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The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
byAnonymous Coward writes:
What will it be in joules, 1 peta electronVolt?
Could I boil a kettle on this neutrino (potentially)?
byclick2005 ( 921437 ) * writes:
FTA:
Out of the countless detections it’s seen, two of them—nicknamed, seriously, Bert and Ernie—were phenomenally, unbelievably energetic: Each had an energy over one thousand trillion times the energy of a visible light photon. That’s huge, far larger energies than even the Large Hadron Collider can create. It’s very roughly equivalent to the energy of a raindrop hitting you on the head which may not sound like much, but remember we’re taking about a single subatomic particle with that much energy
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byP-niiice ( 1703362 ) writes:
are you not familiar with the upside the head measurement of force? measured in FredSanfords
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byAnonymous Coward writes:
You're too young.
bymacraig ( 621737 ) writes:
Not only is he young, he doesn't know how to use the Internet to find out about this "obscure" Fred Sanford.
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byAnonymous Coward writes:
And "here comes the big one" means something completely different to him too...
byAnonymous Coward writes:
I'm 40 and live in the UK so I watched Sanford and Son when it was called Steptoe and Son.
bynewcastlejon ( 1483695 ) writes:
To this day I'm still sure that Dot from Eastenders is secretly Albert Steptoe in drag.
byRockDoctor ( 15477 ) writes:
To this day I'm still sure that Albert Steptoe is secretly Dot from Eastenders in drag.
FTFY
I find it somewhere between amusing and slightly worrying that I'm not sure if the Dot character is dead yet ; but it's probably a couple of decades since I sat through an episode, deliberately or accidentally.
bytehcyder ( 746570 ) writes:
I'm 40 and live in the UK so I watched Sanford and Son when it was called Steptoe and Son.
You dirrrty old man.
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byAnonymous Coward writes:
you big dummy.
bymacraig ( 621737 ) writes:
The comment modding system exists precisely so you can register your admiration without the rest of us having to hear about your nostriladamus incident.
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●urrent threshold.
●rrent threshold.
byloufoque ( 1400831 ) writes:
But can we harness that power to make magic?
byDoug Otto ( 2821601 ) writes:
Not without, at least, dinner and drinks. (tits would be a big help too)
byRene S. Hollan ( 1943 ) writes:
160 uJ, give or take.
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bytrum4n ( 982031 ) writes:
But what is that in m/s?
byceoyoyo ( 59147 ) writes:
Lots. You'd have to know the neutrino mass to calculate it precisely.
bytrum4n ( 982031 ) writes:
Lots as in near light speed?
byceoyoyo ( 59147 ) writes:
Yup. If you want a number, 3 x 10^8 m/s (i.e. the speed of light in a vacuum) works pretty well. A neutrino with that much energy must be going at 99.many-nines % of the speed of light. The actual number of nines depends on the mass.
Even regular solar neutrinos go at essentially the speed of light, as far as the m/s scale goes, and they have energies that are far lower.
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byfemtobyte ( 710429 ) writes:
Actually, rounding to the nearest 10^-20 m/s, it would be 299,792,458 m/s.
We don't know what the mass of a neutrino is, but we do know they're light ( 10^15. Thus beta = v/c = sqrt(1-1/gamma^2) 1-0.5*10^-30: the neutrino is moving at a velocity within 1 part in 10^30 of the speed of light.
byfemtobyte ( 710429 ) writes:
D'oh, formatting ate my math symbols. Above should read:
We don't know what the mass of a neutrino is, but we do know they're light (m < 1 eV / c^2). Thus, a neutrino with total energy E = 10^15 eV has a Lorentz factor of gamma = E/m*c^2 > 10^15. Thus beta = v/c = sqrt(1-1/gamma^2) > 1-0.5*10^-30: the neutrino is moving at a velocity within 1 part in 10^30 of the speed of light.
byRoger W Moore ( 538166 ) writes:
We don't know what the mass of a neutrino is, but we do know they're light (m
Not quite - IceCube looks for muon neutrinos and these have a mass limit of 0.19 MeV/c^2 [lbl.gov]. The lowest mass constraint is actually 2 eV/c^2 for electron anti-neutrinos from tritium decay spectrum measurements.
byfemtobyte ( 710429 ) writes:
We've got poor direct limits on muon neutrino mass from muon neutrino experiments; however, there are other sources of much stronger constraints on neutrino masses. See the "summed mass" limits a few pages down in your reference.
From a Borexino neutrino experiment page at Princeton [princeton.edu]:
The current limits from cosmological considerations are less than about 0.5 eV (one millionth of the electron mass!) for the sum of the masses of all three neutrino types. The known values of the mass-squared differences imply that the heaviest neutrino type cannot be less massive than about 0.05 eV.
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bywonkey_monkey ( 2592601 ) writes:
We don't know what the mass of a neutrino is, but we do know they're light
I thought that was photons.
bydimeglio ( 456244 ) writes:
Interesting. So if one of these neutrinos hits me, will I feel it? I understand due to electroweak unification (of these very high energy neutrinos) it will cause interaction with our body.
byspectrokid ( 660550 ) writes:
The neutrino is going to go straight through you with a 99.99999% probability. But if it does stop inside your body and deliver its energy, it should give of one hell of a whack. Wonder if you would be able to feel that?
byfemtobyte ( 710429 ) writes:
If the neutrino does interact inside your body, it's highly unlikely that much of the energy will stay there. The neutrino would transfer some chunk of its 10^15 eV of energy to another particle, such as a proton, in your body. A 10^15 eV proton will also shoot right through you --- smashing up nuclei and creating a big cascading shower of ionizing radiation (the signal this scientific experiment is looking for in the antarctic ice), most of which will escape your body. The "impact" will thus not be a "loca
byRoger W Moore ( 538166 ) writes:
The neutrino is going to go straight through you with a 99.99999% probability.
Actually that is probably not quite true. For the vast majority of neutrinos you encounter on a daily basis (from radioactive decay, relic Big Bang neutrinos, solar etc.) you are completely correct. Indeed for these, as the article states, they will pass through the earth without blinking.
However PeV neutrinos are NOT your everyday neutrino. These guys have such an incredible energy (over 100 times the proton energy in the LHC) that the earth is actually opaque to them. In fact if you look at the IceCube analysis they look for down going neutrino i.e. ones coming in from above despite the problems with the back grounds from cosmic rays. This is because they cannot look for neutrinos which have passed through the earth because, at these energies, there will be none!
The reason for this is that neutrinos interact with matter through W and Z bosons. These have a mass ~80 to 90 times the mass of a proton. The reason that normally neutrinos do not interact is that there is insufficient energy to make a "real" W or Z in the interaction and this heavily suppresses the chance of it happening (due to quantum mechanics it can till occur though). Above a PeV the energy becomes high enough that this energy suppression effect gets a lot smaller and so the chance of interacting becomes a lot higher - eventually becoming slightly stronger than electromagnetism at really high energy when real W's and Z's can be created.
So the upshot of this is that a really high energy neutrino might actually have a reasonable chance of interacting in your body and the article is completely wrong when it describes the earth as basically transparent to these neutrinos...although it is an understandable mistake given that it is transparent to most neutrinos.
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byfemtobyte ( 710429 ) writes:
Putting some rough numbers on this:
Atlower energies, neutrino cross sections [cupp.oulu.fi] scale roughly proportional to energy with sigma/E ~ 10^-38 cm^2 / GeV. At high energy [fnal.gov], the cross section at 10^15 eV is around 10^-33 cm^2. Thus, compared to an ~1MeV neutrino with a cross section on the order of 10^-41 cm^2, the PeV neutrino has ~10^8 greater cross section. You are about 10^-7 the thickness of the earth. Thus, you are roughly 10x more likely to be hit by a PeV neutrino passing through than the earth is to be hit
byRoger W Moore ( 538166 ) writes:
Yes - you have to go a above 1 PeV to get a decent chance of an interaction in a human - I did say "really high"!
byedumacator ( 910819 ) writes:
I have no idea what this means, but I will memorize it and use it at a party. I might not walk away with the ladies, but if people think I'm smarter than them after repeating this, then maybe the next time I say something stupid, they might just think it was over their heads.
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byFishOuttaWater ( 1163787 ) writes:
For maximum effect, make sure the subject is politics or the weather when you do this. They will be *extra* impressed.
byRoger W Moore ( 538166 ) writes:
I tried to explain it without maths in the post above - the more energy you have the easier it is to make a W or Z boson which is how the neutrino interacts with matter. Think of it like a the neutrino being trapped in a valley and in order to interact it has to get over the valley sides. Fortunately it can tunnel so it does not have to clear the peak but the more energy it has, the higher up the valley side it can get and the easier it is to tunnel through. If it does have enough energy to clear the peak t
●r current threshold.
byK. S. Kyosuke ( 729550 ) writes:
It’s very roughly equivalent to the energy of a raindrop hitting you on the head
Does that mean that hitting people repeatedly with PeV neutrinos is a form of torture, too? Damn, the current administration won't be amused.
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