[HN Gopher] Record-breaking neutrino is most energetic ever dete...
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Record-breaking neutrino is most energetic ever detected
Author : lnauta
Score : 140 points
Date : 2025-02-12 16:52 UTC (6 hours ago)
(HTM) web link (www.nature.com)
(TXT) w3m dump (www.nature.com)
| cylinder714 wrote:
| The article references the "Oh-My-God particle, the most
| energetic particle yet encountered. Here's the late John Walker's
| excellent piece on that:
|
| https://fourmilab.ch/documents/OhMyGodParticle/
| epistasis wrote:
| > These calculations involve some elementary but easy to mess
| up algebra and some very demanding numerical calculations for
| which regular IEEE double precision is insufficient. If you'd
| like to double-check these results, be sure to use a multiple
| precision calculator with at least 30 significant digits of
| accuracy.
|
| So you're saying my iPhone built-in calculator app is going to
| have problems....?
|
| Time to whip out dc on the terminal.
| jiggawatts wrote:
| https://www.wolframalpha.com/
| Onavo wrote:
| Or ChatGPT to output Julia code
| eq_ind wrote:
| > So you're saying my iPhone built-in calculator app is going
| to have problems....?
|
| Your Android phone's built-in calculator app, however, will
| not. :^)
|
| https://dl.acm.org/doi/pdf/10.1145/3385412.3386037
| pixelpoet wrote:
| That was indeed excellent reading, thank you.
| pfdietz wrote:
| If I understand correctly, the interaction length of such an
| energetic neutrino in rock is only in the tens of kilometers.
| jihadjihad wrote:
| The Nature paper itself can be found here [0], for those curious.
| Was just published today.
|
| 0: https://www.nature.com/articles/s41586-024-08543-1
| ziddoap wrote:
| Ars Technica has an article, as well, with some additional
| context/explanation.
|
| https://arstechnica.com/science/2025/02/most-energetic-neutr...
|
| And an interesting, somewhat related, video from PBS Space Time
| exploring how supernovas act as particle accelerators (but don't
| quite explain particles like this one or the 'Oh My God'
| particle):
|
| https://www.youtube.com/watch?v=2sSNWIJbV3Q
| insane_dreamer wrote:
| also reported in the NYT:
| https://www.nytimes.com/2025/02/12/science/astrophysics-univ...
| antognini wrote:
| For context, 120 PeV is about 10% the kinetic energy of a ping
| pong ball during typical play.
| lnauta wrote:
| One of the lead researchers in KM3NeT mentioned that the
| particle was emitting 2 horse power in light during detector
| transit. A typical body builder expends about 1 horse power
| while performing, so its 2 body builders in a single particle.
| A_D_E_P_T wrote:
| > _typical body builder expends about 1 horse power while
| performing_
|
| Close, but ackshually...
|
| Bodybuilders just oil up and pose in beauty pageants.
|
| 1 horsepower is basically one 250-pound bench press in one
| second. (550 foot pounds of work; the aforementioned bench
| press assumes a 2.2-foot stroke length.)
|
| Most bodybuilders and serious weight lifters can do that, but
| they can't keep it up for long.
| idlewords wrote:
| Neither could this neutrino.
| lnauta wrote:
| Ha, that made me laugh, thanks for the correction!
| h0l0cube wrote:
| So the neutrino is just doing a PB 1RM?
| 01HNNWZ0MV43FF wrote:
| It must have been a very short amount of time. 2 HP is 1,500
| watts, probably more light than all lightbulbs in my house
| combined.
| idlewords wrote:
| 1500 watts is about what an electric kettle uses.
| mr_toad wrote:
| American kettles. Kettles in hard core countries push
| 2300 to 2400 watts ;-)
| idlewords wrote:
| Slow-boiled water gives superior flavor!
| kevin_thibedeau wrote:
| Keeps the midichlorians from jumping out.
| wiredfool wrote:
| Meh, Lidl sells 3200w kettles.
| lnauta wrote:
| The muon traverses a few hundred meters of detection volume
| very close to the speed of light, so in the order of one
| microsecond.
| rq1 wrote:
| Particle on steroids.
| zozbot234 wrote:
| Fun fact, a typical horse exerts about 1 horse power of
| usable work while performing. That's so weird, I'm sure
| almost no one would've been able to guess that - but it's
| true.
|
| (To be clear, that's sustained effort over time, not just
| momentary. Athletically trained humans can do about 1 HP of
| peak momentary effort, and around 0.3 HP if sustained over
| time.)
| mikepurvis wrote:
| And a horse can do quite a bit more in peak as well-- 1 HP
| is definitely meant to be the long term continuous output
| of a typical horse under load, especially a consistent load
| such as turning a millstone.
| loeg wrote:
| That's an all-day number. Peak HP/horse is somewhere in the
| 6-15 range.
| wiredfool wrote:
| Track cyclists (sprinters, world class) do 2KW+ peak for a
| few seconds at a time. That's potentially ~3HP. (and while
| doing so, average more than 70kph over a 200m distance)
| m3kw9 wrote:
| Can we harvest that energy?
| AnimalMuppet wrote:
| This particle spread this energy through a volume of
| seawater a few km deep in the Mediterranean. It's going to
| raise the temperature of that volume a few billionths of a
| degree, if that. So, no, we can't.
| the_arun wrote:
| What if our existing solar panels are optimized to detect
| these? Then will it improve the quality of solar panels
| to capture more energy from sunlight as well? Sorry, I'm
| no expert in this - asking more of a curiosity.
| ars wrote:
| It's an enormous amount of energy packed into a single
| tiny particle.
|
| But it's still just a single tiny particle, so it's not a
| lot of total energy.
|
| It's like how you can lift a heavy weight for a second,
| but that's all you can do. You would need to be able to
| lift it for hours to be useful as a replacement for a
| crane. Same idea: Intensity vs total work.
| mr_toad wrote:
| If we had the ability to detect neutrinos in such a small
| volume as a solar panel they'd be _immensely_ valuable
| for communication - we'd be able to beam signals directly
| through the Earth, or through deep water.
| tadfisher wrote:
| Neutrinos interact extremely weakly with ordinary matter,
| which is why the detectors are typically huge volumes of
| water. Even then, the neutrinos interact with the
| purpose-built detectors on the order of one in a
| trillion. A neutrino power generator is not a feasible
| thing to build.
| tsimionescu wrote:
| There's nothing to optimize here, neutrinos just interact
| very very weakly with anything else because they don't
| carry charge (so no electrical interactions), don't carry
| color charge (so no nuclear interactions), don't carry
| weak charge (so no weak force interactions) and have tiny
| tiny masses, but they are still bosons (so don't act as
| field carriers like photons do, they're just regular
| matter). Their low chance of interacting with matter is a
| fundamental property of them, there's nothing you can do
| about it through technology, just like you can't create
| heavier electrons or weaker quarks.
| whyenot wrote:
| So, 2,000 milliSchwarzeneggers if we use SI units?
| gattr wrote:
| Yes, but please observe SI rules [1]: it's
| millischwarzeneggers.
|
| > This means that they should be typeset in the same
| character set as other common nouns (e.g. Latin alphabet in
| English, Cyrillic script in Russian, etc.), following the
| usual grammatical and orthographical rules of the context
| language. For example, in English and French, even when the
| unit is named after a person and its symbol begins with a
| capital letter, the unit name in running text should start
| with a lowercase letter (e.g., newton, hertz, pascal) and
| is capitalised only at the beginning of a sentence and in
| headings and publication titles.
|
| [1] https://en.wikipedia.org/wiki/International_System_of_U
| nits#...
| jihadjihad wrote:
| Right, and it is this amount of energy _in a single particle_.
| A ping-pong ball is comprised of who-knows-how-many billions of
| particles, so the energy of any one particle is a fraction of
| the whole.
| grey413 wrote:
| A ping pong ball would be roughly 2 trillion trillion atoms,
| for reference
| GuB-42 wrote:
| Now, what will happen if you get hit by a ping-pong ball mass
| of 120 PeV neutrinos? 120 PeV is about 2e-16 grams, so a ping-
| pong ball will have about 1e16 of them.
|
| From nothing, to detectable, to lethal, to big boom?
|
| My intuition would be "detectable" but I don't know enough to
| do the maths.
|
| And by the way, I am using the mass-energy, not proper mass,
| because the question is crazy enough not to even consider what
| would be the mass of a neutrino.
| dahousecat wrote:
| Sounds like a great topic for an xkcd video
| bauruine wrote:
| There is a what if about it. https://what-if.xkcd.com/73/
| antognini wrote:
| The mean free path of neutrinos through lead is around one
| light-year. So, taking the thickness of the body to be 1/2 a
| meter, you would expect the probability of any individual
| neutrino to interact with the body to be ~5 x 10^-17. So
| you'd ballpark have around a 20--40% chance that a single
| neutrino interacts with your body. It would probably cause a
| localized radiation burn. Detectable, but probably not lethal
| unless you got really unlucky with where it hit you.
| pfdietz wrote:
| The mean free path of much lower energy neutrinos in lead
| is about a light year.
|
| The MFP of a 120 PeV neutrino in lead would be something
| like 10 kilometers, I think.
| cozzyd wrote:
| More like 100 km I'd think but yeah, the neutrino nucleon
| cross section gets much bigger at high energies
| queuebert wrote:
| Total energy of impact would be 120 PeV x 10^16 = 120 x 10^31
| eV = ~60 kilotons TNT, or 4 Hiroshimas.
|
| So BIG boom.
|
| Since the velocity is so close to the speed of light, you can
| think of this like the energy released by annihilating a ping
| pong ball made of antimatter.
|
| Edit: Commenter asked what would happen if they "hit", so I'm
| assuming a hypothetical 100% collision. But yes to stop 1/e
| of a neutrino beam with normal matter, you'd need a light
| year of lead.
| mppm wrote:
| > big boom
|
| The probability of interaction of neutrinos with matter
| increases with the energy. I've asked o1 to estimate the mean
| free path of a 120 PeV neutrino in water and it came up with
| 1000km. So let's say, conservatively, that 10^-7 of the total
| energy gets deposited in your body when the beam goes
| through. The mass equivalent of a ping pong ball is about
| 2.5x10^14 J, which gives us 2.5x10^7 J total, or about 6kg
| TNT equivalent. This is only an order-of-magnitude estimate,
| but it would definitely not be healthy.
| jl6 wrote:
| So, according to basic Ant-Man theory, if I were hit by one of
| these, it should be like getting all that (10% of a) ping pong
| ball energy concentrated in a tiny spot, causing me to fly
| backwards across the room?
| BobaFloutist wrote:
| I would expect it to be more likely to punch through skin
| than to actually propel you.
|
| But also neutrinos don't typically collide with things very
| easily, they're more likely to pass through you without you
| ever knowing.
| moffkalast wrote:
| Yeah there's no way it would be able to grip onto anything,
| probably more like the Bugorski case, where he stuck his
| head into a particle accelerator and a proton beam went
| right through his head.
| Aachen wrote:
| I was thinking the same though. It doesn't interact often,
| but if it randomly does annihilate with another particle in
| your body, at such a small scale (subatomic) that
| force/pressure just destroys anything in its path no? Like
| a paint flake hitting a space ship. Or is it more like
| "light" (since they're iirc their own antiparticle), which
| is then absorbed by surrounding matter and turns into heat?
|
| In the wrong spot, this sounds to me like it kills you?
|
| Nothing to be afraid of, of course, for the reason you
| mentioned. Just wondering, xkcd "what if" style
| parineum wrote:
| Isn't Ant-Man logic that he still has the same mass when he
| shrinks and, as such, can generate the same force?
|
| Unless you get thrown back by ping pong balls normally, I
| think you'd be fine.
| class700 wrote:
| And yet when he grows he still has enough strength to punch
| a leviathan out of the sky. I'm not sure there's such thing
| as ant man logic - It doesn't seem like it should result in
| strength both ways.
| s1110 wrote:
| Does this count as "Americans will measure with anything but
| the metric system"?
| ziofill wrote:
| It's mentioned in the article that the highest energy ever
| recorded for a single particle was 320,000 PeV which is about 50
| joules, i.e. the energy of a golf ball at 100 mph @_@
| queuebert wrote:
| That was a cosmic ray proton, which has probably 10 billion
| times the mass of a neutrino and interacts much more strongly
| with normal matter. A nuclear juggernaut vs a ninja by
| comparison.
| dooglius wrote:
| It looks like they detected a muon and are inferring a neutrino
| from the fact it went through a lot of solid. Couldn't it be any
| other weakly-interacting particle though?
| Sniffnoy wrote:
| How? Quarks can't change into leptons. Charged leptons can't
| change directly into other charged leptons. And neither charged
| leptons nor hadrons are going to pass through such a quantity
| of matter, as you say. I mean I assume other cases are
| technically _possible_ but they don 't seem very _likely_...
| nxpnsv wrote:
| Nothing else that we know of would create a muon of that energy
| deep inside bedrock.
| AnimalMuppet wrote:
| Nit: As I read the article, they aren't sure that it went
| through _any_ solid. Went through a lot of seawater, though.
| And your argument still applies.
| cozzyd wrote:
| It could be beyond the standard model physics but no other
| standard model particle could work other than a neutrino.
| yapyap wrote:
| bit of a redundant title
| ge96 wrote:
| What's faster than satellite communication? Neutrinos baby
|
| Not even sure if that's worth doing, either create/emit or use
| encode data into them as they fly by to be received by someone
| else
|
| Edit: that's cool people have tried though
| queuebert wrote:
| Neutrinos can go straight through the Earth, yes, but since
| they have mass their velocity is less than c.
| mr_toad wrote:
| It's very close to c though, close enough that it beats
| sending a signal around the Earth.
|
| The drawback is the impractical size and cost of a receiver.
| shagie wrote:
| That's covered in RFC 1217. https://www.rfc-
| editor.org/rfc/rfc1217.html
|
| Its in section 4: Jam-Resistant Underwater Communication
| PaulHoule wrote:
| Would have really been faster if this result was true
|
| https://en.wikipedia.org/wiki/2011_OPERA_faster-than-light_n...
|
| which was something that would have happened in
|
| https://en.wikipedia.org/wiki/Steins;Gate
|
| Funny the idea that the neutrino might be a tachyon never seems
| to go away. The best fit of OPERA results is within error bars
| of the speed of light but towards the superluminal side.
| Superluminal neutrinos of the energy they were generating with
| the kind of mass we expect wouldn't be going measurably faster
| than the speed of light.
|
| I visited the site of this experiment
|
| https://permalink.lanl.gov/object/tr?what=info:lanl-repo/lar...
|
| where the best fit for the squared mass was just a tiny bit
| negative but within bounds of zero. There is the classic 1985
| Chodos paper
|
| https://www.academia.edu/27606971/The_neutrino_as_a_tachyon?...
|
| and people still keep writing papers about it
|
| https://www.mdpi.com/2073-8994/14/6/1172
|
| somebody is going to have to measure a positive mass squared to
| really put a stake in its heart.
| queuebert wrote:
| It's worth noting that we received the neutrinos from
| Supernova 1987a before the photons. We think that's because
| the photons have a difficult time escaping the ejecta cloud,
| while neutrinos stream away freely, but who knows ...
| PaulHoule wrote:
| Oddly another detector caught a burst of low energy
| neutrinos that came a few hours before the burst that
| everyone accepts was from 1987a
|
| https://www.sciencedirect.com/science/article/pii/S09276505
| 1...
|
| Low energy tachyons would go a little faster, but you've
| got the additional problem of explaining why neutrinos got
| emitted in a spectral line.
| hammock wrote:
| We already do, so the conspiracy theory goes. In Antarctica
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