that in furlong ounces?
This is science dammit, so please use standard units. If joules were good enough for Jesus, they are good enough for us.
So 40 joules, the energy of a girl's punch. Or if you must cater to average Americans, the energy of a very small 0.22" handgun.
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Unknown physics ? (Score:1)
Re:Unknown physics ? (Score:4, Interesting)
Because it we currently do not have good models that fit the known structure of the Universe that can explain a particle accelerated to this energy, and be able to keep it long enough to reach Earth from its origin. With particle energies this high interactions with the Cosmic Microwave Background Radiation field acts as brakes. We do not "need" unknown physics, but it is one of the options in attempting to resolve this problem.
Re: Unknown physics ? (Score:1)
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there's a fair bit we don't know. We'll eventually figure it out.
Re: Unknown physics ? (Score:2)
Cherry-pick, much?
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Uh...I think it could be aliens:
Rep. Jim Jordan: This House Oversight Committee will come to order. The ranking member and myself will each be allowed 5 minutes opening remarks.
Rep JJ: : Double, double toil and trouble....
Ranking Member: Get on with it, muppet.
Rep JJ: : Ms Marjorie Greene, you are first up for questions.
Marjorie Greene: Okay General, tell us what are these UFOs?
General Puff-n-Huff: I cannot Ms Greene, and they are called Unidentified Aerial Phenomena (UAPs).
MG: Skip the nomen-name-ature, Ge
Re: Unknown physics ? (Score:2)
Remember when black holes were like aliens?
Less Clear (Score:3)
Because it we currently do not have good models that fit the known structure of the Universe that can explain a particle accelerated to this energy, and be able to keep it long enough to reach Earth
I'm not really convinced that this is true anymore. We know from Icecube that supermassive Black Holes produce extremely high-energy neutrinos that are very likely produced by even higher-energy protons slamming into matter. There are plenty of such Black Holes not that far away cosmologically speaking - including the one at the centre of the Milky Way only 26,000 light years away.
Cut off is 50EeV GZK limit (Score:5, Informative)
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https://en.wikipedia.org/wiki/... [wikipedia.org]
At those speeds it interacts with the cosmic back ground radiation to produce electrons and positrons or muons and thus loses momentum relative to velocities of the local area of space. So statistically it had to start very close to us but then we should see the source.
So what you're saying is...
ALIENS!!!
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He's not saying it, but it is.
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He's not saying it, but it is.
It's well known that every astronomy paper needs to include Aliens as an alternate hypothesis.
Re: Cut off is 50EeV GZK limit (Score:2)
What rules it out, other than fickle arbitrary social convention?
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Re: Cut off is 50EeV GZK limit (Score:2)
Can you please handwave a little harder, pray tell?
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Re: Cut off is 50EeV GZK limit (Score:2)
Why should your suggestion be taken any more seriously than aliens?
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Why should your suggestion be taken any more seriously than aliens?
The entire premise was that proximity isn’t a limiting factor as presented. No one thinks close by is a hundred million light years, it’s even a stretch for astrophysics. The suggestion is closely aligned with scientific consensus, unlike “aliens”.
Cosmologically Close is not That Close (Score:2)
So statistically it had to start very close to us but then we should see the source.
It's only close on cosmological scales. We recently got clear evidence that the supermassive Black Holes at the centre of galaxies produce extremely high energy neutrinos strongly suggesting that they also produce extremely energetic protons too and I believe that there are plenty of such objects within the allowed range that could be sources.
Re: Cut off is 50EeV GZK limit (Score:1)
> statistically it had to
So the probability was 1? That's the only probability that equates with "had to". ...or is my understanding of statistics seriously flawed. ...or both?
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In a galaxy where there are stars, whose size are big enough to cover Neptune's orbit, why do we need "unknown physics" to explain a cosmic ray ?
Because there isn't one of those stars in the direction this came from.
And you'd still need to explain how that star is creating these things.
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Even regular cosmic rays are considerably higher energy than anything going on in a star except during its collapse.
Damn those half-gods! (Score:3)
Playing x-ray laser-tag again with no care who they confuse!
I think it means we are small (Score:3)
I think it means we are small. This level of energy just means that something really big is happening near us.
Like bacteria in a barren area of sand, suddenly experiencing shockwaves from somebody stepping foot nearby.
We are super small floating in dust clouds that to us look like planets and this energy release is something happening near us and due to time dilation we just experience it in super slow motion.
Thats my thought.
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Weeelll ...
Firstly, the speed of things has an upper limit - the speed of light in a vacuum, so your assertion should be that "something really big has happen-ed near us in the last few centuries".
But, the space between "it" and us has a small but non-zero amount of gas in it, which will absorb some of this high-energy radiation. Which effectively imposes a curtain on our vision at some distance. Exactly what that distance is, is hard to calculate, but it is there
Re: I think it means we are small (Score:1)
> which will absorb some of this high-energy radiation
Will? Or probably will? Isn't it possible to pass through without hitting anything? Maybe it did, and we don't see it very often because it is very improbable and rarely happens?
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> which will absorb some of this high-energy radiation
Will? Or probably will? Isn't it possible to pass through without hitting anything? Maybe it did, and we don't see it very often because it is very improbable and rarely happens?
People have been mentioning the cosmic background radiation which is everywhere in huge quantities. I'm understanding that these move fast enough (at high enough energy) that the photons from the background seem to have lots of energy relatively and so hitting some of them in a big way becomes inevitable. That will definitely cause collisions which will cause them to definitely slow down and lose energy. So, over a long enough distance, "will".
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Yeah, that's probably not the answer you were expecting, but that's it.
The probability of a high energy particle interacting with (and most likely, losing energy to) another particle is - big surprise! - proportional to the number of times it encounters lower energy particles in it's flight. There aren't many such low energy particles per cubic metre (Order-of(a million)) in interstellar space. But there are a lot of cubic metres between us and the source.
That's a statistical argument, bu
Re: I think it means we are small (Score:2)
So, electric universe theory has no problem explaining such particles as having been accelerated by electric fields hitherto left out of mainstream storytelling?
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Could such be "EM-Freak-Waves"? (Score:3)
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It's a particle, not a wave, unless you look at it, then wave back.
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That's an interesting thought.
One of the key points with particle/wave duality is that at higher energies these wavy things become a lot more particle-like. That's why you don't see a fastball showing weird quantum effects -- the wavelength of a fastball (considered as a single object) is miniscule.
Achieving a "superposition of less extreme electormagnetic waves" in this context would have the same level of difficulty as achieving a superposition of fastballs.
Re: Could such be "EM-Freak-Waves"? (Score:2)
Are water molecules the fastballs?
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One does get quantum superposition with cats. Late at night when the humans are asleep, you get all kinds of weird noises...thumps, etc. Get up and turn on the light to investigate, and the cat's superposition collapses into the cat as a body looking at you like you are some alien species. Turn off the light, go back to bed, and the thumps restart.
Re: Could such be "EM-Freak-Waves"? (Score:2)
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You can, and they do. Matter particle wavefunctions were proposed by De Broglie in 1924 and confirmed experimentally the year after. Interference between matter waves of whole atoms was demonstrated shortly after.
In our modern understanding of physics, every "particle" is a wave in a superposition of waves in a field.
https://en.wikipedia.org/wiki/... [wikipedia.org]
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You can, and they do. Matter particle wavefunctions were proposed by De Broglie in 1924 and confirmed experimentally the year after. Interference between matter waves of whole atoms was demonstrated shortly after.
In our modern understanding of physics, every "particle" is a wave in a superposition of waves in a field.
The waves in quantum mechanics are probability waves. While it is true that those can create interference patterns, when they do so they only alter the probability of finding the particles in particular places. You can't add together two particles together in QM to create a new particle with twice the energy (not least because doing so for massive or charged particles like cosmic rays would violate the corresponding conservation laws).
Pure quantum mechanics per se doesn't even have creation or destruction
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You're assuming you have to add two particles together to create a new particle with twice the energy. You don't. You only have to make the detector register an event with twice the energy. This is trivial to demonstrate as it happens in every double slit experiment ever performed.
The interpretation (and it is just an interpretation) of wavefunctions as probability waves really depends on experiments where you
Re:Could such be "EM-Freak-Waves"? (Score:5, Interesting)
Whoever described tham as "impossible" was murdering English, or the science.
For most of the history of sailing, such waves were reported. Most sailors didn't encounter them, and the few who did, generally died. Dead men, famously, tell no tales.
After the introduction of iron hulls, ships started to survive worse and worse weather - and the interactions of really bad weather with swells travelling into the bad weather zone from somewhere else. And reports of "extraordinarily large waves" started increasing in both frequency and reported wave height.
Quite how that "we haven't received reports of waves greater than 25m tall" statement of fact got transmuted into "waves more than 30m tall are [scare quotes] impossible [scare unquotes]", I'm not sure. But in addition to ships surviving storms better (and their close cousins, life rafts and TEMPSCs [Totally Enclosed Motor Propelled Survival Craft, liferaft's vastly preferred big brothers]), other structures were also going out to sea. Including my former work places on oil rigs. And more and more reports of very large waves started coming in from such places, long before satellites with radar capable of measuring wave height in a "footprint area" were being flown. And the observational statement of "we haven't received reports of waves greater than 25m tall" became irrelevant as reports ofd 26, then 27, then 28 ... metre tall waves started coming in. And the unsupported assertion that "waves more than 30m tall [etc]",became more and more unsupported.
In 30 years of working at sea in four oceans, the biggest wave that I've experienced that was measured was only 22m. But on my first trip offshore I saw (as I dodged between one watertight hatchway and the next) a wave I estimated as 21 to 27 m. None of them remarkable, and none record breaking. But scary enough.
Sorry, but I hate that bullshit assertion that waves above a certain height are impossible. There are definite limits in shallow water (water depth The physicist/ astronomers do look at "interference" as one possible formation mechanism for these ultra-high energy particles, but the interference is postulated to be between the charges on these particles and the rapidly-changing (rotating) magnetic fields around neutron stars. So, you're probably somewhat onto the likely cause (or one plausible cause, of several). But to explain it in any detail needs more magnetohydrodynamics than I have.
Not How Quantum Waves Work (Score:2)
I wonder if those powerful cosmic waves could just be a kind of electro-magnetic freak wave
No because photons are quantum waves and they do not work like classical waves. Classical waves, like water waves, have an energy that depends on their amplitude: the larger the energy the bigger the wave amplitude. However, as Einstein demonstrated in 1905 with his paper on the photoelectric effect that won him the Nobel Prize, with photons it is the frequency that determines the energy. If you increase the amplitude it just means that you have more photons each with the exact same energy.
240 exa-electron volts is 40 joules (Score:3)
Or in American terms this single particle has the energy of a 55mph fast ball.
My relativity is weak. Can someone figure out the particles momentum?
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Not how eV work! (Score:4, Informative)
Divide by 1 Coulomb to convert between electron volts and joules.
No - if you divide by 1 C you just get the same value but now with units of electric potential! You need to _multiply_ the energy in eV by the numerical value of the charge on one electron measured in coulombs which is 1.6e-19. This is because 1 eV is the energy gained by an electron moving through a potential of 1V i.e. 1V*e=1.6e-19J. The number you multiply by is dimensionless since it is simply the ratio of one unit of energy (eV) to another (J).
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So 240e18 eV = 240e18 * 1.6e-19 J = 38J.
A 145 g baseball with a speed of 55mph has energy = 1/2 * 0.145 Kg (1.6*55*1000/3600 m/s)^2 J = ~40 J.
This is also approximately the same as charging a mobile phone at 5V with a 1A charger for 8 seconds, or heating up 1 g of water by 9 degrees K.
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The fastball computation is correct.
Not as it was described! The _result_ might be correct but the original method was absolutely not: dividing the energy by the number of eV in a joule is not at all the same as "Divide by 1 Coulomb".
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I'm trying to decide which I prefer: Getting hit on the he
Twice in 32 years, so nothing will happen (Score:4, Interesting)
For reference, the "sensors" used for detecting these particles are large volumes of low pressure gas, which then fluoresces (or it produce cascades of secondary particles which themselves produce fluorescence). The light (and/ or secondary particles) is then picked up by telescopes, photomultipliers and electronic particle detectors (semi-conductors and spark chambers) on the ground, and when some threshold of coincidence is passed, software adds up the detections and comes up with a particle energy. Quite simple, significant statistical quibbling possible, but it's an approach that has been considered robust for decades of people trying to make something better.
Do people remember the wailing and gnashing of teeth that came in the months before the LHC was turned on (and didn't repeat when the LHC had it's factor-of-2 upgrade)? Same argument then for why the LHC wasn't going to destroy the Earth.
Off by a little... (Score:5, Informative)
So you were only about 10 orders of magnitude off. The argument for why the LHC is safe is a bit more nuanced though since if such particles did produce a microscopic Black Hole it would be heavily boosted and so pass through the Earth without stopping while at the LHC they would be produced with much less energy and could be captured. To show that this does not happen you need to look at neutron stars. These are bombarded by the same high energy cosmic rays but are so dense that a Black Hole created by a cosmic ray would not escape. The fact that none of the pulsars we have seen have suddenly disappeared by being converted into a Black Hole was actually the most compelling safety argument for the LHC.
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We only observe a fairly small population of pulsars. A percent or so of the wider population of neutron stars. Maybe less - it depends on how tightly their radiation is beamed.
I'm ... sceptical of arguments about the Earth being swallowed by a (small) black hole.
We've measur
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"materials and conditions".
Precision Cosmology (Score:2)
Only off by a factor of 10^10. In cosmology, that's agreement!.
Perhaps 30 years ago but not really true any longer. For example, cosmology has dated the Big Bang to three significant figures of precision.
We only observe a fairly small population of pulsars.
Yes, but we know that some of them have been around for thousands of years since the supernova that created them was recorded historically or we can estimate the age from the size of the surrounding nebula. That's a LOT of very high-energy cosmic rays that have done nothing.
my gut feeling is that I can't rule out the existence today of an Earth-eating BH within the planet
The reason we invented science is because "gut feelings" are not at all reliable. However, sc
Scientists? (Score:2)
Scientists named a thing after a non-existing thing?
Shouldn't that be a Fuck-me-that's-a-lot-particle?
Re: Scientists? (Score:2)
Is it referencing the ultimate religious nature of science, because that particle should not exist, just as God should not exist?
Apologies, everyone, it's me ... (Score:2)